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<DIV dir=ltr align=left><SPAN class=953591920-06112018><FONT color=#0000ff
size=2 face=Arial>Hi Rutger,</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=953591920-06112018><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=953591920-06112018><FONT color=#0000ff
size=2 face=Arial>I tempco my 2164s in filters when only using two or three VCAs
in the core (or, for example, in an SVF where I use two in the core, one for
VCQ, and the fourth for tempco). However, in a Roland-esque four-stage
filter, I generally don't do tempco. You would essentially require two
independent CV summers, two tempcos, and then split the core between two 2164s
(two on each) so that each one had an unused spare. It's probably not
worth all the trouble, since filter cutoff doesn't require tempco, and there are
more convenient ways to get sine waves.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=953591920-06112018><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=953591920-06112018><FONT color=#0000ff
size=2 face=Arial>Cheers,</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=953591920-06112018><FONT color=#0000ff
size=2 face=Arial>Dave</FONT></SPAN></DIV><BR>
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<FONT size=2 face=Tahoma><B>From:</B> Synth-diy
[mailto:synth-diy-bounces@synth-diy.org] <B>On Behalf Of </B>Rutger
Vlek<BR><B>Sent:</B> Tuesday, November 06, 2018 7:29 AM<BR><B>To:</B> SDIY
List<BR><B>Subject:</B> [sdiy] 2164 tempco in VCF
applications<BR></FONT><BR></DIV>
<DIV></DIV>
<DIV dir=ltr>Hi list,
<DIV><BR></DIV>
<DIV>I've been impressed with the performance of recent VCO designs (yes, you
David!) using 2164 for temperature compensation. I've been wondering if people
have attempted similar things with respect to VCF applications? When using
integrators in a VCF based on the 2164 you already have an exponential control
law of the inputs, so wouldn't need a full exponential current source as in a
VCO. Can you still apply the same principle for making a VCF temperature
stable? Do you need that degree of stability in a VCF (yes, different opinions
are welcome)? And what would you do if you already used up all 4 sections of a
2164 in the core of the VCF, meaning you don't have another 2164 available in
the same (isothermic) package?</DIV>
<DIV><BR></DIV>
<DIV>Regards,</DIV>
<DIV><BR></DIV>
<DIV>Rutger</DIV></DIV></BLOCKQUOTE></BODY></HTML>