Any Music Man amp modders in here?

[ken]

I was wondering if there are any Music Man amp modders or collectors in the forum. I went to the Music Man amp website, and their forum seems to be dead. I own an RD50 myself, and I'm looking for interesting mods for the amp.

thank you,
ken

[Enzo]

The first question would be: what do you want your mod to accomplish? What areas do you find the amp falling short?

[ken]

The main issue I have is the clean channel is much too bright, so I'm looking for a lowmid boost mod. I play with P90's and sometimes humbuckers, and I have to turn my clean channel's bass control up to at least 8 to get an even sound.

I love my MM because it's extremely loud for its size and very well built.

I've been to musicmanamps.com, but like I said the site seems to be dead. I found many mod ideas in their archives, but nothing for either reducing the clean channel's treble or boosting the lower mids.

ken

[Chuck H]

Looking at the schem I might try changing R19 to 1.5k and just lift one end of C23.

[ken]

Chuck, I have a schematic here and I can see how changing R19 works, but I'm gonna play dumb here. How would lifting C23 make that much tonal difference? It's only 50pf right now.

thank you,
ken

[Chuck H]

Your Q forced me to re evaluate the circuit. While a 50pf across a 1M resistor is well within the audio range, so you would certainly hear a difference, lifting that cap would actually make the amp BRIGHTER. The volume control looks to be a NFB shunt. So that cap is also a NFB shunt to roll off some highs. To mellow the clean channel a little you could actually INCREASE the cap value OR add a larger cap with a series resistor parallel to that 50pf cap to get a deeper effect but less of it, if you get my meaning. I'd experiment with cap values from 100pf to 1000pf and resistors from 10k to 100k.

[ken]

Chuck, I tried out your idea with a 360pf variable (AM radio tuner) cap and a 100K pot. Increasing the cap can drastically remove extreme high treble, sort of a presence control on steroids.

In the end I ended up just soldering a 47pf ceramic cap across the pot terminals to cut some of the 'beaminess' out while still keeping some sparkle in the clean tone.

I WISH the RD had enough room behind the pots to add pullpot switching! I'm thinking about how to move the PCB back about 1/2 an inch while keeping the reverb and footswitch jacks setup.

Thank you,
Ken

[sjturbo]

Ken, I just read your post and although I don't have your issues with my RD50 there are a couple of other mods you may be interested in. Check the following links.
http://music-electronics-forum.com/t204/, and http://music-electronics-forum.com/t24113/. Don't know if any of this will interest you but thought I would let you know they were there.