[PD] biquad~ with elementary filters [was: Re: dinosaurs ...]

[Charles Henry]

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
>
> Chuck


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
-ff3/ff2."

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?