Mark III Ghost Notes (help!)

cardinal · Jan 24, 2021

Hi all,

Im hearing loud ghost notes with a Mesa Mark III. It did it with two sets of power tubes, and I think I've swapped around the preamp tubes. It does it in either channel, whether or not it's in Simul or class A mode.

I thought maybe it was something to do with electrolytic capacitors? So I've replaced all the ones circled in red (including the big black ones underneath to the right):

This made no difference, but at least didn't make it worse.

There are some additional electrolytic caps that I haven't replaced: notably, (1) that axial black one to the left, (2) a black radial one under the right-most power tube, and (3) and the pair of silver ones to the right. I don't know how to replace the axial one, and I can't find replacements for the others.

Any ideas what could be causing the ghosting problem?

Thank you so much!

Markedman · Jan 24, 2021

This may not sound right to some, but it could be a cable, most likely the speaker cable. This was my solution to that exact same problem, I thought that it was a tube also.

Or it could be your guitar?

cardinal · Jan 24, 2021

Markedman said:
This may not sound right to some, but it could be a cable, most likely the speaker cable. This was my solution to that exact same problem, I thought that it was a tube also.

Or it could be your guitar?

Thanks! I've tried a few different cabs and cables unfortunately.

cardinal · Jan 24, 2021

oh, and I tried running just a preamp into the FX return, and the amp still exhibits the ghosting, so it doesn't seem to be a preamp problem.

Eevil · Jan 25, 2021

Just a thought...

I don’t know if it’s safe to test the amp without simul class tubes. If the pair is wired in triode (pre green stripe) that could produce some ghosting in tone (at least does in my XTC)

cardinal · Jan 25, 2021

Eevil said:
Just a thought...

I don’t know if it’s safe to test the amp without simul class tubes. If the pair is wired in triode (pre green stripe) that could produce some ghosting in tone (at least does in my XTC)

Hi! What does that mean: without Simul class tubes? It had four Mesa 6L6 tubes in it now. I've noticed the problem when the switch is in simul or class A. Thanks!