MXR Distortion II...

jonathan perez · February 24, 2007, 02:38:12 AM

does anyone have any information on this sucker? any schems? clones? sound samples? blahblah?

thanx!

Meanderthal · February 24, 2007, 04:38:50 AM

I had one. It's weird sounding as I recall, but useful when stacked with other distortions or overdrives.

aron · February 24, 2007, 02:04:49 PM

I've always wanted to purchase one. Some people really like it. Something like that I'd rather buy than try and make.

Meanderthal · February 24, 2007, 05:50:52 PM

Yeah, it's pretty elaborate for a distortion. Only problem with buying one would be unless Dunlop reissues it you'll be forced to pay an outrageous $um for a distortion that will probably sound a whole lot different than you'd expect. With this one I'd suggest trying before you buy it to make sure you actually like what it does.

Processaurus · February 24, 2007, 08:52:04 PM

Anyone know what the "resonance" section doing? You sure don't hear about this one very much. Someone building could omit a few things invloved in the switching, maybe use a charge pump for the higher voltage PS. Unless it might work fine on 9v (don't see why a distortion would need "headroom")...

Torchy · February 24, 2007, 09:39:46 PM

Easier to read maybe ...

Processaurus · February 24, 2007, 09:47:23 PM

There's an error in that one, the feedback path if U1b's output to r12 is missing, right now it would act like a comparator. Also U2a pin 2 is the inverting input, and pin 3 the non-inverting input.

The resonance stage around U1b is weird, its a clipping stage of some sort, but the output is inverted from the clipped signal from U1a that it gets summed with at U3a. I don't get why the signal from R9 goes through identical sized caps to U1b's input and output, as its different than a typical opamp diode clipper. What kind of filtering does that do?

Some other thoughts looking at this: Filter looks just like the Rat filter. Also I don't see anything that wouldn't run fine on 9v, except maybe the headroom of U2a, but thats getting clipped immediately afterward anyway. Odd they used a cheapo 4558 as the input buffer rather than the TL072, and not use the 4558 for the Vref.

Meanderthal · February 24, 2007, 10:34:15 PM

Funny how a clean looking schematic makes stuff look a whole lot simpler...

Torchy · February 25, 2007, 05:28:55 PM

Corrections applied ...

scaesic · February 26, 2007, 10:37:22 AM

i built two of these and ran them off 9v, minus all that logic switching like tochys diagram. infact i think it was torchy who helped me out with it all that time ago. i think itd give you a lot more ehadroom if it was run off 18v but i havnt tried it, it sounds ok at 9v. i'm really not sure about the sound of it though, it's kind of a "messy" distortion, not fuzzy though.

i have a very similar cleaned up schem, although i did it about a year ago now.

the resonance basically brings in some subs, it acts as a blend between two clipping circuits with different fc's.

on it's own its a very grungey/nirvana bass heavy kind of distortion, i thought it sounded particularly good either with a tubescreamer in front of it both running at medium gain, or on it's own at low drive with resonance all the way up to bring in a low drive/bassy sound.

its probably obvious but you can just cut out all the stuff before and including vr1, i know i preferred to do that because i didnt want a psu built inside a pedal.

Meanderthal · February 26, 2007, 10:40:52 AM

Quotei thought it sounded particularly good either with a tubescreamer in front of it both running at medium gain

That's what I remember. Where this thing really whooped ass.

scaesic · February 26, 2007, 10:44:45 AM

Quote from: Meanderthal on February 26, 2007, 10:40:52 AM
Quotei thought it sounded particularly good either with a tubescreamer in front of it both running at medium gain
That's what I remember. Where this thing really whooped ass.

totally, it'd be good to try and build the best of both in one, either that or build a true bypass box and have them both in the loop. neither of which i can be bothered with anymore. for some reason i got a year long obsession with this distortion, and once i built it i decided i dont like distorted guitar. im on a quest for a super clean sound now.

Meanderthal · February 26, 2007, 11:07:07 AM

What's buggin' me now is the fact that I don't remember trying it on bass... at the time I was just not using effects on bass at all, I was going thru a 'purist' phase of my own. Wonder if this distortion somehow triggers that? Heh.

scaesic · February 26, 2007, 01:27:35 PM

i havnt tried it with bass, i suspect it'd just start farting out though. i dont use any effects with bass either though.

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MXR Distortion II...