Struct synfx_dsp::fh_va::SallenKey

pub struct SallenKey { /* private fields */ }

This is a 2-pole lowpass filter.

This is a 2-pole lowpass filter loosely based on the one found in the second revision of the Korg MS20 synthesizer. It distorts really nicely and gets especially gnarly when resonance is high. My personal favorite.

It’s able to self-oscillate and starts doing so when its resonance is above 0.8.

OTA core, nonlinear op-amp buffers. Resonance is limited by a diode clipper, but it disappears quite quickly at high drives.

Its convergence is generally good, but it does get a bit slower at high drives. The parameter vector for the nonlinear contributions is just 2 entries long, meaning that it might be reasonable to create a lookup table to guarantee stable, fast runtime. <- not as reasonable as I thought, also needs entries for g and res

Circuit solved by Holters & Zölzer’s generalization of the DK-method.

The fast version is optimized by removing unnecessary operations and replacing the general solver with an analytic solution of the specific model. At some point I’ll look into how a simd-optimized version would compare, since most of the operations are dot products anyway, but the current fast version is definitely fast enough for real-time use in DAW projects. pub struct SallenKey { filters: [SallenKeyCoreFast; 2], }

Implementations

impl SallenKey

pub fn new(params: Arc<FilterParams>) -> Self

pub fn process(&mut self, input: f32x4) -> f32x4

Process a stereo sample.

pub fn update(&mut self)

Call this whenver the resonance or cutoff frequency of the FilterParams change.

pub fn reset(&mut self)

Reset the filter.

Trait Implementations

impl Clone for SallenKey

fn clone(&self) -> SallenKey

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for SallenKey

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.