200e

yeah, quadrature introduces a 90deg phase shift in an envelope. nothing to
do w/ audio.

btw, it's pretty easy to make a digital APF with almost-linear arbitrary
phase response. combine a 1sample feedforward and 1sample feedback loop:

y = a*x + x_last - a*y_last

phase delay = p = 2/freq * arctan( (1-a)/(1+a) *tan(freq/2) ),

so a = sin((1-p) * freq/2) / sin((1+p) * freq / 2))
, so for freq small relative to sample rate, a = approx. (1-p)/(1+p)

but all this doesn't have much to do with the 200e. experiments with digital
filter architectures are probably best carried out on a computer.

-eb


On Mon, Apr 28, 2008 at 12:11 PM, nicholas_kent <zaum@optonline.net> wrote:

>   Doesn't make much sense to me (But I don't own any modules). The 227e
> is a quad channel device. In general no one defaults audio as far as I
> know to 90 degree phase shifts to do quad. All you will wind up with
> is more potential of cancellation in an acoustic space. And 90
> degrees for that matter probably requires a pair of allpass filters to
> achieve. It's not something you can get without filters as far as I
> know compared to just inverting the polatity for 180 degrees (though
> filters could do that too).
>
> My guess is people are thinking along these lines because if you are
> mixing quad audio you might very well want to hit your VCAs with 90
> degree quadrature of a *control voltage* in order to do "circular" pan
> effects. Or perhaps someone just wants to identify the speakers in
> numbers rather than ABCD if they represent a quad space
>
>
> --- In 200e@yahoogroups.com <200e%40yahoogroups.com>, "mritenburg"
> <mritenburg@...> wrote:
> >
> > I might be wrong, but I have always assumed that on the 227e, positions
> > A, B, C, and D are 90 degrees out of phase from one another. So C is
> > 180 degrees out of phase from A and D is 180 degrees out of phase from
> > B.
> >
> > Matt
> >
> >
> >
> > --- In 200e@yahoogroups.com <200e%40yahoogroups.com>, "Matt Carpenter"
> <matfhew.carpenfer@>
> > wrote:
> > >
> > > Hi all,
> > > I was just wondering if the 210e allows phase reversal of the audio
> > > signal or if phase reversal is possible via other means, specifically
> > > for the purposes of feedback/feedforward experimentation.
> > > Thanks!
> > > Matt
> > >
> >
>
>  
>


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