Madbean Poindexter noise issue

[M.Spencer]

Hi folks, I'm trying to reduce some high pitch noise in my Madbean Poindexter build. The fizzy noise fades in on long sustained notes, and also when you palm mute the guitar it sounds like a cricket chirp.

I played with the 10p capacitor's value - at 100p the chirp is all but gone, but much more than 27p and the tone gets too box-y.

Any suggestions on how to remove the chirp/fizzy noise without sacrificing the overall high end?

I used this layout with 2n2222 and 2n3904 transistors. 

http://tagboardeffects.blogspot.com/2014/11/madbean-poindexter.html?m=1

https://i.imgur.com/BixfJ2V.jpg


Other mods I made: I internally set the gain at max with a jumper and resistor network, and added an 100nF cap straddling the input pull down resistor.

[M.Spencer]

And here's the schematic:

http://www.madbeanpedals.com/EP/schematics/Poindexter.gif

[GibsonGM]

For high=gain circuits like this, you have to be PRETTY careful with your layout!  Wires shouldn't cross each other, things like that - there are many posts on this, you can probably find some by searching.   Your 'gain on 10' mod is probably mostly to blame!

What you can do:  find some shielded cable, use that to go from jack to input, ground only 1 end of the shield.     Move input/output wires away from each other (any wires really)...wires will couple to each other, creating feedback paths.  If wires must cross, do so at right angles, like a "plus".    Check component leads, be sure they are short.   Same rules for pot wires.

Is the PCB in an enclosure yet?  If not, get it in there!

What is the 100n 'straddling the input resistor' for?  That will eat quite a bit of your highs....I think the squeal/noise you have is probably internally-generated...

Try those things & get back.  Maybe with a pic of the guts, too!

[M.Spencer]

I will have to pick up some shielded wire, but I will give that a try. The 100nF cap was just one of many steps I tried to resolve the issue. To be clear, I was having the noise issue before I ditched the gain pot, all mods were done outside of the box (ie, no wires run together).

Here's a gutshot:
https://i.imgur.com/BixfJ2V.jpg

[GibsonGM]

Your build does look clean!   I would expect a high gain circuit to misbehave outside the box, there is a lot of junk floating around that will couple into it.

Try that shielded wire, see if it helps!  If not, the layout may be a contributor    Don't know if your substitution of 2222 transistors would have an effect on this (?)  Doesn't SEEM like it would, but I"m not a transistor guru...