The Amp Garage

Yeah, nevermind.

Yeah, nevermind.

Yeah, nevermind.

Yeah, nevermind.

I'm not sure if it's worth mentioning here, but when I fired it up, it was pretty noisy (as expected from initial adhoc lead dress). I replaced the lead going from the volume wiper with a shielded cable, changed the 500pF mica cap with a .01 film cap, and the one 47pF mica cap in the phase inverter ...

ITS FIXED.

I had wired the B+4 lead to the wrong side of a resistor.

Holy hell I feel dumb. I greatly appreciate everyone’s input and help.

... Removing bright switch removes all signal Bypassing tone stack removes signal ... The two bolded items consfuse me, but maybe they help narrow down where things are getting dumped? Yea. These are two new bits of information. Your volume pot may be bad and/or the ground connection to the volume ...

Do you have a smart phone with a headphone jack? If so, you can make a crude signal generator with it, a coupling capacitor and a cable. There are many signal/function generators out there for smart phones. Most are free downloads. Then rig up a cable from the headphone out with one of the positive...

It is a common thing to miswire the input jack so that the incoming guitar signal does not have a ground reference and is floating. This might cause what you are hearing. With the amp off and an instrument cable pugged into the input, measure the resistance from the tip of the cable to the chassis....

It is a common thing to miswire the input jack so that the incoming guitar signal does not have a ground reference and is floating. This might cause what you are hearing. With the amp off and an instrument cable pugged into the input, measure the resistance from the tip of the cable to the chassis....

It is a common thing to miswire the input jack so that the incoming guitar signal does not have a ground reference and is floating. This might cause what you are hearing. With the amp off and an instrument cable pugged into the input, measure the resistance from the tip of the cable to the chassis....

I did a pop test on the plates, going from the power tubes back to V1 (to localize where my issue is). My plate on V1 is noticeably quieter than the other tubes, so I’m clearly having an issue somewhere near the front end of the signal.

I wonder about the output transformer. Perhaps it was damaged by the same high current that took out the PT? Measure the DC resistance of both halves of the primary and see if they are reasonably close and in the right ballpark, say 50 ohms each side. You can then put some low voltage AC through it...

Corrected the output jacks, put a set of new EL34’s in and biased them, and while I’m getting more signal, it’s still very quiet. Like no louder than moderately loud talking. And it’s pretty muffled too.

Any ideas?

martin manning wrote: ↑Wed Dec 14, 2022 3:08 pm Yes. The speaker should be the only load connected to the secondary, and the unused taps should be open (unconnected).

Beautiful. I’ll make the revision and report back!