[quote author="thermionic"]Also, is anyone here aware of the (Buchla I believe) "Barber Pole" phasers? I'm not sure phaser is the correct description for them, but I'd love to hear info from anyone that knows the device.
[/quote]
The US-Patent # 04399326 gives a good overview about barberpole phasing. It's basically a Frequency Shifter that runs with very low modulation frequency (LFO range), plus some extra (fixed) all pass filters in the signal path and/or feedback path.
I have never played the Buchla, but I imagine there are a lot of possible combinations of these three parts, fixed APFs, variable APFs (like in ordinary phasers) and the frequency-shifter core which make musical sense, and from the looks of it, the Buchla seems to be a very luxurious variation of this.
If you want to experiment with this, just build the separate blocks and try different combinations. I'm not sure about this, but I think you won't even need the usual precision of frequency shifters for that kind of applications (no audio range modulators that would bleed thru!), but then again creating deep notches might also require some precision.
You might want to try this:
http://www.oldcrows.net/~jhaible/tonline_stuff/hj_fs.html
and combine it with various all pass filters according to the Bode patent.
JH.
