Noisey A/B Switch

eskimoquinn · September 12, 2018, 02:32:50 PM

I just wired up an A/B Switch to switch between two guitars according to the diagram below. However, when the power is plugged in, it is extremely noisey. It is almost dead silent when no power. It looks like I have good working connections as evidenced by a good signal when no power, but the DC is somehow leaking into the audio path. Any thought on what might be causing this:

vigilante397 · September 12, 2018, 02:45:32 PM

Can we see pictures of your build please?

eskimoquinn · September 12, 2018, 05:19:03 PM

Here ya go

PRR · September 12, 2018, 08:31:00 PM

> when the power is plugged in, it is extremely noisey.

Hiss? Or buzz?

If buzz: quality pedal power supply? Or some old wart from the junk drawer?

eskimoquinn · September 12, 2018, 11:05:29 PM

Definitely a not a hiss. I am using a voodoo labs power supply which causes no issues with other pedals.

BetterOffShred · September 13, 2018, 12:36:20 AM

Make sure the grounds are all good, double check all your wiring, and then make sure it isn't the switch. There's not really a whole lot to go wrong in this build.

stallik · September 13, 2018, 01:56:59 AM

Quick look but the led ground appears to be running to the jack ground. Try running it to the 9v negative instead

eskimoquinn · September 13, 2018, 12:31:27 PM

Not sure I follow. 9v negative? 9v battery? No battery in this one.

vigilante397 · September 13, 2018, 12:34:24 PM

He's talking about the negative terminal of the power jack. There's no reason to connect power ground and audio ground in a completely passive box.

eskimoquinn · September 13, 2018, 12:42:50 PM

I see, so complete n00b question, the negative of the jack should go to where? in other words, how would the schematic I posted changed if I followed this suggestion?

BetterOffShred · September 13, 2018, 02:05:40 PM

It only has power to illuminate the switching LEDs .. the actual jack switching just has grounds straight across from the ring lugs on the jacks there.

ayayay! · September 13, 2018, 05:13:22 PM

I love and miss Dano but he got it wrong on that one. Replicate this on the LED wiring x2 to make it work correctly, with the other LED going to the spare lug.

stallik · September 14, 2018, 11:42:51 AM

Thats it Jono, and as it's an A/B, another LED can be attached to the same + but run to the other side of the switch.
Resistors can be adjusted to make both burn at the same visual brightness

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Noisey A/B Switch