Onset of Buzzy Distortion at Low Volume

[Thisismyname]

Hello, I hope everyone is having a good holiday season!

Amp-Single (normal) channel Deluxe Reverb, no reverb, no trem

Mods-100K mid pot, 3-way bright switch, 50uf filtering at first filter amp, a few smaller value coupling cap.

Things I've ruled out- Tubes, guitar, cable, speaker, building power supply, vibration.

Problem- A few days ago during rehearsal with amp on 5, a subtle buzzy distortion started going on, but only when I played. My amp was clean. No hum, just static-type buzz. This occured about 2 hours into the rehearsal.

Using an attenuator at home to use the same amp settings, the problem took an hour to come back. Before changing tubes, I decided to turn off and on the amp just to see if the problem came back. It didn't, even after 45 minutes of playing.

At another rehearsal, I used the amp and brought spare tubes thinking the problem was tubes. The problem came back after an hour, changed all tubes 1 at a time (both power tubes at the same time of course)
The problem remained, even after turning off and on.
The amp also has lower volume.

When turning the amp off, the static comes back for a few seconds, louder than when playing. This makes me think something in the power supply. The 1 year old filter caps look fine.

No resistors look burnt.
Banging on the sides and top of the amp yields no vibration-based symptoms.

In a nutshell- a moderate buzzy distortion when playing, and 3ish seconds of a slightly louder buzzy static when turning the amp off while not playing.

Thank you for any and all help!!

[uki]

Please post the schematic and pictures of the circuit, that does help trouble shooting.

Check if all connections are good, clean tube sockets, check voltages for clues, take notes and report back.

[Latole]

Wich Deluxe Reverb ?

Ask required, post schematic

[Willabe]

Amp-Single (normal) channel Deluxe Reverb, no reverb, no trem

Mods-100K mid pot, 3-way bright switch, 50uf filtering at first filter amp, a few smaller value coupling cap.

Sounds like he built it.

[Latole]

Amp-Single (normal) channel Deluxe Reverb, no reverb, no trem

Mods-100K mid pot, 3-way bright switch, 50uf filtering at first filter amp, a few smaller value coupling cap.

Sounds like he built it.

A home build ?  We need many answers

[Thisismyname]

I'm at work now. I'll update around 4 or so.