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Mushy Breakup on a Princeton Reverb

2/14/2000 10:59 PM
Mark	Mushy Breakup on a Princeton Reverb I have a Late-70's SF Princeton Reverb with the pull-boost switch and I'm getting some abrasive, buzzy, distorted mush as the notes bloom and decay. This occurs at breakup volumes even with the bass on zero and is pronounced at the tail end of ringing chords. Now I have given it a fresh set of caps, which did clear up a slight ghost tone subharmonic problem, and I have completely removed the pull-boost circuity according to instructions provided by a qualified tech with support from on-line experts. Now the amp has almost the same circuitry of a BF PR with the exception of two resistors and one cap. I have a new heavy duty speaker in there too which I know is good. This problem has persisted throughout the above mods and now I am stuck as to what else I can do. I have only read about crossover distortion so I can't say for sure, but it sounds like excessive crossover or blocking distortion if I were to venture a HUGE guess. (The articles only explain what those are and never tell how they sound) Can anyone clue me in on the problem and how to cure it? Thanks to all.

2/14/2000 10:59 PM

Mark

Mushy Breakup on a Princeton Reverb

I have a Late-70's SF Princeton Reverb with the pull-boost switch and I'm getting some abrasive, buzzy, distorted mush as the notes bloom and decay. This occurs at breakup volumes even with the bass on zero and is pronounced at the tail end of ringing chords.

Now I have given it a fresh set of caps, which did clear up a slight ghost tone subharmonic problem, and I have completely removed the pull-boost circuity according to instructions provided by a qualified tech with support from on-line experts. Now the amp has almost the same circuitry of a BF PR with the exception of two resistors and one cap. I have a new heavy duty speaker in there too which I know is good.

This problem has persisted throughout the above mods and now I am stuck as to what else I can do. I have only read about crossover distortion so I can't say for sure, but it sounds like excessive crossover or blocking distortion if I were to venture a HUGE guess. (The articles only explain what those are and never tell how they sound)

Can anyone clue me in on the problem and how to cure it?

Thanks to all.

Replies:

PTJohn I recently worked on a SF Twin bask... -- 2/14/2000 11:44 PM
Scott Swartz If you try all the suggestions abov... -- 2/15/2000 7:24 PM
D.P.Coyle Some of the problems you describe l... -- 2/17/2000 11:23 PM