[sdiy] Linear FM/Noise modulation demo

Paul Schreiber synth1 at airmail.net
Sun Aug 25 00:14:15 CEST 2002

Here is an audio demo of both audio frequency linear FM and VCOs expo FM'd with noise:


scroll down a bit, look for the Robert Rich live demo (it's long, like 6MB).

At the very beginning of the piece (first 30 sec) you will hear a high, "whispy" unpitched sound.
This is a MOTM-300 VCO FM's by an enveloped burst of attenuated white noise (from MOTM-101). The
is also some audio frequency PWM (not much, just enoug to give the sound a slight 'slurring'

Linear FM makes *wonderful* marimba/xylophone timbres. There is a looping 16-note sequence down
in the mix of a marimba pattern. You can hear is around the 1:10 to 1:10 and the 1:20 to 1:29

About 1/2 way through, the 'lead' voice switches from Korg Wavestation to a patch using pink
noise into the linear FM, and fed through a pair of MOTM-410 Triple Resonant filters. The center
frequencies are 'jittered' by white noise passing through a MOTM-820 VC Lag processor. This acts
as a sort of LPF, that in turn "smears" the 6 BP filters about their fixed center points.

This particular live performance is a great overall example of using the 2 techniques mentioned.

Paul S.

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