concurring runaway delay occilations

[Nyklus]

hello, i am looking into unique ways of how to get a delay to tap out when it's occilations get too loud and overbearing

I was on a forums and ran accross this solution

"My guess as to what's going on with the Zero Point Micro is that you have two diodes, one up, one down from the wiper of the feedback pot to ground (lug 2 to ground). This is essentially the clipping configuration for the Distortion + type circuit. Anything over the forward voltage of the diode gets shunted to ground. One diode handles the positive swing and the other handles the negative swing of the signal.

So, you want the diodes to be perpendicular to the signal flow, not inline with it. I haven't built a Sea Urchin, but it looks to me like the easiest way to do this mod would be to wire the diodes directly between lug 2 and lug 1 on the FDBK pot. The original connections on the pot still need to be made the same way they are on the unmodded circuit. Remember that you want the diodes to be reversed from each other and both have one lead to lug 2 and the other leg to lug 1. "


does anyone have anypointers as to what size diodes i should use.



i read that
"It looks like it just takes back-to-back 1N914's from the wiper of the feedback control to ground. You could adjust the level and character of the clamp by using different diode configurations here."


but i also read this later on.
An update - success!  It works pretty well. It still gets louder than the standard signal, but it hits a point where it doesn't get any louder, it just distorts, which isn't unpleasant, as it turns into a sort of wash/crashing waves sound that is a nice ambient noise.
I think you could get different output levels by using different diodes (Schottky or Ge) with lower forward voltages. But, they might get too quiet and would change the character of the distortion.
I like the it ends up in the washy noise thing too. It's fun to play with and tune using the feedback level and delay knobs. On the ZP micro, the modulation enhances the washiness too."


any pointers?

[armdnrdy]

I recognize that there are standards for delay unit "repeat" calibration.

One....is no oscillation. With the repeat control all the way clock wise you will hear roughly twelve repeats.

Then there is self oscillation. With the repeat control all the way clock wise, the feedback will let the signal self oscillate.

There is a "feedback" or "repeat" trimmer that lets you set the amount of feedback/self oscillation.

I have always set this trimmer to the point where it self oscillates nicely......not let it get to that runaway, too loud, overbearing point that you are referring to.

Using a clipping diode configuration to control the feedback and introduce an unintended side effect.......distortion doesn't sound like such a good idea, unless that's the sound you're striving for.

I go to great lengths to alleviate any form of distortion in a delay unit. It is my opinion that distortion belongs in an overdrive/fuzz pedal, not in a delay pedal.

If you want to adjust the amount of oscillation....look to the trimmer. 

[Nyklus]

I'm not into traditional sound occillations, and im pretty good at dialing in on this pedal at this point. I'm just trying to add one more sonic feature this already goreous pedal. If i wanted a clean delay i wouldn't have gone analog and with a tube, or tape saturation. But if anyone could suggest a step up in diodes from the 1N914 i'd like to try them. maybe some that have a pretty distortion, or what about matching two different diodes to handle positive swing and neg swing?

[armdnrdy]

It depends on what you perceive "pretty distortion" to be.

I would look through the many clipping diode threads which give descriptions of different diode tonal qualities from harsh to light clipping.

Socket the diodes and try different combinations until you find one you like.

[R O Tiree]

Or how about strapping a TS-style circuit in there? Smoother distortion than just diodes shunting to GND (as in RAT-style distortion).