I am using lop~ and hip~ filters in a real time audio application, at a sample rate of 48kHz.

Something I read in the help of an external library has me worried they may not be working as I expected.

A variant of [lop~] that has a signal-controlled cutoff. Like [lop~], the filter has no effect when the cutoff is above SR/(2pi)

Is this saying the filters are only working to about 5kHz?

@pure_raspberry the frequency setting only goes up to sr/2pi, so in your case ~7639.44
see here for a full explanation about the frequency-warping and patch https://forum.pdpatchrepo.info/topic/9723/lop-object-argument

@seb-harmonik.ar said:

@pure_raspberry the frequency setting only goes up to sr/2pi, so in your case ~7639.44
see here for a full explanation about the frequency-warping and patch https://forum.pdpatchrepo.info/topic/9723/lop-object-argument

OK, I think I am understanding it. Is this just a limit for the setting? If I set a low pass filter to , say, 7kHz, then the response still looks like a normal low pass one pole filter, slowly rolling off , even at frequencies above 7639.44 ?

@pure_raspberry yes the response will still be a 1-pole lowpass, it's just the pole location that's approximated

@seb-harmonik.ar, are there are similar approximations in [vcf~]? A couple of us noticed that the low pass outlet attenuates at high cutoff frequencies, especially at low Q factors IIRC,

@jameslo said:

A couple of us noticed that the low pass outlet attenuates at high cutoff frequencies

no idea, sorry. I haven't sat down and tried to wrap my head around vcf (especially how the 2nd outlet functions as a lowpass)