Just got a HX Effects and I was tinkering around with my old SP-1 Mission Engineering pedal, trying to get it to double up as a Wah and Volume by using the toe switch to switch. The SP-1 has two 1/4" TRS Outputs and the toe switch contact is Momentary type.
After some experimentation, I found a mod to the pedal and some required settings on the HX Effects to make it do that.
1. First, get rid of the momentary toe switch. Replace with a SPDT toggle switch. Solder two 10kΩ resistors to the Common pin of the switch, one on each side. The common pin needs to be soldered to the 2nd output jack such that it eventually goes to the Tip (T) of cable. The other two pins go to the Ring (R) and the Sleeve (S). See attached photo. Whenever the switch is toggled, either the Ring or Sleeve will read 0Ω with respect to the Tip, otherwise it reads 10kΩ. The switch is wired up to mimic a potentiometer with only two discrete values of either 0Ω or 10kΩ.
2. Program the WAH block such that EXP-1 is "Position" and EXP-2 is "Bypass". Make sure to set the behaviour to "Toggle".
3. Program the same settings for the VOLUME block.
4. Make sure that the WAH block is turned OFF and the VOLUME block is turned ON.
5. Save your settings and test it out. Connect EXP-1 on the HX Effects to Output 1 on the pedal and Connect EXP-2 to Output 2 of the expression pedal.
