Vibrolux Reverb Has Less Gain than Expected -- Help Troubleshooting Please

[lovg...@aol.com]

me (Lovguitar change)






Aug 11 (23 hours ago)

















I picked up a 79 Vibrolux Reverb a few years ago. This had the pull boost circuit, which I didn't like, and kind of weak reverb. The volume level of the amp, from the beginning, was lower than I thought it should be, but this was my first VR, so I thought that's how it's supposed to sound.

It began killing reverb tubes and I decided to remove the pull boost circuit, and revert the amp to earlier SF specs, since I had read that it probably was causing the weak reverb and death of the reverb tube. I also replaced the filter caps but left the rest of the caps alone. Now the reverb is much better and the amp doesn't kill tubes anymore but is still lower than I think it should be. I compared this amp to my brother's Blackface VR and it isn't even close volume wise.

I added a cermet pot in front of the balance bias pot so I can control bias. I have it biased at 35 milliamps and the plate voltage is 426. Sounds good but still way lower than expected.

I've changed pre-amp tubes without a corresponding change in sound.

I'm thinking I should change the rest of the e-lytic caps and check to see if any of the other caps and resistors associated with channel 1 and channel 2 are leaking, drifted way off etc. I figure I should also be checking voltages on the pre-amp tubes to see if they're off.

Am I on target? Other ideas for troubleshooting this?

Thanks for any assistance you can offer.

best regards,


Paul