New digital model of the SID 8580 filter released and updates

Posted by Stefano on Mon, 03 Nov 2025 12:39:32 GMT.

(Original photo by Taras Young, CC BY-SA 4.0)

We just released a new Brickworks Pro algorithm that implements a digital model of the MOS Technology®/Commodore® Semiconductor Group 8580 Sound Interface Device (SID) filter with separated outputs, as found in the later C64 models.

At the same time, we also updated Brickworks and a few Brickworks Pro algorithms.

More specifically:

• Brickworks version 1.4.1 has been released which fixes a bug in debugging-related code (oh, the irony!) in the bw_svf algorithm, that is our state-variable filter, when extremely low cutoff values are used (way below 1 Hz).
• The bwp_svf algorithm, that is the advanced version of bw_svf, got the same treatment and its documentation was slightly improved to clarify the role of its prewarp_at_cutoff parameter.
• The bwp_ladder4 algorithm has seen some minor optimization in smoothing and some documentation fixes.
• The bwp_hera_chorus algorithm version was bumped as it depends on bw_svf.