Mark III Lead channel!

[Reeko81]

Hi! Is it normal that after the crunch volume mod my lead channel has so much feedback (it's a larsen effect??), also with the guitar volume opened but without playing it?I use a fender strato with a seymour duncan hot stack in the bridge.
These are the setting i use.
Volume: 8shift
Treble: 7 shift
Bass:4 shift
Middle:3
Master:2 shift
Lead drive: 8
Lead master:2 shift
Presence:7
I don't remember if before the mod the amp was much quiet, so could anyone check if it is so in your amp?
My mesa is a mark III blue stripes simul class.

 

[vcamargo99]

I'm not sure what the Crunch Volume Mod is. Is it the R2 mod, where a POT is added to adjust the clean/crunch volume difference? If so, I did the R2 Mod several months back. I have no issues other than I can now switch between all channels (good issue!). If it just started, and you've traced your steps ti make sure it was done properly, try swapping out V1 with another 12ax7. Perhaps it's a preamp tube issue. Just a suggestion.

 

[axwielding1]

Mine doesn't squeel either... Probably a pre-amp tube...
ax. :twisted:

 

[jnapo]

I seek enlightenment! Where would I find information about the R2 / Crunch Volume modification? I would like a description of the problem that solves and then I would like directions on how to complete the modification. If you guys are talking about what I think you are talking about I would love to update my Mark III because I have never been able to use my Crunch channel because it is so much loader than the clean. Thanks