Film-Tech Forum ARCHIVE: Dolby CAT 685 vs. 685A

This is topic Dolby CAT 685 vs. 685A in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Tom Ostertag (Member # 8318) on 09-25-2015, 11:10 PM:

Is there any difference between these boards (quality, reliability, specifications, fidelity, etc.), apart from the SMD construction of the 685A? I'm on the lookout for a 6-channel ADC for my CP500, but I'm not sure if I should try for one over the other.

The original 685 looks like it has some potentially nasty tantalum caps, but I can make quick work of those if they're a problem.

The Dolby block diagram says the 685 (not sure which was around at the time) is 18 bit, and I know the rest of the whole system is 44.1 KHz.

Posted by Marco Giustini (Member # 4544) on 09-26-2015, 03:23 PM:

In my limited experience with those boards I've seen some which are constantly displaying some input level on L and R even though nothing is plugged in.
Not sure whether that may be the difference and no, I didn't measure the output to see what that noise was.