You can use any 1/4" TRS to 1/4" TRS patch cable to conect an expression pedal to the CTRL port. Here are some examples, all are available in different lengths with similar part numbers:
- Hosa CSS-103 balanced interconnect cable (CSS-105, etc.)
Monoprice 4792 Premier Series 1/4in TRS male to male cable
Pro Co BP-3 Excellines balanced patch cable (BP-1.5, BP-5, etc.)
Most of the cables above are also available with two right angle connectors or one straight and one right angle. Straight plugs work best with our pedals unless you can drop the cable straight down between the rails of your pedalboard. The expression pedal end depends on whether its jack is on the side or top.
You can also use a TRS instrument cable (Rattlesnake, Sinasoid, etc.), but it is overkill and they typically have larger plugs with stiffer strain relief to stand up to more movement.