Epiphone EA-32RVT Variant

[earache]

I am looking for a schematic to a (approx) 1965 Epiphone EA-32RVT.

This one doesn't match the one that's commonly posted.

The one I need is for an amp with (2) EL84, (1) 12AU7, (2) 6EU7 and has a transformer driven reverb.

If you have this one or the related Gibson schematic I would be very appreciative.

Thanks in advance!

[Jazz P Bass]

Howsabout the GA17RVT?

GA17rvt Scout.zip

[earache]

It's close but not quite there.

I think I am looking for the one as described in this thread

http://music-electronics-forum.com/t24026/

...the schematic that was attached to the post has since evaporated

[Enzo]

Welcome to the world of Gibson amps. They routinely changed the guts of many models over production runs. I have one model with six different schematics in my files.

[earache]

This amp is really harsh and trebly sounding.
The volume control doesn't work right, it's too loud right off the bat.
The tone circuit doesn't look like the amp schematic I have.

[Leo_Gnardo]

This amp is really harsh and trebly sounding.
The volume control doesn't work right, it's too loud right off the bat.
The tone circuit doesn't look like the amp schematic I have.

Common complaints for that line of Epi/Gibson amps. No wonder they weren't great sellers!

There's a filter in there that knocks off all the low end, leaving them sounding tinny. All I can guess, is they were trying to make muffly toned humbuckers sound like Telecaster single coils. Wrong approach, mighty amp designer.... It's easy enough to bypass or eliminate that filter.

Possibly there's a linear pot used as volume control, another dirty trick. "The amp that sounds louder quicker is the one little guitar johnny will be impressed with and buy." That worked well too didn't it? No wonder this series of amps is ripe for modification. You put a proper preamp/control section in there, freshen up the power supply and you'll have a kool amp that really does sound good. I've done it and you can too.

[earache]

Thanks for your input, Enzo and Leo G

I don't have the "chops" to re - engineer something without a schematic.

Perhaps I should ask for "GA15-RVT 1965" that was listed in the previous forum post that I cited.

[Enzo]

I have the big MAster Service Guide from Gibson, a big thick book. And when the drawing doesn't match, I leaf through teh book looking for other models with the same tube complement, in the same order. Each drawing has a small drawing of teh chassis with tubes identified. That way I can tell if a Gibson model might be similar or identical to some Epiphone model. In the case of the one I have six of, I have three published on from Gibson, each different, and three DIFFERENT ones I have hand drawn from the circuits. I often draw my own schematic from a chassis if I can;t find one.

This is not as hard as it sounds. Think about your typical push pull output stage, I bet most of us could draw one on a napkin sitting at the bar. Difference would be details. The tube type, EL34 will use different pins than EL84. Resistors have different values, but the basic shape of that will be similar. There are only a very few different phase inverters we find in 99% of amps, you can quickly see if it is a long tailed pair or a single triode split load type. Gain stages, like the input stage all look pretty similar: Cathode resistor to ground, probably a parallel bypass cap, a plate load resistor, a coupling cap to the next stage. And a trick: unless the tone stack is involved in your problem, I just draw it as a block. Couple from prior stage in one side, signal out to next grid on other side, and a ground connection. Unfortunately, tone seems to be your issue.

I can do that pretty quickly, but even if it is your first, so it takes an hour or so. An hour or so later, you have a schematic. How long does it take to look for one for two weeks? I'd say probably about two weeks worth of hours.

If your tone circuits look different, look at some other Gibson drawings of that era, see any where the tone circuit looks the same? (Ignore the rest of the circuit)

[g1]

Perhaps I should ask for "GA15-RVT 1965" that was listed in the previous forum post that I cited.

Dr.Gonz was kind enough to post this in the other thread.

[Jazz P Bass]

I thought there were two threads for this.

[earache]

The other thread was initially to ask a question of the original poster. Sorry for the double post and also thanks for the help everyone.