I’m working on a Epiphone Valve Senior guitar amp that works fine I will try to attach a schematic with some voltages I measured added, but. Looking at the schematic I think you could borrow two 12AX7s from the Valve Sr to use as a preamp tube in the Valve Junior Reverb unit but. Download GIBSON EPIPHONE VALVE JR service manual & repair info for electronics experts.

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Apr 2, 2. How would I eliminate the PI section?

You should keep a copy of this. Looking at the schematic I think you could borrow two 12AX7s from the Valve Sr to use as a preamp tube in the Valve Junior Reverb unit but you’d get those same tubes from the donor Valve Jr. Apr 2, 1.

Advertise on the most comprehensive and widely viewed musicians’ vslve. I am using a 33K in both of my Valve Srs. Next swapped tubes both power and PI to no avail. Sounds like a great idea, try it, you have to destroy half the Valve Senior for the parts seniorr it won’t work as an amp anymore, and you’ll probably end up hating the sound because of the same reverb tank.

Attacking possible causes is often a waste of time unless you have found out where in the amp the problem occurs.


Thread Tools Show Printable Version. I like to use audio grade electrolytic caps when possible. I saw a bitmo mod for the Junior to turn it into verb-unit. I am finally going to start working on this amp soon.

This may be an oscillation at some stage and past this stage you get only distored signal. This seems to be everyone’s big issue with this amp including mine. Search in titles valvr Search in Amps only Search. Remove the chassis from the cabinet, and remove the board from the chassis.

ShortScale :: View topic – Epiphone Valve Senior Combo Issues

Orange Drops are also very good. Yes the attenuation drop off problem still occurs in that case Installed V2 and put the signal back to the input jack, virtually no output, installed V3 and problem still occurs. You can find a schematic of senioor amp here: Yes, my password is: This still allowed the amp to attenuate sharply at a nominal gain, which stays attenuated until I turn off the plate voltage with the standby switch, and turn it back on again.

A quick fix would be just to replace the tank in the Valve Senior, just find the one that fits dimensionally and mounting schsmatic I think this is a little high. Quick fix would be best. First, you should bump up all of the filter caps.


Epiphone valve Senior reverb

Seems to me the problem is in the power tubes, but they are brand new and matched. It is oscillating at frequencies above audio. When it is slowly turned up by either the gain or master volumes will cause the output to drop to near nothing with noticeable distortion.

I removed the lamp limiter, before attenuation pin 1, V3 is VDC, VDC after attenuation Pin 6, V3 before is VDC, and VDC after attenuation I am starting to think it may have something to do with high freq oscillation as Enzo said because the amp will attenuate sooner with a higher freq input. I tell them young boys all the time “There’s 2 things you really need to be a “bluesman” – Percodan and Whiskey”.

Gibson Brands Forums: Valve senior Mods. – Gibson Brands Forums

Hello, I epiphonee a Senior valve head, but I dislike the reverb. Isn’t this the correct function of the preamp tubes: Originally Posted by The Dude. T here is not really one single mod that will bring the amp to life, but a combination of upgrades and “tweaks”.