[sdiy] Resonator type filters

[Richie Burnett]

If you pass a transient through a whole bank of high-Q analogue bandpass 
filters in parallel and then recombine their outputs what you end up doing 
is dispersing the energy.  Even if their responses combine in equal 
proportions to give a more or less flat magnitude response, different 
frequency components incur different delays unless some measures are taken 
to compensate for this.  As you said the more bands you have in your 
vocoder, for example, the high the Q-factors, and the more rapidly the phase 
changes across the bandwidth of each individual filter, and therefore the 
more severe the dispersion you get when you feed transients through the 
parallel filter bank as a whole.  For example, a click gets transformed into 
a chirp...  Or f####d up as you put it.

-Richie,

-----Original Message----- 
From: Mattias Rickardsson
Sent: Friday, June 30, 2017 2:48 PM
To: Tom Wiltshire
Cc: Synth DIY
Subject: Re: [sdiy] Resonator type filters

On 30 June 2017 at 10:46, Tom Wiltshire <tom at electricdruid.net> wrote:
> Is there some reason why string filters use a large number of fixed bands, 
> rather than fewer variable ones?

Isn't the goal also to make the phase as messy as possible?

I always think it seems to sound more wooden the higher the number of
resonant bands you have in a vocoder-type filter... even if all the
bands are set to middle position. And I guess the phases of the sound
is what's mostly modified then. Steady-state sounds are not as
spectacular, but every sudden transient will be fücked up.

/mr

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