Trainwreck Rocket bad sound when volume goes beyond 4

[TimDude]

As the description says, I have a Trainwreck Rocket that I just finished building! I'm super proud of myself. However, there is a problem, maybe two problems. Problem #1: When I keep the volume below 4, the amp is perfect. Everything sounds great. It's louder than I had imagined. When I push the volume beyond 11:00 o'clock, suddenly a hum magically appears. It's a low hum, somewhere around an open A string on guitar maybe. If I push it higher, there will be a wicked squeal that appears. Very high pitch, but not very loud. An older person may not even hear it. The amp starts to break up, I can hear distortion, but it's like I'm saying "Let's kick it into overdrive... literally" and the amp is saying, "dude, I'm gassed and I don't have the goods to deliver." Oddly enough, even the volume starts to go DOWN after I turn it up past 1:00. The breakup is in the tone, but I have the hum, the squeal, and the dropped volume. My thoughts, it could be bad power tubes. I have read that it could be something with a negative feedback loop and I need to switch the leads going from my output transformer to my power tubes. The reason I don't think that's the issue is because it sounds good at low volumes. It sounds GREAT at low volumes.
Problem #2: This may be a problem, it may not be I don't know. When I go to turn the amp off, I first hit the standby and when I do that I hear a pretty big pop from the amp. It almost sounds like a loud electrical short. But I can't be positive. Maybe it's nothing and I have nothing to worry about. But I thought I would mention it.

If you have any suggestions, please let me know. I got all of my plans from here on the Amp Garage. If you want me to upload photos I can do that too.

[joeboo88]

Tim try swapping the OT secondaries at the power tubes.
Good luck

[M Fowler]

Check your grounding for the pots that can affect volume.

[Stevem]

You have a dead output tube and or a bad OT.

How many putout tubes does this model have ?

[Leo_Gnardo]

Tim try swapping the OT secondaries at the power tubes.
Good luck

Tim, what you're experiencing is most likely an ultrasonic oscillation. If you looked at your TW's output with an oscilloscope, you'd likely see a swarm of super hi frequency "hash". Hi frequency, that is, for audio, say 10K to 100KHz. Joeboo's suggestion is the first thing to try. If that doesn't fix it, or other alarming noises come out, we'll have to look deeper into what's going on here.

Ultrasonic oscillation can be so prolific as to overwhelm the amp's output - resulting in drawing so much current from the power supply that the charging ripple can be heard as an annoying buzz. That's one of the "tells." Of course, a blink with a 'scope would reveal all, but not everybody has an oscilloscope on their workbench.

Lead dress can have a lot to do with this kind of oscillation. Mainly keeping input leads well away from output. Perhaps this has a lot to do with Ken Fisher's notoriety for particular placement of wires in his TW builds. "Everything counts!"

[pdf64]

It’s oscillating, the design is fairly high gain and has little restriction on its bandwidth, so it’s kinda to be expected unless the build is precise and accurate to the ‘recipe’.
If flipping the power amp’s polarity doesn’t fix it, then try a bigger grid stopper after the vol control, eg 22k.
Beyond that, upload some detailed, high resolution build photos to a hosting site and provide links.

[TimDude]

I swapped the output transformer primaries to the power tubes and the problem went away! I'm glad I read Rob Robinette's page on how to start up an amp safely where I found that tip on the "negative feedback circuit." Thanks to everyone who responded.