Yes, I'm aware that clock sync is important and suspected it was somehow at the root of my problems. (I thought I said as much in my OP?) I was hoping to get specific recommendations re capture equipment that's economical and reliable - I'm sorry if this was not clear. (It appears our M-Audio FW Solo, despite having an external sync option in its control panel - which, if not toggled, yields silence when trying to record - it still never properly locked on for whatever reason; in any case that it doesn't support 32kHz inputs limits its usefulness in this case).
It would be pretty cool to have an entire capture chain with word-clock inputs and a separate master clock device - and I should have surmised that many of you here are fortunate enough to have access to such equipment - but as far as I can tell this would unfortch not be cheap and would in fact be far more expensive than the SCSI DDS solution. Our gameplan now is to borrow one of these but I hope to try recording via the SPDIF input of a CM6206-based device as well (for my own edification/to be used in a pinch) and report back, especially now that people here (thanks guys!) have explained that the non-linear 12/32 data is most likely mapped to 16/32 before leaving the deck. I spoke to someone today who actually called me a few minutes after I had posted and mentioned (among many other things) having had success with a C-Media-based card before - likely one with a much older chipset but still heartening all the same. I'm not married to this particular chipset though: I just don't know what other capture equipment is out there that accepts external sync, and supports 16/32 input (to say nothing of not costing an arm and a leg). It was hard enough to find the datasheet on the CM6206 (it has a 32khz input mode, though I'm not sure about external sync: I think I linked to the datasheet in an earlier post) and was only lead there after finding that that's what these eBay boxes use (kind of a backwards way to go about it but I guess it is what it is).
In any case thanks for at least confirming (I think?) that I'm barking up the right tree. Any other comments would be most welcome.
May 2 2017 10:47 PM, "Corey Bailey" wrote:
The bottom line:
You need a capture card (or A/D, D/A converter) that has the ability to sync its internal clock to
the SPDIF stream of the source. Same goes for an AES source. The alternative, which Ellis no doubt
used, is to sync the player, the converter and your ingest computer to an external clock (House
sync or clock) running at the sample rate of the source. Otherwise, you will get clock errors
because everyone is not marching to the same drummer (or: clock source). The end result is dropped
frames by your capture device which manifests itself as random ticks or pops.
Hope this helps,
Corey Bailey Audio Engineering
On 5/2/2017 2:49 PM, Eli Bildirici wrote:
OK great, there is hope! I will try to play back via a CM6206 capture card (spec sheet
(http://www.bramcam.nl/NA/8663-XS/CM6206.pdf (http://www.bramcam.nl/NA/8663-XS/CM6206.pdf)) indicates 32kHz input support - see page 15) or our
G5 and hopefully report back. Thanks a lot for this insight!
May 2 2017 5:39 PM, "John Chester" wrote:
On 5/2/17 5:15 PM, Eli Bildirici wrote:
'Sending encoded 12 bit values to a linear DAC will surely give horribly distorted audio.'
Aha. If that is the case, then can we presume that when output via S/PDIF, a 12/32 DAT has already
had its bits mapped to 16-bit linear values? That would be good news for my purposes, I think...
In order to produce analog output from a 12 bit recording, presumably the DAT machine converts to
16 bit linear, which it then sends to its internal 16 bit DAC. Thus, the sensible choice would be
to send the converted 16 bit values to the S/PDIF output -- but I have no idea if that's what
actually happens. If you listen to the 32 kHz S/PDIF output, and you hear undistorted audio that
sounds similar to the DAT machine's analog output, then I think you can assume that is what's
-- John Chester