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Expression Pedal + A/B Box

Happynoj

Happynoj

Dec 5, 2006
4,237
717
UK
Disclosures
I like turtles.
#1
If you had two pedals with Ex. Pedal inputs, and an Ex. Pedal, and an A/B Switcher box, could you use the A/B to switch the expression pedal between two Ex. inputs?

For example:

Expression Pedal > A/B > (A) Boss PH-3, (B) Boss SYB-5
 
#3
Not with a run-of-the-mill AB box - but it is possible with a modified or DIYed switch box.

Most exp. pedals I've seen utilise three connections, tip, ring and sleeve. Most AB boxes I've seen only switch ONE connection, tip. You need a box that will switch tip and ring simultaneously - the sleeve (being ground) can remain common to both exp. inputs.
 
#4
Also, you run into a problem in that, when you would switch the expression pedal from one effect to another, you "lose" your setting.

For example:

You are using your expression pedal to control feedback on your delay - your setting is maintained because of the position of the pot on the exp. pedal -- but as soon as you switch away to control the other pedal, the feedback will change, because the pot is no longer connected. Depending on how you wire it in, it would either return to the pot setting on the effect pedal, or would leave an open circuit which could cause the effect to stop working.

What you would need is a switching mechanism with "memory" so that when you switch away it can maintain the last setting whilst you are using the exp. pedal for something else.

I wanted something like this for the CV controls on my Moogerfooger pedals, and thru discussions with my bro this is what we decided was required. We were thinking of developing such a thing when Moog came out with their MP-201 pedal which can do this very thing. Unfortunately it's only for Moog -5 to +5 CV, so it wouldn't work for just any pedal.

Still a good idea, but I am unaware of such a device out there today.

Col. Monk
 
#5
I went looking for an expression A/B or A/B/C box a while back. Couldn't find anyone that built one, and a couple people said they couldn't build one (including Loop-Master). WOBO said they could pretty much do one, although I bet the price would be high, and I forgot to email them back. This was their response to me:
"If I understand correctly then you need to control three or four units with a single expression pedal. We can make an ABC switcher with the TRS sockets which will be a stereo A/B/B router. You would connect the expression pedal into input of the unit and to the outputs the units you would like to control. The inactive output will be shortened to ground, so the inactive output will work as the expression pedal turn to minimum (0). I'm not sure if this is something you would like to achieve. Please let me know and we will discuss it further."
 
#6
Bryan R. Tyler said:
You would connect the expression pedal into input of the unit and to the outputs the units you would like to control. The inactive output will be shortened to ground, so the inactive output will work as the expression pedal turn to minimum (0). I'm not sure if this is something you would like to achieve. Please let me know and we will discuss it further."
Click to expand...

Yeah, this I think is the problem. If the value of the exp. pot goes to zero when you switch it, then it negates the purpose of having the pedal in the first place.

Having a circuit that can "remember" your setting when you switch away is in my opinion the only viable option for this.

For the moogers, at least the voltage is consistent thru the diff. pedals -- but if you wanted to do it with different brands or pedals which aren't similar circuits it's not going to be easy.

Well, at least for us who are laymen. I'm sure this wouldn't be so tough for a real electrical engineer.

out
 

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