This does seem to be a problematic circuit. Strange. The way I work with new designs is to breadboard until I'm ready to build, then draw up a schematic from the breadboard, and build from that schematic, so the schematic I built from is the same one you built from. If you still want to experiment with this, can I suggest that you refer back to the circuit I based (stole?) my design on, build it on your breadboard, test it works, then systematically modify it to my design. Thats how I did mine, it started off as the Synbal circuit, then I modified it. I will be relieved when at least one person has built it without issues, as I'm feeling big guilt at the moment for all the wasted man hours. Boogdish at least got the filter section working, though he hooked it up to a different follower.
I've refered back the original circuit as a built and actually did start from scratch after I tried it first, for neatness, to the same result. I'm frustrated that I can't seem to get the envelope section...when I have the two parts connected, there is no filtering, but disconnecting that 10K resistor, I hear the filter, with the resonance pot sounding as if to finction more like a manual filter control...when set high, it's bright, set low it's muffled. Odd.
With the original circuit, it's hard for me to break it down into it's parts, though refering back to your schematic helps as many of the values of course are the same. I don't mind the man hours, it's worth it to me, not a waste! I'm going to give Stephen's space filter a shot next, but I'll come back to this maybe...I do have it sitting on my breadboard still, so maybe it depends on what itch I get.
I have to confess as I hinted at earlier, that I didn't have all the pots breadboarded, and had some as preset resistors. If you could post some good 'starting' points for the pots, since there are a few 'widely' variable values there that I can't even guess at. Twisting them didn't do muchfor me though. I did, for example have a decay set 'halfway' as a 470k resistor to ground the whole time....maybe that was throwing it off a bit. I also ignored the HP/HP taps for simplicity and personal preference.
I understand filter settings theoretically, but from your experience in particular, what are good values to start at here, say? Likewise, have you noticed preference for pickups type/pickup output/running a buffer? Also, looking at the circuit, you have the signal running to the top part, the op amps (this is the voltage control section, correct?) bled off the (potentially unbuffered) input signal splitting also into the filter section (that is, the parts that hits one op-amp stage and then the LM13700 stages)?
