Become a Site Supporter and Never see Ads again!

Author Topic: interface with SPDIF able to handle 32khz/44.1khz/48khz??  (Read 832 times)

0 Members and 1 Guest are viewing this topic.

Offline Barney

  • (0)
  • Taperssection Newbie
  • *
  • Posts: 11
interface with SPDIF able to handle 32khz/44.1khz/48khz??
« on: July 27, 2021, 12:39:34 PM »
Hello,

I'm looking for an interface with SPDIF input(coax) able to handle 32khz/44.1khz/48khz.

I already use a Motu Traveler, but it works only with 44.1khz and 48khz. Not 32khz. And this would imply I need to use the analog output of a DAT deck to the input of the Traveler. This is what I might end up doing... but I was wondering if there was a way to use a small/cheap interface working with 32khz/44.1khz/48khz to convert all my DATs digitally, then use software (Audacity?) to resample to 44.1khz.

Any info?
Thanks.

Offline morst

  • Trade Unionist
  • (2)
  • Needs to get out more...
  • *****
  • Posts: 4716
Re: interface with SPDIF able to handle 32khz/44.1khz/48khz??
« Reply #1 on: July 27, 2021, 04:19:44 PM »
Lock the 32 to a 48 and change the headers after it's transferred?

Offline DSatz

  • Site Supporter
  • (35)
  • Needs to get out more...
  • *
  • Posts: 3149
  • Gender: Male
Re: interface with SPDIF able to handle 32khz/44.1khz/48khz??
« Reply #2 on: July 28, 2021, 09:35:01 AM »
Don't forget that the DAT recordings may have been made with pre-emphasis.
music > microphones > a recorder of some sort

Online Scooter123

  • "I am not an alcoholic. I am a drunk. Drunks don't go to meetings."
  • (9)
  • Needs to get out more...
  • *****
  • Posts: 2709
Re: interface with SPDIF able to handle 32khz/44.1khz/48khz??
« Reply #3 on: July 28, 2021, 11:57:46 AM »
I had what I think was a 32 bit recording, and my transfer deck, a DR-680 simply wouldn't recognize the recording, so I gave up and transferred it via the analog outputs > analog outputs. 

Here is a spirited discussion of 32 bit recording and some people believe that a 32 bit converter does not exist, because 32 bits is actually 24 bits with 8 bits floating, whatever that means.  This is way above my skill set.  But if you can figure it out, go for it.  I gave up and went analog. 

https://gearspace.com/board/high-end/700810-32-bit-d-d-converter-recorder.html
Regards,
Scooter123

mk41 > N Box  > Sony M-10
mk4 > N Box > Sony M-10

Offline morst

  • Trade Unionist
  • (2)
  • Needs to get out more...
  • *****
  • Posts: 4716
Re: interface with SPDIF able to handle 32khz/44.1khz/48khz??
« Reply #4 on: July 28, 2021, 12:48:38 PM »
I had what I think was a 32 bit recording, and my transfer deck, a DR-680 simply wouldn't recognize the recording, so I gave up and transferred it via the analog outputs > analog outputs. 

Here is a spirited discussion of 32 bit recording and some people believe that a 32 bit converter does not exist, because 32 bits is actually 24 bits with 8 bits floating, whatever that means.  This is way above my skill set.  But if you can figure it out, go for it.  I gave up and went analog. 

https://gearspace.com/board/high-end/700810-32-bit-d-d-converter-recorder.html


32 bit is different than 32 kHz. Totally different problems but you can probably still force things with a mis-timed transfer and then some header magic.


Don't forget that the DAT recordings may have been made with pre-emphasis.
True!
There are tools to remove pre-emphasis.
xACT for mac will do de-emphasis.
The option is found under the UTIL tab.


Online Scooter123

  • "I am not an alcoholic. I am a drunk. Drunks don't go to meetings."
  • (9)
  • Needs to get out more...
  • *****
  • Posts: 2709
Re: interface with SPDIF able to handle 32khz/44.1khz/48khz??
« Reply #5 on: July 28, 2021, 04:12:51 PM »
Ah, I misread the post. I thought the OP was talking about 32b. Never mind.
Regards,
Scooter123

mk41 > N Box  > Sony M-10
mk4 > N Box > Sony M-10

Offline Barney

  • (0)
  • Taperssection Newbie
  • *
  • Posts: 11
Re: interface with SPDIF able to handle 32khz/44.1khz/48khz??
« Reply #6 on: July 28, 2021, 06:41:34 PM »
Don't forget that the DAT recordings may have been made with pre-emphasis.
True!
There are tools to remove pre-emphasis.
xACT for mac will do de-emphasis.
The option is found under the UTIL tab.

uh?  Is there any way to know if a DAT recording was made with pre-emphasis?

Offline Barney

  • (0)
  • Taperssection Newbie
  • *
  • Posts: 11
Re: interface with SPDIF able to handle 32khz/44.1khz/48khz??
« Reply #7 on: July 28, 2021, 07:06:49 PM »
My own recordings were made with a Sony TCD-D7 and a Tascam DA302.

I also have recordings done with Sony TCD-D8, Sony TCD-D3, Sony PCM-M1. And maybe some recordings done by the soundmen with their Tascam DA20 I guess (as I think it was the most common DAT deck in venues back in the days).

I might have DATs that are copies - not clone - from a TCD-Dx to a Sony consumer deck. I think the guy coudn't bypass the SCMS and it was the only way to get a copy. Maybe I have some others that are TCD-Dx to Tascam DA20/DA30 done the same manner. Those were done 20/25 years ago, my memories is not what I'd like it to be.

Anyhow, it looks the pre-emphasis is "similar" to the RIAA thing. "Similar" in the sense of an EQ is applied to encode/decode. Treble/bass thing. From what I've already read, I should expect lack of low end and too much high end in the sound. Please correct me if this is wrong.




Offline morst

  • Trade Unionist
  • (2)
  • Needs to get out more...
  • *****
  • Posts: 4716
Re: interface with SPDIF able to handle 32khz/44.1khz/48khz??
« Reply #8 on: July 29, 2021, 12:38:46 AM »
Don't forget that the DAT recordings may have been made with pre-emphasis.
True!
There are tools to remove pre-emphasis.
xACT for mac will do de-emphasis.
The option is found under the UTIL tab.

uh?  Is there any way to know if a DAT recording was made with pre-emphasis?
The DAT machine will light up an EMPHASIS light if it's got one?
The DAT format has a bit in the sub codes which indicates whether a program has emphasis

I found way too much info on this thread: https://gearspace.com/board/mastering-forum/1106263-dat-pre-emphesis.html

Appears that SOX or FOOBAR software can deal with it, if you have those...

Quote
GLouie
Lives for gear

Many DAT machines did not have the preemphasis incorporated, like the Panasonic SV3700/3800.
Most Sony machines I know of did, and would flash an indicator when it was activated by a preemphasized tape (there's a control bit).
Note that the digital output was not affected.

Online Scooter123

  • "I am not an alcoholic. I am a drunk. Drunks don't go to meetings."
  • (9)
  • Needs to get out more...
  • *****
  • Posts: 2709
Re: interface with SPDIF able to handle 32khz/44.1khz/48khz??
« Reply #9 on: July 29, 2021, 10:56:03 AM »
May I ask a fundamental question from someone who is not as technical as you guys.  What is pre-emphasis and why does it matter? 
Regards,
Scooter123

mk41 > N Box  > Sony M-10
mk4 > N Box > Sony M-10

Offline morst

  • Trade Unionist
  • (2)
  • Needs to get out more...
  • *****
  • Posts: 4716
Re: interface with SPDIF able to handle 32khz/44.1khz/48khz??
« Reply #10 on: July 29, 2021, 01:44:05 PM »
May I ask a fundamental question from someone who is not as technical as you guys.  What is pre-emphasis and why does it matter?

Perhaps this exchange will shed light? Pre-Emphasis is similar in concept to Dolby B NR or to the RIAA phonograph EQ curve.
High Frequencies are boosted while recording (Emphasis) and then reduced during playback (De-Emphasis) in order to maximize practical considerations involving signal to noise ratio.
The information on whether a signal has had this done is carried on a single data bit in the sub code section (data like track points are also stored in sub codes)


I notice that my digital DAT clones recorded PCM601esd> S/Pdif> Panasonic SV3500 > DAT have the Emphasis light showing when I play them back on a 3800 or Sony A6.
Anyone care to weigh in on this? DSatz, I would appreciate your take on how to handle that.
Ideally you should get a PCM-601esd as this unit has a spdif out  - this way you can do a digital clone.  Note that PCM NTSC is recorded in 44.056khz and not 44.1k (PCM pal is in 44.1khz)
The answer is simple - the Sony PCM-F1 system used emphasis in the recording and de-emphasis on replay.This improved the signal to noise ratio and, IMHO, sounded better than DAT which came later.So if you do a digital dub then the file will have emphasis and the emphasis light on the DAT will come on.A customer of mine ran into trouble over this.
I had recorded a demo recording for a clarinet quartet with my PCM-F1 rig.  The record company found the recording so good that they decided to release it as it was - just they wanted a few more tracks to fill the album.My client insisted I recorded the extra tracks with DAT rather than PCM-F1.
I warned him that this would be a bad idea, but he insisted.  He then had to edit together tracks with emphasis with other tracks without emphasis (the DAT ones).  He had to call someone in to help.  It would not have been a problem if everything had been done F1............
« Last Edit: July 29, 2021, 01:45:41 PM by morst »

Offline DSatz

  • Site Supporter
  • (35)
  • Needs to get out more...
  • *
  • Posts: 3149
  • Gender: Male
Re: interface with SPDIF able to handle 32khz/44.1khz/48khz??
« Reply #11 on: July 31, 2021, 03:08:18 PM »
Pre-emphasis in DAT (and the earlier "PCM-F1" formats as well as the Compact Disc) is a considerable (max. 10 dB above 4 kHz as I recall) treble boost that was applied to the analog signal before it was digitized and recorded. The point of this was to improve the signal-to-noise ratio of the medium, since affordable converters back then weren't as good as they are today. Most program material has far less energy in the high frequencies than in the midrange or below, so this boost didn't usually cause problems with recording headroom, though it could in some special cases.

To get back the audio signal that you put in, the playback equipment had to detect the presence of pre-emphasis via a "flag" bit in the data stream, and if present, reduce the treble by the corresponding amount. The curve was standardized, only one curve was ever used, and the "flag bit" in the various signal and recording formats was clearly defined so that the equipment manufacturers could handle it perfectly well, at least in theory. But most consumer playback equipment does NOT indicate in any way when pre-emphasis is detected; it simply engages the corresponding de-emphasis and all should be well (one hopes).

As a result, when extracting digital data from older audio recordings, you need to be aware of which recording equipment was used and whether it generally used pre-emphasis or not. I mentioned the old Sony "PCM-F1"--all unmodified F1s applied pre-emphasis 100% of the time. With portable DAT recorders, I frankly don't remember, but I'm sure that information is available somewhere. With CDs it is really a problem. A substantial number of CDs in the early years were originally recorded with pre-emphasis (some were recorded on F1s and "bumped up" to 1600/1610/1630 format), and you could need special, professional equipment to detect the flag bit in the S/P-DIF stream coming out of the player. I don't recall ever seeing a CD player that had a visible indicator of whether emphasis was detected on the disc or not.

With classical music (which is what I've mainly recorded) it's relatively reliable just to listen to a playback without de-emphasis. If it sounds artificially bright and that's not your style of recording, then try applying the standard de-emphasis and listen again--things may "click into place". But with pop and rock music I don't know--I can pretty well imagine a dull-sounding recording that would sound better with the pre-emphasis left in! It is, after all, a kind of EQ, and EQ can sometimes make things sound better. But if I had a dull recording, I might want to choose a different form of treble boost rather than the particular, prescribed pre-emphasis curve for making it sound better, is all.

This all sounds appallingly loose and poorly implemented, but keep in mind that originally, consumer digital audio (including the PCM-F1, DAT, and the compact disc) were intended to be closed systems in which the consumer would never have access to the digital data stream. It was years before the first CD players were available with digital outputs of any kind--while the DAT format was designed so that you couldn't record the output of a CD player (consumer DAT recorders with digital inputs accepted only 48 kHz digital signals, not 44.1 kHz). Eventually the manufacturers' control got broken down and we are now completely used to recording onto multi-gigabyte memory cards, and handling WAV audio files just like all other files on a computer. But for example the PCM-F1 was introduced at around the same time as IBM's first PCs, which didn't even have hard drives yet, let alone hard drives capable of holding a CD's worth of material (I can remember when a 70 MB hard drive cost $600, where that $600 itself would be the equivalent of maybe $2000 today).

--best regards
« Last Edit: July 31, 2021, 03:19:17 PM by DSatz »
music > microphones > a recorder of some sort

 

RSS | Mobile
Page created in 0.053 seconds with 36 queries.
© 2002-2021 Taperssection.com
Powered by SMF