The Amp Garage

This is awesome, Martin!

Can you show photos of the wiring inside, and show what you've used for the input and output AC plug/socket?

martin manning wrote: ↑Mon Feb 19, 2024 6:38 pm The Zeners protect against Vg-s getting anything larger than ~8V. Bypassing Rs with a cap has pretty much the same effect as in a triode stage.

And is the only possible source of this voltage whatever the user puts into the input?

I'm preparing to build a half-wattage (two EL84s instead of four) Liverpool, using Blues Junior iron. My OCD hates the idea of the unused triode, and I'd like to delete one preamp tube, so I'm experimenting with replacing the first gain stage with a LND150. Because it's nearly impossible to overdriv...

Screen resistors serve as current limiters, and help prevent burning up your tubes. These have little effect on perceived performance, and are a good, modern update to classic designs.

Can anyone point me to audio or video examples of acceptable levels of IM distortion in similar amps ie low filtering marshall type amps please? I mean... all amps, when overdriven, exhibit IM distortion. Here is my favorite example. Alex is repeatably bending a note UP, but you can clearly hear a ...

Reeltarded wrote: ↑Sat Feb 17, 2024 4:35 pm

Nothing does... nothing. lmao.. did a powder post beetle get in yur ear?

I hear you. In my mind, piezo is it's own instrument. Electric guitar, acoustic guitar, piezo guitar: three different instruments.

With Trainwrecks, we marvel at the unused triode. With this amp, I am amazed at the UNBYPASSED POWER TUBE CATHODE! This amp is waiting to be unleashed. And the speaker is terribly inefficient.

maxkracht wrote: ↑Sat Feb 17, 2024 12:08 amNot swapping out the coupling caps?

No, they seem to be holding ok. Can caps were shot.

An amazing specimen crossed my bench today. So new looking, I thought it was a reissue, until I realized it's 73 years old! Pasting my notes: All original. Speaker code date 1951. Filter caps are shot—replaced all electrolytics, along with dropping resistors. Replaced 2-prong power cord with 3-prong...

It also sounds incredible with acoustic piezo guitar.

proaudioguy wrote: ↑Fri Feb 16, 2024 1:58 amPlugged the guitar back in and it went away instantly.

The leaf switch on your input jack(s) is dirty and not closing like it should, thus the hum when no plug is inserted.

70% of max. dissipation is a target we used to aim for, but after building for 12 years, I prefer a cooler bias, closer to 50%. That said, your next move is to figure out if this noise is vibration related, or purely electronic. Do that by plugging into an external speaker cabinet, so the loud volum...

This cabinet came out nicely. Sounds great, with a Celestion G12H and Eminence Wheelhouse 150.

While waiting for the paint and polyurethane to dry, I knocked out this 3D printed jack panel.

Totally agree. (Except for sending it to you, Phil...)

Already made a new baffle, sanded and got some gloss poly on the thing. Wowz.