foo_dsp_speaker_range is a foobar2000 DSP component for Windows x64. It adds Speaker Range Crop, a configurable Linkwitz-Riley 4th-order high-pass/low-pass filter intended to limit playback to a loudspeaker’s reproducible range.

The filter sections use Vicanek matched (decramped) coefficients instead of bilinear-transform designs, so the magnitude response stays close to the analog Linkwitz-Riley prototype near Nyquist. In practice this means a 20 kHz low-pass stays active and tracks the intended response at 44.1 kHz, where bilinear/RBJ-style low-pass biquads cramp toward their forced null at Nyquist. The DSP uses causal IIR filters with no lookahead and reports zero processing latency to foobar2000. Reference: M. Vicanek, “Matched Second Order Digital Filters” (2016), vicanek.de/articles/BiquadFits.pdf.

github.com/kidoz/foo-dsp-speaker-range