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Recommend Drive Effect?

5/13/2004 4:07 PM
Recommend Drive Effect?
I'm looking to get a nice heavy 'Marshall' crunch tone. I had planned to build my own amp (AX84 High-Octane) but right now I can't tie up my resources on that big of a project and do it right (read: I'm about to get another guitar and the wife isn't too happy). So I figured I could whip out an OD/Dist pedal to get me by until I can get the amp project going. Right now I have a Boss HM-2 and a Fender Champ. Do I have a chance of acquiring that Marshall OD tone without a real driven preamp? I see tons of great looking effects designs out there but short of building each one and playing with them there is no way for me to know. To all you effects junkies out there: what do ya think?
5/13/2004 4:50 PM
Stephen Giles
Just tie some lead to it - then it'll be heavy!
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5/13/2004 5:22 PM
Ben N

" Do I have a chance of acquiring that Marshall OD tone without a real driven preamp?"  
Well, whatever you mean by "heavy Marshall crunch," you do not have a chance with an 8" speaker in an open-back cabinet. Champ can sound terrific overdriven, IMHO, but nothing like a Marshall.  
If you want more drive than you get just by cranking the amp, check out the "tweed" mod, which adds a switch to lift the tone stack (usually a pull switch on the volume pot). If you want something to push the amp harder, you should probably think about an overdrive that rolls off low end, like a Tubescreamer, or has a bass control, like a Marshall Guv'nor or Drivemaster. Anything full-bottomed will make the amp fart out.  
You may also want to check out several amp emulation pedal designs at, with mp3 samples so you can check them out. Of course, you should try to get a clearer idea of what you want, since "heavy 'Marshall' crunch" is not very specific--there are a lot of different Marshalls out there, all known for their "heavy crunch", but sounding very different.  
5/13/2004 5:52 PM
The champ is optimized for that chimmy fender sound. When overdriven, it doesn't sound like a Marshall. You can resolve that by doing the following mods:  
1. Change the 25uf cathode bypass on the first stage to .68uf, being a critical value in most Marshall amps.  
2. Remove the cathode bypass completely from the 6v6 so that only the biasing resistor is in the circuit. This will simulate the sound of the cathode follower circuit that gives Marshalls their hard driving tone.  
3. Consider jacking up the voltage on the 6v6 output tube by substituting SS diodes for the 5y3.  
4. Change the plate load resistor on the first stage from 100k to 150k to increase the voltage gain so that the rest of the amp gets driven harder.  
5. Connect a 12" celestion to the speaker output.  
Holy Shit! ... it now sounds like a Marhshall when overdriven!  
5/13/2004 10:08 PM
Mark Hammer

People have had very good things to say about a number of the recent FET-based designs at, such as the Matchbox, and Thunderchief, as well as some of Joe Davisson's pedal designs, such as the Blackfire, and the slightly older, but still cherished BSIAB (Brown Sound in a Box), which you can find at  
Of course whether a pedal alone captures what it is you find attractive about a Marshall is another matter entirely. That being said, the pedals mentioned above are proven and inexpensive designs, well-received, favourably compared to the sound you say you want, and do not require anything terribly exotic in the way of materials.  
As an aside, one of the things I keep wondering about is whether any of the "magic" people find in a 4 x 12 stack could be emulated by means of a cheap subwoofer installed into an existing amp/cabinet and powered with a separate amp. I'd be curious to know whether the spare 4" subwoofer I have could be paired up with an 8" speaker and sound a lot "bigger" without necessarily being dramatically louder or physically larger. Having a 4 x 12 sound and feel at low volumes in a portable package is a nice vision.
5/14/2004 6:09 PM
Ben N

Interesting idea about the subwoofer. I have had the same thought and never done much about it--well, I did pick up a cheap powered subwoofer intended for a PC sound system to mate with my Champ, but it won't really work without a decent preamp (not attenuated speaker, but preamp) line out. I still don't think it will sound like a closed 4x12--the diffuse sound of the open back 8"  
is too different for that--but at least it ought to fill in the bottom some.  
5/16/2004 11:35 PM
Steve L

There are pedals that might help. Some of the commercial ones are as expensive as the AX84 project, so don't imagine that they are in the running (like the Hot British). But, there is a pedal that supposedly emulates a Marshall 18 Watter, and the clips sound pretty cool. Check out the one called Eighteen, near the bottom of the page.  
He also has a Tweed version (Princeton clone).  
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