’76 Fender Vibrolux Reverb

This is the only brand-name amp I own. Even still, this amp came to me in heavily-modified form, mostly blackfaced with a multi-tap Bassman OT and a number of circuit changes including a solid-state rectifier and absurdly high B+ on the preamp. It hummed a lot. One speaker had a warped coil and the power tubes were microphonic. The reverb driver 12AT7 had run so hot it was misshapen! Goodness, it needed some help.

So, this amp has seen a LOT of time on my bench. A 5U4GB rectifier went in, preamp B+ was returned to more reasonable levels, the reverb driver cathode bias was brought to blackface spec, and ALL of the tubes (various Fender/Groove Tubes) were replaced with some good stuff. The Jensen reissue C10Qs that were in the amp were replaced with an Eminence Legend 1058 and a Ragin Cajun. I reduced the NFB and added a reverb dwell control on the back of the amp, where the boost footswitch used to be. My last fix was a short 3-spring reverb tank. I had bought one short and one long, intending to use the short one with my ReVibe, but the Vibrolux sounded better with the short one.

This is now an impressive rock machine, especially thanks to the upgraded OT. It has all the power and oomph of a Super Reverb but with the lower headroom expected from a Vibrolux. The only thing that could make it better is true bias-vary tremolo instead of the optoisolator… I’ve drawn out the mod layout, and one of these days it’s bound to happen.

  • V1: (I forget) 12AX7
  • V2: RCA 12AX7
  • V3: Mullard CV4024
  • V4: RCA 12AX7
  • V5: Tung-Sol reissue 12AX7
  • V6: Mullard CV4024
  • V7,8: Tung-Sol 5881s, 1960s
  • V9: GE 5U4GB

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