Expression Pedal Not Callibrating Correctly

jawshua

jawshua

Member
I am using a cry baby Dunlop pedal I converted to an expression pedal with a 100k linear pot. I am also using a trs cable. I’ve tried to calibrate the expression pedal multiple times, but what happens is before it gets to the heel down position it reaches 0, so there’s some part of the sweep on the pedal that does not get used. Also, there doesn’t seem to be much sweep, it seems like it has two extremes for the wah and is very sensitive. The control taper is set to linear and the update rate is set to slow.

Any help would be great.
 
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jawshua said:
I am using a cry baby Dunlop pedal I converted to an expression pedal with a 100k linear pot. I am also using a tea cable. I’ve tried to calibrate the expression pedal multiple times, but what happens is before it gets to the heel down position it reaches 0, so there’s some part of the sweep on the pedal that does not get used. Also, there doesn’t seem to be much sweep, it seems like it has two extremes for the wah and is very sensitive. The control taper is set to linear and the update rate is set to slow.

Any help would be great.
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Try a log 20 sweep.

Alsø wik, when you say 'tea cable' do you mean 'TRS cable'?

Alsø alsø wik, perhaps tip and sleeve wires need to be reversed on the jack?
 
Joe Bfstplk said:
Try a log 20 sweep.

Alsø wik, when you say 'tea cable' do you mean 'TRS cable'?

Alsø alsø wik, perhaps tip and sleeve wires need to be reversed on the jack?
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Yes, trs, my phone autocorrected it to tea. I will try that see if it helps.

I wired it correctly, but I’ll triple check the wiring for safe measure. Wouldn’t it not work at all if the tip and sleeve were reversed?
 
jawshua said:
Yes, trs, my phone autocorrected it to tea. I will try that see if it helps.

I wired it correctly, but I’ll triple check the wiring for safe measure. Wouldn’t it not work at all if the tip and sleeve were reversed?
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I have seen reports of weird operation with those two reversed. Some devices require one polarity, and some the other. Some controllers have a switch to swap them.
 
Joe Bfstplk said:
I have seen reports of weird operation with those two reversed. Some devices require one polarity, and some the other. Some controllers have a switch to swap them.
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I tried reversing the wires. It reversed the pedals actions, so that wasn’t it. Log 20 changed nothing either unfortunately.
 
Double-check the 'plunger'/gear mechanics or setup and ensure the pot is not reaching the zero point before the heel down position. The gear on the pot shaft might be moving even though the pot has reached its limit of movement.
 
So, I’ve tried to change this by turning the pot until it gets to 0 and then using that as the heel down position, but when I use the pedal the 10 is reached before the toe down position. So would the issue be the pot?
 
Do you have a multimeter you can check the pot with?

The Fractal devices support 10-100k.

Electronic components typically have at least a +/- 10% tolerance.

Maybe you're reading 110k? I did one Crybaby conversion using a Dunlop 10k linear pot and that worked fine. Everything else I use is 10k...
 
jawshua said:
So, I’ve tried to change this by turning the pot until it gets to 0 and then using that as the heel down position, but when I use the pedal the 10 is reached before the toe down position. So would the issue be the pot?
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Sounds like it- the pot won't allow for the full throw of the pedal. If it was the other way around, calibrating would take care of that issue.

Caveat- If you have confirmed that the pot is reaching the end of its range of motion before the tread does in either direction.
 
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If tip and ring are the wrong polarity, the pedal will work unevenly, but it will still work.
 
unix-guy said:
Do you have a multimeter you can check the pot with?

The Fractal devices support 10-100k.

Electronic components typically have at least a +/- 10% tolerance.

Maybe you're reading 110k? I did one Crybaby conversion using a Dunlop 10k linear pot and that worked fine. Everything else I use is 10k...
Click to expand...
I unfortunately do not have one.
 
Rex said:
If reversing the wires caused the pedal to work backwards, then you reversed the wrong two wires.
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DE748CB8-7FF3-4144-844A-6D3DD9239057.jpeg


That’s how the wires looked with the initial problem. I switched the wires on the outer terminals of the pot and that is when it worked in reverse. Can you recommend which wires I should swap?
 
that's a 100 Ohm resistor. you don't need it and if I'm not mistaken you should swap the two red wires. you wantthe pot taper middle contact connected to the tip of the TRS jack.
 
It is a 1k resistor, the photo may not show the resistor clear enough but it is 1k. Regardless of the resistor it functions incorrectly without it.
 
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