Recommend a Great-Sounding, Low Parts Count OD

[Ripthorn]

So I've got this project kicking around in my head that involves making up a tiny headphone amp. What I plan to do is an OD, cab sim, and Ruby-style power amp. I've built something like this before and built in an electra, but wasn't too happy with it. So now I'm looking for suggestions for a great-sounding, low parts count OD/Dist (not too interested in fuzz). I'm not looking for the electra or Bazz Fuss, but if you have an interesting tweak on it, then I'm all ears. It can be transistor, opamp, whatever, just looking for something that doesn't take up a bunch of space or have 4 or 5 transistors. So hit me up, what you got?

[PBE6]

At first I thought you were interested in putting a distortion pedal on a headphone amp, and I was like "neat...but wait, what?".  But I think you're looking to make an OD/distortion circuit to feed into a cab simulator that feeds into a power amp that will drive headphones, correct?  If so, "neat".

I like the Pro Co Rat a lot.  It's got a bass cut in the distortion section so things don't get too muddy at high gain, and besides the opamp's own distortion it also drives diodes to ground which I prefer over most other arrangements.  The MXR Dist+ is a simple and clever and design in that the bass is rolled off progressively as the gain is increased, keeping things nice and tight.  Both circuits benefit a little bit from using old low slew rate opamps which blunt high end transients, but I find the effect is relatively mild so don't worry about it too much if you can't find the original chips.  Add the appropriate pre-EQ and/or post-EQ to taste, feed it to your cab sim and I think you'll have a very useful headphone practice amp.

https://www.electrosmash.com/proco-rat
https://www.electrosmash.com/mxr-distortion-plus-analysis

[Strategy]

No matter how many dirt boxes I build I always go back to Red Llama / Hot Tubes / etc.
Lots of versions. Sounds awesome
- Strategy

[roseblood11]

Vox 1901 Distortion. It's just a variant of the DOD 250 / MXR Distortion+, but with some changed parts values to work better with the bright Vox amps, which should work with a headphone amp as well.

http://effectextra.blogspot.com/2010/06/vox-1901-distortion.html
https://www.korguk.com/voxcircuits/circuits/1901dist.jpg

Use a rev log pot for the gain control!

[Kipper4]

Nice to see you around Jeremy.

[Marcos - Munky]

So, how much gain are we talking about?

[snk]

No matter how many dirt boxes I build I always go back to Red Llama / Hot Tubes / etc.
Lots of versions. Sounds awesome
- Strategy

+1
The Red Llama is an easy build, low part count, and highly tweakable.

[bluebunny]

In another recent thread, I recommended Joe Davisson's EZ-250 overdrive.  (I reposted the schematic at the end of that thread: many of the pictures have long since vanished.)

[vigilante397]

Metal Zone MT-2. Obviously.

[Ripthorn]

I'm looking just medium gain, I don't need metal. Just something to spice up the signal of a guitar toted around.

[vigilante397]

I'm looking just medium gain, I don't need metal.

It's not low parts count either, I was just being facetious

[Ripthorn]

I'm looking just medium gain, I don't need metal.

It's not low parts count either, I was just being facetious

I was responding to someone earlier, I knew the metalzone was facetious I don't like it anyway

I'm looking for something no more than 3 knobs.

[Fancy Lime]

Can you tell us a bit more about what you want in terms of sound? The Tube Sound Fuzz / Red Llama ist great for relatively neutral and natural OD. But you may want some preset tone shaping for this application. Unless that is all part of the cabsim.

Andy

[MaxPower]

A simple Jfet source follower mayhap? Or ROG's fetzer valve sim, or whatever it's called.

[Ripthorn]

I love the Box of Rock, but it's a little high on the real estate/parts count side for this particular project. I searched for "simple" on the PCB and perf layouts blog and went through every post. Found a few that look promising. The Mr. Black BB-74x and the Black Cat OD-1 both look very intriguing. I think I'm going to breadboard up my headphone amp and cab sim and then just audition some circuits.

[287m]

clark gainster
zombie screamer
zen drive

dont know how much low parts count for you, but JanRay in 1590a is awesome. No need deep pocket too, hehe

[Marcos - Munky]

Me too suggest the Zen Drive. Mad Professor Sweet Honey is my favorite low to mid-ish gain od, sometimes I play a whole set without even turning it off.

[Ben N]

Agree with tbe CMOS based suggestions above, maybe the ROG UBEdriver. You can't beat the parts count, and you still have couple of inverters left to play with (filters or whatever).

[Ripthorn]

The zendrive looks good. I've worked up a schematic for the whole shebang and will start layout to see if I can make it work with through hole components. Of not, then surface mount it is.