<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div>Uhhh, yeah! Interested!!!<br><br><div>Edward Schultheis</div><div><br></div>Sent from me!</div><div><br>On Jun 30, 2017, at 11:11 AM, Bernard Arthur Hutchins Jr <<a href="mailto:bah13@cornell.edu">bah13@cornell.edu</a>> wrote:<br><br></div><blockquote type="cite"><div>
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<span style="font-family:'Courier New'; font-size:small">Tom Asked </span><span style="font-size:small; font-family:arial">Fri, 30 Jun 2017</span><span style="font-family:'Courier New'; font-size:small"> : Is there some reason why string filters use a large
number of fixed bands, rather than fewer variable ones?</span></p>
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<span style="font-family:'Courier New'; font-size:small">Simply, the filters are sharp (narrow), so you need a lot of them (say 40) to span (overlap) a wide enough processing bandwidth. So (you rightly demand!) why do they need to be sharp? For achieving dynamics,
e</span><font face="Courier New" size="2">ither the filter frequencies or the input frequency typically needs to move. (Else you are merely waveshaping one boring fixed shape to another.) Moving all the filter frequencies is of course impractical while moving
the input is basically just FM of a VCO. If you have only a few broad filters, AND FM depth is small (typically achieving an animated dynamic sound like tremolo), very little equivalent AM (harmonics moving up and down BP slopes) is achieved. With lots of
sharp filters, lots of relatively large motions are achieved (some up, some down, some flat).</font></p>
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<font face="Courier New" size="2">The other application is as a formant filter. (That is, not FM, but note-to-note spectral shape changes.) The ability to get lots of detail (with adjustable depth) is useful, and variable Q, ALL </font><span style="font-family:'Courier New'; font-size:small">39
filters with one control (overall feedback)</span><span style="font-family:'Courier New'; font-size:small">, was demonstrated in my Electronotes EN#115 filter bank. I will see if I can post this if anyone is interested. </span></p>
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<span style="font-family:'Courier New'; font-size:small">-Bernie </span><span style="font-family:'Courier New'; font-size:small"> </span></p>
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