Bright cap mod to MKIV 2nd channel

[jamme61]

I added a 100pf bright cap to the rhythm 2 gain pot. This cap isn't noticeable when you pull out the gain pot, but, I use channel 2 for blues to classic rock, so I don't pull the gain pot out. With the gain pot in, and the 100 pf cap on there, it acts like a bright cap on an old fender. To me it adds just the right amount of cut and sparkle, I'm looking for. Also now when I switch from channel 1 to 2, channel 2 doesn't sound like mud anymore. Again if you run channel 2 pulled out, don't even bother with the 100 pf cap, you won't hear it. I think if you're using channel 2 like me, not pulled and only about on 5 (blues classic rock sound) then you might want to try this mod out. You just have to run the cap from the middle post to the outside post (the one that isn't grounded) and you can hear it for yourself. Be careful when soldering not to use to much heat, or you will fry the pot. You can also try different values, 100pf worked great for me.

 

[Blueshaggis]

Interesting........did you find you didn't have enough highs even
with the R2Treble and Prescence controls dimed then or what? Or
is it a completely different sound? I'd be curious to hear more about
it as well as your settings both before and after the modification.

 

[jamme61]

before the cap I had plenty of highs, and only ran the treble for R2 on 3 and presence on any where from 0 to 4 also the gain pot was pulled. The sound just always seemed buried in the mix, if you will. R2 would sound great and then I would play on R1 for a while, then when I switched back to r2 it would sound buried with no cut. I also had a problem with not liking what I was hearing with the treble on R2 being put to high. Right now my setting for R2 is 5 on the gain(not pulled) 2 on bass, 2 on mids, and 3 on treble, presence is at 4. The only difference from before the cap is, I don't pull the R2 gain out anymore and I run it at 5 instead of 3. I'm also running the amp on class A with el34's on the outside and 6l6's in the middle. I'm also running the amp at tweed power. The big difference for me is a nicer smoother distortion from R2 that sounds good even when I switch from R1. Before i settled on anything I use two alligator clips and tried different caps to see what if any that I liked. i have an old 1967 fender black face bassman head that only uses a 47pf cap, but it still makes a difference. I have a ton of Marshalls that use the bright cap to the extreme, but to me the MKIV is all fender and a little goes a long way IMHO. one last thing is I'm trying to run my channel volumes as high as I can. There's debate on this, but to my ears, after going back and forth, I think the amp sounds best with the channel masters high and the main master low. I'm running my channel masters at R1=10 R2 = 7 R3 +7 and the main master at 1.5 to 2 .