princeton reverb cutoff volume over 5

[anteriorl5]

Going through my "OB" PR, replacing out of spec resistors and put in a grid stopper 470K off the PI pin 7. Sounds good up to 3 on the volume but hitting the strings hard with volume over 4 or 5 starts to sag to the point where the note initially cuts off. Gets worse at 7. Thinking power tubes or rectifier getting weak but sure would appreciate your experiences with this symptom. Haven't checked bias yet but trem works well. Reverb works well but there are subtle popping sounds at 4 and it has a new reverb trans now that didn't help with the noise. Leaky caps? Thanks much!

[shooter]

Going through my


I always start with vdc and compare with original, that includes bias.  once that's done, problems are easier to solve

[sluckey]

...and put in a grid stopper 470K off the PI pin 7.

Well, take it out. Any better?

[anteriorl5]

Love the tone now with the NOS power tubes. The grid stopper I soldered in after the cutoff problem was resolved and I like the tone better with it.

[Willabe]

The grid stopper I soldered in after the cutoff problem was resolved and I like the tone better with it.

How did you fix the problem?   

[anteriorl5]

Just replaced the power tubes is all. Got out the tube tester and one was very strong and the other not so much, though still in the good range. The switch to a new AT7 (NOS) got rid of the pinging reverb sounds. The AT7 tube that was in there was a Telefunken and it too tested good. So both problems were caused by tubes testing good. The amp sounds fantastic now. It had lost it's punch and I was plugging into the brown Princeton or the '55 Deluxe through a Flint reverb. Great tone either one but so simple just to plug straight in to the PR.