Wierd Reverb Problem

[jon]

I recently built a Princeton Reverb circuit into a 17X8X2 chassis. The amp is stock save for a tone control on the reverb circuit. Up to half volume the amp sounds as it should. Once above I get a heavy splatty distortion on the leading edge of the notes. After scoping the amp I found a very ugly wave form on the parcelled plat of the reverb driver. I have tried different tubes, so I know that is not the issue, Does anyone have a suggestions on where to continue troubleshooting.

[M Fowler]

I built a similar amp and found I had the wrong value resistor even though I remember measuring each resistor

Mark

[mr_hankey]

I ran into the same problem on an ODS+fender reverb build. The reverb driver would distort at high preamp volume settings. I fixed it by removing the cathode bypass cap and adding a grid resistor - I went straight for 39k, but you should try a few different values (10k to 68k, maybe).

[Milkmansound]

make sure you have a big grid stop on pin 2 of the PI tube as well. Anything from 330k-1M should smooth it out

[jon]

Stupid problem Solved....

....a bad RCA cable feeding the tank. Once replaced no more problem. But the wave form is still ugly feeding the Tank. If I disconnect the tank and run the reverb Transformer into a dummy load nice signal that clips slightly when the volume knob goes past 9. Just for S&G I put another tank in the circuit and the same result. Could the reactive load of the transducers and springs be causing the wave to look so bad?