ad 3208 ...to Scott and Mark

[swt]

Hey Guys!!. After thinking that perfboard could cause bad coupling/ bad behaviour with the circuit, i decided to make the GGG pcb. It's done and it does the same annoying thing. I have two choices now...one is the one maneco suggested, that both of the compressor/exp (NE570/571) that i tried are oscillating. Or maybe that it's a design problem. Can i send an email with a short demo of what it's doing to understand it deeper?. I'm using a 22k resistor in the repeat loop to get the same as the champ/dm3 setup, and when i maxxed everything, it began self oscillating in the feedback type of thing. Thanks for your help!!!

[Scott Swartz]

With the 22K on the repeat path, it will definitely oscillate at a relatively low pot setting, that's why I changed it to 100K on my schem.  This change was to make the repeat pot  easier to adjust.  You can't compare it to the 22K on some other effect because the mixer and return paths are not set up the same.

Its usually best to build an effect EXACTLY per the schematic and then mod from there.

The fact that it will oscillate is normal, as long as the tone of the repeats is correct.  Think about it.  If the repeat path boosts the signal, even slightly, each time the repeat goes back around to the delay chip it will be louder, until the the dynamic range of the delay chip and/or compander are exceeded.

[puretube]

did we already rule out the possibility, that he/you may have used a log-pot,
which per se, feedsback earlier cc. the rotation of the knob, than a lin-pot would do?

[swt]

Sorry i didn't specified. The feed kind of feedback. The problem is the tone changes after each repetition as a guitar would feedback in an amp, that is, a tendency to go to the octave, it's really difficult to explain. Can anyone post samples or demos of yours with lots of repeats??. Thanks a lot!!