[PD] biquad~ with elementary filters [was: Re: dinosaurs ...]
czhenry at gmail.com
Sat Sep 20 19:58:00 CEST 2008
On Sat, Sep 20, 2008 at 12:53 PM, Charles Henry <czhenry at gmail.com> wrote:
> On Sat, Sep 20, 2008 at 7:09 AM, Damian Stewart <damian at frey.co.nz> wrote:
>> however, there's some weird gain thing going on. check out the attached:
>> notice how the left channel output (biquad~ output) drops gain, while the
>> right channel output (handmade) does not.
>> any ideas how to fix this?
> ah! got it! Remember how I said that ff1 determines the gain? All
> you need to do is add a *~ block in series with the [czero~]'s and
> [cpole~]'s to multiply by ff1
As an afterthought, this approach does not work when ff1 is zero :) duh
But then, I don't think that it's ever useful to have ff1 be zero, is it?
Also, I was wrong about the zeros, when ff1 is zero.
"Now, there's one free variable remaining, ff1. ff1 could be zero,
which would give us a zero at z=0 and another real valued zero at
There is no zero at z=0. I'm not sure about this one--but it seems as
though it's impossible to have a zero at z=0?
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