From alighto–(at)–ualcomm.com Wed Nov 23 18:51:18 CST 1994
Article: 33025 of rec.music.makers.guitar
Path: geraldo.cc.utexas.edu!cs.utexas.edu!howland.reston.ans.net!vixen.cso.uiuc.edu!qualcomm.com!NewsWatcher!user
From: alighto–(at)–ualcomm.com (Al Lighton)
Newsgroups: rec.music.makers.guitar
Subject: mesa Vtwin volume mod FACTS
Followup-To: rec.music.makers.guitar
Date: Fri, 18 Nov 1994 08:57:01 -0800
Organization: Qualcomm
Lines: 39
Message-ID:
NNTP-Posting-Host: alighton-mac.qualcomm.com

I got this info right from David Goodman at Mesa Boogie. I have
incorportated this mod and it works.

As many of you V-twin owners are aware, the volume boost from blues to lead
is unuseable. Maybe later versions were fixed, mine was definitely way to
loud in lead mode.

If you open up the vtwin, you can replace 2 1/4 watt resistors to bring the
voume down to just a small boost over the blues volume by changing
resistors R11 and R12. R11 is a 1 Meg ohm stock, install a 220k ohm in its
place. R12 is a 100kohm, install a 120kohm resistor in its place.

R11 and R12 are located (as viewed from the playing position) just below
the gain pot, just above a small 3 lead transistor, about 1-1.5″ from the
left edge of the PWB. The resistors are side by side, kind of straddling
the small transistor.

I performed the mod, it works about right. It is possible that you could
lower R11 a little bit more, since there is still a reasonable volume boost
to the lead channel. If all you want is a gain boost, but not a volume
boost, lowering R11 a bit more might work I have *not* tried that.

Be careful, the annular rings on the circuit card are quite small and it is
pretty easy to lift a pad. I suggest clipping the original resistor in
half and pulling each side out individually to minimize strain on the pad.

There is an amazing amount of solid state parts in a V-twin. And a very
high parts count overall as well. And the thing is a bitch to take apart
and reassemble.

Mesa told me they would do the mod for free for me if I paid shipping both
ways. If you are a clutz with a wrench of soldering iron, take them up on
it.

—
Al Lighton
[alighto–(at)–ualcomm.com]