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New/ different Preamp for RD-100?


Jay Maria (jaymar)
Username: jaymar

Registered: 01-2012
Posted on Monday, January 30, 2012 - 12:29 pm:   

Hi- I have a RD-100 that I like alot- I maintain that it has a clean and bottom-end sound that I have never heard matched, and over the years I've been thru a Fender, a Marshall, a Mesa, a Randall (tube), and a Vox AC30. So that's saying alot!
However, I dislike the ss front end. Can someone recommend a circuit for a new pre-amp, considering I'd like to add a 12ax7-based drive stage? I'm looking for a classic sound, like the lead sound on "Reelin In the Years". Anyone have an opinion? Also, can I take the simple approach of building a new preamp and routing the signal right to the point on the circuit where the "pre-amp in" jack is? Thanks in advance for any insight. I haven't done this before, but am attracted to the challenge of it. Any pointers at all are welcome.
Lars Verholt (lmv)
Username: lmv

Registered: 11-2009
Posted on Monday, January 30, 2012 - 06:03 pm:   

I may be stating the obvious, but why not just use a good OD/Distortion pedal in front of the amp? The sky's basically your limit on what kind of sound you can obtain that way. My personal favourite is the BK Butler Tube Driver family of gear, but that's just my taste. Tube Screamer, RAT, XXL, Fulltone, EH, MXR, Line6, DS-1 - you name it.

Those of us who use the dual channel MM amps have been doing this for years :-)

Lars Verholt
Mike Kaus (mm210)
Username: mm210

Registered: 05-2006
Posted on Tuesday, January 31, 2012 - 05:51 am:   

Remember that the RD's(and all of the SS driver amps) are cathode driven amps so the drivers are really different from the start. I agree with Lars, why not just pedal it? Yes, you CAN add anything you want-it's your amp but why try to re-invent the wheel? I use various drive peals, all modified of course and the favorite right now is my Boss BD2's that have been modified. The mods are pretty simple and involve changing the caps to allow more bass and drive without sacrificing tone. Also the diodes used for grit are changed in different ways. One is set up for a rythym crunch and the second is for the balls to the wall solo and they ARE used together at times. I've modded cheap ass DS1's to sound really good too so it's not really expensive to get a good sounding pedal for the MM's. The ds1's get a little loud when modded so I have to work out a tamer downer for it but it IS controleable, just touchy.
Jay Maria (jaymar)
Username: jaymar

Registered: 01-2012
Posted on Tuesday, January 31, 2012 - 06:35 pm:   

Thanks both for your replies. I do use pedals and intend to for the future. My rd-100 currently has some problems, and since I have fixed it before, I'm pretty familiar with it. I love to tinker/build, so I thought as long as I am going in there, I might spend some time and try something really unique. I am looking for a project...like I need another.
I am attracted to the preamp design of the old Orange Graphic, with the rotary selectable capacitor chain. I appreciate your advice, I will check all your pedal recommendations!
Ed Goforth (ed_goforth)
Username: ed_goforth

Registered: 06-2006
Posted on Tuesday, February 07, 2012 - 10:41 am:   

Christopher Weldon (csweldon)
Username: csweldon

Registered: 08-2011
Posted on Monday, November 28, 2011 - 05:52 pm:

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Hey Everyone! I recently had my 110RD-50 worked on by Ed Goforth and wanted to share my experiences with you all. If you want the abridged version, I'll keep it simple: He does fantastic work, and if you're on the fence about having any mods done just do it - you'll be happy you did!

Now, the long of it...

Last September, I picked up a 110RD-50 and was pretty smitten; light enough to carry in one hand, loud enough to gig, Fender lineage... If it weren't for the ratty distortion channel and spikey high end, it would've been pretty much perfect! I read a few people's threads on Ed Goforth's work and decided to contact him.

Even before I opted to send it his way, he was very knowledgeable and answered all the questions I had. Very nice, since I had A LOT of them haha He told me about all the mods he could do, (which is NOT a small list) and the prices were more than reasonable. In the end, he
-replaced/upgraded my filter caps
-updated my driver section for more response/punch
-modded my distortion channel/changed the footswitch's reverb button to a gain boost
-Modded my clean channel
-upgraded the rectifier using FREDs

The result? Easily THE BEST tone I've ever had!

The clean channel is clear and articulate, with an excellent midrange character. He somehow found the perfect midrange voicing for what I wanted, and I'm VERY particular about how much mids I like! The bright switch is actually useful now; not too extreme, I usually use with my neck pickup and it makes the sound just a little more glassy. If all I had was this channel I'd still be really pumped!

The drive channel has a much better range than before the mods. It can actually be used as a second clean channel, which is kinda how I set it for my band. With the gain set to 3 or 4 it's like a slightly hairy, thicker clean channel. Leads have UNREAL levels of sustain! Kick the Gain Boost on (which can be adjusted with a trim pot in the back) and it's otherworldly! It's almost enough to make me start another band so I can play more lead haha

The treble is still present, but it's much smoother. Not a trace of ice pick to be found!

Both channels take my pedals MUCH better than before, too. I didn't think it took distortion pedals very well before the mods due to the harsh high end, but now it sounds fantastic!

The biggest surprise, though, is how HUGE the amp sounds! I honestly have to keep reminding myself that it's only a little 1x10 combo. When I played my first gig through it my friends were all astounded! "You got that sound from THAT?!" My one friend said it best, though: "When I walked in, I had to double check the stage. If I didn't see for myself, I wouldn't have believed there was only one guitar being played!"

If it's not obvious, I'll say it again: I am THRILLED with the work Ed's done. His communication before, during, and since the mods have been second to none - he's a true professional that REALLY knows how to get the most from these amps!

Anyway, I just wanted to share that for anyone who's been wondering about his work. Now: back to playing!