Parenthesis - Expression pedal?

jmc1187

New member
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?
 
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 :D!!
 
Haha! I was just kidding :p but I see that BuGG approves your idea ^^ I might do that when I order my next batch of pcbs :)
 
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?
 
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.
 
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.
 
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?
 
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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