I'm creating a very basic synthesizer in purr data.

I start with a fundamental frequency, and send that frequency to a "phasor" object which creates a sawtooth wave at that frequency. By clipping the range of two such waves and then adding them (half of a forward and backward-facing sawtooth wave), I create a triangle wave.

I repeat this process a few times with different starter frequencies, specifically multiples of the fundamental, that is, harmonics. I can then toggle these on or off in combination with the fundamental frequency to create a fuller/thinner sound.

Would I be correct in considering this process to be additive synthesis only? Or does the act of performing operations on the original waves to restrict them to certain sounds mean I'm also incorporating subtractive synthesis? I read somewhere that using a "filter" means you're using subtractive synthesis, and I'm not sure whether clipping the waves as I described above would count as using a filter.

1 Answer 1


It is neither additive nor subtractive, but a form of direct digital synthesis. You have one or more virtual digital oscillators that produce arbitrary numerical output, which is controlled by software code running beneath a graphical user interface.

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