Film-Tech Forum ARCHIVE: distorted sound on J30 and JH3

This is topic distorted sound on J30 and JH3 in forum Digital Cinema Forum at Film-Tech Forum ARCHIVE.

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Posted by Scott Norwood (Member # 30) on 06-05-2009, 08:01 AM:

Has anyone else experienced distorted sound on either of these decks with tapes that are recorded with peaks above -10 dBFS (but not hitting 0dBFS)?

This has been a consistent issue for me with many different decks of both models. The issue can generally be worked around by selecting "variable" audio output (menu option 114) and setting the headphone knob to just under the 12 o'clock position.

I have not seen this issue when playing the same tapes on better decks (HDW-D1800, etc.), so it's not an issue with the tapes themselves, nor does it seem to be an issue with the setup (deck->non-sync input on CP65 or CP500, with processor configured for L/C/R/S decoding, and input gains set up with test tones on tapes).

My current theory is that the digital->analog converters in the J-series decks are just not very good, and that the problem would be solved by using an external converter connected to the SDI output. Has anyone tried this and does it solve the issue? Any other ideas or recommendations?

Does anyone make an SDI->analog audio converter box, or does one need to go from SDI->AES/EBU and then AES/EBU->analog with two boxes?

(I don't remember if this is also an issue with analog Beta SP tapes on the J30. It may or may not be an issue specific to Digi-Beta and HD).

Posted by John Hawkinson (Member # 1135) on 06-05-2009, 11:02 AM:

Honestly, what's wrong with variable? I end up doing that anyway, since otherwise the levels are always weird, and I figure it's best to fix it as early in the chain as possible. And often as not it's more convenient, esp. if it's running into a CP65...

You could use an Aja D10CEA that does audio and video. But of course it costs $700 or so.

--jhawk