New to this so be gentle: Want to mod a Audio Control EQX

[picowallspeaker]

The 2.2 µF value sets the highpass frequency , which would be around ˜10 Hz .
For values till 4.7 µF it's ok to use polyprop or polyester caps instead of electrolitycs because of the size . So if you need to change the highpass frequency point ,you can choose values well under 2.2 µF .Resistor remains unchanged ; also , the circuit that follows would probably have another capacitor at its input.
But this is for passive filters circuits . Probably the ACEQX has also a fixed highpass , I mean ,those resistors on the back of the board would suggest that they could be changed if needed .Are those 12 K ?