Tube Amp Archive

For me part of the fun of a project is ordering the parts. Mr. Worley's BOM list is a great tool. He has done alot of hard work putting together all the information for building one of these amps. There have been alot of people who have successfully built one of these amps and with patience you can ...

My advise would be to follow the original layout and get your lead dress to match the Francesca pictures in the files section. If you encounter any problems this will make it easier for the experts on this site (which I am not one of) to help troubleshoot and get you to a working Express. Any deviat...

Email sent. Enjoy.

I have no problems with a pc board. I was only kidding. I actually played a little Egnater Rebel 20 at GC tonight, cool little amp. Really cool to have 6V6's or El84 and to be able blend them. I wanted to open it up right there and see it's in-nerds and see what makes her tick. The GC guys may not h...

My boy and I spend alot of time at the local G.C. He loves playing different guitars and amps just to see what they are like, but we never leave with anything other than strings and picks. We use the store so he can get the "sound" of an amp so he can relate it to different amps that we want to buil...

I will take a look at the presence circuit tonight. I already removed the split load switch but did not have time to try it without it yet. Again thanks for the help. Eventually I hope to hear this thing sounding like it should.

Take it from me if you do build one stick to the layout and like Mr. Worley said follow the lead dress exactly. On my Express I reversed the layout to have the controls on the opposite side and tried to "change it up some" and I am now trying to get it stable. If I would have stuck to the layout it ...

Have you tried a different guitar? Sometimes pickups are the fault of too much feedback. I plugged my G&L ASAT in tonight and drove the family out of the room by the high pitched squeal. I moved the head off the speaker cab and didn't help. My Les Paul does not get as much squeal, but the pickups a...

I re-wired the grounding scheme to buss wire on the pots, moved the jumper from the .1 coupling cap to the phase inverter to the front of the board, and the amp is alot more controllable. With the amp in the low ("gradual") gain setting I can run the airbrake up to the highest setting and she is man...

The only departure from normal lead dress that I can see is that the two wires coming from the bass pot should be as close together as possible and stay on the deck flat all the way back to the board, where they come 90' straight up and on to the eyelet. The other kinda bad deal is that the OT prim...

Do your tone controls work? Check the ground on the middle control. OK, some one smarter than me should jump in. Tone controls work, not alot of control on the bass but I've heard that is normal. Mid is grounded. I thank you for all your suggestions. How many times is a problem caused by an oversig...

It is grounded.

Disconnecting the NFB would cause quite a bit more gain and possibly the uncontrollable feedback you describe. Check the 150k resistor to ground from grid of the V2, If it is not connected or measures very high you have a bunch more gain as well. I measured it at 149.3k, I installed a 100k to try a...

Did you check your Negative feedback loop ? Make sure nothing is open. I don't see the cap across the PI, not that it is necessary. I guess you have some kind of MV thing going or it is a cut control. I would take a close look at the circuit around the PI. The cap is out at the moment. I do have a ...

I have had my Express running for some time now. It has started to create feedback that is way out of control. I have swapped out V1 with all the 12ax7's and 5751's I have, they are mostly JAN Philips ECG's to no avail. If I run it through my Airbrake at the lowest setting the feedback is no issue. ...