<html><head><meta http-equiv="Content-Type" content="text/html charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Olivier Gillet has several nice 2164 filter examples on the Mutable Instruments site. Ask me if you can't find them.<div><br></div><div>Tom</div><div><br><div><div>On 24 Oct 2016, at 15:50, Quincas <<a href="mailto:quincas@gmail.com">quincas@gmail.com</a>> wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><meta http-equiv="content-type" content="text/html; charset=utf-8"><div dir="auto"><div>Dave, I have a spare 2164... Do you have any filter schematics you'd be willing to share with us diyers? I can make OTA filters just fine, but I'm not terribly familiar with the 2164 yet :)</div><div><br></div><div>Cheers!</div><div>Q<br><br>Quincas Moreira</div><div><br>On 23/10/2016, at 3:12 p.m., David G Dixon <<a href="mailto:dixon@mail.ubc.ca">dixon@mail.ubc.ca</a>> wrote:<br><br></div><blockquote type="cite">
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<div dir="ltr" align="left"><span class="125311120-23102016"><font color="#0000ff" size="2" face="Arial">I gave up on OTAs. Once I discovered the 2164, I never
looked back. The only issue with them is that they must terminate at
virtual ground, and this limits their uses a bit. However, for most
filters this isn't really a limitation, especially for cascaded-stage
filters.</font></span></div><br>
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<font size="2" face="Tahoma"><b>From:</b> Jacob Watters
[<a href="mailto:jacobwatters@gmail.com">mailto:jacobwatters@gmail.com</a>] <br><b>Sent:</b> Sunday, October 23, 2016
11:37 AM<br><b>To:</b> David G Dixon<br><b>Cc:</b> Tim Ressel;
<a href="mailto:synth-diy@dropmix.xs4all.nl">synth-diy@dropmix.xs4all.nl</a><br><b>Subject:</b> Re: Max Filter
Cutoff<br></font><br></div>
<div></div>Ok thanks for the info. I think I need to adjust my circuit a bit.
I am maxing out at 15k using LM13700 and 50pF caps<span></span>. I get a
better range with just a pot as a viltage divider and no expo conversion,
so i am guessing my error is in the convertor. I am reading TH's book on the
3080 right now. I will redisgn the expo conversion based on what I am
learning.
<div><br></div>
<div>Thanks!</div>
<div><br></div>
<div><br></div>
<div>-Jacob Watters<br><br>On Sunday, 23 October 2016, David G Dixon <<a href="mailto:dixon@mail.ubc.ca">dixon@mail.ubc.ca</a>> wrote:<br>
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<div dir="ltr" align="left"><span><font color="#0000ff" size="2" face="Arial">...yeah,
but if the filter doesn't go high enough, then it doesn't allow all the
higher overtones when its fully open. In other words, it doesn't fully
open. This can change the sound of waveforms even if it is above your
hearing range by subtle modulation. I only hear up to a little less
than 13kHz myself. Too much loud rock music.</font></span></div>
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<div dir="ltr" align="left"><span><font color="#0000ff" size="2" face="Arial">In any
case, I would recommend 220pF as a good size for filter caps. It's
always worked well for me. Of course, all my designs also use the 2164
quad VCA chip for expo-controlled variable resistors, with the standard 30k
input resistor. This fixes the "baseline" frequency of my
filters at something like 21kHz.</font></span></div><br>
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<font size="2" face="Tahoma"><b>From:</b> Synth-diy [mailto:<a href="javascript:_e(%7B%7D,'cvml','synth-diy-bounces@dropmix.xs4all.nl');" target="_blank">synth-diy-bounces@<wbr>dropmix.xs4all.nl</a>] <b>On Behalf
Of </b>Tim Ressel<br><b>Sent:</b> Sunday, October 23, 2016 10:48
AM<br><b>To:</b> <a href="javascript:_e(%7B%7D,'cvml','synth-diy@dropmix.xs4all.nl');" target="_blank">synth-diy@dropmix.xs4all.nl</a><br><b>Subject:</b> Re:
[sdiy] Max Filter Cutoff<br></font><br></div>
<div></div><p>Since most ears stop at 16KHz I'd say its safe to stop there.</p><p>--Tim (can't hear above 10K) Ressel<br></p><br>
<div>On 10/23/2016 9:47 AM, Jacob Watters wrote:<br></div>
<blockquote type="cite">I am working on a filter and I was trying to get
the maximum cutoff up to 20kHz. I found that I needed much smaller
caps than what is usually used in most filters.
<div><br></div>
<div>Then I noticed that on the Arp 2600 the max filter cutoff is
labelled as 10kHz.</div>
<div><br></div>
<div>What is the normal max cutoff for a 4-pole -24dB analog
filter?</div><br>
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</pre></blockquote><br><pre cols="72">--
--Tim Ressel
Circuit Abbey
<a href="javascript:_e(%7B%7D,'cvml','timr@circuitabbey.com');" target="_blank">timr@circuitabbey.com</a></pre></blockquote></div></blockquote></div></blockquote>
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