Hi, I'm trying to do a very similar thing but modulating the audio from a file. I want to produce a stereo tremolo by using the sine amod effect, out of phase on the left and right channels. LEN=0 OFFSET=0 PHASE=0 PHASE2=180 The following works for mono, producing the desired tremolo in mono: sox rd73_064__E4_082.flac x.flac synth $LEN $OFFSET $PHASE 2 sine amod 0.5 I thought the following would work for stereo: sox rd73_064__E4_082.flac x.flac synth $LEN $OFFSET $PHASE2 2 sine amod $LEN $OFFSET $PHASE2 but I get a parameter error. Any suggestions? Thanks! On Wed, 3 Jun 2020 at 10:34, Dr. Thomas Tensi wrote: > Hello Darryl, > > > you wrote: > > [modulate a sine wave with another in SoX?] > > What you could do as an easy approach is modulate a sine wave with a > tremolo. Assume a target bit depth of 24bit, a sample rate of 44.1kHz, a > carrier of 1500Hz with a length of 20s and a modulation of 0.5Hz with a > depth of 100% > > sox -n -b 24 -r 44100 test.wav synth 20 sine 1500 tremolo 0.5 100 > > Tremolo can only do a sine modulation with a fixed phase of 90°. > > Even more powerful is the cascading of synth effects. Same logic, the > carrier is amplitude-modulated by a sine with 0.5Hz with the same 20s > length: > > sox -n -b 24 -r 44100 test.wav synth 20 sine 1500 synth 20 sine amod 0.5 > > If you don't want a full modulation (from 0 to 100%), you can add a > dc-offset to the second waveform. > > Hope this helps! > > > Best regards, > > Thomas > > > _______________________________________________ > Sox-users mailing list > Sox-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/sox-users >