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EX1 Expression pedal on M9 doesn't work for 1st 10% of sweep??
by teamjim on 2012-11-21 14:49:03

Hi just got an M9 with expression. Hoped it would be a good volume pedal alternative (with the volume patch) and a good whammy. But i need to be fairly precise with it. Bizarrely it seems that for the first 5-10% of the sweep nothing really happens and then it kicks in after that. This makes it very unsmooth and difficult to control. Obviously they cant be calibrated, have i got a dodgy ex1? Is it a software problem? Should i get another expression pedal?



Re: EX1 Expression pedal on M9 doesn't work for 1st 10% of sweep??
by phil_m on 2012-11-21 16:07:43

The EX-1 has a linear response curve, so it doesn't really make the best volume pedal. I imagine that's what you're observing.



Re: EX1 Expression pedal on M9 doesn't work for 1st 10% of sweep??
by teamjim on 2012-11-24 02:39:33

What's a linear response curve. Which of the compatible expression pedals don't have a linear response curve?



Re: EX1 Expression pedal on M9 doesn't work for 1st 10% of sweep??
by phil_m on 2012-11-24 07:30:02

By response curve, I'm talking about the way the potentiometer inside the pedal reacts as it travels from one end of its rotation to the other. Expression pedals that work like the EX-1 are relatively simply electrical devices. The position of the parameter being controlled by the expression pedal depends on the resistance seen at the expression pedal input jack.

I apologize for the technical jargon in the next paragraph, and if you don't care about the details, just skip it.

In a pedal with a linear response curve, the position of the pedal will be related roughly 1:1 with the position of the expression pedal, i.e, when the pedal it at 10% the value it's controlling will be at 10%. When the pedal is at 50%, the value will be at 50%. For many parameters, this is what you want. For volume and wah, though, most people like something different. Volume is different because are ears don't hear in a linear fashion. For something to sound twice as loud to us, it needs to have ten times the original signal strength. So this is where audio taper pots come in handy. The picture below shows some of the most common response curves:

<a target=new href=http://www.geofex.com/Article_Folders/potsecrets/pottaper.gif"class="jive-image" src="http://www.geofex.com/Article_Folders/potsecrets/pottaper.gif"/>

So, if you want an expression pedal that works like a volume pedal, you'd have to find one of the volume pedals that's compatible with the M-series stuff. The thing is that you'll probably find that using a volume pedal to control other parameters doesn't work the way you'd necesarily like either. I still think that if someone wants to use a volume pedal a lot, the best solution with the M-series pedals is to get a standalone volume pedal.



Re: EX1 Expression pedal on M9 doesn't work for 1st 10% of sweep??
by teamjim on 2012-11-24 14:04:34

The worst part is for the whammy pedal!



Re: EX1 Expression pedal on M9 doesn't work for 1st 10% of sweep??
by phil_m on 2012-11-24 16:23:03

How are you using the whammy effect? I use the EX-1 with that effect, and I don't have any problems with it. Although, I'm doing the sweeps pretty quick - think something like the Edge does in Even Better Than the Real Thing. It's just rocking back and forth quickly. But in any case, it sounds like you might do better with a different pedal.



Re: EX1 Expression pedal on M9 doesn't work for 1st 10% of sweep??
by teamjim on 2012-11-28 15:56:10

I'm using it fairly slowly. In one instance - to recreate the rising pitch effect about 1/2 way through Rihanna's song 'we found love' (yes, yes, i know) - thats when i noticed, it just seems to jump up (even when i go REALLY slowly) from 0 straight to 2/3 semitones and then goes smoothly from there. Annoying! Was hoping the pedal was faulty, or that its just a known fault with the line expression




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