Filter caps shot?

[Chadd]

Plying around earlier tonight and suddenly I lose signal and get a loud (very loud) Bvvvvvvvvvvvvvvvvvv sound from my single recto. I grabbed a pair of tubes from another amp and after 3-4 minutes, same thing. Clean or dirty, doesn't matter. This isn't background noise and appears to interrupt the signal.

Am I right in guessing a filter cap problem? If you think otherwise, please let me know.

 

[94Tremoverb]

Could be, or it could be a broken connection somewhere in the audio path - probably in the power stage if the controls don't affect it. Try pulling the phase inverter tube (V5) - does the noise go away?

 

[mikey383]

If you're using any effects or anything in the loop, remove them and plug straight into the amp. If that doesn't help, try a different cable.

If that still doesn't help, try swapping preamp tubes. I doubt your filter caps went bad just like that.

BTW, what's a dingle Recto? Is that a new model?

 

[Chadd]

Could be, or it could be a broken connection somewhere in the audio path - probably in the power stage if the controls don't affect it. Try pulling the phase inverter tube (V5) - does the noise go away?

Pulled V5, fired up the amp. No noise (or signal) at all.

 

[mikey383]

Try unplugging your guitar and effects, then power up the amp with all the tubes in place.

Still have noise?

 

[Chadd]

If you're using any effects or anything in the loop, remove them and plug straight into the amp. If that doesn't help, try a different cable.

If that still doesn't help, try swapping preamp tubes. I doubt your filter caps went bad just like that.

BTW, what's a dingle Recto? Is that a new model?

Tried several cables, nothing in the loop, tuner is in the slave out will try the preamp tubes in the morning. Fixed the typo, been up for 20 hours or so and it's now 5AM here. At least it was just the next key over, I've been known to make much worse mistakes.

Correction, pulled the tuner when I tried spare power tubes earlier. Also tried different guitars. I'll start picking at it again when I get up, thanks for the troubleshooting help so far guys.

 

[mikey383]

Just giving you some flack. I knew what you meant

I'd try the preamp tubes before suspecting caps. Caps don't tend to go bad suddenly like that.

Or, it could be a shorted power tube. If you have a Dual, you can pull the inner or outer pairs and see if the problem persists, then swap tubes to rule them out.

 

[jamme61]

could be a broken ground on one of the volume or gain pots? Are you able to pull the chasis?

 

[94Tremoverb]

No noise with the phase inverter pulled means the problem is in the preamp, not the power stage. It could still be a failed filter cap, but less likely now. Try replacing V5, and if the noise comes back, plug the guitar into the FX return and dime the Mix knob, then turn the guitar all the way down. If that doesn't stop the noise, it's between the FX loop and the phase inverter. If it does, it's further back in the preamp.

 

[Chadd]

It seems like it may have been V5. Never had a bad tube sound like that before. My spares don't sound all that great, so I might as well replace the whole set of them. There were JJs in it when I got it and they are OK, but I tend to play lower gain stuff lately. So less noise, less gain, smoother top end would be my top criteria.
Thanks for the suggestions guys.