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Offline Bri

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DAT Heads FAQ
« on: October 21, 2002, 09:48:12 AM »
------------------------------------------------------------------------

                           D A T - H E A D S

          F R E Q U E N T L Y   A S K E D   Q U E S T I O N S

                         92sep2, Third Release
                         (release 3.1[beta] sk)
       
       
------------------------------------------------------------------------
I N T R O D U C T I O N

This is a collection of information of potential interest to users of
DAT, especially those who use DAT to record live musical performances
or to archive such recordings.  The information was contributed by the
users of the dat-heads mailing list.  The questions are listed below.
You might find it convenient to search on a question number in
parenthesis to find a specific answer.

------------------------------------------------------------------------
N O T I C E

Copyright 1991, 1992 R. Gilde on behalf of all of the contributors.

This report may be copied by any means, as long as the following
requirements are met: <1> The report is always copied in whole,
unchanged, and with this notice; <2> The report is not sold or used in
any commercial way.

------------------------------------------------------------------------
D I S C L A I M E R S

(1) The contributors are not responsible in any way for their
contributions.  (2) The contributors' employers have nothing to do with
the contributions.  In particular, the contributors are not liable for
any consequences arising from use or misuse of the information
contained herein.  The contributors make no guarantee that the
information contained herein is correct. (3) Vendor names and prices
are included here for reference only.  This is done without the
vendor's permission.  Prices are approximate, actual price must be
established by the vendor.

------------------------------------------------------------------------
F E E D B A C K

Each answer is followed by the author's initials in square brackets.
Authors are listed at the end of this report.  If you would like to
comment on a contribution, email to the contributor or to dat-heads
mailing list.  If you have a question, email it to dat-heads mailing
list.  If you would like to contribute a question AND answer, email it
to gilde@jaco.ds.boeing.com.

------------------------------------------------------------------------
Q U E S T I O N S

GENERAL:

{1}     What is dat-heads? How does it work?
{2}     How can I obtain a copy of the FAQ?
{3}     Is there a public FTP site for dat-heads related data?
{4}     What is digital audio?
{5}     What is PCM?

FORMATS:

{6}     What is DAT?
{7}     What is DCC and how does it differ from DAT?
{8}     What is MD and how does it differ from DAT?
{9}     What is a "PCM deck" and how does it differ from DAT?
{10}    What's the rundown on recordable disks?
{11}    Why can't we run digital audio over the Internet?
{12}    How does VHS HiFi and Beta HiFi compare to DAT?
{13}    What is the reason for the many sampling rates and why are some
        rates recordable from analog/digital and some are not?
{14}    Is there any compatibility between audio DAT and computer
        backup DAT?  Can I use a computer backup DAT to write a DAT
        that is readable by an audio DAT deck?
{15}    What does a computer backup DAT sound like?
{16}    What is emphasis?
{17}    What is ADAT?
{18}    What's the scoop on Scoopman?
{19}    What's the rundown on Long Play mode?

CHOOSING& PURCHASING:

{20}    What DAT machines and tapes are available?
{21}    Where can I buy DAT machines?
{22}    Where can I buy DAT blank tapes?
{23}    Where can I buy Ampex brand DAT blank tapes?
{24}    Where can I buy DAT machine extended warranties?  Are they
        necessary?
{25}    Where can I buy batteries for portable DAT machines?
{26}    What are some of the new high-tech batteries?
{27}    Where can I buy a SCMS filter?
{28}    What kind of mics are good for live recording with a DAT?
{29}    What are the differences between microphone transducer types?
{30}    What are the differences between microphone response patterns?
{31}    What are some of the techniques for stereo microphone
        placement?
{32}    Where can I buy mics to use with a DAT?
{33}    What are some other sources for hard to find mics?
{34}    Are any prerecorded DAT tapes available?
{35}    What kind of recordable CD systems are available?
{36}    How can I obtain the Crystal Semiconductor AES/EBU transceiver
        chipset?
{37}    What is the grey market?  Should I get my deck that way?
{38}    What specs on DAT equipment are meaningful?
{39}    Which features are worth paying for?
{40}    How much has the price of DAT equipment dropped in the past?
{41}    How far can DAT equipment be expected to drop in price in the
        future?
{42}    Are DAT->DAT machines available, or do you need two decks?
{43}    Should I buy a Portable or non-portable deck?
{44}    Who makes products to interface a PC to a DAT?
{45}    What are the differences between the Sony DTC-75ES/DTC-700 and
        Panasonic SV-DA10/SV-3700?
{46}    What are some of the differences in the circuitry between the
        SV-3700 and SV-DA10?
{47}    How can I get more info from manufacturers?
{48}    Can I Use Computer-Grade DAT blanks for audio?
{49}    What are the differences between professional and consumer
        decks?
{50}    What PCM decks are or were available?
{51}    Where can I buy DAT carrying cases?
{52}    Where can I find DAT mastering and remastering services?
{53}    Should I upgrade my Crystal 5326 DAC to a 5328?  How do I do
        it?
{54}    Where can I buy wet cleaning tapes?

COPY PROTECTION:

{55}    What laws govern dubbing tapes and circumventing copy
        protection schemes?
{56}    How does SCMS work?
{57}    What does it take to modify a deck to disable SCMS?
{58}    What does it take to build a SCMS filter?
{59}    What organization is looking out for our taping rights?
{60}    What sort of copy protection schemes and legislation are on the
        horizon?

DUBBING, OPERATIONS, AND TECHNOLOGY:

{61}    Is there loss from digital transfer?  Do I need to be anal
        about how many digital generations it has passed through?
{62}    Can a digital copy sound better than the original?
{63}    Is there loss from analog transfer (ie, D->A->D)?
{64}    What are the standards for interconnecting digital recorders?
{65}    How can I convert SPDIF to AES/EBU, AES/EBU to SPDIF?
{66}    How do I transfer from CD to DAT?
{67}    How do I transfer from PCM to DAT?
{68}    What is the effect of slightly different sampling rate for PCM?
{69}    What types of batteries have "memory"?
{70}    What are Start, Skip, and End IDs?  When are they transferred
        during recording?
{71}    What is Absolute time?   Time-of-year time?
{72}    What levels should I use during recording?  What happens if I
        go over?
{73}    What are the holes on the edge of a DAT for?
{74}    Is digital audio a form of data compression?
{75}    What is oversampling?  Digital filtering?
{76}    How can I get my deck to display the Block Error Rate?  What
      does it mean?
{77}    How can I get my deck to display the SCMS code on a tape?
{78}    What is a dropout?  How do I avoid them?
{79}    How can I clean the heads on my DAT deck?
{80}    For analog connections, how do I adapt between XLR and RCA
        connectors?  Do I need to match impedances?  Should I use a
        transformer?
{81}    What is the difference between "+4dBm" and "-10dBv" levels?
{82}    What is a balanced line and how does it differ from an
        unbalanced line?
{83}    What's the deal with the secret button on the Sony DTC-75ES?
{84}    My old open-reel tapes have a white flaky deposit and they
        squeak.  What should I do?
{85}    What other pointers can you give me?
{86}    How can I defeat SCMS on my Tascam DA-30?
{87}    How can I dub between two Sony TCD-D3's?  How can I get a
        digital output on a TCD-D3?
{88}    How can I connect an external battery to a Sony TCD-D3?  How
        can I connect an external battery to a Denon DTR-80P?
{89}    What voltage do I need for a Denon DTR-80P?  How many batteries
        should I use?

LIVE TAPING AND TRADING:

{90}    How do I start trading if I don't have any shows (especially
        DAT shows) to trade?
{91}    What does "fob" mean?  What does "ts" mean?
{92}    What are the tradeoffs between fob and taper section tapes?
{93}    How do you get "taper's tickets" for Grateful Dead shows?
{94}    Can you get AC power in the taping section, or do you need
        batteries?
{95}    What am I allowed/expected to do in the taper section?
{96}    If I make a copy of a tape, what should I include on the label
        in order to be polite/legal?
{97}    My deck has SCMS or I only have 1 deck.  How could I build up a
        DAT show collection if I can't make tapes to trade?
{98}    How can I control myself from spending more on blank DATs than
        I do on rent?

------------------------------------------------------------------------
A N S W E R S

------------------
{1}     What is dat-heads? How does it work?

dat-heads is a digestified mailing list for discussion of Digital
Audio, especially pertaining to Grateful Dead Audience taping and GD
tape trading.

Requests to be added to or deleted from the dat-heads mailing list,
questions about the list, and requests for the current version of the
Frequently Asked Questions file must be sent to one of the following
service addresses:

    Internet: DAT-Heads-Request@Virginia.EDU
              DAT-Heads-Request@uvaarpa.Virginia.EDU
    BITNET:   DATH-Req@Virginia
    UUCP:     ...!uunet!virginia!dat-heads-request

Any questions about dat-heads may be addressed to the above addresses.
[sk]

------------------
{2}     How can I obtain a copy of these FAQ answers?

The FAQ is now also available via FTP.  See below.  

If you don't have FTP access, you can get the FAQ by email.  Send your
request to DAT-Heads-Request@Virginia.EDU or the other
service addresses listed above and it will be sent by email to you.

When someone mistakenly requests the FAQ in a posting to the dat-heads
list, rg takes care of sending a copy out.

------------------
{3}     Is there a public FTP site for dat-heads related data?

Yes.  DAT-heads anonymous ftp is available on ftp.funet.fi in directory
/pub/culture/music/DAT This service is unsupported. We are working on
improving this archive. If you don't know how to use FTP, please find
someone at your site to show you how.

------------------
{4}     What is digital audio?  

Sound consists of rapid pressure variations, called "waves", in a
medium such as air.  Sounds have traditionally been recorded,
processed, and transmitted as electrical signals which have waveforms
that are analogous to the waves in the air.  This is where the term
"analog" comes from.

Digital waveforms don't look anything like sound.  They can only be
used to represent the binary values 1 and 0.  But a whole bunch of 1's
and 0's can be strung together to represent any number.  And a whole
bunch of numbers can be strung together to represent the "image" of
almost anything.  Digital audio uses numbers to represent the image of
an audio waveform.  With enough binary digits (bits), the image can
have such great resolution that it would be impossible to tell it apart
from the original analog signal.

A digital audio system typically involves analog to digital conversion,
storage of digital data, digital signal processing, and digital to
analog conversion.  There are many advantages and disadvantages to
digital audio and they are often the subject of intense debate.  In
general, for a given level of fidelity, it is more economical to use
digital than analog. [rg]

The A/D conversion is done by sampling the analog signal so many times
a second (referred to as the sample rate) and generating a binary
number to represent the analog waveform for each sample. The rate at
which the analog waveform is sampled (32K, 44.1K or 48K) determines the
highest frequency that can be reproduced by converting the binary
numbers back to an analog waveform. The highest frequency that can be
reproduced is one half of the sample rate, ie for 32K, 44.1K and 48K,
the highest frequency that can be reproduced is 16K, 22.05K and 24K
respectively. This determines the frequency response of the digital
recording mechanism. The number of bits used to determine the value of
each sample will determine the dynamic range (difference between
softest and loudest sounds) and the signal to noise ratio (S/N). Using
16 bits for each sample (as normal mode DAT does) gives a range of
values from 0 to 65,534 and results in S/N and dynamic range figures of
96dB. Conventional cassettes are able to support a dynamic range of
only 65dB. [raj]

------------------
{5}     What is PCM?

PCM stands for Pulse Code Modulation.  It is a method by which an audio
signal is represented as digital data.  Virtually all digital audio
systems use PCM, including, CD, DAT, F1 format, 1630 format, DASH, DCC,
and MD.  Many people get confused because "PCM" is also slang for
Sony's F1 format which stores PCM digital audio on videotape.  (See
below).  [rg]

------------------
{6}     What is DAT?

Digital Audio Tape is a new format to store music developed in the
mid-1980s by Sony and Philips.  As digital music was popularized by
compact discs, the need for a digital recording format for the consumer
existed.  The problem is because digital music contains such a high
volume of data (over 5 megabytes of data per minute before error
correction and supplementary information) an aggressive way of storing
it is needed.  Prior to DAT, the only way to record digitally was to
use a video deck or a reel-to-reel, not convenient consumer products.

The solution was to use a rotary-head format, where the read/write head
spins diagonally across the tape (also called a helical scan).  This is
the way that VCRs are able to store their large amounts of data.  Thus
the proper name is "R-DAT", where "R" for rotary distinguishes it from
"S-DAT", a stationary design that did not make it out of the
laboratories.  Studio reel-to-reel decks are able to use stationary
heads because they can have wider tape and faster tape speeds, but for
the desired small medium of DAT the rotary-head compromise was made.
This means more moving parts and potentials for problems, but the
results are stunning.

Most decks appear to be a cross between a typical analog cassette deck
and a compact disc player.  In addition to the music, one can record
subcode information such as the number of the track (so one can jump
between songs in a certain order) or absolute time (counted from the
beginning of the tape).  The tape speed is much faster than a regular
deck (one can rewind 30 minutes of music in 10-25 seconds), though not
quite as fast as a compact disc player.  Decks have analog inputs and
outputs like on a regular tape player; they also have digital i/o.
This allows one to make a copy onto another DAT deck directly (without
having the music converted to analog and then reconverted to digital).
This will make perfect copies since all that is transferred is numbers
(no music that can be distorted).  The procedure is very easy since
there are no levels to set or other factors: everything is preserved as
on the original.  Making "clones" like this can thus preserve the
quality of the original recording through a theoretically infinite
number of copies, though some respected producers dispute this.

As the deck is similar in technology to a video deck, so too is the
tape similar to a video tape.  The tape shell is about half the size of
an analog cassette and is protected by a hinged door like a videotape.
Upon playing, the door is opened and the tape pulled out and wrapped
around the spinning head.  A tape can be as long as 90 or 120 minutes,
and since there is only one "side" to the tape that is uninterrupted
time!  Even if recordable CDs become available for consumers, it will
be a while before they can approach times longer than an hour.  [jfw]

DAT defines the following recording modes with the following
performance specifications...

   2 channel 48KHz Sample rate, 16-bit linear encoding, 120 min max.
   Frequency Response 2-22KHz (+-0.5dB)
   SN = 93 dB   DR = 93 dB
 
   2 channel 44.1Khz Sample rate, 16-bit linear encoding, 120 min max
   Frequency Response 2-22KHz (+-0.5dB)
   SN = 93 dB   DR = 93 dB
 
   2 channel 32KHz Sample Rate, 12-bit non-linear encoding, 240 min max
   Frequency Response 2-14.5KHz (+-0.5dB)
   SN = 92 dB   DR = 92 dB
 
DAT also defines a 4 channel 32KHz mode, but I have yet
to see a deck that will support it. [raj]

------------------
{7}     What is DCC and how does it differ from DAT?

DCC is a digital audio tape format which is slated to be available in
Fall 1992.  The standard was created by Philips (the people who brought
you those funny screwdrivers).  Philips also invented the "Compact
Cassette", the ordinary analog cassette.  DCC stands for "Digital
Compact Cassette".  DCC uses a tape that looks similar to an analog
cassette but cannot be played in analog cassette decks.  A stationary
head is used to write compressed digital audio on the tape as nine
tracks of data.  DCC decks will be designed such that it is able to
play DCC or analog cassettes.  DCC will be targeted at the mainstream
consumer.  The record companies are supporting DCC because they believe
that pre-recorded DCC's will be cheap to manufacture.

DCC relies on data compression to squeeze digital audio on to a tape
using a stationary head.  They use a new system called "Precision
Adaptive Sub-band Coding" or PASC to yield a 5:1 compression ratio.
This is a "lossy" system.  This means that the uncompressed signal will
differ from the original signal.  PASC relies on psychoacoustic
principles to throw away the parts of the signal that you cannot hear.
Thus, to the listener, the uncompressed signal might be
indistinguishable from the original signal.  To Philips' credit,
editors of Stereophile magazine, who are extremely particular about
sound could not distinguish between the original and the duplicate.  In
some other listening test, the PASC tape was distinguishable from the
non-PASC tape.  DCC does not provide the ability to make an exact clone
of a tape that DAT does.  It is possible that DCC will suffer
generational loss as it goes through the PASC process multiple times.

DCC records up to 45 minutes on each side of a tape the size of a
cassette.  DAT records up to 120 minutes of uninterrupted music on a
tape which is 2/3 the size of a cassette.

DAT is now heavily used in many professional applications and by an
increasing number of audiophiles and live tapers.  Since DCC has a
number of deficiencies, it is unlikely to compete with DAT in these
applications.  

Most of the advantages Philips claims for DCC don't make sense.  For
instance, pre-recorded tapes, of any kind, are inferior to Compact
Disks.  The commonality with analog cassette is only advantageous for
portable and car players. [rg]

------------------
{8}     What is MD and how does it differ from DAT?

MD or "MiniDisk" is a new consumer digital audio format being promoted
by Sony.  The launch of MD is planned for Christmas 1992.

Mini-Disk uses data reduction techniques similar to DCC but even more
severely: 6:1 ratio instead of 5:1.  Sony admits that MD will not have
as good sound quality as CD.  But they believe that the format will be
attractive to typical consumers who like to play disks in portable or
mobile sound systems.  MD is a 2.5 inch disk that can hold up to 74
minutes of music.  MD uses magneto-optical technology which allows the
disk to be erased and rewritten.

MD will be competing with DCC.  Consumer acceptance will depend in part
on availability of pre-recorded titles and the willingness of retailers
to stock them.  It is important to note that both Sony and Philips own
major record labels.  [rg]

------------------
{9}     What is a "PCM deck" and how does it differ from DAT?

PCM commonly refers to digital recorders that use videotapes as the
recording media, even though Pulse Code Modulation is the process by
which digital data is encoded on all types of digital recorders and
CDs.  This is mostly because the first decks that could handle the wide
bandwidth of PCM data were video decks and some (namely Sony's) had PCM
as part of their model names.  After converting the analog signal to
digital data, it is converted to a composite video signal compatible
with video cassette recorders and sent to a deck -- often a Beta or
professionally a U-Matic (3/4") VCR.

PCM units are designed for specific video standards.  In the U.S., NTSC
is used.  In some other parts of the world, PAL is used.  NTSC PCM
machines sample at a rate of 44,056 samples per second.  PAL PCM
machines sample at 44,100 samples per second, the same as CD and DAT.

Most PCMs are old, bulky, and have been all but discontinued.  They are
still the preferred format by many, though, and nearly all compact
discs are mastered on the Sony PCM-1630, a $30,000 reference standard.
[jfw]

Beta has been more preferred for PCM because it tracked better than
early vhs decks.

PCM in general has more problems with tracking and drop outs than dat
does, but it does have the advantage of being cheaper. [tjd]

------------------
{10}    What's the rundown on recordable disks?

Tandy Corporation jumped the gun a few years back when they said that
they would soon offer recordable CDs.  The publicity that company
received resulted in confusion and false expectations for the
consumer.  A variety of recordable disk technologies are available
right now but they are very expensive.

Recordable disks fall into two categories:

Recordable CD:  This is a CD that can be recorded (on a special deck)
and played back on any standard CD player.  Some Recordable CD
technologies allow the media to be written to exactly once (analogous
to a camera and film).  Others allow repeated writing and erasing
(analogous to magnetic tape).

Other disk formats:  Researchers have had a tough time implementing
recordable CDs.  It is easier to make a new format which is based on
available inexpensive technology.  Sony's Mini-Disk is such a format.
[rg]

------------------
{11}    Why can't we run digital audio over the Internet?

Let's do a simple calculation.  2 channels of audio sampled 44100 times
per second, 16 bits per sample is about 1.4 MBits/second data rate.
The rate for standard digital audio interfaces would be double that to
allow for subcode and up to 24 bits per sample.  Most of the links in
the Internet backbone are "T1" which is 1.5 MBits/second or leased
lines at 64 kBits/second.  So if 1 wise guy wanted to send a digital
audio program over the Internet, nobody else would be able to use it at
the same time.

If you wanted to ship audio over an Ethernet, you could probably get
away with it.  But why bother?  Ethernet only runs in a local area.
You could probably walk a tape over to the destination faster than you
could transmit it.  The fastest way to transfer large volumes of data
long distances is to place it on a tape and Fed-X it.  [rg]

------------------
{12}    How does VHS HiFi and Beta HiFi compare to DAT?

VHS HiFi and Beta HiFi are analog recording formats which use
modulation techniques to record a video signal and a stereo audio
signal on a videocassette.  The audio capabilities typically surpass
that of the "linear" audio tracks found on all video recorders, thus
the "HiFi" designation.  "HiFi" is essential for getting good sound
quality on your video recordings and out of pre-recorded videos.

HiFi is also touted as an excellent audio recorder for audio-only (no
picture) applications.  On paper, the specifications are typically
superior to analog cassette but inferior to DAT.  In reality, the
quality of HiFi video recorders is better than low quality cassette
recorders but not as good as high quality cassette recorders when they
are used with noise reduction systems.  In no case can a HiFi video
recorder compare to DAT.  It suffers from generational loss and audible
noise.

Many recordists like to use VHS HiFi for recording radio broadcasts,
since VCRs usually have built-in timers and can record for up to 9
hours.

If you use a HiFi video recorder to record from an audio-only source,
beware that some decks will not function properly without a video signal
to synchronize to.  To maintain true high-fidelity, you must use a deck
which allows for manual level control.  Also, you might try an outboard
noise reduction system like Dbx Type II. [rg]

------------------
{13}    What is the reason for the many sampling rates and why are some
        rates recordable from analog/digital and some are not?
       
There are three sampling rates supported by DAT: 48 kHz, 44.1 kHz, and
32 kHz.  The 48 kHz rate offers the highest quality and is also the
rate used by professional studios.  44.1 kHz is the rate used by CDs.
This makes it possible to digitally master or copy CDs without the need
for a sample rate converter.  The 32 kHz rate offers the lowest
quality, but twice the recording time of the other formats.  It uses
12-bit nonlinear digital companding, which achieves a data rate
reduction without reducing dynamic range (but at the cost of increasing
noise).  This format is also used for audio DBS (direct broadcast
satellite) in Japan.  

Various machines support different subsets of these sampling rates.
All machines support recording and playback at 48 kHz from their analog
and digital (if any) inputs.

Some machines support recording and playback at 32 kHz from their
analog and digital inputs.  Since 32 kHz requires a different
anti-aliasing filter than the other rates, it was only seen on the more
expensive professional machines until recently.  With the advent of the
one-bit converter, very little extra hardware is required for 32 kHz
operation, so we should expect to see it in more consumer machines in
the future.

The 44.1 kHz sampling rate is the most interesting because there is so
much confusion about how it should be supported.  Before SCMS, most
consumer machines did not permit digital copying of CDs or DATs whose
copy inhibit bit was set.  However, recording at 44.1 kHz from the
analog inputs was usually allowed.

Since SCMS came on the scene, recording at 44.1 kHz from the digital
input is allowed, even on copy-protected sources, so long as the copy
is first-generation.  Recording at 44.1 kHz from the analog inputs is
not allowed on most consumer machines.  One reason for this might be to
keep CD mastering capability out of the hands of consumers, as this
could threaten the recording industry.  Another reason might be to
force people to buy a more expensive professional machine to get this
capability.  So far, there is only speculation as to the real reason.

With professional machines, most allow recording at 44.1 kHz from the
analog inputs.  However, some do not.  Nobody seems to know the reason
for this. [bm]

------------------
{14}    Is there any compatibility between audio DAT and computer
        backup DAT?  Can I use a computer backup DAT to write a DAT
        that is readable by an audio DAT deck?
       
According to FWB Inc., a SCSI DAT Backup manufacturer:  As long as the
DAT Computer backup drive uses DDS format (as 90% of the drive
manufacturers do) the tapes will be compatible.  Note that there are no
compatible connectors or outputs between audio DAT & computer DAT, so
it would not be possible to use the two drives to copy a tape.  It
would be possible to take a computer DAT tape made on a DDS format
drive and, using the digital outs & ins, duplicate it on a pair of
audio DAT machines.  [jv]

I have tested this both ways with a Sony DTC-55ES and a HP DDS data DAT
on a Sun. Neither drive will playback the other drives tapes!! [hl]

------------------
{15}    What does a computer backup DAT sound like?

A DDS formatted computer backup tape sounds like white noise when
played in an audio DAT machine. [jv]

Note that some if not all audio decks would mute the output when
playing a DDS formatted tape. [hl]

------------------
{16}    What is emphasis?

Emphasis is a form of equalization.  I have no idea about the curve;
its purpose is to move noise into a less audible part of the frequency
spectrum.  It isn't used much nowadays; I think PCM used it, and I'm
not sure if the Sony D10-Pro does.  You don't want to be able to change
it;  the tape will be too dull or too bright if you do. [sb]

------------------
{17}    What is ADAT?

ADAT is a product from Alesis that records 8 channels of digital audio
on a SVHS tape.  The recording format on the tape is not compatible
with any any other tape deck.  The unit uses 16-bit linear encoding
(just like CD or DAT) and can record 40 minutes on a tape.  A principle
feature is that ADATs can be ganged together - up to 128 channels.  The
optional BRC control unit adds MIDI and time code capability,
sophisticated auto-locate functions, and many other features.  The BRC
is not required to gang ADATs together.

The ADAT uses a proprietary 8-channel optical digital interface.  They
plan to sell external interface units to convert to industry standard
interfaces.

Suggested retail price of a single ADAT recorder is $3995, the BRC
will sell for $1995.  Thus, a 32-track digital audio system can be
assembled for less than $18,000, including the BRC remote.

At least one other company (Tascam) is developing a comparable
multitrack digital system. [rg]

------------------
{18}    What's the scoop on Scoopman?

This is a Sony product intended for voice recording.  It uses DAT-like
tapes which are 30mm x 21.5mm x 5mm.  The unit weighs 147g and measures
113mm x 55mm x 23mm.  It records for seven hours on one AA battery.  It
uses 32kHz 12-bit non-linear digital coding.  It records in stereo.
The coding scheme makes it unsuitable for high quality audio.  Sony
does not intend for it to compete with DAT, DDC, or MD. [rg]

------------------
{19}    What's the rundown on Long Play mode?

48, 44.1, and 32 kHz are the three sampling frequencies that can be
used to record on a DAT. The 44.1 and 48 kHz modes are "normal" modes -
a 120 minute tape lasts 120 minutes.

Long-play tapes are recorded at 32kHz, but there are two 32kHz
standards.

The 32 kHz Long Play standard uses a non-linear 12-bit quantization
scheme. That's how they get 92 dB or whatever out of 12 bits - the
buckets at the quiet end of the spectrum are bigger. This means that
you'll theoretically get more distortion at low recording levels than
you would ordinarily. That and the fact that frequency response is
limited to 16 kHz are the trade-offs you make to get twice the time for
your hard-earned DAT dollar. This is because you are storing less data
per second of sound, so you get 240 minutes out of a 120 minute tape.

The other 32kHz standard is a 16-bit one that is (apparently) only used
by the broadcast industry. You get no tape savings as a trade-off of
losing half an octave of music. This is the 32kHz standard supported by
the Panasonic SV-3700 - however, you can only record in 32kHz 16-bit
mode through the AES/EBU digital interface. So unless you have digital
broadcast equipment with an AES/EBU port, you won't have much use for
this mode.

The two 32 kHz standards are not interchangeable.  For this reason you
cannot play back 12-bit Long Play tapes on a 3700. None of the
Panasonic and Technics products that I've seen support the LP mode,
while all the Sony products I've seen do. It's been a few months, so
maybe things have changed. If using Long Play mode is important to you,
this is an important thing to keep in mind when auditioning a new
deck.

For many applications, the reduction in audio quality using Long Play
mode is not very perceptible, especially for tapes that have been
through a couple of lossy analog generations. However, other people
disagree with me here, so you should make a test tape at various
sampling rates and decide for yourself. The 32kHz sample rate is also
suitable for FM broadcasts, which are limited to 15.5kHz bandwidth
anyway.

Many machines, such as the Sony TCD-D3 will switch between sampling
rates while recording or playing back. There will be a pause during
transitions. You can use this to your advantage - make a tape with
several transitions. Make a point of NOT paying attention to which
state you started out in, and listen for differences during playback. I
tried this with the Garcia/Grisman CD and was fairly surprised. I could
not tell the difference through my shitty speakers, but through decent
speakers or headphones you could tell.  I don't think it makes any
difference for those raunchy old '69 tapes though, so that's what I use
LP for. [dc]

------------------
{20}    What DAT machines and tapes are available?

The Market Posting is a summary of information on all known DAT deck
models and tapes.  It is posted to dat-heads mailing list on an
irregular basis.  The data is compiled by Seth Breidbart
(sethb@fid.Morgan.COM) from dat-head inputs.  Included are prices,
specs, features, repair records, and subjective comments.  [rg]

------------------
{21}    Where can I buy DAT machines?

There are a number of stores that specialize in DAT, including:

   The DAT Store
   2624 Wilshire Blvd, Santa Monica, CA 90403
   (310)828-6487
   
Places that give good prices to dat-heads include:

   HiFi Sales & Service
   Thomasville, GA
   (912)228-0093
   (ask for Jim Oade)

   Harvey Electronics
   Paramus, NJ
   (201)652-2882
   (ask for Neal Berkowitz)
   
   Big Daddy Electronics
   Stoughton, MA
   (800)438-4440 (MA only)
   (800)886-2144 (rest of USA)
   fax (617)344-7692
   (ask for Mark Sussman)

Other places with good prices include:

   J&R Music World
   New York, NY
   (800)221-8180

[rg]

------------------
{22}    Where can I buy DAT blank tapes?

Seth is a dat-head.  His prices are generally as low as any other
supplier.   He has a very limited choice of brands (like, whatever's
cheapest this week).  He takes checks, no credit cards.
   
   Seth Breidbart
   sethb@fid.morgan.com
   
The following companies currently offer special prices to dat-heads.
You MUST ask for the person indicated and tell him that you are a
dat-head.  Both companies have supplied many tapes to dat-heads without
any problems.

   W.B. Hunt - ask for Al Rizzo
   Boston, MA
   (617)662-8822
   fax (800)336-3841
   
      prices include shipping
      add $0.20 per tape for 2nd day air
      no extra charge for credit card or COD
   
   
   Big Daddy Electronics - ask for Mark Sussman
   Stoughton, MA
   (800)438-4440 (MA only)
   (800)886-2144 (rest of USA)
   fax (617)344-7692
   
      they add actual shipping charges
      add 2% for credit cards

The following are some of the mail order houses that dat-heads have had
good luck with:

   J&R Music World
   New York, NY
   (800)221-8180
   
   Tape World
   Butler, PA
   (800)245-6000

Other mail order houses are often advertised in the backs of magazines
such as Stereo Review.  Info about who has currently has the best
prices is posted to dat-heads mailing list.  

Note that all of the companies listed also sell cassette tapes. [rg]

------------------
{23}    Where can I buy Ampex brand DAT blank tapes?

   Pro-Tape NW
   (206)441-8273

      Pro-Tape is a very established business - not a discount
      mail-order house.  Their service is excellent and they carry just
      about every conceivable kind of tape.  They generally are not
      competitive with discounters like J&R, though.

  Arcal Corporation
  2732 Bay Road
  Redwood City, CA 94063
  (415)369-7348

     They accept mail orders and credit cards (MC, V, AmEx), no minimum
     order.

------------------
{24}    Where can I buy DAT machine extended warranties?  Are they
        necessary?

Neal Berkowitz at Harvey Electronics sells extended warranties for DAT
decks, approx. $100 for 5 years.  They are available for
non-grey-market decks purchased from legitimate dealers.  Since the
cost of head replacement is about $300, such warranties tend to be
worthwhile. [sb]

   Harvey Electronics
   Paramus, NJ
   (201)652-2882
   (ask for Neal Berkowitz)

------------------
{25}    Where can I buy batteries for portable DAT machines?

The batteries of the type designed for the deck are often available
from the same source as the deck.  For extended play, sealed lead acid
("gell cells") are much more useful (internal batteries tend to give
about 2 hours of use, gell cells are available for up to 30+ hours).

There are two types of chargers commonly used with gell cells: Type I
charge at a constant rate, and it is up to the user to determine when
the cell is fully charged.  Type II charge (generally) faster, and
measure the cell's charge so they can change to a trickle charge when
done.  Type I chargers can overcharge a gell cell, thereby ruining it.
Type II won't.

Power-Sonic is a popular brand of gel cell:

   Power-Sonic
   POB 5242
   Redwood City, CA 94063
   (415)364-5001
   
Sonic Studios makes a line of battery packs (alkaline battery holders
or gel cells) designed for specific DAT models.

   Sonic Studios
   (503)599-2217
   
Larry Sribnik supplies highest quality packs to aerospace and the
serious radio control modeller crowd.  He'll provide custom, high
capacity, matched and balanced packs for very reasonable prices.

   SR Batteries
   Larry Sribnik
   POB 287, Bellport, NY 11713
   (516)286-0079

You can also find sources in the Yellow Pages under "Batteries".

You can make your own battery packs by buying alkaline battery holders
from an outfit like Radio Shack.  Run enough batteries in series to
provide the voltage you need. [sb/rg]

------------------
{26}    What are some of the new high-tech batteries?

In rechargeable cells, NiCds are no longer king.  There are two
technologies that provide higher power density:  rechargeable lithium
and nickel-metal hydride.  Both are currently more expensive than NiCds
but this may change as the technologies become more common.

Rechargeable lithium cells are only available from Molicell (Moli
Energy Limited, BC Canada) in AA size.  Each cell puts out a nominal
1.8 Volts though it starts out fully charged at 2.4 Volts and drops to
1.1 Volt at cutoff.  It has a 600 Ah/1.1 Wh rating.  The Wh rating is
almost twice what you get from the same size NiCd.  You get 4 to 500
charges per battery, comparable to NiCd, with no memory effect.  Best
of all, a rechargeable lithium cell retain its charge 20 times longer
than NiCds, retaining 90% of its charge after 1 year at room
temperature.

Nickel-metal hydride cells (available from Sanyo, Matsushita, Toshiba,
Gates, Ovonics, and others) have roughly 75% greater capacity than
NiCds.  Much like NiCds, each cell puts out a nominal 1.2 Volt per
cell, starting at 1.5 Volts fully charged and dropping to 1 Volt when
spent.  A C-sized Ovonic cell has a 3.5 Ah rating compared to a NiCds 2
Ah (or 2.4 for the newer high capacity versions).  They don't contain
toxic materials while the cadmium in NiCds is highly toxic and disposal
is problematic.  They too can be recharged 4 to 500 times with no
memory effect and hold up well under overcharging as high as 20%.
Charge retention is poorer than NiCds by about 20%.  Internal
resistance is also higher than NiCds so available peak currents will be
lower.  [lm]

------------------
{27}    Where can I buy a SCMS filter?

At least three products are currently available that allow SCMS codes
to be modified.

Digital Designs manufactures a device that allows you to set the SCMS
code while copying.  It requires you to set all the other subcodes
(e.g. emphasis, category, etc.) with dip switches, and does not pass
start, skip, or end codes.  It allows up to four copies at a time.
List price is $450.

   Digital Domain
   309 E. 90 St. unit B,
   New York, NY 10128
   (212)369-2932
   
"Copy-Rite".  Cost around $200.  Measures 4" x 4" x 1" approx. It takes
9v unregulated at 100mA via a 3.5" jack (the powerbrick is not
included), and has four SPDIF connectors: two phono (one in, one out)
and two Sony opticals (one in, one out). There's a little switch for
enabling/disabling the SCMS defeat. The inputs are both wired to both
outputs (with the opticals converted). This means you *can't* leave
both inputs connected to both DAT decks at the same time.  The unit
switches between 32, 44.1, 48kHz automatically.

   Audio & Design Recordings
   Unit 3,
   Horseshoe Park,
   Pangbourne,
   Berks RG8 7JW.
   Phone: 0734-844545
   Fax: 0734-842604

"TCD Stripper", at 149 Pounds + VAT.  The advert says that it allows
you to control the copy protection bits, not just set them to 'copy ad
infinitum', but you can also set the bits so that further copies
(serially) are not allowed (unless you have such a device as this!),
but there were no details of the mechanics of use.  

   Thatched Cottage Audio
   International code+ 44-223-207979
   fax: International code+ 44-223-207952

[sb/nr]

------------------
{28}    What kind of mics are good for live recording with a DAT?

Mic selection is generally driven by budget, personal taste, and
pattern requirements (which are in turn driven by recording location
and venue layout), and stereo recording technique.  There is no such
thing as the perfect microphone, even for a single type of recording
situation.  [rg]

Some of the most popular mics for live taping, along with miscellaneous
comments from users:

High cost:

AKG 414
a very versatile microphone

AKG C460B + CK8X
shotgun, preferable over C460B + CK8

AKG C460B + CK8
shotgun

AKG C451 + CK9
shotgun, not recommended

B&K 4011
$2600/pr + pwr supply

Neumann TLM170
$3400/pr + pwr supply
5 position switch selectable, includes subcard and hypercard. Nice bass
response, even on hypercard because of the very large diaphram.  a very
large mic.  Perhaps the best multifunctional mic out there.

Neumann KMi84
Cardioid - Compact
       
Neumann KMi86
Omni/Cardioid/Figure-8 - Switch selectable pattern.  Large.  Nice
sound. Older model, around $2000 each or more.  2 84-series capsules
back to back for each mic.

Neumann KM1xx 100 Series
mic body, with different replaceable patterns (screw on) KM140 is a
card.  It is compact, and with an optional remote active cable (SKM140)
just the capsule need be exposed making it good for stealth.

Schoeps CMC3 + MK4 = CMC34
cardiod, $1900/pr + pwr supply

Sennheiser MKH815
shotgun

Mid to Low cost:

AKG C568
shotgun, hypercardiod at low frequencies, $700/pr

Audio-Technica 4071

Audio-Technica 813
cardiod, electret condensor, $300/pr

Core Sound Binaurals
true in-ear binaurl, quasi-binaural, and omni-directional

Crown
pzm

Nakamichi CM100 + CP4
shotgun

Nakamichi CM300 + CP4
shotgun

Shure SM94
cardiod, $500/pr

Sonic Studios
quasi-binaural

------------------
{29}    What are the differences between microphone transducer types?

There are two principal types of transducers used in mics: dynamic and
condensor.  Dynamics are often favored for miking individual
instruments because they add a favorable color to the sound.  Condensor
mics are generally more accurate than dynamic and are preferable for
audience recording.  Modern condensors use an "electret" design which
enables the mic to operate from a low voltage which can be supplied by
an internal battery or by an external power supply or by certain mic
preamps.  By contrast dynamic mics need no power source. [rg]

------------------
{30}    What are the differences between microphone response patterns?

Most mics used for live taping fall into one of 4 categories of
response patterns:

Shotgun:  These are the most directional microphones.  Directionality
is useful for increasing the ratio of direct sound (from the stage and
P.A. system) to reverberant and ambient sound (from the rest of the
room).  This becomes more critical as the distance from mic to stage is
increased.  Generally, one must pay more money for a shotgun in order
to get as good sonic characteristics as a less directional mic.
Shotguns are popular in the taper section at Grateful Dead shows.

Cardiod, hypercardiod, supercardiod:  Cardiods are not as directional
as shotguns.  These mics are used extensively on stage because their
directionality offers isolation from other instruments and monitors.
When used in the taper section at Grateful Dead shows, cardiods will
pick up crowd noise and, in the case of indoor sound, reverberations
from the room.  Cardiods are popular for taping near the music source.

Omnidirectional:  These are the least directional microphones.  One can
expect the best sound from an omni, but one must be very close to the
music source.  In live taping, omnis are normally only used very close
to the P.A. at outdoor shows or on stage.

Figure 8:  These have a "figure-8" shaped pattern- the response is the
same from two sides.  This is generally used for picking up a L-R
difference signal in an M-S mic setup.

------------------
{31}    What are some of the techniques for stereo microphone
        placement?
 
There are a multitude of ways to arrange a pair of mics for stereo
recording.  Unfortunately, there is no "correct" method.  Some of the
popular configurations are ORTF, Blumlein, spaced omni, coincident/near
coincident pair.  There are some "stereo" mics on the market which
combine 2 or 3 diaphragms in one mic body.

Another popular stereo recording method is the binaural technique,
which attempts to simulate the way humans hear directional cues by
mounting mics on either side of a human head.  Some people believe that
binaural creates the most faithful recording of the live concert
experience.

--------------------
{32}    Where can I buy mics to use with a DAT?

For Schoeps:
   
   Posthorn Recordings
   New York, NY
   (212)242-3737

For Core Sound Binaurals:
   
   Len Moskowitz
   moskowit@panix.com

     or

   Core Sound
   574 Wyndham Road
   Teaneck, NJ 07666

   Tel: 201-801-0812
   
For Sonic Studios:

   Sonic Studios
   (503)599-2217

For Josephson:

   Josephson Engineering
   David Josephson
   JOSEPHSON@AppleLink.Apple.COM

------------------
{33}    What are some other sources for hard to find mics?

I just went on a mic foraging expedition, and have come up with the
following list of music stores that seem to be willing to get mics of
all descriptions.  I've only had dealings with a few of them, so use
the usual precautions when dealing with someone you don't know.  If
anyone has additions,corrections, warnings, or recommendations about a
particular store, please let us know!

The first thing you need to decide is whether you want to purchase a
mic in a new or used state.  I'm rather partial to saving money, and
used mics (with the possible exception of delicate ribbon designs) are
pretty likely to sound just as good as new ones.  Depending on how
popular a given mic is, what type of people want it, and its condition,
savings can be from 20 to 50 percent for a used item.  Make sure a used
item comes with all the accessories that a new one does before agreeing
to a price (the windscreen on a 414B costs $30, for example, and the
clip doesn't look cheap either!)

I learned the hard way that for used items you're much better off if
you start trying to find a mic well before you need it.  I called over
40 stores and responded to 3 classified ads in my quest for a used
AKG414B/ULS, with no luck.  This mic is so in demand that they are
usually gone within a day of their arrival -- several salesmen admitted
to scoffing them up themselves without even putting them up for sale!
If you want a mic that's this popular, start looking early, and
convince several stores that you're serious and would like to be
notified if one shows up -- but still check on things regularly.  It's
also worth keeping an eye on the "forsale" and music-related newsgroups
on Usenet, as well as any local want-ad sources.

Here's the list of the stores I contacted that seemed reasonable and
will deal through the mail.  I define places as "serious" if they have
things like the Neumann U-87 in stock, will sell you a Neve console or
a Sony 48-track digital, etc.  With business like it is, most of these
people will talk with mere mortals anyway.

Adam's Pro Audio Rentals(617)773-8385 (rentals)
Akron Music             (216)376-6189 / (800)962-3152 (new/some used)
American Pro Audio      (800)333-2172
Audio Pro               (617)926-8020 (repairs, used)
Audio Studio            (617)277-0111
Audio Video Research    (617)924-0666 (big used)
Anything Audio          (617)426-2875 (New/Used, semi-serious-
                                       but-weird hole-in-the-wall)
Boynton Studio Supply   (607)263-5695
Caruso Music            (203)442-9600 (used/some new -- good place)
Dan Alexander Audio     (415)644-2363
DB Engineering          (617)782-4838 (used/some new, *major serious*)
EAR Pro Audio/Video     (602)267-0600 (used/new, serious)
Eight Street Music      (800)878-8882 (new/some used)
Full-Compass            (608)271-1100 / (800)356-5844
Goodman Music           (800)842-4777
Grandma's               (800)444-5252
Mercenary Audio         (617)784-7610 (big used/some new, very serious)
Musicmakers             (800)395-1005
Parson's Audio          (617)431-8708 (helpful, cheap new)
Rhythm City             (404)237-9552
Rock Street Music       (717)655-6076
Sounds Incredible, Inc  (214)238-9393 (new, boiler shop operation?)
Summit Audio            (408)395-2448
Washington Professional Systems
                        (301)942-6800

(if 800 # is listed second, it's "for orders only")
[tb]
------------------
{34}    Are any prerecorded DAT tapes available?

Yes, but not very many.  I've seen mainly jazz, and some classical,
mostly from small labels. [sb]

------------------
{35}    What kind of recordable CD systems are available?

Denon offers a system that can record PCM digital audio, (linear,
uncompressed) on optical media.  The media is then readable on any CD
player.  The media can be written to exactly once but, of course, read
many times.

The DN-7700R has AES3 and IEC958 inputs and outputs.  It costs $16000
US.  A companion unit, BU-0170A, contains A/D and D/A converters,
balanced XLR analog I/O and AES3 digital I/O and costs $4000 US.  The
units are 19" wide but very tall and deep.

The technology uses a Gallium-Arsenide and Terbium coating.  The media
costs $30 US per disc.  Presently, Denon guarantees 63 minutes of
recording time.  As their manufacturing process improves, they will be
able to extend that to the full 74 minutes in the CD standard. [rg]

Studer's D740 Digital CD Recorder.  You can put varying length
recordings on the same CD and the D740 CDRs may be played on any
standard pro or consumer deck.  Studer Revox America, 1425 Elm Hill
Pike, Nashville, TN 37210 (615)254-5651 or in New York City
(212)255-4462, Los Angeles (818)780-4234, FAX (615)256-7619. [is]

Marantz offers the CDR-1 recordable CD system.  It lists at $7000.
Blanks cost $80 each. [rg]
   
------------------
{36}    How can I obtain the Crystal Semiconductor AES/EBU transceiver
        chipset?

I am _investigating_ a group purchase of the Crystal Semiconductor
digital audio interface chips.  I am at this time _not_ committing to
make them available, although it is very likely that I will do so as
soon as the receiver chips are available through distribution.

If you are interested, please email me (eric@telebit.com) a list of the
chips you want and the quantity of each type.  It is important that you
tell me which chips you want, I'm not a mind reader!  If you don't tell
me what kind you want, your email is of no help to me.  Note that I am
not taking _orders_ at this time, I am just trying to find out what
quantity we could possibly purchase.

NOTE: In ANY email that you send me regarding these chips or purchase
thereof, PLEASE include the word "CRYSTAL" in the subject line.  If you
don't do this your mail may not be counted.

There is a list of the chips below, as well as the 100 quantity price.
If we order fewer than 100, the price will be higher.  The drivers are
in factory stock with one to two week delivery.  The receivers are
expected to be available in production quantities in December, with
samples available now.

CS8401CP AES/EBU Interface Line Driver, host mode          $15.90
CS8402CP AES/EBU Interface Line Driver, standalone mode    $11.30

CS8411CP AES/EBU Interface Line Receiver, host mode        $22.35
CS8412CP AES/EBU Interface Line Receiver, standalone mode  $16.00

The host mode chips are for use with a microprocessor.  The standalone
mode chips have dedicated pins for various channel status bits.  Kent
Shephard has stated that the chips can be wired back to back to strip
SCMS.  I haven't tried this, but he is probably correct.  I'm not
willing to guarantee that the chips are useful for this purpose,
though.

If you want to do anything fancy with the channel status, the host mode
chips and a microprocessor would allow a lot of flexibility.

I will also try to get pricing on the Toshiba Toslink optical input and
output modules, so also indicate the quantities of optical receivers
and optical transmitters that you are interested in.  These modules are
made specifically for digital audio, so they are mechanically
compatible with the commonly used optical cables.  They have TTL inputs
and outputs, so they can be directly connected to the Crystal parts
without transformer or capacitor isolation, protection diodes, etc.  If
you want to connect to equipment that uses optical connectors, this is
the easiest way.  It should also be possible to use these to easily
make a simple optical to coaxial converter, or vice versa.

After I have a reasonable estimate of the quantities involved, I will
post a message to this list with the actual pricing and ordering
information.  I will need to charge the price of the chips plus
California sales tax and shipping. [es]

------------------
{37}    What is the grey market?  Should I get my deck that way?

DAT was available in Japan long before it became available in the US.
There are some DAT decks that are not imported into the US (e.g.
Aiwa), and others that are much cheaper elsewhere (e.g. Hong Kong).
Many grey-market decks require a voltage adaptor for US voltage. [sb]

Some grey-market equipment does not include a manufacturer's warranty
that is valid in the US.  [rg]

------------------
{38}    What specs on DAT equipment are meaningful?

One of the biggest advantages of digital audio is that many performance
parameters that are difficult to achieve in analog machines are
perfected beyond the point of measurability in digital machines.  An
example is "wow & flutter".  The goal is to keep this low.  On all
digital recorders, wow & flutter is so low that it is not measurable.

Flatness of frequency response is one of the most important specs in
any piece of audio equipment.  Unfortunately, the accuracy of most
published frequency response specs does not match that of the human
ear.

Signal to noise ratio (dynamic range) is very significant in recording
devices.  But in digital audio, the number of bits places an upper
bound: 6 dB per bit.  So a 16-bit DAT cannot achieve greater than 96 dB
range.  Published specs are always a few dB lower than this due to
dithering and noise from the analog circuitry.  Variances of a couple
of dB between machines are not really significant because they are
often caused by differences in measurement technique.

Linearity is an important spec for digital audio systems.  But it can
get confusing.  Non-linearity is sometimes specified directly, in dB.
The lower the better.  Total harmonic distortion (THD or THD+N) is in
part, an indirect measure of linearity.  Again, the lower the better.
Sometimes linearity is specified as number of bits of precision.  The
higher the better.  Typically, the 16 most significant bits of a 20-bit
converter are more linear than a 16-bit converter.

Some things to look for in A/D and D/A design are: separate converters
for each channel, converters with more than 16-bits (for improved
linearity), oversampling - the higher the better.

You've heard this before:  The bottom line is how the deck sounds.
Differences between decks are generally related to the A/D and D/A
converters.  If you have discerning ears and a decent monitoring
system, you will notice differences between decks.  It is important to
keep things in perspective, though.  Other links in the recording and
reproduction chain are likely to be much more significant.  [rg]

------------------
{39}    Which features are worth paying for?

SCMS, or lack thereof, is a very significant feature if you plan on
copying DAT to DAT.  Generally, consumer decks have SCMS and "pro"
decks ignore it.

Pro decks typically allow recording from an analog input at 44.1 kHz,
while consumer decks do not.  This feature is only useful if you plan
to release CDs from the recordings you make.  (Both pro and consumer
decks will record analog at 48 kHz and digital at 44.1 or 48 kHz).

Make sure the deck has inputs and outputs you want.  For instance, some
people need fiber optic digital input.

A margin indicator is helpful.  It maintains a display of the highest
peak level between the present time and the time it was last reset.  A
resettable real-time counter is sometimes helpful.

Some decks provide an error readout.  This is very helpful in
diagnosing problems with tapes and decks.

There are many features and approaches to searching and writing
sub-code on tape.  Some decks have edit wheels which facilitate
variable speed searching.  Some decks
« Last Edit: June 20, 2003, 10:18:17 AM by Bri »

Offline Bri

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Re:DAT Heads FAQ
« Reply #1 on: June 20, 2003, 10:19:49 AM »
can write absolute time code on
top of an existing recording - others cannot.  [rg]

------------------
{40}    How much has the price of DAT equipment dropped in the past?

The first DAT decks available in the US cost about $900 (list, with
very little discounting).  Currently, the least expensive deck is about
$600 (list, possibly discounted).  There have been special sales with
prices as low as $500 (Sony D-3 DAT Walkman) and $350 (play-only car
DAT). [sb]

------------------
{41}    How far can DAT equipment be expected to drop in price in the
        future?

DAT decks are roughly as hard to manufacture as VCRs.  IMO if DCC and
MD die, DAT decks will be available in the $200-250 range in three
years.  If DCC and/or MD thrive, DAT decks will be the "high-end" and
professional devices, and the prices won't drop as far. [sb]

------------------
{42}    Are DAT->DAT machines available, or do you need two decks?

There are currently no DAT dubbing decks on the market, but they may
appear in the future.  Some professional decks are available in a
duplicating format; this requires buying multiple decks and a special
multi-deck remote control.  It is much more expensive than just buying
several decks.  Almost all DAT decks have digital inputs and outputs.
[sb]

------------------
{43}    Should I buy a Portable or non-portable deck?

Unless you are going to tape on location regularly, it is preferable to
buy a home deck over a portable deck. Home decks generally offer more
features, better durability and longer warranties than portable decks.

If you tape on location a lot now, and are thinking of continuing that
with DAT, consider the quality of your microphones. DAT technology will
reproduce bad microphones. An investment in a second deck and blanks,
could pay off better than a portable and mics. The other option is
patching your deck into someone else who has microphones set up.

Some Home/Port Comparisons (see Quality posting for more details and
features):

   Consumer Portable:  Sony TCD-D3          $500.
   Consumer Home:      Technics DA-10       $600.
                       Sony 75ES            $580 (3yr sony warranty).

   Pro Portable:       Panasonic SV-255    $2100.
   Pro Non-Portable:   Panasonic SV-3700   $1200.

[sk]

------------------
{44}    Who makes products to interface a PC to a DAT?

Digital Audio Labs (6311 Wayzata Blvd., Suite 330, St. Louis Park,
Minnesota, (612)559-6104) makes two cards for the PC/AT that turns your
PC and large/fast hard disk into a digital recorder/player that will
interface directly via S/PDIF with your DAT recorder.  They also have
editing software.  Total package price is about $1200.  It records and
plays back at multiple sampling frequencies.  [lm]

------------------
{45}    What are the differences between the Sony DTC-75ES/DTC-700 and
        Panasonic SV-DA10/SV-3700?

These observations are based on my experience with Sony DTC-75ES and
Panasonic SV-3700.  I assume that all of my observations on SV-3700
apply equally to SV-DA10.  Likewise, I assume that all of my
observations on DTC-75ES apply equally to DTC-700.

Features on Panasonic, not on Sony

        Edit wheel ("Shuttle search").

        Block error rate display.

        2-speed fast wind/rewind which totally disengages tape from
        heads when in high-speed mode.  High-speed mode is faster than
        Sony.

        Write Absolute time code on an existing recording.

        Tape loading is very easy.  No resistance when inserting or
        removing.  No chance of tape falling out of holder during
        eject.  (That sometimes happens on Sony).

        Meters are calibrated so 0 dB = maximum digital value.  (I'm
        not positive this is the case with the consumer model).

        Can write Start ID at beginning of tape on an existing
        recording (versus 4 sec. in for Sony because of rehearse
        mode).

        Transport on consumer model is similar to proven pro model.
       
        When powered up, remembers whether it was set in Auto Start ID
        mode or not.  (The Sony always comes up in Auto).
       
        Seems to apply enough torque to wind a poorly packed tape that
        a Sony cannot wind.
       
        Includes illuminated push buttons for some functions.  
       
        Separate record level and balance knobs.  
       
        By default, displays absolute time code.  (The Sony displays
        the resettable real-time counter by default).

Features on Sony, not on Panasonic

        Margin display (latches highest level until reset).
        (Subjective comment: if you sometimes use the deck to record
        from analog input, this is a fantastic feature.)

        Tape is visible when in transport.

        "Rehearse" mode allows Start ID placement with 0.3 sec.
        accuracy.

        Adjustable fader speed.  
       
        Resettable time counter, independent of absolute time.
       
        Adjustable display brightness (3 levels).
       
        Display modes: off, partial info, full.
       
        Controls are somewhat more self-explanatory than Panasonic.
        (Subjective comment.)
       
        Meters are easier to read than Panasonic.
        (Subjective comment.)
       
        Appearance is compatible with other ES components, some of
        which are excellent.
       
        Can record from analog input in Long Play mode (32 kHz).
        (Maybe the Panasonic consumer model can also, I'm not sure.)
       
        When a fully rewound tape is inserted, the unit (for purposes
        of writing absolute time code) can detect that it is at the
        beginning of the tape.  (The Panasonic requires "REWIND" to be
        pressed.)
       
        Goes from Stop to Record mode faster than Panasonic.
       
        Loads and ejects tapes faster than Panasonic.
       
        More information is displayed on the flourescent display than
        the Panasonic.
       
        When programmed to play a series of selections, it stops at the
        end of the program.  (The Panasonic rewinds to beginning of
        tape after a program.)

        Supplied remote control can also operate Sony CD players, using
        a separate set of buttons.  It can also be used to start and
        stop the DAT and CD simultaneously.
       
        Can display map of sampling rates on entire tape.  
       
        Buffers keystrokes.
       
        Rewinds tape when end is reached.  (Panasonic stops.)
       
        Larger record level control than Panasonic.  Uses coaxial knobs
        for left and right.

        3 year factory warranty (ES model only).
       
        Can operate in D->A mode or A->D->A mode with no tape loaded.
        This enables it, for example, to be used as a D->A converter
        for a CD player or another DAT deck.  The Panasonic would
        require the deck to be in record mode with a tape loaded.

Each brand has it's advantages.  Before selecting one, I suggest you
look at it and play with the controls.  It will come down to a matter
of personal taste.  I have no doubt that these models sound different
from each other; unfortunately I have not had a chance to do a careful
comparison yet.  In any case, the difference will be close.

If you want to impress your friends, the Edit Wheel on the Panasonic
will do it.  I have gotten a few "oohs" and "ahhs" from the Sony's
funky way of loading the tape, though.

------------------
{46}    What are some of the differences in the circuitry between the
        SV-3700 and SV-DA10?

The SV-3700 uses a Crystal 5326 one-bit A/D and a four-times oversampled
"4-DAC" system using two PCM-56 DACs (lowest grade) per channel and a gain-
switching technique for signals below -12 dB, claiming 18 bit resolution.

The SV-DA10 uses a bit stream A/D, but it is the Matsushita MN6460 MASH
part.  The DAC in the SV-DA10 is a noisier bit-stream MASH part, the
MN6470.  Likewise, the op-amps in the two machines for the inputs and
outputs are different: M5219's for the -DA10 and 5532's for the -3700.

For what it's worth, both units use versions of the MN18B161 as the system
control IC, but they have different suffix numbers (one for SCMS and one to
ignore SCMS?). Wonder what would happen if one were to substitute a -3700
system control IC in a -DA10? Just a thought! But who wants to un-solder a
64-pin IC!!! Voiding of warranties is not encouraged here! [fa]

------------------
{47}    How can I get more info from manufacturers?

   Panasonic
   "The DAT Help Line"
   (800)524-1448
   (800)624-1746 inside NJ
   
   Panasonic Professional Audio
   6550 Katella Avenue, Cypress CA 90630,
   (714)373-7277

   Sony
   "DAT Hotline"
   (908)SONY-DAT ((908)766-9328)
   
------------------
{48}    Can I Use Computer Grade DAT blanks for audio?

Computer grade DAT tapes work just fine for audio.  They may, but not
necessarily, have fewer dropouts.  They are generally more expensive
and not heavily discounted.

Computer grade DAT tapes are usually marked by length, not playing
time.  A tape that says "60m" is 60 meters long - the same length as a
120 minute DAT.

90m computer grade DATs are available.  These will run for 180 minutes
but the reliability of these tapes is questionable because they are
thinner than standard audio DATs.  [rg]

------------------
{49}    What are the differences between professional and consumer
        decks?
         
The pro deck might not be affected by SCMS codes when using IEC-958
digital input.  (This can also be accomplished by using a filter to
modify the SCMS codes.)

The pro deck might be able to record analog at 44.1 kHz.  (The only
reason you would want to do this is to master a recording to produce a
CD or one that can be transferred digitally to PCM.  Even then, you
could have a 48 kHz tape converted.)  Some consumer decks such as the
Denon DTR-80P can also record at 44.1 kHz.

The pro deck might be rack mountable.  (If you use a rack, you can buy
custom rack mount adapters for any deck for about $50 or you can build
shelves which mount in your rack.)

The pro deck might have XLR balanced analog inputs and outputs.  (Most
likely, none of your other equipment uses this kind of interface, so
you would have to adapt it if the deck does not also have RCA inputs
and outputs.)

The pro deck might have AES/EBU digital inputs and outputs.  (Most
likely, none of your other equipment uses this kind of interface.  If
the deck does not have IEC-958 digital interface, you may be in
trouble.  The workaround would be to use a digital format converter.)

The pro deck might have professional styling.  (Most likely, none of
your other equipment will aesthetically match it.)

The pro deck might not have fiber-optic digital inputs and outputs.
(This might be a problem if you need to interface to equipment that
only has fiber-optic digital interface.  The workaround would be to use
a digital format converter.)

The pro deck might have analog inputs that require a higher level than
your source equipment is capable of providing.  (You could boost the
level with additional analog gear.)

Lastly, please consider Baum's Second Law:
       
        "Anything labeled professional isn't."

[rg]

------------------
{50}    What PCM decks are or were available?

There are two flavors of PCM digital audio units, one is an outboard
unit which will attach to any video transport and the other includes
the video transport as well as the A/D conversion unit. All of these
units are based on the F1 standard for encoding digital audio as a
video signal. This standard supports 14 or 16 bit encoding. The 14-bit
mode uses more redundant information to yield a greater degree of error
recovery, at the cost of some dynamic range. These units can be used
with any video transport, but the Beta format is more popular than
VHS.  

These are the PCM units that we know of:
 
   Aiwa PCM-800       14 bit      home
   Nakamichi PCM-100  14/16 bit   portable
   Sansui PC-XI       14 bit      home
   Sansui PC-XII      14 bit      home
   Sony PCM-F1        14/16 bit   portable  
   Sony PCM-10        14 bit      portable  
   Sony PCM-100       14 bit      portable  
   Sony PCM-501ES     14/16 bit   home
   Sony PCM-601ES     14/16 bit   home
   Sony PCM-701ES     14/16 bit   home
   Technics SV-100    14 bit      portable
   Toshiba DX900      14 bit      home
 
These units vary in weight from 6 to 8 lbs. All are currently
discontinued by the manufacturer, though the Sony units are not too
difficult to find used. They will run anywhere from $650 to $1200
used.
 
The Toshiba DX-9000 VHS VCR includes a built in PCM encoder (14 bit)
that supports digital recording. [raj]

------------------
{51}    Where can I buy DAT carrying cases?

There's a company called Datrax that makes nylon and flight cases for
DATs.   Available from:

   Bryco Products
   (800)9-DATRAX or (818)783-9133

The DAT Store carries cases which hold 40 tapes for $39.95.

   The DAT Store
   2624 Wilshire Blvd, Santa Monica, CA 90403
   (310)828-6487

W.B. Hunt carries DAT cases made by Media Box / POSSO Corp.
   
   W.B. Hunt - ask for Al Rizzo
   Boston, MA
   (617)662-8822
   fax (800)336-3841

[jfw/rg]

------------------
{52}    Where can I find DAT editing and mastering services?

John Whitehead, a dat-head, has a business doing this called
SpectraSound.  He uses Panasonic pro DAT decks and Digidesign's Sound
Tools computer music editing system.  He can do things like:

Re-order songs and make their levels constant
Adjust the gaps or crossfade between songs
Specialized editing (like reordering verses or cutting out a bad solo)
Correct pops or dropouts
Sample rate conversion
Digital equalization, compression, and noise gating
Create a master with test tones for CD or cassette manufacture

Contact him at jfw@well.sf.ca.us
[rg]

------------------
{53}    Should I upgrade my Crystal 5326 DAC to a 5328?  How do I do
        it?
       
The TCD-D3, 55, 75 and 700 all use the low grade Crystal Semiconductor
5326 chip.  The 5328 is a plug-in replacement and is much better.

The error mechanism of any sigma-delta quantizer is that deviations in
monotonicity of the step size cause limit cycle oscillations in the
output code, which tend to make roughly sinusoidal tones in the output.
These are audible in the 5326 for low level signals; some are steady
and some are signal dependent. Rumor has it that the 5326 and 5328 are
the same die internally, the 5328's are ones selected to have lower
levels of tones while the 5326's (up to some level at which they're
considered unusable) have more noise in the output.  The 5328 also has
an 18 bit serial output mode, however the default is 16 bit which makes
the output signal compatible with the 5326's.

The full part number of the chip is CS5328-KP.  It is pin-for-pin
compatible with the CS5326, the basic mod consists of pulling out one
chip and soldering in the new one (or a socket if you prefer to be able
to swap parts and compare at the expense of some signal degradation).

The chips are made by Crystal Semiconductor.  They can help you locate
distributors.

   Crystal Semiconductor
   Austin, Texas
   (512)445-7222 or (800)888-5016
   
Josephson Engineering sells a kit for $220 (check with order shipped
UPS Blue in the USA) that includes the chip, a machined-pin socket,
instructions for installation in DTC-55/75ES/700 or D-3 and suggestions
for upgrading the rest of the A/D board circuitry.

   Josephson Engineering
   David Josephson
   JOSEPHSON@AppleLink.Apple.COM
   
[dj]

------------------
{54}    Where can I buy wet cleaning tapes?

The DAT-101 uses a non-alcohol hydrocarbon based liquid that is
supposed to evaporate faster than alcohol. It is supposed to clean the
entire tape path. The company sells direct and through retailers. The
regular price is $29.95, $4.00 shipping and handling. He has agreed to
sell it for $2.00 off to those mentioning dat-heads (ask for Neil).

   American Recorder/Intraclean
   Simi Valley, CA
   (805)527-9580

[mn]
------------------
{55}    What laws govern dubbing tapes and circumventing copy
        protection schemes?

There are currently no copyright laws that say anything about copying
copyrighted material for home use only.  There is a court decision that
ruled that use of VCRs to time-shift TV programs does not violate
copyright laws.  [raj]

There are no laws specific to DAT, but there have been agreements made
between the recording industry and the manufacturers of digital tape
decks.  The copyright laws of the United States and most countries
allow taping of copyrighted material for home use only: you can make a
tape of a CD to listen to in your car, but you can not give that tape
to a friend so he does not have to buy the CD.

About the middle of 1990 decks started appearing for the consumer
market with SCMS, which allows one to make a digital copy (a clone)
from a digital master, but which prevents one from copying that copy.
There is no law requiring SCMS.  It was implemented voluntarily by the
manufacturers.

The new royalty agreement between the equipment manufacturers and the
recording industry is not mandated by law.  The recording industry may
attempt to get congress to legislate it.  Assuming this does not
happen, the royalties will be paid voluntarily by the manufacturers.

[jfw/rg]

------------------
{56}    How does SCMS work?

SCMS stands for "Serial Code Management System" and is the way copies
of digital music are regulated in the consumer market.  It is
information that is added to the stream of data that contains the music
when one makes a digital copy (a "clone").  When making an analog copy
only the music is transferred so there is no SCMS, and copying is
totally unrestricted.  Decks considered "professional" -- usually more
expensive and with pro features, such as balanced XLR input/output --
are exempt from needing SCMS.  Different manufacturers' pro decks
behave differently: some allow one to set the SCMS code how one wishes,
some only if the pro i/o is used, and some ignore it completely.


    SCMS Bit Definitions:
   
    Bits    Meaning        Explanation
    ----    ------------   ----------------------------
    00      Permitted      No restrictions at all
    11      Restricted     Allow 1 generation
    10      Prohibited     Do not allow copies
   
   
    SCMS Operation on consumer decks:
   
    Source             Recorded on copy
    --------------     --------------------------------
    Analog input       11
    CD                 10
    Digital, 00        11 or 00 (depending on model)
    Digital, 11        10
    Digital, 10        Will not record


    Dubbing DAT to DAT with SCMS:
   
    Play Deck       Connection     Record Deck     SCMS Problem?
    --------------  -------------  --------------  --------------
    Consumer DAT    Digital        Pro DAT         No
    Pro DAT         Digital        Consumer DAT    No
    Pro DAT         Digital        Pro DAT         No
    Consumer DAT    Digital        Consumer DAT    Yes
    any DAT         Analog         any DAT         No
   
Important: Some DAT decks that are marketed as "Pro DAT" still respect
SCMS.  In particular, the Tascam DA-30, even with SCMS disabled on the
main board, will still refuse to copy SCMS-inhibited tapes.
   
SCMS does not limit the number of times you can copy a certain CD or
DAT.  For instance, you can make 20 copies of a CD - you just can't
copy any of the 20 copies.
   
It is ironic that if SCMS is to prevent unauthorized duplication of
copyrighted information it has the above loopholes that a professional
ripoff artist can easily use.  And it is unfortunate that supposedly
legitimate users, such as musicians recording their own music on
cheaper, consumer decks, are restricted in the number of generations
they can copy their music.  [jfw/rg]

------------------
{57}    What does it take to modify a deck to disable SCMS?

It is unclear whether this is possible.  Some decks were rumored to
have a short jumper that, when disconnected, prevented SCMS from being
either written or read.  Others probably have SCMS implemented at
chip-level and so would be more difficult to defeat.  [jfw]

------------------
{58}    What does it take to build a SCMS filter?

Since digital data is a serial stream of numbers, it is not as simple
as just disconnecting a wire.  One would need a circuit that was able
to recover the clock signal from a biphase-mark encoded serial
stream and use that clock to sort the input into data words; then one
would need to set the two SCMS bits appropriately and reassemble the
words into a continuous stream.  At the moment, it is probably easier
and less expensive to use a pro deck that allows you to set SCMS.  Also
see earlier question "Where can I find a SCMS filter?"  [jfw/rg]

------------------
{59}    What organization is looking out for our taping rights?

Home Recording Rights Coalition
1145 19th Street NW
PO Box 33576
Washington, DC 20033

1-800-282-TAPE

HRRC is a coalition of consumers, retailers and manufacturers of audio
and video recording products.

HRRC has maintained that noncommercial home taping for private purposes
is encompassed in basic rights of American consumers and it has, in
past years, helped defeat several attempts in Congress to enact royalty
taxes that would infringe on such rights.

Call the HRRC and ask to them to send you a copy of their latest
newsletter and ask to be included on their mailing list for future
newsletters. [rg, excerpted from an HRRC bulletin]

------------------
{60}    What sort of copy protection schemes and legislation are on the
        horizon?

SCMS was created by the hardware manufacturers as a way to appease the
record companies (by placing some restrictions on copying), and protect
the mainstream market (by allowing consumers to copy copyrighted
material).  While SCMS may seem tragic from the home taper's point of
view, it has not been sufficient to placate the record companies.

The record companies started out lobbying for a copy protection
developed by CBS which impacted the fidelity of the recording during
normal listening and was easily defeated.  That scheme was defeated in
Congress.  Another alternative discussed was a "debit card system"
which would require consumers to insert pre-paid electronic cards in
order to record copyrighted music.

The record companies also lobbied for a tax on blank tape which would
be distributed to copyright holders and serve as royalties for the
copies that consumers make.  The record companies and manufacturers
have reached an agreement to do this and are now lobbying to get it
legislated.  The agreement will probably take effect regardless of
whether it becomes a legal requirement or not.  The new agreement
applies equally to DAT, DCC, and any other future digital medium.

The royalty on blank tapes (3%) and decks (2% of wholesale price to a
maximum of $8, ($12 for dubbing decks)) will hopefully end the
recording industry's dissatisfaction and allow greater market
penetration.  It is unclear how this royalty will be distributed.
Manufacturers will continue to include SCMS on consumer decks.

In theory, anything that can be listened to, can be copied.  The only
way to prevent copying is to embed signals in the music which are
detected by machines.  There will always be a way to defeat schemes
like this. [rg/jfw]

-----------------
{61}    Is there loss from digital transfer?  Do I need to be anal about
        how many digital generations it has passed through?

When a tape is copied, if there are no major errors (very dirty heads,
broken cable, etc.), the copy is identical (after error-correction) to
the original.  One of the test CD's has a passage cut from a master
tape, followed by the same passage cut from a 100th generation digital
dub.  I have never heard of anyone who could distinguish the two
passages. [sb]

Some noted industry personnel, such as Bob Clearmountain, still dispute
this and claim they can hear differences after several digital
transfers despite the apparent contradictory physics involved. [jfw]

------------------
{62}    Can a digital copy sound better than the original?

If the master tape has errors, but the errors can be corrected by the
error-correction circuitry, the tape will sound the same as a tape
without errors.  If the tape is copied digitally to a second tape, the
second tape will not have the errors recorded.  On the first deck, the
two tapes will sound identical.  On another deck, with lesser error-
correction circuitry, the master tape may have dropouts while the copy
plays perfectly. [sb]

------------------
{63}    Is there loss from analog transfer (ie, D->A->D)?

A test reported in MIX magazine (March 1991) found that professional
record producers could distinguish between a second-generation copy and
a twentieth-generation copy about 63% of the time.  Sometimes, they
preferred the sound of the twentieth-generation version!  Most of the
differences were noticeable in solo instruments and voice; the
complexities of a full bandwidth of sound masked most of the
differences in recordings of rock music.  The differences are probably
due to the unavoidable slight crosstalk and phase alterations in the
analog circuitry. So I would say that there is some loss in going
D->A->D, but not enough to matter.  [sb/jfw]

------------------
{64}    What are the standards for connecting digital recorders?

The professional standard for representing music digitally was agreed
upon by the Audio Engineering Society, the European Broadcasting Union,
the Society of Motion Picture and Television Engineers, and similar
groups in 1985.  This standard, AES3-1985 (often referred to as
AES/EBU), converts music to numbers, adds subcode data, and transfers
it via balanced 3-pin XLR-type (shielded twisted-pair) cables.  Each
sample of music (alternately representing left and right channels)  is
encoded along with extra data that when reassembled identifies the
sampling frequency, emphasis, and other information.  The standard does
not include SCMS or start IDs.  AES3-1985 uses RS-422 compatible
signaling.

There is a revision to AES3-1985 that is presently in draft form.  It
will be titled AES3-1991 or AES3-1992 depending on when it is
ratified.

Further info on AES standards is available from:

   Audio Engineering Society
   60 East 42nd Street
   New York, NY 10165
   (212)661-2355

The consumer standard (IEC 958 Type II, also known as S/PDIF for
Sony/Philips Digital Interface) is similar in concept but the data is
transmitted via unbalanced phono-style (RCA) cables and the subcode
information is different.  Sometimes the phono cables are called
"coaxial".  Some equipment also use fiber- optic interfaces carrying
the same data.  Copy inhibit (SCMS) codes are allotted for.  

Some manufacturers (Yamaha, for instance) offer proprietary digital
interfaces in addition to the standard interfaces.  [jfw/rg]

------------------
{65}    How can I convert SPDIF to AES/EBU, AES/EBU to SPDIF?

Since the first bits of the control code and the following musical
information is the same in both standards, one can theoretically
transfer music between the two types, losing the non-musical data.
According to the AES and an article in J. Audio Eng. Soc. by Mel
Lambert (Vol. 38, No. 9, pp. 681-694), however, the two formats are
"essentially incompatible". [jfw]

AES/EBU is differential signaling.  SPDIF is not.  

In the following explanation, all voltages are approximate or typical.

AES/EBU -> SPDIF

   When you tie the "-" signal of the AES/EBU to ground, the "+" signal
   should be at least +2V for a "1" and at least -2V for a "0".  The
   input threshold of the SPDIF receiver is +1V for a "1" and 0V for a
   "0".  So the AES/EBU exceeds the SPDIF threshold for both the "1" (
   +2V > +1V) and the "0" (-2V < 0), so it works.
   
SPDIF -> AES/EBU

   When you tie the "-" signal of the AES/EBU receiver to ground, the
   AES/EBU receiver will have a threshold of +400mV for a "+" signal
   and -400mV for a "-" signal.  The SPDIF signal, which swings between
   0 and 1V. will exceed the AES/EBU threshold for a "1" (+1V > +400mV)
   but never exceed the threshold for a "0" (0 > -400mV).  So it don't
   work.
   
There are a few other problems with interfacing SPDIF <-> AES/EBU.
AES/EBU receiver may have too low an input impedance for the SPDIF
transmitter.  If this is the case, the SPDIF voltage will get bogged
down and the SPDIF transmitter could get damaged.  Likewise, the
AES/EBU signal could be too high a voltage for the SPDIF receiver to
handle.  This could damage the SPDIF receiver.  Common mode voltage on
the AES/EBU line that would ordinarily get cancelled at the AES/EBU
receiver would false trigger the SPDIF receiver.

Your digital audio receiver must be smart enough (or have manual
controls) so that it can interpret subcode as being AES/EBU even when
it comes from the SPDIF connectors, and vise versa.  This is because
the subcode formats are different.  Fortunately, the most critical
subcode bit, Emphasis, is in the same place for both formats.  If the
device can ignore all other bits, you'll probably be ok.  [rg]

------------------
{66}    How do I transfer from CD to DAT?

To perform a direct transfer from CD to DAT one needs a compact disc
player with digital outputs and a DAT player with the same type of
inputs.  Not all CD players have digital outputs; those that do
generally have a consumer optical or coaxial interface.  Connect the
appropriate cord to the CD player and to the digital input of the DAT
deck and you're all set.  [jfw]

------------------
{67}    How do I transfer from PCM to DAT?

PCM machines designed for NTSC video recorders use a sampling rate of
44.056 kHz, which is slightly different than the DAT/CD standard of
44.1 kHz.  PCM machines designed around PAL recorders use 44.1 kHz.
Because of the difference in rates, one can not make an absolutely
identical copy onto DAT.  One can use the analog i/o which will cause a
very slight degradation of the signal quality.  One can also use the
digital i/o which will record the 44.056 KHz signal properly but will
play it back at 44.1 KHz.  Note that some PCM units do not have digital
outputs, and some DAT decks will be unable to accept data at the 44.056
KHz sample rate.  [jfw]

------------------
{68}    What is the effect of slightly different sampling rate for PCM?

A recording originally made at 44.056 KHz, but rerecorded and played
back at DATs 44.1 KHz rate will be playing slightly fast: for an
original second of music, the DAT will play it in 44,056 / 44,100 of a
second, or .999 seconds.  The DAT will play an hour (3,600 seconds) of
the original music in 3,596.4 seconds -- it has sped up it up by 3.59
seconds, or less than 0.1%.  Considering that this is a better spec
than a Nakamichi tape deck, it is probably not an unacceptable loss!
[jfw]

------------------
{69}    What types of batteries have "memory"?

If a NiCd cell is recharged when not completely discharged, the usable
capacity will be smaller than normal.  But there is no more "memory
effects" than this one.  That is, if the cell is discharged completely
and then recharged again under normal conditions, everything will be as
usual again.  Thus the cells don't have a long-term memory but some
sort of short-term memory.  [rg, from a posting by Guenter F. Schulz]

------------------
{70}    What are Start, Skip, and End IDs?  When are they transferred
        during recording?

Start, Skip, and End IDs are "comments" written to the tape, out of the
audible channel.  They can affect the way a tape is played: most decks
have a "forward to the next Start ID" key (and similar backward key).
Many decks can be set to automatically move to the next start ID when a
Skip ID is encountered while playing.  The End ID marks the logical end
of the tape; all decks will stop playing when it is reached, and some
will automatically rewind the tape.

Start IDs can be transferred during digital copying, depending on the
decks used and the settings.  They are not copied when the AES/EBU
interface is used, and cannot be copied through the analog ports.  Most
decks have an "auto" mode in which a Start ID will be written whenever
sound follows a sufficiently long silence (e.g. 3 seconds). [sb]

------------------
{71}    What is Absolute time?   Time-of-year time?

Absolute Time is the amount of music recorded on the tape up to each
point.  This can be written on the tape.  Some decks (e.g. Sony 75ES)
will automatically write Absolute Time when a new tape is used.  Others
(e.g. Aiwa HD-S1) will only write Absolute Time if the tape is rewound
immediately prior to recording.  (On a new tape, this takes 0 time.)

Time-of-year Time is the actual (Date, Time) that a tape was recorded.
Only certain Sony decks (D10-Pro, 57ES, 77ES, 87ES, 1500ES) use this
feature. [sb]

------------------
{72}    What levels should I use during recording?  What happens if I
        go over?

When copying a digital source to a DAT deck, you don't get an
opportunity to adjust the levels.  But when recording from an analog
source, level adjustment is very important.  DAT decks have a very
large dynamic range.  This means that you don't have to get carried
away trying to keep your levels perfect.  There's just one thing to
remember: Keep the signal below 0 dB at all times.

On an analog deck, you try to keep the average at 0 dB and the peeks
above 0 dB.  But a digital recorder is not capable of recording any
signal at all over 0 dB.  If you go over the 0 dB point, it means
complete annihilation - the end of the universe.  In other words, severe
clipping distortion.  Sometimes you'll go over 0 because somebody bumps
a mic or there's a pop in the P.A. system.  That's OK.

Try to keep the levels down far enough so that it is extremely unlikely
that you'll ever go over 0.  For instance, you might adjust them so you
often see peeks at about -6 dB.  That way, if the performance hits an
unusually loud spot, you'll be safe.  The 6 dB is called a "margin".
Allow a greater margin when recording live.  If you're just copying an
analog recording, you can always start over again if you left too small
a margin.  The dynamic range of DAT is great enough that you can leave
a comfortable margin and not have audible noise.  On the other hand, if
you set the levels too low you will not realize the full potential of
the digital format. If you don't use the top 12dB of dynamic range your
recording will not contain the max dynamic range possible by the
deck.  [rg/raj]

------------------
{73}    What are the holes on the edge of a DAT for?

bottom view of tape

-------------------------------
O O O   O              O    O O
-------------------------------
^ ^ ^   ^              ^    ^ ^
| | |   |              |    | |
| | |   |              |    | --(4)-> blank/pre-recorded
| | |   |              |    --------> write protect on/off
| | |   -----D a t u m  h o l e s---> for mechanical alignment
| | ----------------------------(3)-> Track pitch 13.591um/20.41um
| ------------------------------(2)-> tape thickness 13um / thin (9um)
--------------------------------(1)-> RESERVED

* hole (1), (2), (3). (4) are called Recognition holes      

-------------------------------------------------------
"1"     open hole       Wide track pitch  =  20.41 um
"0"     close hole      normal track pitch = 13.591 um
-------------------------------------------------------

hole 1  hole 2  hole 3              remarks
=========================================================
0       0       0       Metal powder tape or equivalent 13um  thickness
0       1       0       Metal powder tape or equivalent  9um  thickness
0       0       1       Wide track / 13 um thickness
0       1       1       Wide track / 9 um thickness
1       x       x       Reserved

hole 4
==========================================================
"1"     open hole       pre-recorded tape
"0"     close hole      blank tape

[kt]

------------------
{74}    Is digital audio a form of data compression?

This is a another common misconception about digital audio.  Digital
audio actually requires much greater bandwidth than analog audio.  But
it can be stored more compactly because the digital format has far
greater immunity to noise.  Some new digital audio systems such as DCC
perform lossy data compression on the digital signal to lower the
bandwidth, making it more economical to store.  But CD and DAT use a
brute force approach with no compression. [rg]

------------------
{75}    What is oversampling?  Digital filtering?

When you convert an analog signal to digital, you have to pick a
sampling rate which is at least 2X the highest frequency found in the
signal.  (This is known as Nyquist's theorem).  Suppose we have a 48
kHz sampling rate.  Then any part of the analog signal which is higher
than 24 kHz (half of 48) will cause "aliasing", a form of distortion.
So a basic A to D converter uses a low-pass filter to allow everything
below 24 kHz to pass and to block everything above 24 kHz.  We call
this a "brick-wall" filter.

Unfortunately, it is impossible to build an analog brick-wall filter.
In reality, the filter is more gradual.  Thus, we have to start sloping
it down around 22 kHz just to make sure it's not going to let anything
pass above 24 kHz.  These filters have other distortions which I won't
get into.

Now suppose we made the sampling rate 8X the highest frequency we need
to deal with.  Suppose the rate is 192 kHz.  Now we just have to make
sure nothing higher than 96 kHz gets through the filter.  That's easy
because we don't care about anything between 24 kHz and 96 kHz.  It's
out of the audible range.  So we make a very gradual filter (called a
"low order filter") that starts rolling off at 24 kHz but doesn't
really get down all the way until about 96 kHz.  This kind of filter is
much easier to make and sounds much better than the brick wall filter
we needed when the sampling rate was lower.  This approach is called
"Oversampling".

But now we've created another problem.  If you multiply the sampling
rate by 4, you multiply the amount of data by 4.  You can't fit all
that on a DAT or CD.  So this is what we do: we run the digital signal
into a processor which acts as a "digital filter".  This filter
generates a new digital data stream with a sampling rate that we can
live with - 48 kHz.  We don't lose anything.  Since there is virtually
no music above 24 kHz, the extra samples are no longer needed.  The
digital filter and the gradual analog filter together work better than
the brick wall analog filter alone.

We use the same process in reverse for D to A conversion.  We get a 48
kHz sampling rate off the DAT.  Run it through a digital filter and get
a signal with 192 kHz sampling rate.  Put that through a fast D to A
converter.  Then, the final step in reconstructing the waveform is to
apply another gradual analog filter.

Oversampling and digital filters are what distinguishes different
digital audio products from each other.  For instance, if two CD
players sound different to you, it's probably because they are using
different digital filtering algorithms. [rg]

------------------
{76}    How can I get my deck to display the Block Error Rate?  What
        does it mean?

Decks thatdisplay Block Error Rate have digital readouts which show
the number of errors each second, out of a total of 10,000 (5,000 per
head).  If the error rate is over 100, then the heads may need to be
cleaned.  With high error rates, the error- correction circuitry will
be unable to restore the information, and the sound will mute.  Good
tapes with clean heads usually give numbers well below 50.

Panasonic SV-3700 and SV-3900:

        (1) hold down "mode", "reset", and "pause"
        (2) release the three buttons simultaneously
        (3) push "mode" to cycle through the different display modes:

               (a) Digital interface selected
               (b) A+B head error rate (displayed on the counter), and
               SCMS codes (displayed in the PNO area).
               (c) A head error rate (displayed on the counter), and
               SCMS codes (displayed in the PNO area).
               (d) Diagnostics
               (e) Diagnostics

        (4) push "reset" to exit this mode

Technics SV-DA10:

        (1) hold down "mode", "reset", and "pause"
        (2) release the three buttons simultaneously
        (3) push "mode" to cycle through the different display modes:

               (a) A+B head error rate (displayed on the counter), and
               SCMS codes (displayed in the PNO area).
               (b) A head error rate (displayed on the counter), and
               SCMS codes (displayed in the PNO area).
               (c) Diagnostics
               (d) Diagnostics

        (4) push "reset" to exit this mode

Denon DTR-2000:

        (1) hold down "mode", "reset", and "pause"
        (2) release the three buttons simultaneously
        (3) push "mode" to cycle through the different display modes:

               (a) A+B head error rate (displayed on the counter)
               (b) A head error rate (displayed on the counter)
               (c) Operation mode display for the system controller and
               mechanism controller
               (d) Error code display for the system controller and the
               mechanism controller

        (4) push "reset" to exit this mode

Panasonic SV-3500:

        (1) turn it off
        (2) flip the timer switch to "play"
        (3) hold down the "recall" button
        (4) turn the machine on
        (5) when you see the display read "O - - 6", you can
            let go of the recall button
        (6) now, whenever the tape is in play mode, you can
            hold down recall to see the error rates.
        (7) turn off the auto play switch to exit this mode

Panasonic or Technics portable:

        (1) press the light switch
        (2) in succession press and hold "stop", "rewind",
            "skip forward", "skip backward"
        (3) once you have them all pressed" at once, let go
        (4) Now the counter will have some weird number between
            0000 and 9999 on it
        (5) Press play
        (6) press the light switch to exit this mode

[jfw/sb/rg/km]
------------------
{77}    How can I get my deck to display the SCMS code on a tape?

For the Panasonic SV-3700, SV-3900, and Technics SV-DA10, the SCMS code
will display along with the error rate.  For the Sony DTC-700 and ES
series, press "mode" and "6"  to get a display of the SCMS code only.
[sb/jfw]

------------------
{78}    What is a dropout?  How do I avoid them?

A dropout is what you get when the error-correction circuitry cannot
remove all the errors.  The deck mutes the sound.  They are less likely
when using high-quality tapes and a deck with clean heads. [sb]

------------------
{79}    How can I clean the heads and tape path on my DAT deck?

If you can hear errors or your deck has an error display that is
reading too high, it may be time to clean the heads and/or tape path.
There are basically three ways to clean the heads on a DAT deck: Manual
cleaning with swab and cleaning fluid; Dry cleaning tape; Wet cleaning
tape.  Unfortunately, only the first method cleans the entire tape
path.

Some DAT users have recently correlated deposits on the capstan with
mistracking.  The tape is mistracking when the analog output sounds
like a chainsaw for seconds at a time.  In most cases we have seen,
capstan grime builds up to an unacceptable level long before the heads
are dirty enough to warrant cleaning.  We do not know if this is true
for all brands of equipment and media.

Most manufacturers recommend the exclusive use of dry cleaning tapes.
But dry cleaning is abrasive, that is, it is harsh on the heads.  So
manufacturers recommend that dry cleaning be performed seldomly and
only when the error rate is unacceptable or when there is dropouts.  If
you use a dry cleaning tape, never rewind it or attempt to reuse it
once it has reached the end.

Manual cleaning without a tape requires opening up the deck.  This is
best left to a qualified technician.  dat-heads and the authors of this
document cannot take responsibility for any damage you cause to your
equipment.

If you use foam swabs or plastic handled swabs to clean your deck, be
sure that the solvent you use will not dissolve the foam or the stick.
Use a solvent that is not harmful to the rubber and plastic parts.
Make sure you use a solvent that does not dry out rubber parts.  The
most popular solvents are ethyl alcohol, isopropyl alcohol, freon-based
chemicals, and halogenated hydrocarbon-based chemicals such as
Intraclean S711.  Alcohol is said to dry out the rubber parts.  On the
other hand, rubber parts such as the pinch roller should probably be
replaced periodically anyway.  Beyond that, I'm not sure what the
differences between the solvents are but I would love to find out.

To perform manual cleaning, swab all of the parts that the tape makes
contact with with a solvent.  This includes stationary guides, rollers,
capstan, pinch roller, drum, and heads.  Use foam tipped swabs, chamois
tipped swabs, or a chamois cloth.  Do not use cotton swabs.

To clean the heads and drum, you may need to partially disassemble
and/or remove the tape loading mechanism.  Hold a swab or a chamois
cloth wrapped around your finger lightly against the side of the drum
and simultaneously turn the drum.  This will clean the drum and it will
also clean each head as it passes the swab or chamois.  Important:  Do
not apply any up/down pressure to the head or it will break off.  Be
very gentle.

The capstan is surrounded by a half-cylinder.  It will be off to the
take-up reel side of the drum.  The pinch roller will likely be quite a
ways away from the capstan when no tape is loaded.  If you don't know
what I'm talking about, you should get someone to show you.  The
half-cylinder gets in the way of cleaning the entire capstan.  The only
method I know of is to clean the exposed half, power up the deck, load
a tape, unload the tape, and power down.  Now you have a 50% chance of
having access to the other side of the capstan.  Do this a couple of
times and you'll probably be in good shape.

There are some wet cleaning tapes on the market.  This seems like a
good idea but there is no performance data available at this time. [rg]

------------------
{80}    For analog connections, how do I adapt between XLR and RCA
        connectors?  Do I need to match impedances?  Should I use a
        transformer?
       
The four characteristics of interest when working with inputs and
outputs are:

   Signaling (ie, balanced or unbalanced)

   Level (ie, -10dBv or +4dBm)

   Impedance (ie, high or low)

   Connector (ie, RCA or XLR)

CONNECTOR

There is no magic in adapting between RCA and XLR.  It's just wires.
Connect the wires as described below under SIGNALING.

SIGNALING

Most equipment I have seen with "balanced" inputs and outputs is also
designed to interface to unbalanced inputs and outputs.  All you have
do is:

   On an XLR: connect the shield (ground) of the incoming cable to both
   "-" (pin 3) and "ground" (pin 1) of the input.  Connect the center
   conductor (hot) of the incoming cable to "+" (pin 2) of the input or
   output.

   On a 1/4" TRS: if you plug a normal "mono" tip-ring 1/4" plug into a
   tip-ring-sleeve jack, the ring on the plug will contact with both
   the ring and the sleeve of the jack.  This results in the same
   arrangement as the XLR above.
   
The reason for using balanced signaling is that it reduces the amount
of noise in the audio system.  It is desirable to always use balanced
signals.  If you must use some unbalanced signals, it won't kill you.
But you must take care to practice good noise control techniques:  Keep
cables short, use cables with high shield coverage (ie, braided or foil
wrapped), run unbalanced cables away from or perpendicular to power
cables and balanced cables, not parallel.

LEVEL

Pro equipment typically uses levels referenced to +4dBm.  Consumer,
semi-pro, and some pro equipment uses -10dBv levels, which are lower.
If you feed a +4dBm signal into a -10dBv input, you may overload it,
but probably not.  If you feed a -10dBv signal into a +4dBm input, you
might not have enough level to drive the equipment correctly.  In the
majority of cases, equipment has enough dynamic range to accommodate
both +4dBm and -10dBv.

For instance, a home stereo (-10dBv) driven by the +4dBm output of a
pro DAT would require you to set the volume lower than you would for
your cassette deck.  Similarly, a recording console with a -10dBv input
driven by a pro DAT (+4dBm) would need to have it's input gain control
reduced to compensate.  In the rare circumstance that the equipment is
overloaded by a +4dBm signal at it's input, you can use an attenuator
to reduce the level of the signal.

Conversely, a pro DAT (+4dBm) driven by the output of a home cassette
deck (-10dBv) might need to have it's recording level control turned up
quite a ways.  In some cases, you might not get enough signal in the
DAT, even with the recoding level at maximum.  If that is the case, you
need a line amplifier to boost the signal.

IMPEDANCE

Impedance is perhaps the most often misunderstood aspect.  First of
all, the assumption that an XLR input or output is always low impedance
is totally wrong.  Secondly, the assumption that matched impedances is
essential is not entirely true when working with audio.

Professional style microphones typically have low impedance outputs and
work best when connected to a low impedance input.  With a mic, if you
have a high impedance input, then you might want to use an impedance
matching transformer to convert from low to high.

Most new design XLR inputs use transformerless designs.  This means
that the input goes directly to an amplifier.  The input impedance is
high.  On a mixing console, a gain controlis used to accommodate a
wide range of inputs.  For instance, a mic is a very low level and a
line level is much higher.  Equipment that has line-level inputs (not
designed to also work with mics) generally has high input impedance.

The bottom line is this:  if you are dealing with line-level signals,
you should not need to worry about impedance matching.  In particular,
a low impedance line-level output can drive a high-impedance line-level
input with no difficulty.

Every impedance matching transformer I have used has had uneven
frequency response.  I recommend avoiding them at all cost.  There
should never be a reason to use one with line level signals.  A good
active converter will not impact the fidelity as much.

SUMMARY EXAMPLE

The Panasonic SV-3700 pro DAT has high impedance XLR line-level
balanced inputs and outputs.  The input is referenced to +4dBm.  The
output features a switch to select between -10dBv and +4dBm levels.
Both input and output are designed to also interface to unbalanced
signals.  To connect the output of the SV-3700 to a home stereo, make a
cable with female XLR at one end and RCA at the other end.  The proper
wiring is shown on the back of the unit (and is also described above).
Set the output to -10dBv.

To send an input to the SV-3700, make a cable the same way (but with
male XLR).  You will need a strong signal to drive the SV-3700.  Your
typical home cassette deck won't cut it.  A mixing console (even one
with -10dBv levels) can probably have it's output turned up high enough
to drive the '3700's +4dBm inputs. [rg]

------------------
{81}    What is the difference between "+4dBm" and "-10dBv" levels?

Decibels (dB) is a convenient way of expressing the ratio of one
signal's level to another.  When we want to express an absolute level,
we use the ratio of the signal to a reference level.  "dBm" means that
the reference level is that of a signal of 1 milliwatt into 600 ohms,
or about 0.775 volts.  "dBv" means that the reference is 1 volt.  That
boils down to: 1dBv = 2.214dBm.

Therefore, the difference between a +4dBm and a -10dBv level is about
11.8 dB

Audio equipment is designed to operate over a range of levels to
accommodate music's dynamic range.  But two pieces of gear could have
similar dynamic ranges but be operating at totally different levels.
[rg]

------------------
{82}    What is a balanced line and how does it differ from an
        unbalanced line?
       
Unbalanced (single-ended):

+-------------+                    +-------------+
|             |     Hot            |             |
|             |--------------------|             |
|   Driver    |                    |  Receiver   |
|             |     Neutral        |             |
|             |--------------------|             |
|             |                    |             |
+-------------+                    +-------------+


Balanced (differential):

+-------------+                    +-------------+
|             |     Hot +          |             |
|             |--------------------|             |
|             |     Hot -          |             |
|             |--------------------|             |
|   Driver    |                    |  Receiver   |
|             |     Neutral        |             |
|             |--------------------|             |
|             |                    |             |
+-------------+                    +-------------+


In an Unbalanced signaling configuration (also known as
"single-ended"), the Driver varies the voltage on Hot with respect to
Neutral.  The Neutral is typically the same as "Ground".  The Receiver,
in turn, senses the voltage on the Hot wire with respect to the
Neutral.

In a Balanced signaling configuration (also known as "differential"),
the Driver varies the voltage between Hot + and Hot -.  In practice,
two single-ended drivers are used to put opposite signals (with respect
to Neutral) on the two Hots.  The Receiver senses the voltage between
Hot + and Hot -.  A good Receiver design will not really care what
happens to the Neutral signal.

Balanced lines are used because they have excellent noise immunity.
Professional applications often run signals 200 feet through
environments with alot of electromagnetic interference.  Consumers have
less noise to deal with so the less expensive unbalanced configuration
is usually used.

Here's how balanced lines reject noise:  the noise gets picked up by
both Hot + and Hot -.  This is called "common mode noise".  The
receiver only detects differences between Hot + and Hot -.  If the
noise is the same on the two Hots, then the receiver cannot detect it.
In practice, not all noise is common mode, and receivers do not
perfectly reject common mode noise. [rg]

------------------
{83}    What's the deal with the secret button on the Sony DTC-75ES?

There is a test mode switch inside the remote.  The remote is difficult
to open, but it is not impossible. It consists of two halves snapped
together; to open it, start at the battery compartment and note the
separate pieces which the housing consists of. With a lot of force,
applied in proper directions (please don't just hammer it) it can be
opened.

You get all sort of mechanical/electrical information:. cassette
mechanism status, diagnostic info regarding the tape-end sensor, drum
phase generator adjustment parameters, drum operation hours.... etc.

As you can see nothing interesting... you are not going to find
anything that will allow you to bypass SCMS.

I really don't recommend using this switch, you can put the machine
into a weird test mode and maybe destroy your precious recordings. [kt]

------------------
{84}    My old open-reel tapes have a white flaky deposit and they
        squeak.  What should I do?
       
This is a well known problem with top-of-the-line backcoated Ampex
(406,456) and 3M (206,226) tapes from the late 70's and early 80's.
The problem is that the binder they used is hygroscopic.

The cure is to bake the tapes overnight in a 170 degree oven to drive
off the moisture.  This gives you about a day make dubs.  Don't use a
kitchen regular oven, though, because the temperature regulation is not
accurate to keep from melting the tapes.  If the tapes are on plastic
reels you should probably spool them on to metal ones and remove the
top flange before baking.  I got this procedure from a friend who
worked at the Rogers and Hammerstein Sound Archives at Lincoln Center.
I have tried this and it works.  You might want to call 3M or Ampex to
get more precise instructions.

Also, be very careful when playing them in their current condition,
because if any of the parts on your tape machine are magnetized, the
squeaking can actually get recorded onto the tape (rapidly changing
magnetic flux, do to the uneven movement of the tape). [ah]

------------------
{85}    What other pointers can you give me?

Retensioning:  Before recording on a fresh tape, fast-wind it to the
end and back to the beginning.  This has been known to result in more
reliable operation.

Cueing:  If you are using the DAT in a recording session, you may find
yourself cueing to a specific spot on the tape repeatedly.  If this
spot is at the beginning of the tape, searching for the start-ID will
be slow because the deck must decrease winding speed at the beginning
of the tape.  Instead, start your recording about 30 seconds into the
tape.  That way

Offline Bri

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Re:DAT Heads FAQ
« Reply #2 on: June 20, 2003, 10:23:20 AM »
That way, the deck can wind back to the cue point rapidly.  

Storage:  Store tapes wound all the way to the beginning or end. Store
tapes on their sides.  Virtually everybody stores tapes on one of their
sides.  The trick is to store it on one of the 4 small sides, not the
two big ones.

Other Uses For DAT Boxes:  Those cardboard boxes that hold 10 DAT tapes
are the perfect size for storing cancelled checks or check receipts.
[rg]

------------------
{86}    How can I defeat SCMS on my Tascam DA-30?

The spring/summer 1992 issue #8 of Tascam User Guide includes a
procedure to defeat SCMS in the Tascam DA-30. You can obtain a free
copy of this newsletter by calling Tascam at (213)726-0303 (Ext. 634).
[jl]

Note that with this modification, the DA-30 still will not copy SCMS
protected tapes.

------------------
{87}    How can I dub between two Sony TCD-D3's?  How can I get a
        coax digital output on a TCD-D3?
       
The Sony TCD-D3 has a proprietary 7-pin connector for digital I/O.
Sony offers three products which mate with this:

   RK-DA10 (about $50) provides coax input.
   
   POC-DA12 (comes with TCD-D3) provides optical input and optical
   output but not both at once.
   
   RM-D3K (about $150) provides both optical and coax input and output
   (and also provides remote control).

Therefore, these are your options for dubbing between two Sony TCD-D3's:

   (1) Use the combination of one RM-D3K and one RK-DA10 to form a coax
   link.
   
   (2) Use two POC-DA12's.  The problem here is that each POC-DA12 has
   a male optical connector body.  Since the connectors won't mate with
   each other, you need to align them together and immobilize them.  At
   least one dat-head has had success doing this with shrink tubing.
   
   (3) Modify a POC-DA12 to provide a coax output.  Here's how dat-head
   Carl Schwink did it:
   
         "Inside the module you'll find an LED and a phototransistor.
         Basically, I took the signal that drives the LED and used that
         for digital out.  For digital in, I drove the base of the
         phototransistor with the input signal.  You can't just bypass
         the transistor, because it represents a level of inversion in
         the signal path."
         
   (4) Find a device that converts an optical input to a coax output.
   Some format converters are sub-code editors may do this.

[rg]

------------------
{88}    How can I connect an external battery to a Sony TCD-D3?  How
        can I connect an external battery to a Denon DTR-80P?

The Sony TCD-D3 external power input jack is not perfectly compatible
with most mating plugs available.  Here are some options for connecting
external power to the TCD-D3:

   (1) Use the slightly different plug that is widely available (eg,
   Radio Shack).  You may need to secure this to the deck.  Some tapers
   have had problems with intermittent connections doing this.
   
   (2) The TCD-D3 comes with an AC adapter that has the perfect plug on
   it.  You can hack that off and use it.  But you may not want to
   waster the AC adapter in the process.  The solution is to purchase
   one female and two male connectors which mate with it.  The
   connector types can be almost anything but it is best to choose
   connectors which cannot be inadvertantly connected backwards.  Also,
   use a connector that does not short when it is being mated.  Cut the
   plug off the AC adapter, leaving about a foot of cord.  Attach the
   female connector to the end of that cord.  Attach a male connector
   to the cord remaining on the AC adapter.  Attach the other male
   connector to your alternate power source.
   
   (3) Cannibalize the supplied Sony battery pack for the bracket that
   mates with the deck.  dat-head Leonard Zubkoff describes how:
   
         "Specifically, by repeatedly running a sharp knife around the
         ridge where the two pieces of the battery pack appear to have
         been joined in manufacture, I was able to separate the two
         pieces.  I then cut the connections to the NiCd cells with a
         scissors and removed them from the back part of the battery
         pack shell.  I drilled two 7/16 inch holes in the back part of
         the battery pack shell and installed a pair of Radio Shack
         274-1576 Coaxial DC Power Jacks (5.5mm OD, 2.5mm ID).  I wired
         the two jacks in parallel to the terminals marked + and - that
         connect to the back of the TCD-D3.  I then cemented the
         battery pack back together.  
         
         "I installed dual power jacks so that if one battery is running
         low while I am recording I should be able to connect another
         and then remove the first one, in theory not interrupting the
         recording at all.  I made two cables to connect the tabs on
         the gel cells to Radio Shack 274-1573A Coaxial DC Power Plugs,
         and connected a Radio Shack 274-1578 Inline C oaxial DC Power
         Jack to the battery charger."

   (4) Fabricate something that mates with the deck the same way the
   supplied Sony battery pack would.  Provide power jacks on it.

   (5) Purchase a battery pack specifically designed for the TCD-D3
   from Sonic Studios.
   
The Denon DTR-80P external power input jack is not perfectly compatible
with most mating plugs available.  Options (2) or (4) listed above for
the Sony are also applicable to the Denon.  Here are some other options
for connecting external power to the DTR-80P:

   (1) Use the slightly different plug but reduce the inside diameter
   by lining it with aluminum foil.  Hold the foil in place with
   superglue.
   
   (2) Procure the proper plug.  This may not be impossible.
   
   (3) Purchase a battery pack specifically designed for the DTR-80P
   from Sonic Studios.
   
Note that both the Sony TCD-D3 and the Denon DTR-80P are difficult to
find mating connectors to but that they do not both use the same
connector.  [rg]

------------------
{89}    What voltage do I need for a Denon DTR-80P?  How many batteries
        should I use?
       
The Denon DTR-80P can be powered by 6 Alkaline AA cells (9V), by 6 NiCd
AA batteries (7.5V) or with any other/external source giving reliably
more than 6V. The unit still works with power as low as 5.2V but sound
quality seems to suffer from this quite a bit (distortion becomes
audible).  With one Alkaline set it would successively record two 120s
tapes while (fresh) NiCd AAs (6*600mAh) would only last for one hour
recording at best.  [gs]

------------------
{90}    How do I start trading if I don't have any shows (especially
        DAT shows) to trade?

- Get a decent dubbing setup.

- Get in on tape trees conducted in the various net newsgroups and
mailing lists.

- Find people in your area who will let you borrow their tapes.  Don't
wait around for somebody to make tapes for you.

- Sometimes, a good recording of a radio broadcast is good trading
material.

[rg]

------------------
{91}    What does "fob" mean?  What does "ts" mean?

Some artists attempt to restrict audio taping to a specific section:
the "taper section", or "ts" for short.  Generally, the location of the
ts does not coincide with each taper's personal preference.  For
various reasons, some tapers like to make recordings from the area
between the soundboard and the stage.  This is called "forward of
board", or "fob".  There are advantages of each location.  Recording
location is one of the most important parameters of a live tape, so
taper's like to label their tapes "fob" or "ts" when trading.  [rg]

------------------
{92}    What are the tradeoffs between fob and taper section tapes?

The most significant advantage of the taper section is that it is the
only section in which the artist has permitted audience recording.
People taping outside of the taper section are not complying with the
artist's wishes and also risk being shut down, having their tapes
confiscated, having their equipment held or confiscated, being thrown
out of the concert, being arrested, sued, etc.

The taper section offers some distinct advantages to the taper.  Since
you are surrounded by other tapers, you can expect less talking.  Since
you are not trying to avoid detection, you can use bulkier equipment
and taller mic stands.  Most sound engineers control the P.A. system in
such a way that the best sound is right at the house mixing location,
or "soundboard".  If the taper section is close to the soundboard, then
you can expect good sound quality there.

Some artists position the taper section towards the back of the venue.
When this happens, the ratio of direct sound (from the P.A. and stage)
to other sound is decreased.  The "other sound" is reverberations and
audience noise.  People in the taper section typically use directional
microphones to counteract this effect.  Unfortunately, for a given
budget, one must trade off other sonic properties for directionality.

Some tapers go covert and attempt to tape from forward of the board.
Reasons for this may include: more direct sound, less reverberation,
better viewing location, higher volume, thrill of doing something
against the rules.  [rg]

------------------
{93}    How do you get "taper's tickets" for Grateful Dead shows?

You have to request seats in that area when you order tickets.  When
ordering via mail from GDTS, you need to specify on your order "taper
section or anything" -- the first part so they know what you want, the
second so if they are sold out for that section you can still get in
the show! [jfw]

Usually, the tickets will be for one or more particular sections
(behind the soundboard on the back of the floor) and will be labeled
'TAPER'.  For some shows (i.e. Hartford 1990) taper tickets can be
obtained at the box office, but this is rare.  For some shows general
admission shows, there are no taper tickets, and anyone can tape.
Listen to the hotline for the details for any given show. [ejs]

At general admission shows, they may limit the amount of taping
equipment let in to ensure that the tapers section does not overfill;
eg. when it is full they may stop people at the door and say "no more
taping equipment to be let in." In practice, I have rarely seen this
done although it may occur more than I know about. [js]

------------------
{94}    Can you get AC power in the taping section, or do you need
        batteries?
       
Most arenas don't supply AC outlets and extension cords for those
attending concerts :-).  Bring batteries, and only use new ones.  Bring
extras in case they're not so fresh or in case someone else forgets
some. [jfw]

------------------
{95}    What am I allowed/expected to do in the taper section?

A taper ticket entitles you to carry your equipment into the shows
(there are restrictions on the type and amount of audio equipment - but
this is rarely enforced), and to set up in the taper section.  You are
entitled to audio tape from the section, absolutely no video is allowed
(they will kick you out if you are found 'taping').  The taper section
is generally free-form, in that you are not necessarily taping from
only your seat, but if someone has a ticket for a seat, they may demand
it, and you must relinquish it. [ejs]

Be polite.  Don't yell.  Don't clap loudly if you have to at all.
Don't step on your neighbor's equipment.  Don't hog seats.  Don't spill
drinks.  Don't promise 30 people after the show that you can make dubs
for them.  Do stay out of the way of others, especially if it's
crowded.  Do be nice: if some guy is running your deck for you, pass
him a drink or food or whatever. [jfw]

There's very little talking in the taping section.  Be quiet and
respect the fellow tapers.  If you need a patch out of someones deck,
then show up early.  Maybe arrange it in advance.  Bring plenty of
patch cables.  [awl]

------------------
{96}    If I make a copy of a tape, what should I include on the label
        in order to be polite/legal?

If the source has a copyright notice then that notice should be carried
over to the copy.  If the source is your own original performance or
composition then you should copyright it for your own protection.  All
it takes is (1) a "c" enclosed by a circle (parentheses don't count)
and/or the word "Copyright" or the abbreviation "Copr.", (2) year, (3)
your name.  You don't need to fill out any paperwork to receive
protection under U.S. copyright law.

The next most important piece of info is the genealogy of the tape.
Collectors usually want to know how the master was recorded.  This can
include: type of mic, stereo mic technique, mic location in the venue,
recording equipment.  Collectors also want to know how many analog
generations a tape has been through.  Be specific about whether or not
you are counting the mastering as a generation.

The number of digital generations is regarded to be of less
significance.  Songs, timing, sampling rate, and SCMS code are
convenient to know but can easily be discovered when playing back the
copy, so providing that data is not critical.  Traders typically agree
in advance as to whether or not to supply song lists. [rg/jfw]

------------------
{97}    My deck has SCMS or I only have 1 deck.  How could I build up a
        DAT show collection if I can't make tapes to trade?

One way to get some DATs is to get in on tape trees where the root
makes you a DAT and you make 4 or 5 cassette dubs for the leaves.

You might also search out people in your region who also have lonely
machines.  You can get your machines together for a little digital
intercourse.

Typical DAT tapers have many analog taper friends who are always
pestering :-) to get cassette dubs off their DAT's.  If you can find
somebody like this, make a deal with them.  They make you DAT->DAT
copies.  You make DAT-cassette copies for their friends.  This works
out well for the source because DAT->DAT copies are much easier and
convenient to make than DAT-cassette.  Of course, you probably need a
decent cassette deck to do this. [rg]

------------------
{98}    How can I control myself from spending more on blank DATs than
        I do on rent?

As someone who currently shells out more than my rent on DAT tape, I
don't offer much of a example, but I do offer suggestions.

a) Don't buya DAT deck.
b) If you have already bought the deck, send it to me postpaid.
c) Join the Spinners, they take away all your money, material
   possessions....
d) Lighten up, enjoy the tapes. (And make sure your landlord likes
   digital auds)
e) Buy twice as many tapes, every other month.  This will solve half
   the problem.
f) Get a more expensive apartment.

CAUTION: Some users have been known to become dealers to support their
habits.

[sk/sb]

------------------------------------------------------------------------
A U T H O R S

[ah]   heller@balltown.cma.com (Aaron Heller)
[awl]  AWL2346@ritvax.isc.rit.edu (Adam Lentz)
[bm]   bill@thd.tv.tek.com (Bill McFadden)
[dc]   shunter@igrad1.ucsd.edu (Dave Chesavage)
[dj]   JOSEPHSON@AppleLink.Apple.COM (David Josephson)
[ejs]  SIMON@XTAL0.HARVARD.EDU (Eric J. Simon)
[es]   eric@Telebit.COM (Eric Smith)
[fa]   fredar@videovax.tv.tek.com (Fred Armentrout)
[hl]   hans@smab.se (Hans C Larsson)
[is]   IWS@ssmic.ssd.ray.com (Ihor Slabicky)
[km]   kmarko@hpdmd48.boi.hp.com (Kurt Marko)
[kt]   torii@aedd.sony.co.jp (Ken Torii)
[jfw]  jfw@neuro.duke.edu (John F. Whitehead)
[jl]   ludovicj@pwfl.com (Jay Ludoviconi)
[js]   well!jordan2@apple.com (Jordan Silber)
[jv]   vermilye@oswego.Oswego.EDU (Jon R. Vermilye)
[lm]   bendix!moskowit@uunet.uu.net (Len Moskowitz)
[mn]   jstraw@well.sf.ca.us (Michael Newman)
[nr]   nick@dcs.ed.ac.uk (Nick Rothwell)
[pt]   BETPAUL@CALSTATE.BITNET (Paul Tumolo)
[raj]  raj@ctt.bellcore.com (Randy Jackson)
[rg]   gilde@jaco.ds.boeing.com (Rob Gilde)
[sb]   sethb@fid.Morgan.COM (Seth Breidbart)
[sk]   liam@bbn.com (Sean Kennedy)
[tb]   tonyb@juliet.ll.mit.edu (Tony Berke)
  ttonino@bio.vu.nl (Thomas Tonino)

------------------------------------------------------------------------


Offline Stumptown Matt

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Re:DAT Heads FAQ
« Reply #3 on: June 20, 2003, 04:28:02 PM »
nice :coolguy:
When cleaning out her attic, Grace found several bootleg recordings her mother had made while traveling around the world with the Grateful Dead. Grace is not permitted to sell these bootleg recordings on eBay.

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