I’m dealing with a squealing issue with all my amps into the Fryette.
When using high gain on any of my amps (mark vii, jp2c, revv generator 120) if the master volume goes above 12 o’clock a squeal noise shows up. If I bypass the power station the noise doesn’t go away.
However if I connect my amp into the cabinet directly with the same settings and even higher volume no squeal is heard.
Here are videos demonstrating the issues, my guitar volume is rolled all the way down in all videos and the guitar is around 3 meters aways from the amp and cabinet.
Squeal in operate: Watch Squeal in operate | Streamable
Squeal in bypass: Watch Squeal in bypass | Streamable
Since I can’t post three links in the same post, here is the link showing that there is no squealing when connected directly to the cabinet with the same settings on the amp: Watch No squeal when connected direct to cabinet | Streamable
I just hooked up my PS-100 and have the same issue. I’m running the generator 120 and jcm2000 dsl100 through the zmacs and using the ps-100 in the attenuator loop. I know I have a ground issue in my pedal board as with it hooked up using 4cm I get the squeal at all volumes. However if I completely unhook all pedals I get the exact issue you have. My ps-100 isn’t as close to the amp as yours, but it’s about as close to the zmacs and the power conditioner. Have you had any luck fixing this? I’m going to keep tinkering around and will come back with my findings.
My unit ended up blowing up shortly after.
In the short while before it did, pressing the ground lift button on the back of the device eliminated the problem.