Tube Amp Archive

Took a long time to get back to this project, but I thought I owed a closing note to those who helped: - I never did figure out the the deal with the PAB/Rock-Jazz interaction. It seems that if the Rock/Jazz is in the Rock position, PAB has very little effect (maybe because, as someone pointed out, ...

Finished building my first Dumble. It sounds amazing. Every time I pick up my guitar, the next thing I know, 2 hours have gone by. But I have two issues: I have a very weird interaction between the Rock/Jazz switch and the PAB switch. Set on Jazz, the PAB has a big effect. However, switched to Rock,...

Thanks! Problem solved!
Didn't make sense to have infinite resistance from grid to ground. (Thought I checked this already.) OD Level pot wasn't grounded. (doh!)
Thanks again. I never thought I'd get this much help this fast.

Well my amp doesn't work, but at least I've learned something. I couldn't figure out: where was that plate current going, if not through the tube? Answer: through my meter! Now I know what I'm getting for Christmas (maybe a little early). Still frustrated. I've tried your (collective) suggestions. C...

Hi Gang I need some help troubleshooting my new build. Full disclosure: 1) This is a Ceriatone kit. I know what that means to many of you (although I didn't when I bought it). 2) I'm a pretty new amp builder. (This is my 3rd amp). I read schematics and understand the concepts. I have what Ceriatone ...

This is a gorgeous build. Your amps are a work of art. You should build one with a plexiglass top, so your wiring can be part of the art. (only half joking) Would you mind sharing your grounding scheme? I'm confused by the use of both an isolated buss bar and the pot backs with the chassis masked. I...

Doh! Thanks.

Hey guys. I've loved reading about this build. Congratulations so far, Marcus. Looks great! I've been wrestling with a similar FET switching problem, so this has been really helpful for me. My problem now is that I've been unsuccessfully trying to download Martin's explanation for battery testing an...

Right, I guess most of those mini pots are made for guitar. Thanks again.

Hey thanks Martin. I love the idea of a switched FET gain pot. A question about that idea: What needs to be grounded if the FET circuit is not engaged? Both input and output leads or just one? Also, I'm going to cheat and ask another, unrelated question (well, actually the idea of fitting a pot in t...

Forgive me if this question has already been answered - I couldn't find it. Is there any reason the FET jack can't be replaced with a simple switch? From my reading of the schematic, the FET input just routes the signal through the FET circuit, then on to V1. If the Normal jack is used, the signal g...