FS and "AKO Phasing" update
Magnus Danielson
magnus at analogue.org
Fri Jan 16 21:46:32 CET 1998
>>>>> "DT" == Don Tillman <don at till.com> writes:
DT> From: Haible Juergen <Juergen.Haible at nbgm.siemens.de>
DT> Date: Thu, 15 Jan 1998 14:46:28 +0100
DT> Second, another look into Bode's patent showed that he uses
DT> a configuration with a pure all pass filter in front of the FS, and
DT> not a whole phaser/comb filter as I thought. Sorry Don - you
DT> were absolutely right. The effect is there (slightly). And you can
DT> further increase the effect with additional phase shift in front of the
DT> hilbert transform network. I tried pure all pass, a complete phaser,
DT> and a phaser with its own resonance. All different, and all interesting.
DT> Very cool! So those initial phase shift stages in HB's patent just
DT> make the effect more pronounced. That makes sense.
DT> 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
DT> I always thought the doppler effect would really cause a pitch
DT> shift, not frequency shift, but I am not sure at all, so I have to
DT> think of this again.
DT> Yes, absolutely. Think about the mechanism involved -- storing the
DT> soundwave in air is effectively the same as storing the sound in a BBD,
DT> or tape for that matter -- so it'll definitely be pitch shifting.
So sorry, was a bit tired at the moment, so I forgot connecting the
brain into the processing stream... so sorry.
Cheers,
Magnus
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