Me and the dog are building an 18 watt amp

[viniciusvalenca]

It's turning out great! Congrats. I'm following this thread.

[Dolamike]

It's alive! Initial startup went good, I had my inputs wired wrong so had to re-wire those. Non-tremelo channel is sounding good. Getting a significant thumping from the Tremelo channel in both channels when the volume for the tremolo is turned up. Nothing when the tremolo channel is fully turned down.

I've been reading the threads on tremolo issues, getting caught up there. I've definitely got some re-work to do on thegrounding of my shielded wire. I placed a diagram of how I plan to do it. Would love some advice on if this is what other people do. I currently grounded it at the audio ground.

Also posting my voltages below. Going to drop the B+ with zeners as suggested by the forum. Also seeing high and oscillating at V2 Pin6 and that seems off...

Anyway more work to do but excited to have the amp passinga signal.

[Dolamike]

I have updated the shielded wire grounds to match the diagram I posted above. Definitely helped the tremelo thump but it is still there.

Waiting on zener’s from mouser to drop the voltage. We’ll see if that helps.

With the Tremelo off, this is the quietest tube amp I’ve ever owned, I can barely tell it’s on… really great. And that’s with the chassis sitting open on my bench.

Huge thank you to @jmpguitars for the exceptional layout and the community for all of the circuit enhancements over the years.

Now, onto tolex if the cabinet. Yikes.

[JMPGuitars]

Correcting the B+ voltage with the zeners may very well tame the thump. If it doesn't, start rolling tubes.

[Dolamike]

@jmpguitars what brand tubes have you had good luck with in this circuit for the thump. Got the zeners in, B+ is at 330… still have a slight thump.

[Bieworm]

Usually any Sovtek, or rebranded Sovtek 12AX7 will do. Try switching out with the tubes you already have in the amp. It's very possible you notice a difference in thumping between various 12AX7 tubes. Lead dress is also very crucial. Try moving wires while listening to the thumping. Sometimes that is the culprit..

[JMPGuitars]

Bieworm is correct, you should also chopstick the wires around the tube.

I like new production Mullard, TungSol, EH, Sovtek, etc. Just nothing that says JJ on it!

330VDC is a little low for B+. We typically target 345VDC +/- 5VDC. If you like how it sounds, cool. It might sound a little muddy compared to the target B+ though. You decide.

[Dolamike]

Woot! Tolex is done and the amp is sounding great. I made a speaker cab to go with it as well. Thanks again to the forum for such a great project and amp.

[Daviedawg]

Nice job. I hope the dog got treats.

Dd