FX order swapping toggle switch seems to be causing a feedback loop (squeal)

[Jamez0r]

Hey guys, I'm relatively new to pedal building. I am making a two-in-one overdrive pedal.

The left side is a Klon Centaur clone and the right side is a Timmy OD clone. I built them separately and they both worked fine separately, but then when I combined them into the enclosure (which has a toggle switch that swaps the effects order for the two OD's) it started squealing when you turn up the volume and gain. I believe it is making a feedback loop from having the high-gain high-volume signal carrying wires near the line-level "input" wires. I've narrowed it down to the issue being the FX order switch (or the wires that go into it).

This is the toggle switch I'm using for the FX order swapper: http://smallbear-electronics.mybigcommerce.com/4pdt-on-on/
(its 4PDT but I only use 3 of the poles for the order swapping)

Has anyone ever dealt with this issue before? I am not using shielded cable anywhere (didn't think/know that I would need to). I'm trying to figure out whether the issue is 100% with the toggle switch (in which case I couldn't do much about it besides remove it), or if the issue is more likely the wires going into the toggle switch (in which case I could maybe uses shielded cable or something?)

Side note: I googled the issue as best as I could, and found one or two people who had feedback issues when using a similar toggle switch. They had suggested making a mini faraday cage around the toggle switch with aluminum foil, which I tried and it did not fix the issue)

[midwayfair]

Someone on Reddit had a nearly identical question with the same circuits.

http://www.reddit.com/r/diypedals/comments/2rsigw/buddy_is_building_me_2in1_od_getting_squeel_but/

If that's you, apologies for just repeating, but this is what I said:

This is a common problem with FX order switchers. I've had a couple nightmare projects where I tried to deal with that. In part it's the proximity of wires and lugs on the switch, which you can't change.

I can tell you that one project the problem was solved by using a relay, but I don't have any information on the relay used, because the pedal was out of my hands by then.

The other project was solved with a replacement op amp, though I don't know the reasons the op amp change helped.

Sometimes putting a buffer in front before the order switcher helps, but that requires a buffered pedal.

[Jamez0r]

Hah! Yes, that is indeed my friend. Thank you for the response.

At this point I'm thinking of just removing the order swapper. Just sucks that I already drilled the enclosure 

Thanks for your DOUBLE ANSWER!

=)

[midwayfair]

Hah! Yes, that is indeed my friend. Thank you for the response.

At this point I'm thinking of just removing the order swapper. Just sucks that I already drilled the enclosure 

Thanks for your DOUBLE ANSWER!

=)

So you have a spot for an extra switch ... do a clipping diode switch for the Klone or something. Not a disaster!

[duck_arse]

timmy will scream, shielded may well stop it. if you have a four pole and are using only three poles (is one for a led?), you could ground all three lugs of the unused pole, with one pedal either side it might get you the separation you need.