Weird Expression Pedal Behaviour

[dannyboyee82]

So I've had my HX Effects a few weeks now but I've recently noticed something very odd with expression pedal input 1 - it reaches 100% of whatever parameter you set at the mid point of the pedal, and then tapers back down to 0% when the expression pedal toe is fully down. 

 

It only happens with input 1 - the issue does not follow the expression pedal. I have two expression pedals, both are M-Audio. So if I assign the exact same parameter to EXP2, it works as you would expect. If I swap the pedal plugged in to EXP1, over to EXP2.. it works as you would expect. So I don't see it being a fault with the pedal. 

 

Any ideas? It's driving me mad. It's probably something I've changed in some obscure setting somewhere, but I can not for the life of my figure it out! 

 

Thanks for taking a look.

[dannyboyee82]

Just been doing some experimenting. I've got it working by inverting the polarity of EXP1, and having the pot on the expression pedal fully clockwise (the reverse of EXP2). 

 

I wonder why this is?

 

EDIT - nope, it didn't fix it. I then went to setup a new preset and added a wah.. EXP1 had no effect on the position at all. EXP2 worked fine. So I went back in to global settings and set the polarity to normal and turned the pot on the pedal fully counter clockwise.. now it's working as it should. Except that when I power off the HX unit, then power it back on.. it's back to doing the same thing 0-100-0%.

 

I just don't get this. 

[Mturner]

Sounds like your pedal is set up to use a TRS cable and you are using a TS cable.

That would effectively short the outside lugs of the pot together which makes the largest resistance value show up in the middle of the travel.

Build a TRS to TS cable. Connect T to T and S to S. Leave the R connection open. Plug the TRS side into your pedal.

 

Mark

[dannyboyee82]

The M-Audio pedal has a TRS cable and it's a fixed wire. I've read that Line 6 expression inputs are TS, rather than TRS. But it doesn't explain why the same expression pedal works fine in the second expression pedal input. The problem is only present in the first input. 

 

 

[Mturner]

It could be something mechanically different with the two input jacks resulting in a short on one and not the other. I don't know. I have a Floor so I don't have a way to test the HX Effects.

You could build a small adapter cable (female TRS, male TS). Or you could open up the pedal and disconnect the lug going to the "R" terminal.

 

Mark

 

[dannyboyee82]

Thanks for your replies Mark. 

 

I found this on another thread.. 

 

It's the same wiring as the M-Audio. Trouble is that the M-Audio is all PCB inside. I'm tempted to just disconnect everything and wire up a simple TS pedal inside.

[jbuhajla]

I'd bet that the pots in the two pedals are different. Are you using a TS cable for each pedal?

[mrmrsn]

I use an insert cable (TRS-2xTS) connected with a TRS coupler to the TRS plug on my pedal. Then I plug one of the TS connectors into my helix. Works great.