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Other Digital Hardware

 

 

This page is a catch-all for information regarding other digital-audio hardware you might use in your studio. In this section, I've placed all the information I've discovered by experimentation, and any interfacing and operational hints I can offer.

The Hosa ODL-312 AES/EBU to Optical S/PDIF Converter

I was planning to use the Hosa ODL-312 to convert the main output of the DA7 from AES/EBU to optical S/PDIF so it could go to an M-Audio DigiPatch 12x6 patcher. The ODL worked fine feeding the DigiPatch, a Marantz CDR-630 CD recorder and a Sonorus StudI/O card (set for S/PDIF, of course); everything worked well. Except the Tascam DA-30 DAT.

I had the DAT connected via coaxial S/PDIF to the DigiPatch, but two things went wrong. When I played any tape, the DA7 would get a horrible crackle from (probably) rotten word clock being sent on the AES/EBU line. Nothing worked to fix this problem, and I began to suspect the ODL. But the other digital devices (the Marantz and StudI/O) worked fine, so then I turned my suspicions to the DA-30 DAT.

When I pressed record on the DAT, things were even worse. The DAT display showed a 48K sample rate (I was feeding it 44.1) and it displayed the Copy Protection warning. With that warning lit, I could not record at all — never mind what the sample rate said.

But the DAT worked fine using S/PDIF to play and record to/from the other digital units, even through the DigiPatch. It was definitely the ODL that was annoying the DA-30.

What about subcode?

By changing the digital subcode format from AES/EBU to S/PDIF at the DA7, I could get the DA-30 to record properly, but it still wouldn't play any differently than before. This led to a discovery about the ODL-312.

The ODL-312 does not appear to be converting the subcodes. Inside the unit is a single Maxim MAX491CPD IC, which is simply a line-driver part. The only other active part is a single transistor. Nothing inside the ODL is complex enough to convert the data stream; it just converts the digital audio at the physical level from balanced AES/EBU to unbalanced optical.

Why is the DAT annoyed?

I don't know. Either the DAT is extremely picky about its input data stream (and the other devices are not), or the DAT is so dumb that it gets confused. The end result is that I have the DAT running from AES/EBU, and the DigiPatch (and its connected devices) hang onto the DAT's S/PDIF connectors.

This requires that the DAT be operated in record-monitor mode to feed signal through to the S/PDIF side of things; it's an annoyance, but at least it works. So, to mix onto a CD-RW, for example, I have to put a tape in the DAT and press record. The transport doesn't have to be moving, or even in pause mode, which is nice. (The Tascam DA-40 has a monitor mode that doesn't even require a tape in the tray.)

 

The Tascam IF-TAD TDIF/ADAT Converter

The Tascam IF-TAD converts lightpipe to TDIF, for use between ADAT and DA-x8 machines.

The IF-TAD allows either the TDIF or the ADAT side to be the clock master, which is fine. If TDIF is the master, then clock will be routed to the ADAT side via the lightpipe. If lightpipe is the master, however, the IF-TAD does not route clock to the TDIF connector, but instead sends clock to a BNC connector. All DA-x8 decks except the DA-88 now route clock via the TDIF connector; because the IF-TAD was designed when only the DA-88 existed, it could not forsee the need to send clock via TDIF.

Unfortunately, this separation of clock presents some problems. The IF-TAD has no switch to allow the user to simply say "Take this clock and ignore the other side," which can be very useful in some cases. One example is when copying from ADAT to the Mackie MDR24/96 DIO-8 card via TDIF. You wire up the lightpipe to the IF-TAD, then its TDIF to the DIO-8 TDIF connector. Then you add a BNC word clock cable to slave the Mackie to the IF-TAD's clock (which is derived from the lightpipe). Sounds easy.

But it won't work. The Mackie insists upon sending its clock out the TDIF cable, as if it were feeding a DA-x8 deck. The IF-TAD detects clock coming in from both sides, and it shuts down, flashing its LEDs to alert you that it doesn't know who is the master. There is no way to make Mackie stop sending TDIF clock, nor to make the IF-TAD ignore that clock. You're stuck.

The Panasonic DA7 digital mixer is smart enough not to send clock out the TDIF cable if it's slaving to external BNC word clock. It's also smart enough to slave to the clock coming along the lightpipe to an ADAT card.

At least you can use the ADAT port on the DIO-8 card, but that's not the point: the example was to illustrate why the IF-TAD doesn't always do the job.

Strangely, while the IF-TAD won't simply send clock via the TDIF cable, it knows to check for incoming clock there!

 

The Mackie MDR24/96 (and probably HDR24/96) and ADAT lightpipe

These hard-disk recorders will not take audio from lightpipe alone; they require a BNC word clock input as well. They will, however, happily send clock along with outgoing lightpipe audio! Go figure...

Copyright © 1995-2016 - Rick Auricchio