Hello, recently I implemented and published a music plugin with faust [1], which implements the digital model of a bass tone circuit.
A problem encountered during this process is the discretization of the EQ section, located on the bottom part of the schematic [2], running from C25 to C20 not included. This circuit describes as a low-frequency peak filter (+ or - gain), combined with a high-frequency shelf, parameterized by a pair of coupled knobs labelled as bass and treble. I have produced a program for computing the expression for the analog transfer function [3], and applying the bilinear transform. While the analog transfer function matches the SPICE results, I observed the digital filter does not meet the criterion for stability (that is, poles inside the unit circle). There is faust source code [4], the unstable EQ is replaced with an adhoc substitute having a relatively matching transfer function. Any hints on producing a more valid discretization of this system? Thank you very much [1] https://github.com/jpcima/Bass21 [2] https://blog-imgs-91-origin.fc2.com/d/r/u/drugscore/02_49_4SABDsch.png [3] https://git.io/JcQi5 [4] https://git.io/JcQPy _______________________________________________ Faudiostream-users mailing list Faudiostream-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/faudiostream-users
