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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Epiphone Valve SENIOR

Page 1 of 1 You cannot start a new topic You cannot reply to this topic. Any help will be greatly appreciated. I have a “recipe” that I’ve been dying to share. These amps can easily be transformed into little boutique monsters that will urinate all over just about any other amps in the Watt range.

T here is not schemaric one single mod that will bring the amp to life, but a combination of upgrades and “tweaks”. That being said, I am about to write a novel, so please be patient. I can assure you that it will be worth schrmatic time, and hopefully mine, too. Be sure that when working on your amp, the power supply is unplugged, and the filter capacitors are fully drained.

If you don’t know how to drain the filter caps, you can Google it, or shoot me a PM. I really have no idea what I’m doing, but what I’m doing seems to work.

Wpiphone opinions are based on my personal experience. If anyone has a different opinion, please do not be a “hater” as the kids like to say on the World Senjor Webbut offer an alternative suggestion. Tubes make a HUGE difference. I have found that the Mullard and Tung Sol reissues sound far superior to any other tubes.

Valve senior Mods. – Gibson Brands Forums

They just seem to “feel” better. Using a 12AT7 as a PI will compromise gain, but in return, your amp will have much more “touch sensitivity”‘ or “dynamic response”. And yes, a new 12AT7 will do just fine. I am running two 12AT7s, which draw considerably higher plate current than 12AX7s, but this has not been an issue for the power transformer sand I’ve been running both of mine very hard, for some time now.

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You can find a schematic of the amp here: You should keep a copy of this. I will be referring to it often. Remove the chassis from the cabinet, and remove the board from the chassis. This will help greatly when putting everything back together. First, you should bump up all of the filter caps.

This will smooth the AC hum, and keep your amp whisper quiet, even when epipgone.

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

Next, all of the poly caps should be upgraded. I like the M series caps, which are currently produced by Cornell Dubilier. Orange Drops are also very good. Funny, in a guitar, ODs are always my first choice, but in an amp, Ms are my first choice.

I’ve never tried it the other way.

If I try something once, and it works, i stick with it. So, that being said, you should upgrade the following capacitors with the same values: Not very expensive, or labor intensive, and wow, what a difference.

Next, Let’s address the reverb circuit. This seems to be everyone’s big issue with this amp including mine. The problem is that the tube is running too hot for the reverb tank. Schsmatic as I stated earlier, change the reverb driver vakve to a 12AT7.

This will transform the reverb from “Out of control, Useless, Over the top” to just about the best tube driven reverb circuit you’ve ever heard. An other thing that can be improved upon is the tone stack. Next on the agenda would be the pre-amp, and gain. Before I address the tube, I would like to look at resistor 3.

The factory value is 68K Ohms. I think this is a little high. Most people use a 10K in that application, but I’ve found epipjone to be just epipohne little too hot and my intention was to build a really dirty amp.

I am using a 33K in both schemwtic my Valve Srs. As I’m running them right now, I think I might like just a little bit more clean headroom, but I am running the preamp tube a little hot, and I can make a huge difference by simply rolling back my volume knob on my guitar L.

Epiphone Valve SENIOR | Harmony Central

You can experiment with different values for that resistor, but i think 22K or 33K is where it’s at. So, on to the tube In case you didn’t know, a 12AX7 is a twin triode, and the tube can be thought of as two separate valves. The first triode is the first gain stage, and the second triode, the second I am currently using K Ohm resistors for the plate loads although I think K would be optimal.

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A value of 2. I am running 2. You will not be disappointed. After all of these issues are addressed, you can, if you feel the need, tweak the “Voicing” of the amp. This is not nearly as difficult or expensive as you might think. This would simply involve changing a few capacitors. I like to use audio grade electrolytic caps when possible.

C25 is a 22uF 50V electrolytic. Increasing the value will give you more bass response. Some people like to use as high as uf for the sebior amp C This can be very “boomy” sounding, but the factory Valve Sr. I think I have a uf in C25 for the combo, but a uf or a uf will offer more bass response than the stock 22uf.

For C8 the first cathode coupling capI’m using a uf, for more bass response. I could talk about output trannies save your money, no audible difference swnior speakers shoot me a PM, I’ll let you know what I sfniorbut what I’ve laid sdhematic should really get you there. Let me know if this helps you, and if anyone else has anything to offer, I would be very interested myself.

Thank you for posting all of this. I am finally going to start working on this amp soon.

I have a Valve Sr combo way out of warranty that the head sounds like the opening 10 minutes of “Saving Pvt. Ryan” when I turn it on, and I’ve been going to take it to my favorite luthier who also does amp repair for a going over. I’ll also give him your list and ask for his opinion as well no offense intended.

As for your warnings, I know two things about amps. The first is that if you don’t know what you’re doing, they can kill you. Delete From Topic The post will be removed from this topic completely. Skin and Language Theme: Board Classic Stanton Language: Dec 31