5e3 build buzzing/overtone noise

[mike the dog]

Hello all! I have a 5E3 clone I built using 6AQ5 tubes. It was my first build, and have built 3 other amps from scratch that work great. This one has a strange buzz over the top of the output, usually when playing chords or single notes on the lower strings. Sounds like a bad speaker, then trails off as the notes fade away. Tried many different speakers. Tried having the chassis away from the speaker. Tried tapping on everything, and nothing triggers the noise. All my grounds go to one point to avoid ground loops. Anyone have any suggestions before I tear this apart and save the good parts for another build? Thanks in advance-Mike

[Jazz P Bass]

It 'sounds' like crossover distortion may or may not be the culprit.
Do you have access to a scope?
Check the bias.
It may be a tad too cold.

[mike the dog]

Thanks for the reply, I haven't checked the current or power dissapation, but my power tube plates are running at 273 volts, V1 is 110 volts at #1 and #6, V2 is 182 volts at #1 and 225 at #6. I have tried other tubes with no change. I must add that this this sounds great at mid volumes untill the notes start to trail off. One more thing, if I turn the volume to max on the opposite channel I am on, the volume drops to about 5%.

[pdf64]

Oscillation, possibly just parasitic, is a likely cause, due to 'less than ideal' layout / lead dress.
Ensure that grid stoppers are fitted to grid terminals at the sockets.

'if I turn the volume to max on the opposite channel I am on, the volume drops to about 5%'

That's what the back to front vol control arrangement on a 5E3 does.
Change to the 6G3 vol / tone arrangement if it bugs you.
Pete

[mike the dog]

Thanks for the input! I checked the grid stopper wiring. Was routed under the board, and too close the controls. Rerouted wiring, and noise is gone! Thanks for the replys, and hope I can help someone else out in the future! MR

[mike the dog]

Hi friends,
So I went to play this amp the other day, and now it makes this strange thumping noise when pushed that stays with it till the volume is turned off. Almost sounds like tremolo. Thumps hard enough the speaker moves like crazy, and there is a constant hum. Also the output tubes have blue glow that swells with the thump. I have substituted all tubes one at a time. checked voltages, tapped everything with a chopstick, and moved wires around, with no change. I am ready to disassemble and toss it in the trash. Sorry to keep asking for help, but any Ideas?
Thanks-MR

[loudthud]

Have you checked or substituted the filter caps?

[mike the dog]

That's what I was wondering, but the caps have no more than an hour on them, and they are Sprauge and TAD brands. I wish I had a scope to see if there is any A/C ripple.

[Jazz P Bass]

You can use your DVM to measure any ripple.
Set it to read Vac.