The filter will filter any channel you assign to it, assign the 2nd slider to the cut off, and play around.
You get 3 types to chose from, low pass, high pass, and band pass.
They operate from different directions so don`t flick between filters in the mix.
The low pass opens up from left to right
the high pass from right to left.
I can`t live without em any more.
Careful you don`t overdo the resonance.