The BOM’s back: https://www.lookmumnocomputer.com/s/FartBox_BOM.xlsx
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Not sure if it has been mentioned but -
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Replaced an old cap that I thought might of been the culprit, no dice. Resonance seems to be doing something, but Cutoff does absolutely nothing. See video. I assume the TL074 is the filter, correct? It is the only chip that is quite hot, not sure if that’s normal. The only thing I can think of is that I’m using on-off-on SPDT for the switches as listed in the BOM, but looking at the schematic it seems like they should be just on-off?
Only thing I substituted were BC556 instead of BC558. The 558 were unavailable and they are seemingly the same. But I’m not 100%.
Attached is a video demoing what mines doing. (fyi the beeps at 1:13 is my multimeter turning off). Anyone have any ideas? 
The switches are not the culprit. They should be on - on, but it’s fine that there’s an off in the middle.
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Just had another thought, for the LEDs I assumed the square was the anode (+) and the circle was the cathode (-), but from looking at one of the images on the splashback LMNC specifies the opposite. Could I have fried the ICs for the filter by having those incorrectly? I have tried putting the LEDs in a different polarity and they still light up (with the resonance cranked only), the only difference is the volume is not as loud. ¯\(ツ)/¯
The pad shape isn’t really a reliable indication of which way to turn a diode, but the outline is – for LEDs, the flat side is the cathode (−), see e.g. here.
This doesn’t really matter on the Fartbox, though, since the two LEDs there are driven by the same signal, in opposite directions…
…so the worst thing that can happen is that you put one of them the wrong way so they end up in the same orientation in the circuit, and you get asymmetric clipping in the resonance feedback loop.
In general, it’s very unlikely that putting a LED the wrong way would damage a circuit, and the same applies for most small-signal diodes. Getting e.g. rectifier diodes wrong can cause a lot more trouble, though (including damaging shorts and supply reversals).
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Just realized I put in 470 ohm instead of 470k resistors. Oof… Well, it is working a bit better, but still no cutoff, so I think I’ll order a couple replacement TL074 and LM13700. At least the TL074 isn’t super hot anymore, but I bet I broke something in it.
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had that problem with a power supply. it had a short and the regulator got really hot , I cleared it and it worked but the next time I plugged it in the regulator wasn’t working properly . luckily it was just the regulator so quick fix .
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Some progress.
Haven’t decided if I should power with external ±12 V or 12 VAC, and I thought I had a BC107 somewhere but apparently I didn’t, so testing will have to wait a bit longer. Will also have to reshuffle the front panel a bit to better fit the 4 units wide enclosure (moving things around is of course the entire point of these things, so shouldn’t complain 
).
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@lookmumnocomputer Hey Sam you might wanna edit the BOM to say “on-on” SPDT switches instead of “on-off-on”.
In other unrelated news, I am an idiot and have too short of potentiometers for mounting in a Hammond case. Time to hit the order button again. Hopefully when my replacement ICs show up the filter will work nicely.
So far the Fart Box kind of reminds me of a souped up Atari Punk Console actually, which I love. The way the oscillators and mods kind of all effect each other is very APC like!
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believe it or not - pot shaft extensions exist 
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by the way! here are the fart boxes I mentioned a couple of weeks ago. yep! sorry itis on the to do list to get a video out building and explaining this. the top trimmers are scale and the others offset the triangle outputs to modulate the other oscillator, so you can choose where in the offset you would like the modulation of the other oscillator to be ifthatmakes sense
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Oh shit, I didn’t know those existed. Definitely gonna look into that vs. soldering 11 new pots. Thanks!
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so i ordered one of those fart box pcbs.
now i have one of these buttons:
how do i wire it? i know about the two led connectors, but what about the other three? they are labeled like this on the button:
COM1
NO2
NO3
cheers
The second one says NC, not NO. NC is “normally closed” (i.e. it opens when you press the button), NO is “normally open” (i.e. closes when you press the button). Opens and closes here are in relation to COM, which is the common terminal. To use this as a plain momentary switch, connect to COM and NO.
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Thanks for clarifying! Btw are there holes in the pcb for mounting bolts or do you need to use the pots for that?
pots are the way to mount 
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There are no holes in the ones I have, at least, so it’s either PCB pots or some custom approach.
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Damn. I have lots of vertical 9mm pots lying around wirth plastic shaft, but without winding and nut… i Think i will never be able to use those:D