Barberpole Through-Zero Flanging

[DrAlx]

The link I posted no longer works.  Here is the doc shared again.

https://1drv.ms/p/s!AvrH61utWEtEg3EMUPPypvZwGLUj?e=jTx4l8

If I was going to do this I would do it on the FV1 since I know how to code one now (I posted a DIY Tonewoodamp project on the forum).

It should actually be a no-brainer on the FV-1 because of the way that pitch-shifting is typically implemented on that chip.

http://www.spinsemi.com/Products/appnotes/spn1001/AN-0001.pdf

You achieve pitch-shifting on the FV-1 by taking two offset ramp waveforms (like in my document).
Each ramp sweeps though the delay line memory, reads it, and dumps it to the output.  The faster the sweep, the bigger the pitch shift you get at the output.
You repeatedly fade between the two ramp outputs to avoid discontinuites at the ramp ends.
So at the beginning and at the end of a ramp's sweep, the output signal is faded to zero, and at the middle of the ramp's sweep the output signal is not faded at all.  The end result is a pitch shifted signal but with a tremolo in the volume (due to the repeated fading between ramps).

All you need to do to get "barberpole flanging" is mix that pitch shifted signal with a (fixed) delayed version of the clean signal.
And to make it "barberpole TZF" you just need to choose the fixed delay appropriately. (i.e. read from the middle of the delay line).

See http://www.spinsemi.com/knowledge_base/effects.html and you will even see it mentions barberpole flange.

[Rob Strand]

Thanks for reposting.

I found this recently while working on a related project,
https://www.researchgate.net/publication/286861511_Barberpole_phasing_and_flanging_illusions

It shows the LFO and VCA waveforms.  It also has a lot of details which you probably don't need to know if you use the FV-1 pitch shifter.