Lectric-fx Flintlock Flanger noisy going through the null

[slowpogo]

I built this flanger and calibrated it according to instructions, with assistance from some helpful youtube walkthroughs. 

It sounds good but at slower speeds there is a noise every time the flanger goes "through the null," a kind of soft crackly white noise which dissipates.  It's not super loud; busy playing will cover it up, but it's very noticeable with quieter chords or just less busy playing.  Obviously it kind of ruins the effect, when the pedal is sounding awesome and clean and then this fizzy noise pops up. To be clear, this is not just the flanger effect itself, I'm familiar with flangers and this is extraneous noise.

What might be causing this?  Everything is properly calibrated, including the range/manual which were quite tricky to get right...I played around with the bias, volume, enhance pots a little but that didn't help. 

[Scruffie]

Probably some charge pump heterodyne bleed leaking through, some people seem to get issues with it, some don't.

What's your supply like? Is it chained with any effects that you can isolate it from? Got a photo of your wiring? Anything in the room that could cause interference?

[slowpogo]

I'm using the 1 Spot CS-12 isolated power supply. The flanger is not daisy chained. My studio has lots of other electronics in it, but everything (including the 1 Spot) is plugged into a Furman power conditioner. I'm not sure what other interference you might be referring to.

Here's a photo...the enclosure ended up being pretty tight. The stomp PCB is almost touching the inline ICs and is actually resting on the corner of another one. I used some bigger caps I had lying around so they got pretty crowded on the right side and leads are longer than ideal.

[Bret608]

You might have a bit of a wire routing issue. Plug a cable into each jack and see if the tips are contacting any of the wires. I managed to turn a chorus I built into an antenna by doing this. I pretty much had to rebox it in order to redo the jack and switch wiring.

[slowpogo]

I played with the input/output wires a bit to make sure they're out of the way, but it didn't change anything.

Any ideas scruffie?

[Scruffie]

Have you got an 18V supply you can test it with? You'll have to remove the charge pump first of course. Two batteries in series will do if you don't.

I'm not 100% without hearing it the noise you're describing is heterodyning, usually that is more like a chirpy/whiney noise than a static noise. I assume when you say 'through the null' you just mean at the very top of the sweep, which is not normally where one would hear it either... it almost sounds like the clock is struggling to drive the BBD properly so do check that your max frequency isn't sweeping above where it's supposed to.

As was stated, your wires from the stomp switch are basically sitting right on top of the clock so I know you said you've moved them about but do you think you could take the whole stomp switch out and pull the wires away from the board entirely?

[slowpogo]

Thank you, I will pull it out of the enclosure sometime soon and check all those things.