<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">Some of the models of Dave Rossum’s 14 pole Z-plane filters attempt this.<div class="">They have been made availble again recently:</div><div class=""><br class=""></div><div class=""><a href="http://www.rossum-electro.com/products/morpheus/" class="">http://www.rossum-electro.com/products/morpheus/</a></div><div class=""><br class=""></div><div class=""><div><br class=""></div><div><br class=""></div><div><br class=""></div><div><br class=""><blockquote type="cite" class=""><div class=""><div class=""><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><br class="">
When I hear "Resonator type filters", I'm thinking of "Body modelling<br class="">
filters" - e.g. filters that allow you to model the body (and other)<br class="">
resonances in acoustic instruments to either synthesise them more<br class="">
accurately, or to add another dimension to other synth sounds that may not<br class="">
be a copy of a particular acoustic instrument, but which might have a<br class="">
particular character ("woodwind" say).<br class="">
<br class="">
What is required for this varies a fair bit. What I knew already was about<br class="">
brass, woodwind, and vocal resonances, which are fairly few in number (5<br class="">
would cover it - 4 is ok, even 3 does a reasonable job, as Elhardt's<br class="">
PolyMoog video demonstrates). You need less for brass and woodwind and more<br class="">
for vocals.<br class="">
<br class="">
What I've learned from the paper posted above is that for strings this is<br class="">
not sufficient, although there might be a couple of major resonances lower<br class="">
down that you could copy fairly easily. But the "lush", "rich" quality which<br class="">
we're after seems to come from the amplitude modulation of the harmonics<br class="">
caused by many narrow bands coupled with a limited vibrato. So we need lots<br class="">
of peaks (20-30 seems like the best, from their results) and the peaks need<br class="">
to not match any *particular* note's harmonics so all notes are similarly<br class="">
affected. Finally, the peaks need to be spaced enough that's there's roughly<br class="">
a -12dB trough between them. Much more than than that, and you get a "hole"<br class="">
and dead notes, less than that and you don't get enough movement in the<br class="">
notes.<br class="">
<br class="">
So there are really two basic types of resonator bank you could build. One<br class="">
would be basically a sophisticated parametric EQ with several bands (say, 3,<br class="">
4 or 5) with variable frequency, Q, and gain. The other would be a much<br class="">
larger bank of fixed filters. This would have individually variable gain,<br class="">
and could potentially have overall variable Q by wrapping feedback round the<br class="">
whole lot, as described in Bernie's Electronotes posting.<br class="">
<br class="">
The first style is probably good for woodwinds, brass, and vocal sounds. The<br class="">
second is what you need for strings, at least according to that paper.<br class="">
<br class="">
Ok, that's the results of my researches on the subject, and my understanding<br class="">
of what's been discussed here so far! I hope it helps.<br class="">
<br class="">
Tom<br class="">
<br class="">
==================<br class="">
Electric Druid<br class="">
Synth & Stompbox DIY<br class="">
==================<br class="">
<br class="">
<br class="">
<br class="">
<br class="">
On 3 Jul 2017, at 16:43, ezion <<a href="mailto:ezion67@gmail.com" target="_blank" class="">ezion67@gmail.com</a>> wrote:<br class="">
<br class="">
> Think the Elektor Formant resonator module might also be of interest to<br class="">
> you.<br class="">
> Sorry no link, but the Formant schematics (a DIY modular from the late<br class="">
> '70) are on the net for sure.<br class="">
> Basically its a 3 band boost only parametric EQ.<br class="">
> Personally now days when working with VSTs I just abuse a EQ plug-in.<br class="">
><br class="">
> Groetjes Theo<br class="">
><br class="">
> On Thu, Jun 29, 2017 at 12:43 PM, Elaine Klopke <<a href="mailto:functionofform@gmail.com" target="_blank" class="">functionofform@gmail.com</a>><br class="">
> wrote:<br class="">
> Hey list,<br class="">
><br class="">
> So I'm sure that I'm not aware of all of the variations, but....<br class="">
><br class="">
> I've run across the Scott Stites triple Wilson SVVCF (and still plan on<br class="">
> building it!), and the Cwejman QMMF, and was thinking of cooking up my<br class="">
> own. But how many filters is overkill? Above are examples of three and<br class="">
> four filters in parallel with independent controls and a master section to<br class="">
> alter them all together. What about five filters? Six? 40?<br class="">
><br class="">
> Just another silly question going through my brain..<br class="">
><br class="">
> Sent from my iPhone<br class="">
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