Clari(not) Modifications

[benny_profane]

Hiya all. I'm not sure if there's still interest in this circuit, but I'd appreciate some advice here. I've been working on modifying the Clari(not) circuit. I've added an envelope/LFO modulation switch and a feedback path. I'm currently stuck on a gain switch.

Instead of the usual mod of cutting the connection between pins 1 and 8 of the LM386 (since there can be a loss in the wild modulation with this method), I'm trying to split the input into two buffered paths: one path (always on) goes to the LM386 while the other bypasses the LM386 and connects to the junction of the 10k and 22k resistors leading to pt2399 pins 15 and 16. In clean mode, the input goes to the LM386 to drive the LED for the LDR, but the audio signal goes to the 10k/22k resistor junction. In fuzz mode, the circuit input is buffered, but otherwise the same as stock.

All of the modifications work as expected—except for the input in fuzz mode. I'm getting an extremely gated, sputtery fuzz that completely cuts out with high amplitude input (i.e., hard strums with humbuckers). I've used an audio probe and can confirm that the sputtering is present at pin 5 of the LM386. I'm attaching the schematic for the input of the circuit and the power section. Any insight here would be greatly appreciated. Also, I can post the entire schematic if there's interest.

Cheers

[matmosphere]

My suggestion is to start eliminating possibilities. First i would remove the buffer from the input of the fuzz path and see what happens. Or try a different buffer and see if it works better.

I'm a little confused here. It looks to me like you're cutting the tracking out, and by extension the modulation, with the switch as well?

So are you trying to make it just a standard unmodulated 2399 delay when the fuzz is off.

[benny_profane]

I'm a little confused here. It looks to me like you're cutting the tracking out, and by extension the modulation, with the switch as well?

So are you trying to make it just a standard unmodulated 2399 delay when the fuzz is off.

Those nets are connected to a separate DPDT that switches between envelope and LFO for modulation. That circuit block works fine. The clean/fuzz switch is the 'GAIN' SPDT after the input stage. That's the area I'm having difficulty with.

[matmosphere]

I think you should try a different buffer or no buffer, and see what happens.

[benny_profane]

I think you should try a different buffer or no buffer, and see what happens.

I'll do that as my next step. I'm hoping to understand why this is happening, though, since I didn't anticipate this occurring with a unity-gain buffer into an LM386. If the design is sound, I need to do more actual debugging; but if there's a conceptual fault, I'd like to better understand what's going on.

[matmosphere]

You have to determine the why before you can understand it though. Taking out the buffer is the first step to doing that imo.

[benny_profane]

I replaced the op amp buffer with a JFET buffer and things are working as expected. I used a modified version of the common drain JFET buffer from AMZ with two 10µF caps as source followers to split the signal.

Now that I have something that works, any idea why that method works and the op amp buffer doesn't?

[matmosphere]

Without doing much research I'm guessing it's an impedance issue. I think op amp buffers have a high impedance output, but transistor buffers can be high or low depending on the design. In my experience The Claire-not is a picky circuit as far as what input signal it will take.