Loud Noise in BYPASS mode when using tube amp

Stage & Studio Power Station PS-100
1

I have an Axe FX 3 plugged into the FX Return, a tube amp plugged into the amp in, a cab into the speaker out, and a 1/4" in the line out to computer interface. All of the impudences are set correctly. Everything seems fine with the axe fx using the PS-100 as a power amp. When I am using the tube amp and attenuating to a speaker cab it works fine in OPERATE mode. However, when using a tube amp and I switch to BYPASS on the PS-100 and the power on, I get a lot of hissing and sometimes squealing coming out of the speaker cabinet. It also lets guitar signal through very loudly and “clean” (not really making the amp sound).

I’m trying to record silently into my computer using the tube amp and the PS-100 as a load box. I see that I can leave the PS-100 power off and it should still work as a load box, but there is also a note to turn it on so you can have the fans running.

SO, is there something I’m missing? Can I have the PS-100 on and NOT have it plugged into a speaker cab? (worried it needs a load for the power amp). Or will I be fine running it as a load box with the power off when using a 120 watt tube amp? Or is there something that needs to be fixed? Any help would be much appreciated.

2

Hi @Elan442 and welcome to the forum,

This sounds like a ground loop. Joe’s video is really useful, do you get these kind of sounds?

Your setup is something like this but with the FX running in the amp and not the PS-100

image
image1920×820 110 KB

Some initial suggestions:

  • Connect everything to an extension cord running to a single wall socket/outlet. The cabling in the wall can be long and could add resistance between sockets that would put the grounds at different potentials
  • Remove any FX in the front of the amp
  • Remove any FX in the loop
  • Power front of amp FX with a different power supply than FX connected in the loop

Basically you need to simplify your setup as much as possible. Then you can add things back in one at a time and discover what is causing the issue.

If that does not work, then it is worth getting a cheapo audio isolator. You want to replace this with a good one if it works. Probably the best place for this is between Axe FX line out and the amp’s FX return.