req for opinions on amp intermodulation prob (tone clip)

[dylan]

at some point in modding my valve junior its developed this problem where any time i play more than one note its generating extra ghost notes.

ive undone each mod one by one and tested, nothing fixes it, ive changed valves, cables and guitars, has no effect.

here is a tone clip of a diad bend that clearly shows the problem - the way the extra note plummets in pitch as the bottom note is bent up makes me think its an amplitude modulation issue...

modulation problem.mp3

modulation problem clip

(74.31 KiB) Downloaded 115 times

btw when you look at the clip the wave is not centered vertically , it seems to have a dc offset. could this be the problem?

any info much appreciated,

[sirvill]

Woah... that is weird!!

[dylan]

ive been testing my other amps for this issue - on my pignose i get the same effect, but its much reduced in volume, just a tiny swoop under the notes.

same with my jansen bassman 25 - the extra tone is audible, but super quiet.

on my marshall solid state bass combo i cant hear the extra tone at at all.

plugged into my audio interface instrument input i cant hear the extra tone either.

[tubeswell]

You probably goosed up one or more of the trace pads while taking stuff on and off the PCB.