# Parenthesis - Expression pedal?



## jmc1187 (Mar 15, 2020)

Hi all!  So here's an interesting one for the Parenthesis: what if you wanted to include an expression pedal input to control the Octave blend instead of (or I guess in addition to) the included potentiometer?  Is this something feasible with the current board layout?


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## Nostradoomus (Mar 15, 2020)

This works. I just tried it on my parentheses mini with a Moog EP3. Probably needs a tweak or two as the Moog is 100k and the pot is 50k but it’s not bad as is.





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						Expression Control Wiring - PedalPCB Wiki
					






					wiki.pedalpcb.com


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## Bobbyd67 (Mar 15, 2020)

This is very cool !!! It's just a shame that in the mini there's not much room for it... Well now we need a 1590bb version I guess !!


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## Nostradoomus (Mar 15, 2020)

I’m just going to put the mini in 1590bb, align the filter pot (board mounted) and toggle switch in the middle and run wires to the other pots so they fan out a bit.


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## Bobbyd67 (Mar 15, 2020)

Haha! I was just kidding  but I see that BuGG approves your idea ^^ I might do that when I order my next batch of pcbs


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## jmc1187 (Mar 16, 2020)

Oh damn there's a whole wiki... lol I missed that entirely.  Thanks!


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## palelight (Jul 30, 2020)

Hey all, thought I'd bump this rather than start a new thread. Recently built a Parenthesis mini with an expression input for the octave. Wired up like the above link in the wiki page. Using a Moog expression pedal (100k) and it works...sorta. With the treadle about half way depressed you get the full octave effect, depressed all the way down things start sounding crappy. Figured I could throw some parallel resistors across the expression pedal pot to get it down to match the 50k of the octave pot, but it had no discernible change to the sweep. Is there something I'm missing?


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## Nostradoomus (Jul 30, 2020)

How do you have the polarity and output knob set on your expression pedal? Mine does not act like that at all, it blends it pretty well.


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## palelight (Jul 30, 2020)

Output knob is set to full (so, out of the circuit?) and the switch set to standard. When set to "other" I get a high pitched squeal.


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## Nostradoomus (Jul 30, 2020)

Maybe turn the output knob down to half...play around with it. I’m not at home or I’d check mine!


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## palelight (Aug 2, 2020)

I guess I was wrongly under the impression the output knob limited the sweep the other way (no idea where I got that from). Anyway, with the output knob around 1 o'clock it works as it should. Out of curiosity I swapped the GE diodes for some higher output ones (around 35fv) and that allowed the output pot on the expression pedal to be turned a little more toward max. Seems the GE diodes in this guy are incredibly particular. I ended up with my original D9K's (around 26fv) as I liked the effect a bit more. Curious what diodes are you running in your builds?


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## Nostradoomus (Aug 2, 2020)

1n5817


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## palelight (Aug 12, 2020)

Just in case anyone sees this and is apprehensive about expression pedal mod/capability, I found the issue (for me anyway) - way too long TRS cable. Shortened my expression cable and everything works as it should. I think there may have been some slight parasitic oscillation with the overly long cable I was using.


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## Nostradoomus (Aug 12, 2020)

Could be, I use the 6’ one that came with the EP3.


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