AB Box with a twist [not working...]

[Glenouille]

Boys, I'm struggling here. My knowledge of all this is frustratingly limited; therefore I would welcome any ideas/recommendations you have.

My bass is midi. I have the standard signal going to one amp and the MIDI signal going to another one. I asked a guy to build a A/B A+B pedal that would allow me to alternate between 2 signals so that it would somehow sound like I’m playing 2 instruments.

He put 3 footswitches in a box:

1. Alatching footswitch to select signal A or signal B
2. A momentary one that would mute whichever signal has been selected by the latching footswitch and un-mute the other one (i.e. if A has been selected with the latching footswitch, when you press the momentary footswitch A is muted and you can hear B whilst your foot is on the switch, etc.)
3. A momentary footswitch that would let signal A and signal B go to their respective outputs.

Sounded simple and straight forward? I thought so too, but it is only partially working the way it should have been.
I have looked inside and have not been able to actually found a way to make it work with 3 footswitches, I think it could work with 4 footswitches like so (Sorry for the pic, PowerPoint is all I have at work! Red is ground), what do you think?

[morange]

I though about it for a while. I think you need 4pdt switches for it to work with 3 switches. Or some active switching.

If I were going to compromise, though, I would use 2 latching switches, an on/off switch for each signal, instead of 4 or more switches. 2 switches are easy enough to control: you can stomp them both at once, or one at a time, and they're easy to keep track of when you're using them. Each signal only needs one pole of a DPDT, so you could have an indicator LED for each switch. A on or off, B on or off. That's how I would do it.

[Glenouille]

Thanks for taking the time to think about this! Your solution makes sense and is probably simpler to build too.

[eatyourguitar]

stop right there, you do not need 4PDT. you can do it all on 2PDT . I can do it on 3PDT with LED's working correctly for every function. I am the master of AB boxes, trust me. here is proof of something almost what you want. this is a tested working layout of A or B on one footswitch, A and B on the other footswitch. give me a day and I will draw the version you asked for with 3 footswitches.

[morange]

stop right there, you do not need 4PDT. you can do it all on 2PDT . I can do it on 3PDT with LED's working correctly for every function. I am the master of AB boxes, trust me. here is proof of something almost what you want. this is a tested working layout of A or B on one footswitch, A and B on the other footswitch. give me a day and I will draw the version you asked for with 3 footswitches.

There should be two inputs.

[eatyourguitar]

stop right there, you do not need 4PDT. you can do it all on 2PDT . I can do it on 3PDT with LED's working correctly for every function. I am the master of AB boxes, trust me. here is proof of something almost what you want. this is a tested working layout of A or B on one footswitch, A and B on the other footswitch. give me a day and I will draw the version you asked for with 3 footswitches.

There should be two inputs.

I can do that too

[eatyourguitar]

I see the problem now. yeah this might get complicated. still doable but complicated.

[multi_s]

no im pretty certain its possible with 3x dpdt.

let me jsut make sure i understand the op.

"1. Alatching footswitch to select signal A or signal B"

so what? so input A OR B shows up on... Output A? is that what is meant?

and

"2. A momentary one that would mute whichever signal has been selected by the latching footswitch and un-mute the other one (i.e. if A has been selected with the latching footswitch, when you press the momentary footswitch A is muted and you can hear B whilst your foot is on the switch, etc.)"

jsut swaps what is on out A?

if so i am almost certain it can be done with 3 dpdt.

[morange]

I think he wants the signal that goes into A to come out of jack A, and what goes into B to come out of jack B, and we're switching whether those individual outputs are on or off. He's got two signals coming from his guitar and he wants to send them different places.

[Glenouille]

In the entire pedal signal A always goes to output A and signal B always goes to output B.
If you press the latching footswitch you do the following:
1. Signal A goes to out A & Signal B goes to ground
Or
2. Signal B goes to out B & signal A goes to ground

Now let's say we are in scenario 1 (signal A goes to out A & Signal B goes to ground), if I press my first momentary switch, signal A goes to ground and signal B goes to out B as long as I press the switch.
If I was in scenario 2, pressing the same momentary switch would ground B and signal A would go to out A.

And finally the second momentary switch allows signal A to go to out A and signal B to go to out B regardless of the scenario as long as I keep it pressed. If I remove my foot from this switch, I return to whichever scenario I was in based on the latching footswich state.
That's the idea, hope it's clearer!

[multi_s]

hmm ok so the latchiong one picks what signal is passing, either input a to output a OR input b to output b. the first momentary flips that and allows teh opposite one to pass, and the second momentary allows both to pass?

if this is the case then it seems possible with dpdt only.

[eatyourguitar]

[Glenouille]

Yes that's the case. The only way I can figure this is by adding another latching switch, but frankly if there was a way to have only 3 footswitches it would be easier to juggle playing different parts on the bass and the tap dancing on the pedal!

[eatyourguitar]

1. Signal A goes to out A & Signal B goes to ground
Or
2. Signal B goes to out B & signal A goes to ground

I did not make it grounded when off because it is unlikely that you would have any stray signal on a good shielded cable when the tip is lifted at the pedal. as long as the AB box is made of metal and you have no cheap cables, your good.

P.S. my design is reversible. it does not care what is input and what is output. you can hook it up in the dark with no worries.

[Glenouille]

Noted! Give me 2 sec I need to diggest your drawing!

Edit: the only thing I'm not sure of is how you link the last momentary switch to the rest.