Momentary A/B Switch Troubles

[iwazaru]

Hi, I made a momentary A/B switch by replacing a DPDT latching stomp switch in an off-the-shelf  A/B pedal with a DPDT momentary stomp switch. I used the same wiring schematic that the original switch had. It works well...85% of the time.

The two issues I have are that occasionally there is a small pop when "closing" the switch (stomping on it) and occasionally there is some distortion/poor signal quality when "opening" the switch (releasing the stomp switch); seems like the switch doesn't always open cleanly/completely.

For a second prototype I'm considering an electrical switch with a short delay (is this what the FET switches are?) or a Reed switch or DPDT Reed relay in which the coil voltage is supplied by a mechanical stomp switch. 

Does anyone have any thoughts or suggestions? I'm using this pedal to switch quickly between distorted and clean guitar tones.

Much appreciated,
Vadim

[garcho]

I play with a number of momentary stomp switches in pedals and have never had that problem. It's called 'bounce' when referring to digital crap and stuff. I have cheap plastic momentary push buttons that do what you describe. They work just fine for a de-bounced digital trigger but you can't really de-bounce analog audio through a mechanical switch, eh? It sounds like you might just want to buy another switch or two? As a guitarist I love having the ability to 'punch' in without worrying about punching out, I think you're on the right track with the momentary, IMO.

[Mike Burgundy]

Using a momentary suggests this is an AB meant for quick on the fly switches *while playing*.
If that is the case, I'd go with electronic switching. If there is any signal present at all when switching, you will possibly get pops with a mechanical switch. Electronic switching can be made to "ramp", slowing switching down a bit - not so much that you'll hear it, but enough to prevent popping. Mechanical switches also tend to bounce as stated by Garcho.
Lastly, if you heat up the switch terminals for too long soldering, you may inadvertently boil the grease in the switch and the switch will pop, make bad contact, behave erratically etc. I think Mark Hammer pointed that one out.
Dig around on GEOfex for lots of goodies on electronic switching.