The αρπ Filter (alpha-rho-pi) of NLC sounds great. .... very much like the diode ladder used in the Roland TB 303
It's actually a hybrid/variation of the vintage Electronotes and ARP designs.
Hard to describe it's sound ... inorganic, man-made (in a good way).
The filter design has 2 audio inputs, two CV modulation ins and two audio outs (Bandpass & LP).
I'm not aware of NLC's producing a Eurorack version of this great module. So for now, if you want one
you'll have to build athe 4U banana-fied panel .... it's well worth it.
As you can seen from the pics I'm using just the BP out & one in & one CV mod in.
The CV is being modulated from a jerkoff.
This is a old video using the αρπ Filter: