<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><br id="lineBreakAtBeginningOfSignature"><div dir="ltr">No specific modules off the top of my head, other than stuff I’m working on at the moment, which is an EQ coincidentally. A lot of drum circuits are based on the Twin T. </div><div dir="ltr"><br></div><div dir="ltr">Controlling one current isn’t hard. Controlling two in concert is much harder. And any circuit that needs both sides of a pot (like a Baxandall EQ) will need both sides to match and work together in a consistent, particular way. </div><div dir="ltr"><br></div><div dir="ltr">For the one capacitor bass boost/cut Baxandall, where the cap is in parallel with legs 1 and 3 of the pot, it’s worth nothing that the pot value determines not just how much boost/cut, but also the frequency of EQ itself. So the two sides have to rise and fall in opposite, consistent ways and the equivalent resistance needs to add up to a constant amount.</div><div dir="ltr"><br></div><div dir="ltr"> And for dual gang pots you’re looking at 4 different areas that will need to be controlled at the same time with specific matching curves. As more parts are added tolerances get more important. Temperature stability would be another nightmare I’m sure.</div><div dir="ltr"><br></div><div dir="ltr">-Stephen</div><div dir="ltr"><br><blockquote type="cite">On Feb 9, 2024, at 17:20, cheater cheater <cheater00social@gmail.com> wrote:<br><br></blockquote></div><blockquote type="cite"><div dir="ltr"><div dir="ltr"><div dir="ltr"><br></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Fri, Feb 9, 2024 at 11:04 PM Stephen Makdisi <<a href="mailto:shmakdisi@xvetrd.us">shmakdisi@xvetrd.us</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="auto"><br id="m_3892582184876285301lineBreakAtBeginningOfSignature"><div dir="ltr">I got a feeling a Baxandall is going to be a real pain to get under control with a 2164, but probably easier than tuning a Twin T or a Wein bridge network.</div></div></blockquote><div><br></div><div>Can you suggest some modules that use those topologies? Am I right to think that the 808 BD is a Twin T? What module uses a Wien bridge?<br></div><div> </div><div><br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="auto"><div dir="ltr">I think pretty much any circuit that requires both sides of the potentiometer, or even worse, both sides of a dual gang pot, is going to be difficult.</div><div dir="ltr"><br></div><div dir="ltr">But not impossible. Not something I plan on trying, but not impossible. <br></div></div></blockquote><div><br></div><div>Thanks a lot! Where do you think the difficulty comes from?<br></div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="auto"><div dir="ltr"></div><div dir="ltr">-Stephen</div><div dir="ltr"><br><blockquote type="cite">On Feb 9, 2024, at 14:20, David G Dixon via Synth-diy <<a href="mailto:synth-diy@synth-diy.org" target="_blank">synth-diy@synth-diy.org</a>> wrote:<br><br></blockquote></div><blockquote type="cite"><div dir="ltr">
<div dir="ltr" align="left"><span>Not sure about Baxandall,
but recently I figured out how to put the Korg morphing LFO circuit under
voltage control using 2164. I figure that if that is possible, then the
Baxandall circuit should be a piece of cake. The big problem with 2164 is
that it has to terminate at a virtual ground, so that means that some inverting
opamps always have to be shoehorned in there, even if they are not really needed
or wanted.</span></div>
<div dir="ltr" align="left"><span></span> </div>
<div dir="ltr" align="left"><span>I'll work up the
Baxandall circuit this weekend and report back with my findings, and maybe a
demo, next week.</span></div><br>
<div dir="ltr" lang="en-us" align="left">
<hr>
<font size="2" face="Tahoma"><b>From:</b> Mike Bryant
[mailto:<a href="mailto:mbryant@futurehorizons.com" target="_blank">mbryant@futurehorizons.com</a>] <br><b>Sent:</b> Friday, February 09, 2024
2:18 AM<br><b>To:</b> Adam (synthDIY); David G Dixon<br><b>Cc:</b>
synth-diy<br><b>Subject:</b> Re: [sdiy] Unique sounding modules that can't have
voltage control?<br></font><br></div>
<div></div>
<table style="padding-left:0px;border-collapse:collapse">
<tbody>
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<td><font style="padding:3px;line-height:1.6;background-color:rgb(255,236,179);font-style:normal;font-family:Arial,sans-serif;color:rgb(0,0,0);font-size:12px;font-weight:normal">[<b>CAUTION:</b>
Non-UBC Email]</font></td></tr></tbody></table>
<div style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif;color:rgb(0,0,0);font-size:12pt"><br></div>
<div id="m_3892582184876285301appendonsend"></div>
<div style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif;color:rgb(0,0,0);font-size:12pt"><span style="font-size:11pt"><br>> On 9 Feb 2024, at
2:27 pm, David G Dixon via Synth-diy <<a href="mailto:synth-diy@synth-diy.org" target="_blank">synth-diy@synth-diy.org</a>>
wrote:<br>><br>> I doubt that there are many things that couldn't be put
under voltage<br>> control with a 2164 and a bit of
ingenuity.<br></span></div>
<div style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif;color:rgb(0,0,0);font-size:12pt"><span style="font-size:11pt"><br></span></div>
<div style="font-family:Aptos,Aptos_EmbeddedFont,Aptos_MSFontService,Calibri,Helvetica,sans-serif;color:rgb(0,0,0);font-size:12pt"><span style="font-size:11pt">Baxandall tone control
? I imagine it would make the op-amp unstable without a lot of
extra caps.<br></span></div>
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