Klon klone whistling issue (not 7660s related?)

[Bandwagonesque]

Hi everyyone. I recently finished up a a couple of klon klones this weekend. one was utilizing a vero board layout with all the bells and whistles. the other was a pcb kit meant for mini 1290b enclosures that is the same sans the buffer (iirc). Both of my builds utilized 7660s chips from the same source for the voltage section. I have a weird issue though. While my vero board build turned out fantastic, my mini build has been suffering from a strange whistling when the tone and gain knobs are cranked passed 3 o'clock. its a very annoying whistling sound that i can get rid of when reeling back the controls, but nonetheless it doesn't seem like it should be happening.
        I consulted around the internet and noticed that others have ran into the same issue. mostly from using the max 1044 chip like the original klon and have been suggested to replace the chip with the 7660s. That solution seems to alleviate the problems for most everyone. For me though, I used a 7660spca from the start and still have the same issue. I went ahead and swapped the 7660s that was in my faulty mini klon and replaced it with another from the same stash of 7660s and the issue remained. I then went ahead and yanked the 7660s I used in my 'fantastic' klone build and the problem still persisted. So now I am left scratching my head other than trying other like IC's to which I have none on hand (just a bunch of 7660s, thanks coronavirus for closing all the parts shops within a drive of me).
         I'm beginning to wonder if this whistling sound may be from something other than the IC's. Has anyone else encountered this same whistling issue with their klone and can tell me what solution they were able to use to get rid of it? any help would be greatly appreciated.

[stallik]

Not with a Klon but with other pedals. Is the input signal cable (input socket to switch and switch to board input) shielded? Both bits of shielded cable should be earthed at one end.

I spent hours on a recent build chasing the same issue only to realise that I'd not earthed one of the shields.

[Rob Strand]

Both of my builds utilized 7660s chips from the same source

If it's a dodgy source they still could be different chips.   Fake/refurbished chips are remarked to look the same.  See Mark Hammer's excellent video link in the Lounge.

https://www.diystompboxes.com/smfforum/index.php?topic=123697.0

Otherwise go with stalik's suggestions.

[Bandwagonesque]

hi everyone. thanks alot for your replies. I went and checked my grounds and everything seems to be kosher in that regard. I am using plastic enclosed jacks so making extra sure things are grounded off but I don't see any issue. I was hoping though that would be the culprit though. Does anyone know if it may be the zener diode or the tone knob? i'll go ahead and pull some voltages of the chips here in the morning.

Not with a Klon but with other pedals. Is the input signal cable (input socket to switch and switch to board input) shielded? Both bits of shielded cable should be earthed at one end.

I spent hours on a recent build chasing the same issue only to realise that I'd not earthed one of the shields.

are you talking about coaxial shielded cable? I'm only using single lead wire.

[stallik]

Yup. Coaxial

[Bandwagonesque]

ahh i see. I didn't have to use coaxial for my bigger klone which has zero issues. Do i need to use coaxial for this smaller build since things internally are a bit more compact? thanks for your help again.

[Rob Strand]

ahh i see. I didn't have to use coaxial for my bigger klone which has zero issues. Do i need to use coaxial for this smaller build since things internally are a bit more compact? thanks for your help again.

A lot of factors come into play.  If any wires carrying high-ish gain output signals are near wires carrying input signals you can get problems.  That includes pot wires.  You get positive feedback which causes oscillations.   

The reason why the switch is often an issue is it forces the input and output to be close together.  Coax can often  help in that region.