Unmirrored waveform oscillator

Steffenvy

I think it would be nice if the oscillator node had the option to give a custom wave curve, like this:

Setting the oscillator to sawtooth, multiplying by 1.5, and then using a waveshaper node almost works, but the result has random noise.

j_w

Steffenvy the result has random noise

To reflect specifically on this...

This is caused by the fact that the oscillator node's output is band-limited (or anti-aliased) for the sawtooth wave (and triangle and square), which causes the signal to swipe through the shaping curve not in a perfect linear fashion, but with some "shaking" going on near the edges -- if that makes sense the way I'm describing it.

A quick and easy fix is using one or more lowpass filter nodes to try to attenuate the noise in the higher frequencies, like this:

Note that I'm also using a highpass filter here to remove the DC offset.

Another, slightly more complex alternative is using the Timer Node to construct a mathematically accurate sawtooth-like wave.

j_w

Steffenvy I think it would be nice if the oscillator node had the option to give a custom wave curve

This sounds like a great idea (pun intended), how do you suggest this would work? Something like just simply drawing the audio signal on a canvas, or something more advanced, like drawing the spectrum of the signal? The latter is something that's in the works, but is kinda far from release.

Steffenvy

Drawing the audio signal would be nice, just like using the waveshaper node, except with the end points defaulting to a value of 0, and an option to mirror it or not. It could also be done in a way that the deprecated horn and organ are presets of this curve (even sine (approximation), sawtooth, square, and triangle could be presets), and it would be useful and informative to be able to modify these default curves and see directly how modification (asymmetric or not) of the waveform affects the sound. Especially because multiplying by the square root of 2 wouldn't be necessary:

j_w

Steffenvy

If it helps, the 0.5.7 update added the Fractional Node, which you can use to create a perfect sawtooth wave without band-limiting, and then feed that into the waveshaper to avoid aliasing around the edges.

Here's an example: https://www.audionodes.com/s/yQvZ5hHsQS/