Korg Forums

[Xenophile]

I am currently using a Moog EP-3 expression pedal with my Kronos2-61.
I am not happy with the response curve as I depress the pedal from minimum to maximum position. The volume rises too quickly during about the first 1/4 of the pedal travel, and then there is barely any change during the bulk of the pedal travel.

I get a somewhat more linear response if I turn down the maximum level adjustment pot on the pedal, but I don't like to do that because it limits the overall range of the pedal... Instead of midi values 0-127, it gets limited to something like 0-70 in order to get a fairly linear response.

I couldn't find any Kronos parameter to adjust this. Would you have to use Karma to do something like this in Kronos? I know that Mainstage has a handy scaling function to adjust the response of just about any controller.

[HardSync]

Perhaps using an AMS Mixer, such as Offset or Shape, would allow you to modify the expression pedal input values... I don't have the Parameter guide handy, but have a look for AMS Mixers in the guide (or experiment on the Kronos). The guide gives examples on how to use and apply them, so imo, it's definitely worth reading up on a bit. :)

[Xenophile]

Great suggestion! Thanks!

[voip]

The "polarity" switch on the bottom of the EP-3 pedal apparently alters the response curve, so might be worth trying. However, looking at the EP-2 schematic, with which the EP-3 apparently shares the same basic internals, the jack plug wiring is different to that required by the Kronos for correct operation. The sleeve terminal is the same for Kronos and Moog, but the Kronos expects the jack plug ring terminal to be connected to the "wiper" of the expression pedal potentiometer, whereas on the EP-2 it is the tip on the Jack plug that is connected to the wiper. A simple TRS jack to jack cable could be made up, or an existing one adapted, where tip and ring are swapped at one end. Label it clearly as "not for audio".

[Xenophile]

Well there's some useful info! According to this schematic, the switch swaps the ring and tip connections. I didn't realize the pedal had a switch!

[HardSync]

That is cool. :) Did the pedal's switch solve it then?

[Xenophile]

The switch solved the problem. The response of the pedal is much better now. I'm embarrassed to admit that I didn't even know the pedal had such a switch, but without the schematic, I would have no idea what a "polarity" switch on an expression pedal would do.

[HardSync]

Great! Glad that voip's post got you pointed in the right direction. :)

[voip]

Great, knowing that the switch did the trick, and a good case of collaborative thinking. I would have thought the polarity switch might have swapped the ends of the potentiometer round so that, had it been a logarithmic pot, the curve would have swapped from the greatest rate of change being at one end of the pedal travel to the other end.

Curiously, the EP-3 user manual is not available from the Moog website.

[Hector Space]

For those that need to know, Korg and Yamaha use the same wiring for their expression pedals, Roland, Fatar, Studiologic, Kurzweil etc use a different configuration.

Basically the difference is simple as shown in the moog pedal circuit diagram. They both use linear potentiometers connected via a stereo 1/4 jack. But whereas the Roland camp wires the pot wiper to the jack tip and the pot hotend to the jack ring, Yamaha and Korg do the opposite for them the jack tip is pot hotend and the ring is pot wiper.

If you use a Roland pedal on the Kronos you’ll get a classic abrupt change in volume (a bit like in the old days of analog volume pedals if you used a linear pot instead of a log pot)

To use a Roland, Fatar or Kurzweil Expression pedal on the Kronos all you need to do is swap the jack ring with the tip and it’ll work fine!

So there! Now wasn’t that riveting Lolol