Delay clipping diodes?

[SprinkleSpraycan]

I have this circuit on a breadboard and am very curious about diodes D1 and D2 next to the repeats pots. What are they for? I dont hear a difference when i pull them or put them back. Please someone enlighten me.

[idy]

probably there to prevent nasty overloading of the PT if you go to runaway repeats, louder and louder....Better to clip before it goes back in again.

[ElectricDruid]

+1 agree wot he said. Feedback limiting.

That schematic with the PT2399's op-amps drawn as separate parts outside the main block is *really freaky*. It wouldn't be so bad, except that the internal connections aren't shown, so the signal goes to dead ends, and then pops up again out of nowhere! Mad!

Lucky we all know the 2399 datasheet circuit backwards and forwards or we'd get more-than-somewhat confused

[johngreene]

I have this circuit on a breadboard and am very curious about diodes D1 and D2 next to the repeats pots. What are they for? I dont hear a difference when i pull them or put them back. Please someone enlighten me.

It's to limit the level of the regen audio. If the regeneration is "positive" so it grows the regeneration signal will eventually hit the rails and overdrive the input and it sounds like a mess. But even if you hard limit with with diodes it is still within the delay chip's dynamic range and it just "blooms" rather than gates and other nasty things.