My take on the Distortion+

[Max]

OK, nothing fancy, classic distortion circuit from MXR. But.
I had a look at the mods proposed here and there, I tried some and decided I didn't like them.
Two of the mods (bass and compression) were very subtle (i.e. I couldn't hear the difference) so, I discarded them. And I didn't like the way the tone control was implemented: instead of a potentiometer in series to ground with the shaping cap before the volume pot, I replaced the 10k resistor at the op-amp output with a 10k potentiometer, and put a capacitor on the centre pin of the pot to ground. Actually, I put two caps, with an on-off-on switch, so I can have two settings or disable it entirely.
Then the diodes: since I'm dumb, I misunderstood the circuit, and the result is unexpected: I have an on-on switch that connects the diodes EITHER to the op-amp feedback (soft clipping) or to the output (hard clipping), but I can't have them together. Plus, and here comes another mistake, I ordered the wrong switch, an on-off-on instead of an on-on, so when it comes to switching diodes types I have three options:
- fully symmetric (parallel of 2 1N34 in series)
- "slightly" asymmetric (parallel of 2 1N34 and 1 1N4148 + 1 BAT41)
- "very" asymmetric, that is, 2 1N34 in series to ground only.
The effect is very pronounced, also the tone control is much more effective. I think I tried a 741 and an LF351 as opamp, but I don't remember which one I left in, I suspect the 741.
Ah, yes, the graphic: I didn't really know what to do so I made this sort of faded grey&white which includes part of the schematic.
OK, enough talking (or writing... or reading? whatever) here's a couple of pictures (and the final schematic, maybe it's clearer than my attempt at explaining it)
Ah, there's a lot of space in the top of the enclosure because it's recycled from another project.
Enjoy!

[jimilee]

Wow, that's damn fine. Nice mods.


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[3tonesnd]

Wow

I really like the switching clipping stage
What effect does 2 diodes in parallel to the ground produce?

I want to build something like this, but with switching between diodes and FETs, something like Fulltone FullDrive 2

[Max]

Well, when the switch called symmetry is in the OFF position you only have 2 diodes in series to ground, that is D2 and D3. The result is that you're clipping only one half of the waveform. It's sensibly louder than the other two settings but not so distorted, since half of the waveform is untouched (or should be). I should make a little demo of this one, maybe tomorrow I have some time to do it.

[EBK]

What does the ground lift switch do?

[cooder]

Very nice, great graphis too that remind me of function f(x)... 
Mods sound like happy accidents, well done! I'm also curious how you find the usefulness of the different settings and stuff, a demo would be great! Cheers!

[sjaustin]

Great looking build! I like those flat bat toggle switches. Where'd you get them?

[Willybomb]

May I suggest that next time you try a pair of back to back red LEDs across pins 1 and 3 of the gain pot as well as the clippers to ground, and change the gain pot to a 1MegC?

I did that with my Bass Bomb and Darth Punk builds, and it really takes it to a new level of distortion.

[Max]

What does the ground lift switch do?

It was an experiment: I'm using a daisy-chain for some of the pedals, depending on the current drained, and I was afraid of some possible ground loops. The ground lift was an attempt to prevent these loops disconnecting the negative of the power jack, but in the end it's not necessary.

Great looking build! I like those flat bat toggle switches. Where'd you get them?

Musikding.de

May I suggest that next time you try a pair of back to back red LEDs across pins 1 and 3 of the gain pot as well as the clippers to ground, and change the gain pot to a 1MegC?

I did that with my Bass Bomb and Darth Punk builds, and it really takes it to a new level of distortion.

Initially the gain pot was a 1M C, but I didn't like the response, so I changed it to a 1M A. It's possible I tried a linear as well, but I don't remember, this build is almost 1 year old 
As for the LEDs: I'm aware of that mod, I've read of a lot of people really happy with it, however, as it is now all the clipping diodes (in whatever combination) are either connected as hard clipping or soft clipping. It would be an interesting experiment by all means, but then in the soft clipping mode I would have all the diodes plus the LEDs connected on 1 and 3 of the gain pot.
As I understand it, the idea would be to have hard clipping diodes plus the LEDs as soft clipping, right?
I have the LEDs so I may as well just give it a try 

[Willybomb]

It's interesting you didn't like the C taper.  On my vero build all the gain was either minimal or flatout, possibly in the last bit of turn.  When I swapped to the C, the gain increase was smooth through the whole throw, surprising me so much that I now use C tapers in the gain pots for all my builds.  But, that was just my experience and it wasn't how it worked for you, so that's cool.

You could, feasibly, possibly... for another version of this.... and you might want to look at my Magnum Opus build as an example, have separate hard on/off, soft on/off, and clipping diode selection switches for both hard and soft.... but that way leads to madness.  Ask me how I know...

You could also make a dual channel version....

Dammit.  I was supposed to be taking a break from building pedals but now you've got me thinking again.

[Max]

Yeah, I know what you mean, it's a rabbit hole. I wanted to reuse an old enclosure that already had the holes for three switches, so the options were limited.
Luckily