Korg Poly800/EX800 Users

I tried implementing a delay and depth control, with mixed results. After
the sine generator there is an opamp buffer cicuit. I replaced one resistor
in the feedback loop to change the depth - works fine, but doesn't quite
get the range nessessary. I'll have to play with it a bit more. As for the
delay, there are two resistors forming a divider connected to the + input
of the opamp. I connected another 100k knob in here.

The delay control proves useless. I could probly do it better in a different
way, but the sound of the delay line being underclocked is just BAD. No
distortion, no interestingly brutal signal degredation - just a high pitched
buzzing sound. I've only got room for three knobs with the way I'm laying them
out, so this one will probly be replaced, and maybe the depth as well should
it prove less interesting then wet/dry mix and feedback.

As for wet/dry and feedback, how would you go about implementing them? There
appears to be some form of raw mixture between the original signal and the
delayed one near the end, I suppose I could simply add another knob in here..
and then for the feedback I'm clueless. The basic signal path of the chorus
is as follows: Ne570 stage one, buffer, delay IC, buffer, 570 stage two. Where
would you mix the signal back in? I'd assume the signal would be taken off the
second stage of the Ne570, right before it's mixed with the original, or just
after the second buffer. And ideas?