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Homemade A/B - X/Y switch problem...

Posted: June 2nd, 2013, 9:41 am
by allanhurd
Hope someone can help me on this --
I play in a band where we are 2 guitar players, thus we alternate playing bass. AND we only have 1 bass : mine.
Hence, when I play guitar, Steve grabs my bass.
We each have our own pedal board for our guitar effects, but I would like to be able to use some of my pedals (compression, wah, tuner) when playing my bass.
This means that, for quick instrument switching AND to avoid unplugging and re-plugging instruments, I need to have both instruments AND both amps hooked up to the pedal board, then use a switch to choose which instrument goes through the pedals, thus having the other instrument bypassed directly to its amp (or vice-versa)
So I devised a plan to build an A/B - X/Y switch, using 2 DPDT on/on switches, where the "up" position sends the input signal directly through to its output (input 1 to output 1 and input 2 to output 2), and the "down" position sends it through my pedal board and then to its output.
FAIL : nothing but noise on the bypass and massive tone sucking through the pedal chain.


Re: Homemade A/B - X/Y switch problem...

Posted: June 2nd, 2013, 4:42 pm
by allanhurd
Ok, since my first post I've kept experimenting and partly solved the problem ; so now I now have the "bypass" position working fine, but the "send & return" loop sounds very muddy and I have about a more-or-less 50% volume drop.
Since this unit is an on-board switching board permanently mounted on my pedal board, I pre-soldered a wire to the "send" DPDT switch, with a 1/4" mono jack on the other end to go into my first pedal (Vox wah), and a 1/4" female TRS jack soldered to the "return" DPDT switch to connect the return cable from my last pedal (Line-6 DL4 delay). Between these 2 cables, I soldered a ground wire from the ground shields in the cables to all the other grounds on the input & output jacks.
On the female TRS jack, I connected the tip (hot) to the 2nd DPDT switch and ignored the ring connection... could this have an impact?
Here is a diagram :

Re: Homemade A/B - X/Y switch problem...

Posted: June 3rd, 2013, 9:41 am
by EzraplaysEzra
Where are you located? Guitar center used online always has aby's for under $20 and they'll ship to your local store. DO you have the schem you used? I can't imagine why you'd have that much tome suck in a passive system, did you try to add a buffer? Could be a cold joint try everything back from the out put. I'll see if I can find a simple schem but I don't get on too often.

Re: Homemade A/B - X/Y switch problem...

Posted: June 3rd, 2013, 9:52 am
by allanhurd
i have a picture of the thing -- how can I post it? I click the IMG button but it only inserts in the dialog box...
I'm located in Montreal