https://cdn.imagearchive.com/boogieforum/data/attach/4/4646-Mesa-Boogie-Mark-IIB-Lead-Bright-cap.pngI thought I pointed that out but maybe it was in another thread. I even posted pics with the info, did you see them?
https://cdn.imagearchive.com/boogieforum/data/attach/4/4646-Mesa-Boogie-Mark-IIB-Lead-Bright-cap.pngThat is V3 in the pic with details in Red
22uf was used in the previous stages but for the drive, you will get what you are experiencing, bass no treble... Like I said earlier, try a 2.2 if or even .22uf as in the pics you posted last week
Well it's not posting the schematic for some reason ...
In your earlier pic, I saw a 22uf cap, easily transposed from the factory, but should have been caught in final inspection.
This last link is a pic with the 226 (22uf cap) in question.
I'm not near my computer so I cannot just send the pics, I am pulling from our previous postings that clearly shows this
Greetings! I've been following this. Its been interesting and I've learned A few things. Don't mean to step on Edge59's toes, he is very knowledgeable. But that cap and resistor is just your basic cathode bypass circuit. Its mainly used to bias the tube. And to some degree add gain and frequency enhancement. They can be tweakable but best be left alone. Of course replace if fails. Most if not all preamp circuits have them. But be cautious of cathode follower circuits. They have high voltage present. Blessings.
Does your amp have Bass Shift? On amps with Bass Shift, when the bass knob is pushed in, the smaller, silver cap (usually .47uf) is the cap that is always engaged, with less bass/mud at higher gain settings, with the bass pulled out, it engages the bigger 22uf cap-more bass... Fuller cleans, lower gain, general rule if thumb, higher gain, less nmbass/mud
Agreed, but in his posted pics the cathode bypass cap is a 22uf, too big for a lead bright cap and easily mis-transposed, and cause too much bass/mud. If anyone is not experienced with tube amps, they really should find a tech to work on it and mentioned that there are deathly high voltages there, we cannot stress that enough, so my toes have not been stepped by any means
but I have been trying to help him understand what may be going on with his amp, I have been in these amps over 40 years and know a few things, not everything of course, I'm still learning but love to share what I can especially with those that don't have experience or someone near that can help. I repair and modify various amps and find something new or interesting all the time, and it happens sometimes that a component values gets transposed and gets through inspection, it's happened at the high end electronics companies that I have worked for, no one is perfect and we all make mistakes, especially me 
that 226 22uf cap that is connected to the lead bright switch normally is either a .22. If (224) or 2.2uf (225), 226 (22uf) as in the prevention stages. 22uf is too big a value in the lead bright switch location causing the issue of too much bass, it's no conspiracy by any means Ty my friend! Indeed! We all make mistakes. Boy, I have my share!!! I know a thing or two about amps. And thats about it!! I am no amp tech by any stretch. Theres this member on here that is very knowledgeable like you who has been instrumental in helping me. He is in the process of building kits. Yes, waaaay too bassy. My C+ has a .22 for the pull bright .Agreed, but in his posted pics the cathode bypass cap is a 22uf, too big for a lead bright cap and easily mis-transposed, and cause too much bass/mud. If anyone is not experienced with tube amps, they really should find a tech to work on it and mentioned that there are deathly high voltages there, we cannot stress that enough, so my toes have not been stepped by any means
Dang, I really, really wish I could help. My years of experience has only been a C + RP11A board. When I view your pics, I get kinda lost.
