Tubes buzzing with UA Ox

[TUBEDUDE]

What does the input of the Ox look like? Does the load impedance, even though 8R, have a large capacitave reactance, rather than inductive or resistive?

I am not sure as UA does not disclose that info. It only shows that the ground input goes to ground across a 10k resister and the tip goes to reactive load.

Wow, I get keeping the signal return above ground, to be above noise and digital hash, but 10k seems a little high no.

[Stopping-by432]

I am not sure exactly, I just relayed what I was told by UA.

I was able to find out what was causing the oscillation and I fixed it this evening One of the switches was bad and it caused a grounding issue. I replaced the switch and the oscillation was gone! Thank you to everyone that assisted with the troubleshooting. I learned a lot during this process. Now I get to enjoy the amp for a while until I get the itch to build the next amp.

[rooster]

....one of the switches controlling one of the Robinette mods? When you seek help here remember the door swings both ways. If you made a mistake wiring something up or you ran into a modification that caused a problem it's best to leave your ego at the door and tell the ppl that tried to help you what caused the problem.

[Stopping-by432]

It was the raw switch mod that I tweaked by using a DPDT switch. The ground of the presence pot was lifted when it was supposed to stay ground at all times. I should have just grounded the presence pot directly but I tried to accomplish the same with the switch and keeping it connected to ground with the middle control so the circuit remained in tact when off. I ultimately did this when I replaced the switch. My apologizes for not explaining this earlier.

[rooster]

Thanks for this update!

[Stopping-by432]

Sorry I posted to an old message by mistake.