Mods for a Mesa Boogie Mk II B

The Boogie Board

Help Support The Boogie Board:

StratBoogie

New member
Joined
Feb 18, 2013
Messages
2
Reaction score
0
Hello. :) This is my first post. My name is Andrew, I have been a regular at the Seymour Duncan forum for about 4 years (under user name Andrew Lamprecht).

I picked up a slightly beat up Mesa Boogie MkII for $500 about 4 months ago. I love the amp but the one thing I really don't like is the massive jump in volume when I have the volume on the clean channel all the way up. I keep the gain on the lead channel pretty low and the clean volume high, it gives me a nice sustained overdrive that I really like. however, having the clean volume up all the way makes it a bit difficult to switch back and forth between channels. I was a Fender amp guy and really like the clean channel of this amp... I would like to utilize it if I could but I really need the lead channel. :mrgreen:

Are there any mods I could do that would help this? I don't know much about amps so I have no clue. Someone on the Les Paul forum said to put a volume pedal in the effects loop, again, I don't know much about amps so I don't know if this would work and I don't want to spend money if it won't work (I'm a college student).

Sorry if I said something stupid but even after a few months I am still working on getting how the knobs work straightened out. :mrgreen: This is my first Mesa... any help would be greatly appreciated... thanks guys!
 

mark2boogie

Well-known member
Joined
Jun 2, 2011
Messages
273
Reaction score
0
Location
France
StratBoogie,

There is a little mod which can be done to your MKIIB, without destroying anything even the value. I have done it on my IIA and IIB, and indeed I wouldn't go back.

But I am not sure that it is what you are searching for, since that in your explanation, you do not use the correct frontpanel potentiometer denomination to understand the problem, nor mention the settings that you use.

Nonetheless :

> the MASTER 1 pot is wired as a rheostat, not like a conventional potentiometer. Why did MESA done that, I don't know exactly, I have only suppositions... But this gives 2 problems :

- the MASTER 1 and LEAD MASTER are inter-dependent, making volume balance between LEAD and CLEAN variable with MASTER 1 re-adjustment needs.

- the MASTER is not progressive : you reach quickly full volume, and its done.

Rewiring the MASTER 1 as a conventional pot, will radically eliminates the 2 problems above, and I do not experimented any drawback from that. So it is worth to have a try...

TiPiMods and may be McBarry have followed my advice and can confirm. Here is the local schem of the mod, derived from the well-known RS hand-drawn MKII schem :

858853master1rewiring.gif


A+!
 

dino2sf

Well-known member
Joined
Feb 4, 2011
Messages
48
Reaction score
0
Send it to Mike B at Mesa for the effects loop mod. You will love it after that. See my thread from after I had it done:

http://forum.grailtone.com/viewtopic.php?f=27&t=51959
 

gonzo

Well-known member
Joined
May 29, 2007
Messages
2,003
Reaction score
0
Location
SL.UT
mark2boogie said:
StratBoogie,

There is a little mod which can be done to your MKIIB, without destroying anything even the value. I have done it on my IIA and IIB, and indeed I wouldn't go back.

But I am not sure that it is what you are searching for, since that in your explanation, you do not use the correct frontpanel potentiometer denomination to understand the problem, nor mention the settings that you use.

Nonetheless :

> the MASTER 1 pot is wired as a rheostat, not like a conventional potentiometer. Why did MESA done that, I don't know exactly, I have only suppositions... But this gives 2 problems :

- the MASTER 1 and LEAD MASTER are inter-dependent, making volume balance between LEAD and CLEAN variable with MASTER 1 re-adjustment needs.

- the MASTER is not progressive : you reach quickly full volume, and its done.

Rewiring the MASTER 1 as a conventional pot, will radically eliminates the 2 problems above, and I do not experimented any drawback from that. So it is worth to have a try...

TiPiMods and may be McBarry have followed my advice and can confirm. Here is the local schem of the mod, derived from the well-known RS hand-drawn MKII schem :

858853master1rewiring.gif


A+!


i never knew this about the master/rheostat setup...

that so makes sense.


damn.


now i gotta mod it.......

gotta mod it.....

mod it.....

it.
 

gonzo

Well-known member
Joined
May 29, 2007
Messages
2,003
Reaction score
0
Location
SL.UT
is there a preference for make and model of POT to change out for this mod?
 

mark2boogie

Well-known member
Joined
Jun 2, 2011
Messages
273
Reaction score
0
Location
France
gonzo said:
is there a preference for make and model of POT to change out for this mod?

I am not sure to understand what you mean here, but in fact you do not need to change any pot : stay with the original CTS pot and just rewire it...

A+!
 

McBarry

Well-known member
Joined
Jul 9, 2009
Messages
387
Reaction score
0
Location
Canberra, Australia
Hi,
do the mod to the existing pot as Bruno's picture above.
I've actually got my 100w IIB on the bench - send any Q's as it'll be open for a few days..

And agreed, the volume spread is more even..

I'm even planning to do it on my main gigging IIB shortly...

FWIW, I strongly suggest U read Bruno's IIB thread - there is a wealth of info and great detailed pictures.


DB
 

StratBoogie

New member
Joined
Feb 18, 2013
Messages
2
Reaction score
0
Thanks guys, what I have been doing is using the lead channel with not much gain and boosting it with either an old 77 ross distortion, or another one of my dirt pedals. Then when I want cleans I turn the pedal off and turn the vol on the guitar down to about 7 and I get a nice warm clean sound.... These mods have me interested however, I will have to look into them, it would be nice to just take a strat and the mesa to a gig.... thanks for all the help guys!!
 

gonzo

Well-known member
Joined
May 29, 2007
Messages
2,003
Reaction score
0
Location
SL.UT
McBarry said:
Hi,
do the mod to the existing pot as Bruno's picture above.
I've actually got my 100w IIB on the bench - send any Q's as it'll be open for a few days..

And agreed, the volume spread is more even..

I'm even planning to do it on my main gigging IIB shortly...

FWIW, I strongly suggest U read Bruno's IIB thread - there is a wealth of info and great detailed pictures.


DB

thanks mcbarry...
is there another thread other than this one that delves into the mod?
do you have a link to this "Bruno IIb thread"?
 

mark2boogie

Well-known member
Joined
Jun 2, 2011
Messages
273
Reaction score
0
Location
France
Thanks McBarry (& Cheers...)

gonzo,

Here is the linl for my MKIIA, where (AFAIR) I spoke about the Master1 mod :

http://forum.grailtone.com/viewtopic.php?f=27&t=54614

A+!
 

mark2boogie

Well-known member
Joined
Jun 2, 2011
Messages
273
Reaction score
0
Location
France
And here is the one for my (now sold) MKIIB :

http://forum.grailtone.com/viewtopic.php?f=27&t=59554

A+!
 

RobXK120

New member
Joined
Apr 29, 2013
Messages
1
Reaction score
0
I simply had my techie add 2 Pots into the "Volume 1" circuit, and switching between the two via relay activated through the footswitch. Voila! total control of the volume in switching between Lead and Rhythm without any change to the characteristics of the amp. Volume 1 now acts as a full master volume. You can have no idea how much easier it made this amp to set up and to control!!

The two new pots are placed where the heat sink on the back of the amp was, so that the amp can be reconfigured, the heat sink replaced and no one would ever know that it had ever been modified! The heat sink doesn't seem to be near anything hot in my 1982 60watt + reverb IIB amp, and appears to be for aesthetics alone.

I tried to attach pictures, but havn't worked out how, just yet. apparently I need to download them to a publicly available server (where do I get one of these?).

Sadly, I have just bought a Limited Edition (62 of 75) MK V, and in order to appease my Best and Beloved (slightly), must part with the IIB after 30 years. Will be placed on e-bay in the next week or so (May 2013): pictures of mods should be able to be seen there.
 

lester57

New member
Joined
Mar 3, 2022
Messages
1
Reaction score
0
Can anyone send me a schem of the master 1 mod? The picture on the thread doesn't seem like its available...
 

Rmolina5

New member
Joined
May 22, 2018
Messages
1
Reaction score
0
Same. I am looking for the Master 1 Mod also. Pic above not available .
Will it address the volume on both clean and dirty. I hate when I dial in the my dirty channel then switch over to the clean channel and have to readjust volume.
Send here please.
[email protected]
 

Latest posts

Top