vintage ea-32rvt with strange wiring, factory experiment?

[unclerny]

Hello Forum, I'm looking for anyone who can tell me if this Epiphone ea-32rvt I have may be a factory experiment. I need to know if this may be worth more as is to a collector than a major rewire job. It would take all day to rewire.

 

This particular 32rvt is in good working order and really good condition for it's age but it has one MAJOR "flaw". This thing has the reverb tank driven directly off the speaker!! This being said the amp can't be turned up with the reverb on as it goes into a feedback loop and just rumbles. I have the schematic from schematic heaven and that pretty much looks like what I'd expect from about any tube amp. This amp is no where near normal or the schematic.

 

I know someone is going to say it's been modified but whoever did it did this either right after purchase or in factory. Every solder joint in here looks exactly the same. Perfectly identical. I've tried to figure out what the reverb control does and it appears to be a mid control tied off the bass control, all done right at the pots.

 

Another thing that stands out is that it has two chokes in there that the SH schematic doesn't have. One is clearly for the power supply and the other is a bit hard to follow. It's tied off the plate of one of the tubes and not going to the phase inverter tranny. The PI is handled pretty much as the schematic shows except they've swapped some of the triodes around. A lot of resister values don't match up either. It all feels like a R&D experiment.

 

The workmanship is above average throughout and the amp sounds great with the reverb off. The owner would like to have the reverb fixed. I'm hoping to tell him it's worth more like it is. Have him buy another amp and collect this one.

 

This is a serious mystery and any help would be most useful.

[m-theory]

It's not unheard of for 60's era Gibson amps to stray from published schematics, and sometimes rather far. Using my Falcon as an example, not all of these "factory experiments" were what you'd necessarily call "perfect mods," either. That Falcon had 1/2 the available gain shunted away, for instance, and the reverb is built into a loop from the preamp section, so it can get rather noisy (although it's a very impressive reverb, despite the noise tendancy).

 

I never was able to find a schematic online for my Falcon, so the fact that you haven't found one for this circuits freak doesn't necessarily mean that it wasn't built this way from the start. What to do with it is the toss-up question. If all else looks original, I'd probably be inclined to leave it alone and sell it as is, as a collector. If it's been messed with at all over the years and you can build it correctly without mangling the chassis, all options are on the table, imo. Everyone's opinion on this varies, however, so, ultimately, it's up to the owner to decide.