Expression pedal sweep question

R

RomanMtz

Member
Hello! I'm running into a similar situation as described here: https://forum.fractalaudio.com/threads/expression-pedal-not-working-well-for-volume-swel.152276/

Going straight into my FM3 with a TRS cable using this Melo Audio EXP-001 expression pedal that uses a 10k pot: Amazon item B07MJQH9PR

Basically after calibration I get the full range of sweep on the modifier, but the last maybe 25% of the physical sweep (going toward toe down) of the pedal is pretty much at 100% on the controlled parameter. I've tried editing the modifier line into a curve to try to address this but I haven't been able to get a smooth sweep.

Would anyone have any suggestions? Is it the pot value or type (linear/log) that's influencing this behavior? Any examples of expression pedals connected directly to the FM# pedal port that in your experience has smooth sweep?

Thanks!
 
You might be interested in this review of the EXP-001 on Amazon:

https://www.amazon.com/gp/profile/a...SDJTY3B74LVJLQ/ref=cm_cr_arp_d_gw_btm?ie=UTF8
3.0 out of 5 stars Beware: Needs inverted polarity cable for some devices. But good pedal.

Reviewed in the United States on April 3, 2019
Color: expression pedalVerified Purchase

This had no sweep out of the box. It was going from 0 to full before reaching 20% of the sweep. Tried it with my Axe FX2 XL and an Atomic Amplifire. After reading about it I tried to re-solder one of my TRS cables and invert the tip and the ring of one of the sides. With that modified cable the pedal now works fine. It would be great if there were a switch on the pedal for that as there is on other models.
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fabiodrs92 said:
I have the exact same problem. Did u find the solution?
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Did you read what he quoted? He didn't have the problem, he was replying a solution someone else posted.

You have the same problem with the same expression pedal, or with a different one?

If it's the same one then the posted solution sounds like it will work. You could also look for a polarity changing cable if you're not handy with a soldering iron.
 
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unix-guy said:
Did you read what he quoted? He didn't have the problem, he was relaying a solution someone else posted.

You have the same problem with the same expression pedal, or with a different one?

If it's the same one then the posted solution sounds like it will work. You could also look for a polarity changing cable if you're not handy with a soldering iron.
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Dude if I'm saying it's the exact same problem it's because it's the same pedal. The solution didn't work for me. I change the tip and ring polarity with a soldering iron. No results.
 
fabiodrs92 said:
Dude if I'm saying it's the exact same problem it's because it's the same pedal. The solution didn't work for me. I change the tip and ring polarity with a soldering iron. No results.
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Dude, that's why I asked. You can have same problem without the same pedal.

Since you didn't say, I asked for clarification. Many people say "I have the exact same problem" only to find out they don't

In order to help we need to make sure we understand the issue.

Also, you only changed wiring on one end, correct?

Do you have a multi-meter? You can try measuring the resistance between tip and sleeve as you move from heel down to toe down and then do the same between ring and sleeve.

You should see a pretty linear change across the sweep from 0 to 10k ohm or vice versa.
 
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