Barber Pole .uhm?

[hakey]

I'd like to get my head around scripting. So, how would I go about making a Barber Pole wavetable .uhm?

This type of thing:

Barber Pole.png

The sketch shows the amplitude of partials for one wavetable frame. With successive frames the curves shift along the Y axis until we arrive back at the initial frame.

This should, I think, produce the illusion of a constantly rising or falling tone.

[Urs]

A one-liner as quick starting point:

Code: Select all

Spectrum "(0.5 + 0.5*sin( (4 * (phase+1))^2.5 * pi - 2 * pi * table )) / (1 + sqrt(index))"

Set Position to 0, switch on Cycle mode, adjust Auto to taste for some barber pole phasing.

A brief explanation:

"Spectrum" lets the formula work in the frequency domain (magnitudes of harmonics)

"0.5 + 0.5*sin( 2 * pi * ... )" creates a unipolar sine wave

"(4 * (phase+1))^2.5" scales the sine wave a bit so that notches appear more balanced in spectrum. This is the part where one would experiment with.

"2 * pi * table" wraps the sine exactly by 1 cycle from the first frame to the last. Table is 0 for the first frame and just below 1 for the last frame

"/ (1 + sqrt(index))" is a 3dB-ish filter to round off the higher harmonics. Use "/ index" to get the frequency roll-off of classic analogue waveforms.

Happy experimenting!

- U

[hakey]

Will have a play around with that.

Cheers!

[Howard]

I'd like to get my head around scripting.

[hakey]

Well, I've been asking for some mathsy way of making wavetables for a while now, and this is just that.

My poor scrambled brain, though.