The DFM-1 is a digital filter module based on a real analogue filter circuit, the AFM-1. The
purpose of the DFM-1 is to demonstrate that a digital filter can sound as good as an analogue
filter, and, by making it open source, to show how this was done.
The DFM-1 is dual licensed under the terms of the DFM-1 License
or the GNU General Public License version 2 or later. Full licensing information is included
with the download.
The AFM-1 is a 12dB per octave resonant filter loosely based on the MS10 and MS20 synthesizer
filters that were manufactured by Korg in the 1970s, with a greater emphasis on distortion.
The DFM-1 demonstrates most, but not all, of the artefacts exhibited in this recording:
The AFM-1 CAD files are licensed under the GNU General Public License version 2 or later.
Further research
The remaining differences between the analogue AFM-1 and the DFM-1 are the subject of ongoing
research.
Credits
The DFM-1 was ported to SuperCollider by Jonny Stutters, who also supported and encouraged the
idea in its early stages. The AFM-1 and DFM-1 are only possible thanks to discussions with
many people. Thanks to Martin Naef for recording the AFM-1 filter demo, and to
Marc Nostromo for ongoing discussions.
