FS and "AKO Phasing" update

[Don Tillman]

   From: Haible Juergen <Juergen.Haible at nbgm.siemens.de>
   Date: Thu, 15 Jan 1998 14:46:28 +0100

   Second, another look into Bode's patent showed that he uses
   a configuration with a pure all pass filter in front of the FS, and
   not a whole phaser/comb filter as I thought. Sorry Don - you
   were absolutely right. The effect is there (slightly). And you can
   further increase the effect with additional phase shift in front of the
   hilbert transform network. I tried pure all pass, a complete phaser,
   and a phaser with its own resonance. All different, and all interesting.

Very cool!  So those initial phase shift stages in HB's patent just
make the effect more pronounced.  That makes sense.

   Magnus:
   >This is similar to the Lesley dual doppler effect where you
   >would have an table close to this:
   >
   >Number	Original	Horn1	Horn2
   >1	100		99.8	100.2
   >2	200		199.8	200.2
   >3	300		299.8	300.2
   >
   >And so on... 
   >
   >Horn1 - moving away from you
   >Horn2 - moving towards you


   I always thought the doppler effect would really cause a pitch
   shift, not frequency shift, but I am not sure at all, so I have to
   think of this again.

Yes, absolutely.  Think about the mechanism involved -- storing the
soundwave in air is effectively the same as storing the sound in a BBD,
or tape for that matter -- so it'll definitely be pitch shifting.

  -- Don