A question about my Mark III.

[Vilhelm J.S Bachstein]

Hey guys,

For just over a year now, I've had a Mark III green stripe long head that's fully loaded. It's a wicked sounding head, but I find that Rhythm Two is a really weak sound, and I don't like it. I considered selling it, and getting a Mark Five, but before I do that, I was wondering if anyone can give me a diagram of how to do the stacked R2 Gain/R2 volume mod in place of the empty hole in the back (Normally the location of the Reverb on the short head). Thanks.

 

[rvschulz]

if you mean a "weak" sound as in you have issues with balancing the R2 volume with R1 and the Lead channel - welcome to the club. I don;t know anyone who doesn't want to make this a 3 channel amp. I did this. on both of my Mark IIIs.

You need to look up the R2 volume mod. I am not an experienced electronics modder, so I bought a couple of Volume pots directly from Mesa, and had a local Amp guy do the mod. He wanted to get schematics, review everything ... blah, blah, blah. I printed the photos in the thread, brought them to him with the amps and told him "do THIS".

i think your only question is how/where to place the R2 pot. others on the board have gotten a "double pot" with an inside and outside control ... very cool and wish i had thought of it myself. i had a place on the back of each amp where a control could have been but was not = i think on the long head it is the simulclass switch which is on the front, and on the combo it is the reverb (no reverb on the combo).

good luck.

 

[Vilhelm J.S Bachstein]

if you mean a "weak" sound as in you have issues with balancing the R2 volume with R1 and the Lead channel - welcome to the club. I don;t know anyone who doesn't want to make this a 3 channel amp. I did this. on both of my Mark IIIs.

You need to look up the R2 volume mod. I am not an experienced electronics modder, so I bought a couple of Volume pots directly from Mesa, and had a local Amp guy do the mod. He wanted to get schematics, review everything ... blah, blah, blah. I printed the photos in the thread, brought them to him with the amps and told him "do THIS".

i think your only question is how/where to place the R2 pot. others on the board have gotten a "double pot" with an inside and outside control ... very cool and wish i had thought of it myself. i had a place on the back of each amp where a control could have been but was not = i think on the long head it is the simulclass switch which is on the front, and on the combo it is the reverb (no reverb on the combo).

good luck.

I know users Jay and Joey. B did a stacked gain/volume mod, but I can't decipher how to wire it from the pics they posted...

 

[JOEY B.]

I know users Jay and Joey. B did a stacked gain/volume mod, but I can't decipher how to wire it from the pics they posted...

It is a stacked presence control/Rhythm 2 Volume pot mod. The yellow and buss wire are the factory presence leads. The two fat red wires are the R2 Volume, wired in after resistor R130 was cut out. See picture 2. Solder the wires to the front terminal where R130 used to be and to the righthand terminal of R131, when looking from the rear of the chassis.