# Pulse width modulation

I’m still very new to making music with a modular synth (or any synth for that matter), and recently discovered something about pulse width modulation at audible (higher than usual LFO) frequency. It adds so much more overtones, and they differ depending on the frequency as you find a few sweet spots in the sweep. I thought it was really neat. Is this a common method of PWM?

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What’s the deal? I didn’t really get much from Google or you tube…

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It sounds ( ) very similar to what you can achieve with FM modulation. I personally find it very hard to use, to me it mostly has sweet spot sounds, for drone type thing

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Experimentation is all part of the fun, not sure if it matters so much to find labels to identify certain “effects”

If you are looking for a theoretical understanding of whats going on, I think we need a mathematician, do we have a resident mathematician?

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Oh, Nick Batt is a vlogger linked to the sonicstate youtube channel who seemingly often comments on PWM-capabilities of synthesizers. So it is a running joke among youtubers who do synth related videos to associate him with all things PWM:

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I saw a video montage on you tube. I thought it was about to educate me on some pulse with mod but it was just clips of him goin on about it.

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Even the experts dont seem to agree on a mathematical definition for PWM
as evident here

I came across a brief mention of it being employed in telecommunications for signal processing, but not how or what for.

Not that such a definition is necessary for the creative manipulation of sound, Im now quite intrigued by this question. I understand that @analogoutput has an interest in mathematics puzzles (from reading his blog) might he have anything to add on this one?

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Other than music, I know it is used to manipulate electric motor speeds by increasing or decreasing pulse width (duty cycle). I always just used it for texture or to make the sound “move” more. I had no idea it could add so much tone at higher frequency on the modulation.

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Just to have a comparison I tried fm on the same synth with the same method (modulation at high frequency) and I like the pwm sound much better than the fm sound. It just sounds better to me. I’m a pwm fan for sure.

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Yeah, narrow pulses contain a lot more high order harmonics than the usual 1st,2nd,3rd,etc

It’s quite a fascinating effect. I too am a fan of PWM. I have this idea for a module that does multiple PWM on the input signal, each with its own LFO.

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