Tube Amp Archive

Nice Board! Good idea too. I added a rotary switch on my AC30 build with three 25W Dale resistors mounted on the chassis. The switch can then add them in series to get different bias settings. I think it was 100 ohm, 50 ohm and 25 ohm. Sometimes I want the Hot bias sound and other times I like it Co...

I had an odd problem with my 6V6 Marshall Hybrid amp. (Front end of the 2022, into the 2204 driver and Phase Inverter) I installed the VVR and it dropped the B+ from 400v to about 285 volts. I tried many things, but ended up replacing the 12v zener, and now it works from 400v down to about 50v. I sc...

Hello! Welcome to the forum. Sometimes when I have a problem with a new build, especially one with mods, I remove the mods! I guess it is like starting with a clean slate. I first try to get the "stock" circuit up and running before I start tweeking or changing things. Once I have it running, then I...

Hello! I've had good results by using the pan with the highest input impedance for Ampegs. There is no reverb transformer that takes the hi-z from the driver tube and changes it to low-z to drive the pan. If I recall the accutronics number was 4fb3c1b. It was the highest input-z that they made. The ...

Hello!
I would try reversing the plate wires from the primary of the output transformer to the power tube sockets. If they were reversed, then the negative feedback would become positive feedback, and it would oscillate. Of course if you don't have feedback then it would not matter.

Hello! I just finished mine a few days ago. I had no output also. Then I took my ohm meter and hooked it between the input jack "hot" and the output jack "hot", and rotated the switch. The meter showed open, or infinity. I finally tracked the problem down to the variable resistor. I had to sand the ...

Hello! One thing to consider is the 6.3 wires have a center tap, and the 5 volt windings don't. (According to the schematic that is) So the secondary wires should be fairly easy to figure out. The HV windings have a much higher ohms, then by finding which winding is center tapped, you can find the 6...

Hello! I've built a few. If I recall, I used a nice University Sound driver. It had the standard thread that would thread on to the horn, and I used clear PVC tubing that slipped over the threads. If you can't find the correct size tubing, then get some slightly larger and use a hose clamp to secure...

Hello Again, I remember when I was a kid, (1880??) we used to make crystal radio sets. They were what amounted to a diode (galena) and a cat's whisker (wire). To pick up strong nearby stations in an amp, it would only take a bad solder joint, that would "detect" or pick-up the station. The bad solde...

Hello! I'm a ham radio operator and a musician. Perhaps you should pick up a copy of the Radio Amateur's Handbook which is put out by the ARRL. I go to "hamfests" several times a year, where I buy tubes, books, and all kinds of tube gear. In the handbook there are chapters on basic electronics, desi...

Hello! My favorite one is a 15" Jensen Neo. I put one in my custom built bassman combo. (I made it with a guitar channel and a bass channel). The highs are nice and crisp, and the bass response is smooth too. I play mainly light rock style music, and I also take it to church too. The neo speakers ar...

Hello!
I find it quite humorous reading the disclaimer on the rear of the amp:
"NO GUARANTEE IS APPLIED WHEN USED OUTSIDE OF JAPAN."
Perhaps that is because it is a 100V unit?

Hello! Congratulations on your first build! I agree with the great advise of the previous posters. I've built many small sized amps. The tweed Champ is one that I like to change the filament wiring on. I like to make the filament wiring like the silverface models. I first twist the green transformer...

Hello and welcome! Spoiled? Yes, that is exactly how I feel now after building my Express! The Express sounds so nice I'm spoiled and don't want to play my Marshall clones, or dare I say, my Dumble clone! The Dumble is sweet, but it really uses too many parts and I have to adjust too many knobs to g...

Hello! My favorite caps are the Sozo ones. They are more "clear" sounding to me. One of the best ways to audition different caps is with a single ended amp, or should I say a "simple" one. I have a hi-fi design that uses an SRPP preamp with one coupling cap into a single 6L6 tube. The idea here is t...