Adding clipping to fatpants

[HKimball]

Would I connect the start of the circuit to the source of Q1 and then to ground? I imagine I'll need a capacitor in series with the clipping diodes to roll off some bass?

Also, (and this is a separate question) if I wanted to get Q2 to clip, would I increase the value of R9? I was reading about the jfet Vulcan and he uses diodes to prevent hard clipping of the transistors, would this be necessary/a good idea in this application?

To be clear I'm just curious. Thank you in advance for any and all help.

Edit: when I say curious I mean I'm definitely going to add this feature to the fatpants... I'm just not super well versed in circuit design so I'm uncertain as to how to proceed.

[midwayfair]

Put the diodes after the output cap to ground.

The only other reasonable place to put them would be at the gate of Q2, but you won't have anything more than your pickups driving them, so there won't be much if any distortion.

FWIW, you can tinker with the biasing and turn the fat all the way up and it'll distort with hotter pickups.

There are better circuits IMO for doing this, like pedals that are designed as dedicated overdrives. For one thing, there's no tone control or treble cut after the diodes if you just tack them onto the circuit, so it might not sound very good.

[HKimball]

Put the diodes after the output cap to ground.

The only other reasonable place to put them would be at the gate of Q2, but you won't have anything more than your pickups driving them, so there won't be much if any distortion.

FWIW, you can tinker with the biasing and turn the fat all the way up and it'll distort with hotter pickups.

There are better circuits IMO for doing this, like pedals that are designed as dedicated overdrives. For one thing, there's no tone control or treble cut after the diodes if you just tack them onto the circuit, so it might not sound very good.

Thank you for the help. That's one thing I was curious about - the buffered bypass is essentially just the first half of the circuit but I just barely know how transistors function in the abstract so I figured (after looking at a very simple circuit that used a single transistor to clip a pair of diodes) maybe there was a way to use Q1 to do the clipping and Q2 to amplify like normal. I'm hand on heart honestly looking up the difference between voltage, current, and resistance as I type this.

I've heard before that Q2 starts to clip some at the highest "fat" settings - I kind of secretly hoped that there'd be one or two components you could change (like in the jfet vulcan for example) that would up the gain of Q2 and allow you to use the "fat" control as a "gain" control.

Lastly I had found a dead-simple treble rolloff circuit which I was planning on using as a stand in for the "soft" switch. The whole concept was not dissimilar to something like a transistor-driven prince of tone, but with that just magical character you get with these echoplex-type boosts.

When my fatpants was half-working (something happened to the charge pump and it only ran on 10.6v) it was the best sounding pedal I had (charge pump #2 is in the mail)... I just was curious about how it would sound if it was a drive pedal itself. Really I need to just leave it well enough alone - just getting it to work in the first place was pretty impressive for a luddite like myself.

At any rate thank you again and my apologies for the long post. I frequently speak at length out of habit for no good reason... It's something I'm trying to improve about myself.