------------------------------------------------------------------------
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
Topic: DAT Heads FAQ (Read 42969 times)