The beast distortion...(kind of)

[lars]

Recently I've been using a Gallien-Krueger Backline 250 bass amp head for regular guitar, and really like the sound. I was interested in what they were using for the "overdrive" circuit, since it's one of the most explosive distortions I've ever plugged a guitar into. You can get some serious heavy tones from it. Turns out, GK made that exact circuit into a pedal called the "Diesel Dawg". It's a ridiculously huge pedal (makes a 70's Big Muff look small). It uses a very unique clipping arrangement and has something like 7 gain stages! Since it was marketed for bass, I don't think many people have tried it on guitar...but it seriously rocks. Worth looking into.
Here is a vero layout for it:

[blearyeyes]

I used a GK G200 head for many years playing live.
Just bought one and built a 4x12 for my son.
I would love to see the schematic for their early guitar heads.
Loved mine and shouldn't have parted with it.

[oip]

what a monster

be interested to see how this compares to the deizel vh4 and be-od pedals.  the deizel in particular gets extraordinarily heavy.

[JackSkellington]

[...] I don't think many people have tried it on guitar...but it seriously rocks. Worth looking into. Be warned though:  no other high gain pedals sound good after you try this one.
[...]

Then we want a demo of this pedal with the guitar. No, seriously, we really want it, now.

[Willybomb]

This.  I am building this.

[lars]

[...] I don't think many people have tried it on guitar...but it seriously rocks. Worth looking into. Be warned though:  no other high gain pedals sound good after you try this one.
[...]

Then we want a demo of this pedal with the guitar. No, seriously, we really want it, now.

I was recently able to purchase one, so as soon as it gets here I will record a demo, and post some pics of it's ridiculous largeness.
*update 5/16*
The pedal arrived today, and I have to say, I'm disappointed in it compared to the amp distortion. I'll have to dig into the schematics a little deeper to see what things might be different (on the surface they look pretty much identical), but it just seems like the pedal doesn't have the Ooomph that the amp's built-in dirt channel has. A lot of this probably has to do with the pedal running on a 9v battery, compared to the amp which is getting a solid/regulated 15v to the overdrive circuit.
*update 5/18*
I found some differences between the pedal and the amp overdrive channel that would definitely affect the overall sound. First off, on the amp, it has a TL072 booster circuit before the overdrive that can slam it with 15db's of boost. I don't know why they didn't put that in the pedal, but it definitely reduces the explosiveness. The output cap on the amp's overdrive circuit is a big 10uf, whereas on the pedal it's a guitar-like small .1uf, so goodbye heavy bass. The big key I've found though is a single resistor (R18 on the pedal schematic) that is 1K to ground off the TL072 recovery stage after the EQ. On the amp schematic it is 220 ohms. By changing out that one resistor, it brings back a ton of the gain that the pedal should have to sound right. I've noticed now by making those changes, and then adding an overdrive pedal for clean boost in front of the Diesel Dawg, I can get it to sound more like the amp. I think eventually I will add in a daughter board with the 15db booster circuit from the amp into the pedal. There is plenty of room for it!
*update 7/12*
I found another key resistor change that can really take this over the top. The 1K resistor marked "R8" (it comes off pin 2 of the first TL072) really boosts the distortion as you reduce the value. I put in an 820 ohm resistor in that position, and now at max gain the distortion is pretty massive. At first I thought the EQ controls would be really nice to have, but ultimately I like the amp distortion settings, which are non-adjustable. In the amp schematic, the pots are just fixed resistors. I might mod it when I re-box it to just fixed eq settings. It wouldn't be the first time a circuit actually sounds better without an adjustable EQ.

[JackSkellington]

Great! We will wait.