Weird Zombii Issue

[Guybrush]

Hey all

I recently built a Madbean Zombii and it all worked perfectly. However over the last week it has developed a high pitched whistle whenever the pedal is engaged.

I know it is inherently a noisy circuit but it didn't start making this noise until very recently which is obviously annoying.

I can dial it out by turning the Comp knob up to full but anything less than that and the whistle comes back.

Anyone have any ideas?

Thanks.

[lincolnic]

I'm pretty sure it's supposed to do that. Did you turn your Stability knob down?

[Guybrush]

Yeah, I've turned all the knobs and tried different settings but to no avail. The only thing that works is having the gate or compression knob fully dialled but that obviously has an effect on the sound.

It's strange though because when I first built it it definitely didn't do it. I'm starting to wonder if it's an issue with my power supply. I might build the Beavis Audio power filter to see if that helps.

Cheers.

[jimilee]

I was gonna say, have alook at the power supply. Have you built a 9volt battery adapter yet? It's just a battery snap with a barrel adapter on it. Great for quick and dirty tests. I saw jacob do that in one of his build pictures.

[icecycle66]

I'm pretty sure it's supposed to do that. Did you turn your Stability knob down?

I love this:

"It sounds broken"

"That means it's working."

[lincolnic]

It's strange though because when I first built it it definitely didn't do it. I'm starting to wonder if it's an issue with my power supply. I might build the Beavis Audio power filter to see if that helps.

This might be it, actually. The Stability control is just a voltage starve, as far as I can tell, so if the pedal isn't getting a proper voltage, maybe it's acting like the Stab pot is already turned down. Are you getting a full 9v (or near enough) from your power supply?