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 reverb

Login or Sign Up. If it’s none of those things then we might have to ask what is the next suspect problem – but it does sound very much like oscillation. I will schematiic referring to it often. Maybe epiphone will reveal more news at the upcomming Winter Namm Using a 12AT7 as a PI will compromise gain, but in return, your amp will have much more “touch sensitivity”‘ or “dynamic response”. The time now is You must log in or sign up to reply here.

I was reluctant to probe with the scope around the sebior voltages so used a meter set to AC volts. Sounds like a great idea, try it, you have to destroy half the Valve Senior for the parts and it won’t work as an amp anymore, and you’ll probably end up hating the sound because of the same reverb tank. If I try something once, and it works, i stick with it. Apr 2, 1.


I am using a 33K in both of my Valve Srs. Attacking possible causes is often a waste of time unless you have found out where in the amp the problem occurs.

Skipping on a bit, my first two suspects for causing oscillation would be a bad tube, and poor arrangement of the leads inside the amp, especially the OT output leads. Yes, it looks like you are conducting every possible test but not the basic one we suggested: Posted 11 September – Be sure that when working on your amp, the power supply is unplugged, and the filter capacitors are fully drained. This seems to be everyone’s big issue with this amp including mine.

Search in titles only Search in Amps only Search. If gain actually decreases with R15 disconnected, then the OT is phased wrong. I could talk about output trannies save your money, no audible difference and speakers shoot me a PM, I’ll let you know epi;hone I usebut what I’ve laid out should really get you there.

So I checked the feedback and it appears to be correct as the output goes up when the feedback is removed Then I chased the signal backwards. Looks like Epi is putting out a new head to compete with the Ceriatone 18watt clones, the 15 watt Blackheart, and the Orange TT.

Lately I have gone more in the acoustic direction so I haven’t really looked around for amps in a few months.

ShortScale :: View topic – Epiphone Valve Senior Combo Issues

Next swapped tubes both power and PI to no avail. We haven’t yet taken it. If you don’t like the sound of the reverb in your Valve Senior I wouldn’t reuse any of the parts to make a Valve Jr into a reverb unit.


What happens in this case? In this way you will learn at least at which stage the problem appears. Originally Posted by Jazz P Bass. I do not accept any liability for anything said in the above post. Since you cannot see it, I would suggest detecting at which stage the signal dissapears.

We’re trying to work out which section of the amp has the problem. Changed the tubes 1 ssnior a time more than once. So, that being said, you should upgrade the following capacitors with the same values: Let me know if this helps you, and if anyone else has anything to offer, I would be very interested myself. Epiphone Valve Standard- Please Help?

Epiphone Valve SENIOR

If it’s oscillation then output transformer leads are the suspect – I see you twisted and rerouted them. Heater voltage pin 2 or 7 referenced to ground starts at 3 VAC until standby switch is turned off, then stays steady at 2. I eipphone my next suspect would be a bad OT but that’s a long way second to oscillation. Bookmarks Bookmarks Digg del.

You should keep a copy of this.

Remove the chassis from the cabinet, and remove the board from the chassis.