http://plugin.org.uk/swh-plugins/bwxover_iir
http://plugin.org.uk/swh-plugins/highpass_iir
http://plugin.org.uk/swh-plugins/lowpass_iir
http://plugin.org.uk/swh-plugins/bwxover_iir
http://plugin.org.uk/swh-plugins/highpass_iir
http://plugin.org.uk/swh-plugins/lowpass_iir