<div dir="ltr"><div><font face="arial, sans-serif">>> </font><span style="font-family:arial,sans-serif;font-size:12.727272033691406px">The real part may be used as a resonant</span></div><div><span style="font-family:arial,sans-serif;font-size:12.727272033691406px">>> </span><span style="font-family:arial,sans-serif;font-size:12.727272033691406px">bandpass filter and the imaginary as a </span></div>
<div><span style="font-family:arial,sans-serif;font-size:12.727272033691406px">>> resonant low-pass filter, but </span><span style="font-family:arial,sans-serif;font-size:12.727272033691406px">they can be</span></div>
<div><span style="font-family:arial,sans-serif;font-size:12.727272033691406px">>> combined to make other possibilities."</span></div><div><font face="arial, sans-serif"><br></font></div><div><font face="arial, sans-serif">> w</font><span style="font-family:arial,sans-serif;font-size:12.727272033691406px">hat sort of possibilities???</span><br>
<div><span style="font-family:arial,sans-serif;font-size:13px"><br>
</span></div><div><span style="font-family:arial,sans-serif;font-size:13px">I wouldn't expect much about this. I guess it's like any other filters that can be combined in many ways.</span></div></div><div><span style="font-family:arial,sans-serif;font-size:13px"><br>
</span></div><div><font face="arial, sans-serif">Another thing I wanted to inquire is about bp~ having a frequency response that is not symmetric. The lower part of the spectrum has more energy. Could one consider it more of a "</font><span style="font-family:arial,sans-serif;font-size:12.727272033691406px">resonant low-pass filter", similar to [vcf~]'s second outlet?</span></div>
<div><span style="font-family:arial,sans-serif;font-size:12.727272033691406px"><br></span></div><div><span style="font-family:arial,sans-serif;font-size:12.727272033691406px">By the way, while we're at it, I'd like to share something that may not be too important, but it's related. I was able to implement [cpole~] in [fexpr~]. Here it goes:</span></div>
<div><span style="font-family:arial,sans-serif;font-size:12.727272033691406px"><br></span></div><div><span style="font-family:arial,sans-serif">expr 1:</span><span style="font-family:arial,sans-serif;font-size:12.727272033691406px"><br>
</span></div><div><span style="font-family:arial,sans-serif;font-size:12.727272033691406px"><br></span></div><div><span style="font-family:arial,sans-serif;font-size:12.727272033691406px">[</span><font face="arial, sans-serif">fexpr~ $x1 + ($x3 * $y1) - ($x4 * $y2);</font></div>
<div><font face="arial, sans-serif">$x2 + ($x4 * $y1) + ($x3 * $y2)]</font></div><div><font face="arial, sans-serif"><br></font></div><div><font face="arial, sans-serif">if we consider $x3 and $x4 as variables named, respectively, </font><span style="font-family:arial,sans-serif">coefr (coeficient for the real part) and coefi </span><span style="font-family:arial,sans-serif">(coeficient for the imaginary part), we then have:</span></div>
<div><span style="font-family:arial,sans-serif"><br></span></div><div><font face="arial, sans-serif">expr 2:</font></div><div><span style="font-family:arial,sans-serif"><br></span></div><div><div><b><span style="font-family:arial,sans-serif;font-size:12.727272033691406px">[</span><font face="arial, sans-serif">fexpr~ $x1 + (coefr * $y1) - (</font><span style="font-family:arial,sans-serif">coefi</span><span style="font-family:arial,sans-serif"> * $y2);</span></b></div>
<div><font face="arial, sans-serif"><u>$x2</u><b> + (</b></font><span style="font-weight:bold;font-family:arial,sans-serif">coefi</span><span style="font-weight:bold;font-family:arial,sans-serif"> * $y1) + (</span><span style="font-weight:bold;font-family:arial,sans-serif">coefr</span><span style="font-weight:bold;font-family:arial,sans-serif"> * $y2)]</span></div>
</div><div><font face="arial, sans-serif"><br></font></div><div><font face="arial, sans-serif">Now, by checking the code of [vcf~] I was able to narrow down to its core formula, which is something like this</font></div><div>
<br></div><div><span style="font-family:arial,sans-serif">expr 3:</span><br></div><div><span style="font-family:arial,sans-serif"><br></span></div><div><font face="arial, sans-serif"><div><u>ampcorrect * oneminusr</u> * <b>f1 + (coefr * re2) - (coefi * im)</b>;</div>
<div><b>(coefi * re2) + (coefr * im)</b></div><div><b><br></b></div><div>the bolded letters in "expr 3" seem to match perfectly to "expr 2". The differences are underlined ($x2 in expr 2 and ampcorrect/oneminusr in expr 3).</div>
<div><br></div><div>That gets me closer to being able to implement [vcf~] with a [cpole~] I guess, but I find it weird that the imaginary output does not have the $x2 signal input to be added to the rest of the expression. I worry that actually prevents it from being successfully implemented with [cpole~]. Am I missing something?</div>
<div><br></div><div>Anyway, the thing is that I'm still really curious to learn wether vcf~ is a "two pole" filter or a "one complex pole" filter, and the reason behind it is because I believe we could make a biquad~ version of [vcf~] (at least for its real output). That's the bottom line.</div>
<div><br></div><div>cheers</div></font></div><div><span style="font-family:arial,sans-serif;font-size:12.727272033691406px"><br></span></div><div><span style="font-family:arial,sans-serif;font-size:12.727272033691406px"><br>
</span></div></div><div class="gmail_extra"><br><br><div class="gmail_quote">2014-07-24 6:45 GMT-03:00 i go bananas <span dir="ltr"><<a href="mailto:hard.off@gmail.com" target="_blank">hard.off@gmail.com</a>></span>:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">just chipping in with my 2 cents that it would be fantastic to get more documented info on all this.<br>
<br>especially curious about: "<span style="font-family:arial,sans-serif;font-size:13px">but </span><span style="font-family:arial,sans-serif;font-size:13px">they can be combined to make other possibilities."<br>
<br>what sort of possibilities??? </span></div><div class="gmail_extra"><br><br><div class="gmail_quote"><div><div class="h5">On Thu, Jul 24, 2014 at 5:07 PM, Alexandre Torres Porres <span dir="ltr"><<a href="mailto:porres@gmail.com" target="_blank">porres@gmail.com</a>></span> wrote:<br>
</div></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div class="h5"><div dir="ltr">Hi Miller, still trying to get my head around this. But anyway, one thing I have to note is that the source code of [vcf~] says it is a "two pole filter", not a "one complex pole" filter.<div>
<br></div><div>Should that description be changed? If not, why?</div><div><br></div><div>thanks</div></div><div class="gmail_extra"><br><br><div class="gmail_quote">2014-04-12 14:13 GMT-03:00 Miller Puckette <span dir="ltr"><<a href="mailto:msp@ucsd.edu" target="_blank">msp@ucsd.edu</a>></span>:<div>
<div><br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Yep - vcf~ is essentially a wrapper for cpole~.<br>
<br>
cheers<br>
<span><font color="#888888">M<br>
</font></span><div><div><br>
On Sat, Apr 12, 2014 at 02:10:19PM -0300, Alexandre Torres Porres wrote:<br>
> that's great to know, thanks!<br>
><br>
> Let me just see if I get a bit of the theory. Can I get [vcf~] with just<br>
> one [cpole~] object and the right coeficients?<br>
><br>
> Cheers<br>
><br>
><br>
> 2014-04-12 13:36 GMT-03:00 Miller Puckette <<a href="mailto:msp@ucsd.edu" target="_blank">msp@ucsd.edu</a>>:<br>
><br>
> > They're quite different. bp~ is the cheapest possible bandpass filter<br>
> > (as far as I know). vcf~ is a one-pole complex filter whose outputs are<br>
> > the real and imaginry parts. The real part may be used as a resonant<br>
> > bandpass filter and the imaginary as a resonant low-pass filter, but<br>
> > they can be combined to make other possibilities.<br>
> ><br>
> > It's possible to graph their frequency responses using the help patch<br>
> > "H10.measurement.pd' in 3.audio.examples.<br>
> ><br>
> > cheers<br>
> > Miller<br>
> ><br>
> > On Sat, Apr 12, 2014 at 04:28:11AM -0300, Alexandre Torres Porres wrote:<br>
> > > Hi there, who can confirm that both [bp~] and [vcf~] are exactly the<br>
> > really<br>
> > > same thingy? The code looks quite different...<br>
> > ><br>
> > > Moreover, why the two outlets for vcf~? Help doesn't say anything.<br>
> > ><br>
> > > Thanks<br>
> ><br>
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