> > > > On 12/05/2023 11:47 PM EST Andrew Simper <[email protected]> wrote: > > > > > > Apart from when the algorithm has numerical issues, for example an f32 > > direct form 1 biquad does get a much better near 20khz frequency and phase > > response when running at 192khz, but watch out of you try and do some low > > frequency rumble removal or dc blocking with this algorithm in high pass > > mode with low cutoff eg 20hz. > > That's one of the reasons to use trapezoidal (besides just the time-varying behavior). Off the top of my head and from some experience, it would still have precision issues at lower cutoffs, but those would kick in much later and be much more predictable, mostly amounting to some cutoff variations, or, if the cutoff is very low, to the low-pass part of the filter simply freezing. Probably it's more complicated that that, didn't experiment too much.
But that kind of problem is not specific to filter design. Even simple things like updating a sawtooth oscillator are prone to exactly the same issues. -- Vadim Zavalishin Reaktor Application Architect Native Instruments <https://www.native-instruments.com/> – now including iZotope, Plugin Alliance, and Brainworx
