1974 Deluxe Reverb.....Reverb control at 6+ = SQUEAL!

[acorkos]

Reverb control at 6 or higher causes loud midrangey squeal....guitar plugged in or not, independent of volume control setting, with or without reverb tank plugged in, with or without footswitch plugged in. Pulled 12AT7 V3....no change. Pulled 12AX7 V4...no squeal (not much overall volume, either).

Any ideas as to what's wrong? Thanks for your help!

[txstrat]

V3 is the driver, V4 the recovery tube for the reverb section of the amp.
Try a new or known good recovery tube (7025 or 12AX7). Squeal gone?

[acorkos]

V3 is the driver, V4 the recovery tube for the reverb section of the amp.
Try a new or known good recovery tube (7025 or 12AX7). Squeal gone?

tubes are new and tested good

I was searching this forum and came across a similar post....Bruce from Mission Amps suggested replacing the recovery tube cathode bypass cap. i tried it and squeal is gone. Thanks Bruce! (ps....6 years later, my Mission 5E3 kit homebuild is still my favorite gigging amp)

[Bruce / Mission Amps]

tubes are new and tested good

I was searching this forum and came across a similar post....Bruce from Mission Amps suggested replacing the recovery tube cathode bypass cap. i tried it and squeal is gone. Thanks Bruce! (ps....6 years later, my Mission 5E3 kit homebuild is still my favorite gigging amp)

There ya go... that's how to use this forum!!