Musicman RD-50 112 mod

[buckeyesound]

hey -- i'm interested!

I just checked the musicman site and saw that someone had posted a reply to my posting suggesting I should look at your mods.

From looking at your mods, it appears that you have toned down the gain in the limiter channel? and, brightened the amp?

My biggest concern with the amp is that I find the limiter channel to be loose in the lows. I've modified my tone stack to mirror the clean channel, which addressed the amount of mids and i've changed the filter caps from 60uf to 100uf and 2uf to 4uf. My lastest mod makes my limiter channel like the specs on the last rd50 model. I like this best of all with a 12dw7 tube rather than 12ax7. But, I still think the lows have flabby.

I'd like to know more about why you made the changes you did. I think i follow the idea. Otherwise, I love this amp.

[BobW]

For all the schematics you've shared with everyone Steve? No problemo, I'm glad to share this one. btw, my amp was an early REV A version.
thanks, Bob

[Steve A.]

BobW

I took your post and added the schematic, and voila! magically converted it into a PDF file:

http://www.blueguitar.org/new/schem/...m_rd50_mod.pdf

If that doesn't meet with your approval I can delete it.

Thanks for posting your mods!

Steve Ahola

[BobW]

No replies? I guess no one else has an RD-50?

[BobW]

All,
I'd like to share some of the mods I did to smooth the harsh top end of the Limiter channel typical for Musicman amps. In general, changed the V1a and b stages per the *umble OD stages.
In Particular:
1. disconnected the cathode grounds and ground leads from C10,R12 at V1-8.
2. Added a 5uf and a 1.8k at V1-8 and connected the grounds to the C10,R12,ground node.
3. replaced plate resistors R9 (470k) with a 180k, and R11 (4.7M) with a 150k.
4. replaced R10 with a wire jumper.
5. removed grin wire at V1-7 and added a 150k series grid resistor.

Initially also added a 470pF across the Clean Vol pot, and a 1000pF across the Limiter Vol Pot to smmoth the harshness at all vol levels in either Clean or Limiter mode.
The amp is much more useable and it definitely earned it's keep at last weekends gig. BobW