Phase 90 with script switch LFO tick help

[beedoola]

I built this according to the layout with the depth control.

When I have the switch engaged with the 22k I get some LFO tick. I tried what someone suggested and cut the link for the 9v + on pin 8 for the bottom IC and put a 100R resistor between the 9v supply pin 8 on that IC and also added a 22uf electro cap from pin 8 of that IC to ground. This unfortunately did not help with the ticking. Its more thumping like sound.

Anyone have any suggestions as to how to remedy the issue?

http://tagboardeffects.blogspot.com/2014/05/mxr-phase-90-with-script-switch.html

[PRR]

...put a 100R resistor between the 9v supply pin 8 on that IC and also added a 22uf electro cap .....Its more thumping like sound.

Hard saying without a schmatic to think on.

But 100r+22uFd is about 80Hz. Indeed "thump". How about 220r and 100uFd to shove it three octaves down from 80Hz? Unless you have multiple 30" woofers you won't hear(feel) 10Hz thumps.

[CheapPedalCollector]

All phase 90s have this issue, the only way to solve it is to create a separate VREF source for the LFO so it's isolated from the audio portion of the circuit.

[beedoola]

Is there a layout for that for a separate power board?

[ElectricDruid]

Hard saying without a schematic to think on.

The perennial problem of the Tagboard site - no blinkin' schematics! Why?! We don't know.

I might have to write to them and moan about it. We finish up doing a ton of extra work over here because they never link to the schematics that the layouts are based on. It's frustrating!

<later>You can't write to them unless you're on Facebook.The site provides no contact details at all, only links to their social media, and you have to sign up for that. Useless.

[MrStab]

I agree that a separate Vref will probably make a significant change, but also: do signal grounds and LFO grounds travel down the same wire back to the power supply?

[beedoola]

As to the grounds: Yes. When I built it I used my testing pedal which has terminal strips on it for the I/O/9v/G so there was only one ground wire and it had the issue.

I also get some weird almost clipping when using the Script mode so I'm thinking of just removing the switch and using the normal mode. I feel defeated a bit but I can let it go.

[MrStab]

Ideally, ground from power supply filtering and LFO circuitry should follow its own wire back to PSU, and signal ground connected to PSU via. its own conductor. But for similar reasons, this is likely negated by the fact the LFO is using the same Vref as the signal. An oscillator's transients are getting dumped onto lines being used by the signal for reference. Keep your drinking water and black water apart!