[ProAudio] DAT Transfers

Tue Apr 6 17:58:59 PDT 2021

I think "sync to usb" might be a misnomer, but definitely interfaces
will sync to an internal oscillator (not clock) and oversample the
incoming digital stream, which will then be synced to using a PLL
and/or flywheel sync and finally recovered from the oversampled (eg
64xfs) stream back down to the normal (1xfs, in this case 44.1 kHz)
sample frequency. The value recovered will usually be the one that
falls on where the recovered PLL clock falls. If the recovered clock
has a sub-sample shift to the original, then you might end up looking
things up at edge transitions, which will result in bit flips. The
quality of the recovery system changes from device to device. It would
make sense to have a device that can record the oversampled stream and
apply offline processing in software later on. There is no good way of
doing this that I know of.

If you want the ultimate in magnetic digital media preservation, you
should be using a KryoFlux-like approach. It overrides the control
logic in a magnetic reader and essentially treats the magnetic
recording on the data carrier as an analog signal, which it is. Then
you can fix any issues in post processing. KryoFlux is a commercial
product which was developed for preservation of floppy disks. There
are Open Hardware projects that aim to do the same. There is no ADAT
solution that I know of.

https://en.wikipedia.org/wiki/KryoFlux

A survey of tools for working on flux images (the high resolution "raw
flux" images KryoFlux will create). It was made before KryoFlux
alternatives existed:
https://forum.winworldpc.com/discussion/7877/a-comparison-of-current-disk-archival-tools

Development of such a solution is not trivial, but given the amount of
collective knowledge surrounding this due to the floppy disk
preservation movement I'm sure there would be far less snags than one
might think.

On Tue, Apr 6, 2021 at 10:45 PM Bob Katz via ProAudio
<proaudio at bach.pgm.com> wrote:
>
> Dear David:
>
> The MOTU interface does not have any available SRC and it does not have an option to sync to the USB, ever. Which is a good thing given the nature of USB.
>
> In fact, ALL USB interfaces give you clock options based on their I/O sections (AES, SPDIF, Analog), not on their connnection to the computer (USB). Generally the USB just carries DATA between the computer and the interface, and any clock that may be in the USB is ignored. Industry practice is to try to ignore any clock in a USB line and to use a handshake and FIFO method to exchange data via USB.
>
> The MOTU can only sync to AES/EBU or wordclock or SPDIF or be on internal clock. The DAW itself may or may not do bad things with sample rate. You want to avoid those sorts of DAWs (the kind that adapt to any incoming rate and perform an SRC on the fly.... ouch! Apple is notorious with that in their operating system. That's why you can intermix any sample rate material in iTunes without getting a glitch, if using an Apple internal interface.
>
>
> Bob
>
>
> On 4/6/21 4:36 PM, David Josephson wrote:
>
> Bob, what I was getting at is that some of these interfaces sync to the USB and perform a sample rate conversion no matter what. If the MOTU doesn’t do that, fine.
>
> David
>
> On Apr 6, 2021, at 1:21 PM, Bob Katz via ProAudio <proaudio at bach.pgm.com> wrote:
>
> Dear Jim:
>
> I don't know what David is getting at. If you put your DAT machine on internal sync and lock the MOTU via SPDIF or AES/EBU it will do a good job capturing the DAT.
>
> The major cautions working in this mode (slaving to the DAT) is some DAT machines revert to outputting 48k clock when they are stopped, so you need to ensure that the DAT machine is putting out the intended (44.1k) clock before you hit record in your DAW. And if you have a MOTU control panel, watch what rate it says it is slaved at.
>
>
> Best wishes,
>
>
>
> Bob
>
>
> On 4/6/21 2:04 AM, Jim Brown via ProAudio wrote:
>
> I need to transfer a few dozen DATs to a hard drive for archiving before it's too late to find hardware on which to do it. 20-25 years ago when I was recording this material, I had a tower machine set up as a DAW with all the interfaces needed to do the transfers. It's been 15 years since that machine was booted, and it was more than ten years old then. And I don't remember the logon. :)
>
>  So I need advice about hardware. I still have the Tascam DA-P1 on which they were recorded, but I'm not sure it will live long enough. I'll try it first. It outputs S/PDIF, so I need an interface to get into my Windoze machines. All use USB, but I think I might have one with Firewire.
>
> I found a MOTU 8D with USB 2.0 and S/PDIF I/O. David Josephson has cautioned me that some interfaces may not sync well enough to the stream for a clean transfer. Can anyone advise about this particular product? The material is all acoustic jazz with important artists, so quality is paramount. Most if not all of the masters are 44.1.
>
> Can anyone suggest another interface? Also suggestions of a source for a good used DAT if mine doesn't make it through the process? I'll be 80 in the fall, my last recording was 12 years ago, this project is going to be a one-off, so I don't want to spend big bucks if I don't need to.
>
> Thanks, Jim Brown
> _______________________________________________
> ProAudio mailing list
> ProAudio at bach.pgm.com
> http://bach.pgm.com/mailman/listinfo/proaudio
>
> --
>
>
> If you want good sound on your album, come to
> Bob Katz 407-831-0233 DIGITAL DOMAIN MASTERING STUDIO
> Author: Mastering Audio
> Digital Domain Website
>
> No trees were killed in the sending of this message. However a large number
> of electrons were terribly inconvenienced.
>
> _______________________________________________
> ProAudio mailing list
> ProAudio at bach.pgm.com
> http://bach.pgm.com/mailman/listinfo/proaudio
>
>
> --
>
>
> If you want good sound on your album, come to
> Bob Katz 407-831-0233 DIGITAL DOMAIN MASTERING STUDIO
> Author: Mastering Audio
> Digital Domain Website
>
> No trees were killed in the sending of this message. However a large number
> of electrons were terribly inconvenienced.
>
> _______________________________________________
> ProAudio mailing list
> ProAudio at bach.pgm.com
> http://bach.pgm.com/mailman/listinfo/proaudio