hi
yes it's a littlebit academic :)
i'm using my doepfer in combination with a argon-krypton laser to make visuals :)

the thing i'm looking for is a static wide band 90° phase shifter (90° shift from 40Hz-1kHz)



/martin

----- Original Message -----
From: Florian Anwander
To: Doepfer_a100@yahoogroups.com
Sent: Monday, December 27, 2010 11:48 AM
Subject: Re: 1 how many stages



Hi Martin

either me do not understand what you are asking for, or you do not
understand that the basic principle of an allpass filter IS the phase
shift. It is the reason why someone is building an allpass filter.

Or do you mean "phase distortion" as: deviation of the "real (measured)
phase shift over frequency" from "the ideal phase shift over frequency"

If the latter is the case: I fear there is no voltage controlled allpass
filter that suits your (a littlebit academic) requirement. Simply
because you will not be able to trim 12 variable stages to exactly the
identical characteristics. You should also obey, that the page you are
quoting speaks about a static phaseshifter!

From the musical and sound-engineering approach, this kind of
phasedistortion is irrelevant.

Florian

martin sörensen schrieb:
> i was hoping for a wider bandwith
> with less phase-distortion
>
> something like figure 5 in this article
> http://webpages.charter.net/wa1sov/technical/allpass/allpass.html
>
>
> /martin




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