Frequency: It always helps to understand the circuits you design with, but it's obvious that you aren't all that lost. Understanding op-amp design is really not that hard once you understand a few limitations, and even those LM13700 OTA's aren't hard once you understand how a transconductance amplifier works. TBH, everything in your schematic is pretty dang standard and so explaining the circuit isn't as hard as you think. If you want, I can break it down for you in more detail than you'll care to know 
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That would be awesome if you could actually Cliff - I can 'do stuff' with electronics but it's quite scary to me that I know how much I don't know - if that makes sense. I design with pre-existing 'blocks' and tweak on the breadboard. There is very little theory underpinning what I do. Scary huh? I probably understand tubes more than I do opamps.
Rick, I am wondering which of the opamps in the schematic you used the tl062 and the lm324 for? Is it possible that having the TL062 performing the function of a specific part of the circuit has something to do with the problem?
In my pedal the output buffer and the unity gain buffer are the TL062.
BUT
When I breadboarded it I used two LM324's. I only used the TL062 in the final build.
Thinking it through though, it was only in the final build that I replaced the resistor between the unity gain buffer and pins 1/16 of the 13700 with a 10K. It had previously been 22K I think. So maybe a TL062 gives out less current than a LM324? And therefore needs a smaller current limiting resistor? The 22K that I replaced was holding the filter too 'open'. So maybe you should try a few different values in that position.
Having played about with this pedal for a couple of months, I have to say I just love the sound of it, some great stuff can be coaxed out of it. It is THE FUNK. I knew I would like it before I built it - I've been putting guitars through synths for years, and have a very similar Oberheim SEM multimode filter in one of my modular synths. But 'coaxed' is the operative word. It's a very 'touchy' device, and needs to be set up just right to get the good sounds. That means not only how all the knobs are set, but also which guitar you use, which pickup (bridge or neck), how the guitar's volume and tone are set, and which effects come before it. I would not dare to tweak in a sound on the fly in a live-on-stage situation. The only way I would consider using it live would be to have it on its own loop with a dedicated distortion before it, and set both up beforehand and not touch either apart from to stomp it in and out on the a/b switcher. Maybe it's the nature of envelope filters - a guitar really being an 'imperfect source' to derive gate and control voltages from.
I had a brainwave re the envelope follower this morning. I'm thinking of maybe dropping a couple of clipping diodes in just before the range control. I have this idea that the follower works better with a clipped waveform, so adding the clipping diodes would do this, particularly if the gain stage before the range control was increased from x100 to x1000 by replacing the 10K to vref with a 1K. It would be kind of like having a Distortion+ before the follower. I don't know if it will work out but I'll try it. I've try it when I get some time - I have two tube builds to finish this week.
