DBX 165 Noise

[MicDG]

Hello,

I'm trying to figure out what could cause the noise I hear when operating this unit on manual attack/release mode.
I am attaching a bounce of a bass track processed with attack and release set at 400 dB/ms and 1k dB/ms where you can easily hear the issue and one where the unit is on auto A/R mode and everything is fine.

As it's limited to the manual mode I'd think it should be something in the time-constant generator section (looking at the schematics here).

Do you have any idea what could cause this?

Thank you,

Michele

 

[radardoug]

Well, its a very crappy bass sound for a start. If you pull up the two files in Audacity or a similar program, you can clearly see the difference. I would say you have your attack and decay set too fast. Fast decay will modulate a low frequency signal, not in a good way. But I would start with getting a cleaner bass signal.

 

[TwentyTrees]

I don't know that it's necessary to single out the tone of the instrument here - surely that wouldn't be a factor in the issue the OP is having, and for all we know that tone might be perfect for the mix.

I do agree that it might be caused by having your attack and release set too fast though, to the point the compressor may be trying to act on individual cycles in the waveform. Do you still get this issue if you slow down the release? If so, the manual timing part of the circuit is probably quite small so with a schematic there shouldn't be too many variables to investigate.

 

[MicDG]

Hello, thank you both for your contribution though it wasn't a problem caused by having a fast attack/release, but 4 tantalum capacitors being way out of spec due to ageing.

For future reference, if anyone needs it I wrote all the components' names on the photo of the PCB I am attaching to help identify them more easily. I also attach the original schematic though It can be found on google.

PS. bass tone is FORQ's Kevin Scott playing live

 

[TwentyTrees]

Excellent, glad you were able to identify and address the problem. Thanks for sharing your solution, may help someone else down the road.