Finally plucked up the courage to attempt breadboarding this ridiculous circuit. After a small amount of frustration, it's working pretty well now. Hooray!
For anyone else who attempts this, a couple of things helped me get it going: First off, the attack and decay controls are highly interactive: The filter won't trigger unless they are set so the decay is shorter than attack (or vice versa - my pots have the wrong tapers and are wired backwards so it's confusing). I read it in the manual, and again elswhere online several times, but as I was testing it I kept forgetting this and assuming it wasn't working, until I found the trigger point again by twiddling those two knobs relative to each other. This is made much easier by my second tip, which is to definitely breadboard it with the sweep indicator LED that's paralleled with the LEDs in the vactrols: You get a clear visual indication of if, and how the vactrols are sweeping as you debug.
Thirdly, I was working off two very similar schematics - One which didn't have the colour pot lug 1 clearly connected to the output of the second opamp in the envelope section, and neither of which had the colour pot lugs 2+3 connected. This seems to be known as the "colour mod" online, but I'm convinced it's how the originals were done - Without it the colour pot does very little until the last quarter turn, which doesn't appear to be how it works in demo videos of the OG pedal. These titbits are buried in the "Building the Meatsphere" thread at DIYSB and scattered elsewhere across the internet, but I thought it might be handy to record them here.
For anyone who has already built it: What controls do you use the most and least? I'm going to box this up as a pretty straight clone for a bass-player friend, but I'm going to drop a few switches for a version for my own personal use. I only really like the lowest range setting caps, and might just have a high/low two-way switch for variety. I'm equally not that fussed with the high pass mode, though this probably personal taste. Also, I've only tested the bandwidth by physically swapping the caps a couple of times, settled on the lower 22n and left it be: Is it that useful?
mmolteratx wrote:absolutely zero commercial use allowed. If I find anyone selling these, I'll fly to your house and kick you in the nads. And you may or may not find yourself in trouble.