Help Ben Adrian resto-mod his Pro Reverb
Posted: Wed Sep 04, 2024 12:45 pm
Hey all. Back in 1999 I bought a totally blasted 1966 Pro Reverb. I restored it as best as I could, but I had to replace a lot of parts; resistors, caps, speakers, baffle, grille-cloth, torlex, etc. A few years later, the tiny transformer got kind of cooked, so I replaced it with bassman-sized one with the correct screw hole spacing. The result was an amp that sounded and looked great, and could fool many that it was a vintage amp in nice condition. Even though the circuit remained the same, enough bits had changed to make it not really have a vintage value. It was quickly becoming the amp of Theseus.
However, I've not used it much in the last 10 years. My tastes were changing and I didn't want to mod it in any sever manner. Plus, it was acting funny. When trying to model it for Helix, I realized what had been happening. The fiberboard with the components was becoming capacitive and conductive. So now I'm at a crossroads. If I want this amp to perform well and truly be reliable, I need to replace the fiber circuit board. I figure I can go down one of three paths, but I'm not sure which one to take.
However, I've not used it much in the last 10 years. My tastes were changing and I didn't want to mod it in any sever manner. Plus, it was acting funny. When trying to model it for Helix, I realized what had been happening. The fiberboard with the components was becoming capacitive and conductive. So now I'm at a crossroads. If I want this amp to perform well and truly be reliable, I need to replace the fiber circuit board. I figure I can go down one of three paths, but I'm not sure which one to take.
- Restoration. Pull the fiberboard, clean everything up. rebuild the circuit on a new fiberboard while trying to use as many vintage parts as possible. Get it as close as I can to the spirit of what rolled off the line in 1966. I may not what to play it a ton, but that will give the most value.
- Upgrade construction. Rebuild the mostly-vintage circuit on a turret board. I might make some component changes where it makes sense or revoice the normal channel, but for the most part it will perform like the vintage amp, but be reliable and more easily repairable for the next 50 years.
- Modification. Rebuild the circuit with mods that might make me want to use the amp more. At the core it will be the classic vibrato channel circuit. In addition I might put in a mid knob, maybe a mod to revoice into a trainwreck style preamp. Perhaps a single stage tube gain boost from the normal channel. Change some cathode bypass caps to tame the lows below 50Hz. Maybe a Lar-Mar Master volume. I'm not going to drill, but it will eliminate the normal channel and reorder the knobs on the front. I might use the amp a bit more, but it also might be stuff that could be achieved my just using a damn EQ or boost pedal.