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Nos402

Boss Expression Pedal works backwards

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I have a Boss Stereo Volume pedal that can also be used as an expression pedal, but with the Helix, it works backwards. I'm guessing it's just a polarity incompatibility that I can't do anything about?

 

Aside from that, I'm LOVING the Helix every bit as much as I hoped I would. So far, my only niggle is that I wish there was an "insert character" when naming patches.

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you can always just reverse the numbers in the tone... set the min to the max, and the max to the min.. then it will work backwards.

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you can always just reverse the numbers in the tone... set the min to the max, and the max to the min.. then it will work backwards.

A better way is to do like all keyboards do and have switch polarity in the master section in the helix and all expression pedals will work.

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I have a Boss Stereo Volume pedal that can also be used as an expression pedal, but with the Helix, it works backwards. I'm guessing it's just a polarity incompatibility that I can't do anything about?

 

Aside from that, I'm LOVING the Helix every bit as much as I hoped I would. So far, my only niggle is that I wish there was an "insert character" when naming patches.

I use a boss fv5 I think. make sure the volume on the pedal is turned down all the way. I also had to put a screw through the pedal as a stop otherwise it would go to 100% then start going back down. These pedals aren't ideal for use on L6 products.

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which is not an option for the average person.. i was trying to help the guy... not get his hopes up that things may one day change to fit his desires....

 

A better way is to do like all keyboards do and have switch polarity in the master section in the helix and all expression pedals will work.

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which is not an option for the average person.. i was trying to help the guy... not get his hopes up that things may one day change to fit his desires....

A couple lines of code would solve the problem. This would not take long to fix. All keyboards that I have bought has a polarity option for expression pedals. Some expression pedals have a polarity switch on them.   I think all expression pedals should have a polarity switch, but they don't. The best fix is make max min and min max code wise for a polarity change. A customer can also do the same thing, but they should not have to. It is not that hard of a fix.

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to the best of my knowledge... you me or him.... cant add a couple of lines of code to the helix.... which was my point... it doesn't help him now.

 

A couple lines of code would solve the problem. This would not take long to fix. All keyboards that I have bought has a polarity option for expression pedals. Some expression pedals have a polarity switch on them.   I think all expression pedals should have a polarity switch, but they don't. The best fix is make max min and min max code wise for a polarity change. A customer can also do the same thing, but they should not have to. It is not that hard of a fix.

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to the best of my knowledge... you me or him.... cant add a couple of lines of code to the helix.... which was my point... it doesn't help him now.

Exactly ... and while we're on the subject, I can tell you from 13 years experience as a software engineer, nothing is as simple as it seems. Just changing "a couple of lines of code" to fix THIS pedal could break functionality for all of the OTHER pedals that were working correctly.

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This is from a thread where I had asked about my GC mission engineering EXP......  Hope it helps.

 

Posted 19 October 2015 - 01:27 PM   BEST ANSWER

BigRalphN, on 19 Oct 2015 - 09:21 AM, said:snapback.png

Forgive me if this is dumb but I have never looked at expression pedal circuits. Could you just simply wire a patch cable backwards and solve it or is it more in the circuit?



Yes absolutely that's a brilliant idea I didn't think of doing that I thought of taking apart the pedal but yes you're absolutely right you just have to find the right combination of wiring because really the expression pedal is basically just a volume pot or a potentiometer.

Well I should start taking orders now anyone wants one I'll pick up a TRS cable cut it in half and add some female ends too it in the right combination of wiring 

stevekc, on 19 Oct 2015 - 2:36 PM, said:snapback.png

FWIW - here is the Roland EV-5 that works with a TRS cable to my XTLive, HD500X, Firehawk

 

10K Linear POT

 

1410890697_2076475294_EV5_diy.jpg

thanks for this I had not had a chance to look this up and I can see simply swap the tip and ring and it will do the trick...

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I have a Moog expression pedal with some funky wiring to add a calibration pot (basically to set it to zero) and a mode switch (not a polarity switch). With the switch set to "Other", the pedal behaves exactly as Nos402 described (basically backwards). I went in and modded the pedal to make it work as desired:

 

(Disclaimer: Unless you know your way with a soldering gun, DO NOT ATTEMPT).

I disassembled the pedal and removed the pot, which had three wires soldered to it: CW (clock-wise), Wiper and CCW (counter-clock-wise), in that order. I took my soldering gun and de-soldered both the CW and CCW leads and swapped them (leave the wiper lead alone). So now my pot has the CW cable soldered into the CCW lead of the pot and vice-versa. Then, I re-melted the clear plastic that was holding the leads in place to firm them down (or you can use a heat gun and put fresh plastic to secure the leads down again). Re-assemble the pedal, set the switch on the bottom of the pedal to "other" and test.

 

My only issue now is that the pedal, due to its much higher resistance, goes to "100" at about 90% of travel, but it stays there once I go past 100. If I really want to, I can cut down a foam block to size, place it between the pedal and the case and make it so that the pedal hits the foam at 100% exactly, but I don't care, as long as it works well as a volume pedal.

 

Why did I do this, rather than just wire a TRS cable backwards? Basically because the leads that I needed to change were the Shield (also called "sleeve" - i.e. the "ground" lead) and the tip. Never, ever, ever, ever (Did I mentioned "ever") mess with the ground lead. I know the pedal is cheap plastic, but you can always get noise that way (if you are lucky) or, worst-case scenario, if metal parts of the pedal touch metal parts on the amp or Helix, you just short-circuited something. I never bothered to check but, there is another way to wire an expression pedal so that it has a +V lead, rather than a ground one. It does not matter which one it has, it is still a bad idea to wire it backwards. When your pedal works backwards, the only safe mods you can do are either to flip the pot 180 degrees so that it rotates in the "correct" direction, which is not always feasible if there is no place ot mount it facing the opposite direction within the case, or re-wire the pot so that the (pot) signals are reversed, but not the circuit ground.

 

One last note about 3rd party pedals: some of the (like the Moog), change very quickly at the beginning of travel and then slow down towards the end of travel. This is an indication that an audio pot is being used, rather than a linear one. If this happens to you with any 3rd party pedal, change the pedal curve over to "Logarithmic" (it defaults to "Linear"). This will make the pedal more consistent over the travel distance. You will probably have to make the change on each patch that uses the external pedal, as the setting does not seem to global, but rather per patch.

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