Expression pedals for Mojo organs explained
We currently have two pedals designed for Mojo61, Mojo Classic/suitcase and Mojo desktop: one is called EXP-20-MS (switchpedal) and one is calle EXP-10.
EXP-20-MS : to control the expression or swell, it has an internal 10kohm potentiometer with max (voltage) on tip, signal (brush) on ring and min (groung) on sleeve. The polarity can't be changed. It also has two side switches used to control the internal rotary simulation: left one is for start/stop, right one is for slow/fast. The box includes 2 jack cables: connect one in the plug named "SWELL" and plug the other side of it in your instrument, in the plug named "SWELL" or "EXPRESSION" (silkscreen name can vary depending on the model of instrument), the other TRS jack needs to be plugged in the hole named "ROTARY" and, on the other side, it needs to be plugged in the instrument in the hole named "ROTARY" or "HM/FS" or "HALFMOON OR FOOTSWITCH" (silkscreen name can vary depending on the model of instrument).
EXP-10-MS: this has an internal 10kohm potentiometer with max (voltage) on tip, signal (brush) on ring and min (groung) on sleeve. The polarity can't be changed. The box includes 1 jack cable: connect one side in the plug named "SWELL" and plug the other side of it in your instrument, in the plug named "SWELL" or "EXPRESSION" (silkscreen name can vary depending on the model of instrument).
Our instruments accept pedals of other brands but please be sure that the internal pot for expression is rated at maximum 20kohm. Pedals with higher resistance values can cause problems. The internal pot of our pedals is not able to do the entire travel, meaning that, on a scale from 0 to 127 (for example), it won't do that entirely, but something like 80%. This is the mechanical design of them, it can't be changed. We usually set our pedals to reach the maximum level but not to reach the lower level, that's because this system is very suitable for expression control of a tonewheel organ. The internal software is compensating this limit.
Please note: when you are in VB3 mode (tonewheel organ) those are not volume pedals but expression pedals and the volume when completely closed is never going to zero (no sound). This is how a real tonewheel organ works.
EXP-15-MS was a pedal designed for "old" Mojo dual and MojoXT, they are not compatible with Mojo Classic/Suitcase, Mojo61 and Mojo desktop.
If you have a pedal with side switched but you are not sure if it's a EXP-20-MS or a EXP-15-MS (maybe because you bought it second hand) you can check the internal wiring opening the bottom metal plate of the pedal exposing the wiring configuration.