Question I have connected an expression pedal to my  Flashback X4, but I cannot manage to make it work.  Answer  You must use a pedal with a low impedance pot 25/50 KOhm. The connection on the Flashback X4 is a TRS jack. Depending on the pedal model, you might need either a TRS jack to TRS jack cable, or a TRS to 2x TS jack cable. Instructions in the manual for assigning parameters are correct: 
  • Select a preset. Set the pedal in the max position, then set the parameter knob (i.e. delay LEVEL)to the wished max position.  Then set the pedal to the minimum position and set the knob to the minimum value you want to reach with the pedal. 
  • Store the preset. 
The only thing that does not work compared to the manual is when you want to de-assign the pedal from a parameter in the preset. The manual says: 
  • Recall the preset 
  • Set the pedal in max position 
  • Store the preset.
In fact you must also add the following steps to the procedure 
  • Set the pedal in minimum position 
  • Re-store the preset.