Maybe it's amplifying a signal that's interfering with your sound card or cables? My old video card would interfere with my Lynx card, and I've been in studios where cell phone signals, especially when connected to wifi, would interfere with all kinds of equipment, including amps.
 

brundlefly
 
I can't repro that. I get pure digital silence out of both PC4K Channel and Bus compressors.

 
I must admit it does not happen every time, today is ok.

Resonant Serpent
Maybe it's amplifying a signal that's interfering with your sound card or cables? My old video card would interfere with my Lynx card, and I've been in studios where cell phone signals, especially when connected to wifi, would interfere with all kinds of equipment, including amps.

I suppose it's all in the box. I have total silence when PC4K is off. Strangely same settings of compressor on several tracks result in very different level of noise. That happens even when I clone tracks.

People who are suggesting that ProChannel plugins might amplify internal noise... that's not how this sort of system works. If you don't have an input assiged to a plugin, absolutely no signal is going in. You could put a whole radio mast next to your PC and nothing will get picked up by the plugin unless an active input is assigned to it.
 
In my case - and a few other people's, it seems - this is noise being generated by the plugin when there is absolutely no other signal going into it. No input assigned, no input monitoring, no playback, nothing.
 
Can I see a reason to generate 490Hz tones (or 187, or whatever)? Maybe, if you're simulating some old hardware that did that. Seems pointless to me but lots of people like that sort of thing. Now I don't know if this is deliberate or a bug, since at least one poster is saying they get silence from their PC compressor.
 
But I think it's a bug, and for this reason - the tone doesn't appear at all, even during playback, until you make an adjustment to the Output level of the compressor, and apparently only you use the FX bin. Try it for yourself - pick an audio track with no ProChannel enabled, enable ProChannel, adjust the Output value a bit, then click the 'Bypass rack' button in the FX bin for that channel, and watch the peak value appear at -120dB or similar. I sometimes find it goes away of its own accord after that; and sometimes it doesn't.
 
Can anyone else repro this? I'm running the latest Manchester update, at 44.1KHz / 24bit recording / 64 bit engine, if that helps.

I do remember a thread from a couple of years ago where the 64bit engine could cause noise issues in the Pro Channel. May have been the emulator, though I thought it had been fixed. Have you tried turning off 64bit processing?
 
Regards,
Dan

I attempted to reproduce using your recipe as I understand it and am not able to reproduce the issue you describe on my system.
 
I will, however, keep aware of this and let you know if I see the symptoms you describe.
 
Paul

I get it with the 64 bit engine turned off as well. Quickest repro route for me is: add audio track, show pro channel, drag the 'output' knob near the top, and I instantly get a pulse of noise. Usually after playing around for a few seconds this ceases to work, until I start with another track.

Does it still happen if you up your latency/buffer size? 

Kylotan
...at least one poster is saying they get silence from their PC compressor.

It depends on which compressor you're talking about. As I posted, I can replicate getting a low-level tone from the PC76 U-type module, but I consistently get nothing from PC4K channel and bus compressors using Bitmeter at 32-bit resolution to detect output.
 
You didn't mention which compressor you're referring to, but I assumed is was the default 'PC76...?
 
 
 

I have no idea which compressor it is, since I don't use the ProChannel at all. It's just a bunch of dials at the top of the strip, there by default.

That's the 76 alright.