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<div><br></div><div dir="ltr" data-setdir="false">(Hi Mark, nice to see you here!)</div><div dir="ltr" data-setdir="false"><br></div><div dir="ltr" data-setdir="false">Based on my experience, Mark is right. Douglas Self outlines the problem well. As I remember the desired control curve isn't really based on an easily realized control law so linear or exponential responses don't really do it by themselves.</div><div dir="ltr" data-setdir="false"><br></div><div dir="ltr" data-setdir="false">I'm mostly considered this in the context of crossfader design.</div><div dir="ltr" data-setdir="false"><br></div><div dir="ltr" data-setdir="false">I've done a mastering grade 4x crossfader (for Salt Mastering) based on the THAT part and app note. Worked well enough for that application.</div><div dir="ltr" data-setdir="false"><br></div><div dir="ltr" data-setdir="false">For the Moog Matriarch I remember using a much simpler diode based piece-wise control signal for the x2164 for some volume control VCAs and another crossfader (maybe it was the wet/dry mix?). That worked well for that circuit.</div><div dir="ltr" data-setdir="false"><br></div><div dir="ltr" data-setdir="false">In pickier applications one could certainly go deep with this, probably better to use a LUT if you had a spare DAC channel laying around.</div><div dir="ltr" data-setdir="false"><br></div><div dir="ltr" data-setdir="false">Ben</div><div dir="ltr" data-setdir="false"><br></div>
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On Tuesday, December 22, 2020, 05:19:16 AM EST, mark verbos <markverbos@gmail.com> wrote:
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<div><div id="ydp772113dayiv3960329954"><div>Douglas Self wrote pretty extensively about this in “Small Signal Audio Design” (very recommended), though mostly not voltage controlled.<div class="ydp772113dayiv3960329954">If you want to really go down the rabbit hole, start with a goal of using just a pair of VCAs to do level and panning on a mixer channel. Then ask yourself if you want to use exponential or linear VCAs. Then let the games begin. Serge did us the service of designing this type of thing for both kinds of VCAs (in his case a discrete Blackmer cell and a CA3280), so his circuits are a good jumping off point. That Corp makes an evaluation board for their THAT2162, which is a bit like half of a 2164 (exponential), they have a circuit that allows you to adjust the pan curve.</div><div class="ydp772113dayiv3960329954"><br clear="none" class="ydp772113dayiv3960329954"></div><div class="ydp772113dayiv3960329954">I worked with Michael Zähl on the "CV channel” for the AM1 high end mixing board. Since everything is voltage controlled, it has a LOT of VCAs. He became so specific about the curve of not just the panning, but the level control that he ended up adding a transistor pair logging circuit in the control path of each VCA to tweak the curve. And each of those has to be trimmed.</div><div class="ydp772113dayiv3960329954"><br clear="none" class="ydp772113dayiv3960329954"></div><div class="ydp772113dayiv3960329954">Mark<br clear="none" class="ydp772113dayiv3960329954"><div class="ydp772113dayiv3960329954"><br clear="none" class="ydp772113dayiv3960329954"></div><div class="ydp772113dayiv3960329954"><br clear="none" class="ydp772113dayiv3960329954"></div><div class="ydp772113dayiv3960329954"><br clear="none" class="ydp772113dayiv3960329954"></div><div class="ydp772113dayiv3960329954"><br clear="none" class="ydp772113dayiv3960329954"></div><div class="ydp772113dayiv3960329954"><br clear="none" class="ydp772113dayiv3960329954"></div><div class="ydp772113dayiv3960329954"><br clear="none" class="ydp772113dayiv3960329954"><div><br clear="none" class="ydp772113dayiv3960329954"><blockquote class="ydp772113dayiv3960329954" type="cite"><div class="ydp772113dayiv3960329954yqt4170133286" id="ydp772113dayiv3960329954yqtfd29021"><div class="ydp772113dayiv3960329954">On Dec 16, 2020, at 12:17 AM, Tom Wiltshire <<a shape="rect" class="ydp772113dayiv3960329954" href="mailto:tom@electricdruid.net" rel="nofollow" target="_blank">tom@electricdruid.net</a>> wrote:</div><br clear="none" class="ydp772113dayiv3960329954Apple-interchange-newline"><div class="ydp772113dayiv3960329954"></div></div></blockquote></div></div></div></div><div class="ydp772113dayiv3960329954yqt4170133286" id="ydp772113dayiv3960329954yqtfd34275"><div><div class="ydp772113dayiv3960329954">There’s a load of similar and useful circuits here, including dry/wet mixing:<div class="ydp772113dayiv3960329954"><br clear="none" class="ydp772113dayiv3960329954"></div><div class="ydp772113dayiv3960329954"><br clear="none" class="ydp772113dayiv3960329954"></div><div class="ydp772113dayiv3960329954"><a shape="rect" class="ydp772113dayiv3960329954" href="http://www.geofex.com/Article_Folders/panner.pdf" rel="nofollow" target="_blank">http://www.geofex.com/Article_Folders/panner.pdf</a></div><div class="ydp772113dayiv3960329954"><br clear="none" class="ydp772113dayiv3960329954"></div><div class="ydp772113dayiv3960329954"><br clear="none" class="ydp772113dayiv3960329954"><div class="ydp772113dayiv3960329954">
<div class="ydp772113dayiv3960329954">==================<br clear="none" class="ydp772113dayiv3960329954"> Electric Druid<br clear="none" class="ydp772113dayiv3960329954">Synth & Stompbox DIY<br clear="none" class="ydp772113dayiv3960329954">==================</div><div class="ydp772113dayiv3960329954"><br clear="none" class="ydp772113dayiv3960329954"></div><br clear="none" class="ydp772113dayiv3960329954Apple-interchange-newline">
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<div class="ydp772113dayiv3960329954"><br clear="none" class="ydp772113dayiv3960329954"><blockquote class="ydp772113dayiv3960329954" type="cite"><div class="ydp772113dayiv3960329954">On 15 Dec 2020, at 19:35, Didier Leplae via Synth-diy <<a shape="rect" class="ydp772113dayiv3960329954" href="mailto:synth-diy@synth-diy.org" rel="nofollow" target="_blank">synth-diy@synth-diy.org</a>> wrote:</div><br clear="none" class="ydp772113dayiv3960329954Apple-interchange-newline"><div class="ydp772113dayiv3960329954"></div></blockquote></div></div></div></div><div><div class="ydp772113dayiv3960329954"><div class="ydp772113dayiv3960329954" dir="ltr">Is there a simple way to do a similar circuit but reversed, like for a dry/wet pot? </div><div class="ydp772113dayiv3960329954" dir="ltr"><br clear="none" class="ydp772113dayiv3960329954"><blockquote class="ydp772113dayiv3960329954" type="cite">On Dec 15, 2020, at 12:38 PM, David G Dixon <<a shape="rect" class="ydp772113dayiv3960329954" href="mailto:dixon@mail.ubc.ca" rel="nofollow" target="_blank">dixon@mail.ubc.ca</a>> wrote:<br clear="none" class="ydp772113dayiv3960329954"><br clear="none" class="ydp772113dayiv3960329954"></blockquote></div><blockquote class="ydp772113dayiv3960329954" type="cite"><div class="ydp772113dayiv3960329954" dir="ltr">
</div></blockquote></div></div><div><div class="ydp772113dayiv3960329954"><font class="ydp772113dayiv3960329954" size="2" face="Arial"><span class="ydp772113dayiv3960329954893392018-15122020">Hey
Team,</span></font></div>
<div class="ydp772113dayiv3960329954"><font class="ydp772113dayiv3960329954" size="2" face="Arial"><span class="ydp772113dayiv3960329954893392018-15122020"></span></font> </div>
<div class="ydp772113dayiv3960329954"><font class="ydp772113dayiv3960329954" size="2" face="Arial"><span class="ydp772113dayiv3960329954893392018-15122020">I've been thinking
about this panning thing, and I came up with the following very simple pot-based
panning circuit:</span></font></div>
<div class="ydp772113dayiv3960329954"><font class="ydp772113dayiv3960329954" size="2" face="Arial"><span class="ydp772113dayiv3960329954893392018-15122020"></span></font> </div>
<div class="ydp772113dayiv3960329954"><font class="ydp772113dayiv3960329954" size="2" face="Arial"><span class="ydp772113dayiv3960329954893392018-15122020"></span></font><div class="ydp772113dayiv3960329954"><SimplePanner.png></div></div>
<div class="ydp772113dayiv3960329954"><font class="ydp772113dayiv3960329954" size="2" face="Arial"><span class="ydp772113dayiv3960329954893392018-15122020"></span></font> </div>
<div class="ydp772113dayiv3960329954"><font class="ydp772113dayiv3960329954" size="2" face="Arial"><span class="ydp772113dayiv3960329954893392018-15122020">The gain responses
of this circuit are shown below, and compared with sin and cos
responses:</span></font></div>
<div class="ydp772113dayiv3960329954"><font class="ydp772113dayiv3960329954" size="2" face="Arial"><span class="ydp772113dayiv3960329954893392018-15122020"></span></font> </div>
<div class="ydp772113dayiv3960329954"><font class="ydp772113dayiv3960329954" size="2" face="Arial"><span class="ydp772113dayiv3960329954893392018-15122020"></span></font><div class="ydp772113dayiv3960329954"><PanPlot.png></div></div>
<div class="ydp772113dayiv3960329954"><font class="ydp772113dayiv3960329954" size="2" face="Arial"><span class="ydp772113dayiv3960329954893392018-15122020"></span></font> </div>
<div class="ydp772113dayiv3960329954"><font class="ydp772113dayiv3960329954" size="2" face="Arial"><span class="ydp772113dayiv3960329954893392018-15122020">I believe that I can
create a voltage-controlled version of this simple pot panning circuit fairly
easily by replacing the pot with a pair of modified Irwin 2164 circuits. I
did this for the Morphing LFO.</span></font></div>
<div class="ydp772113dayiv3960329954"><font class="ydp772113dayiv3960329954" size="2" face="Arial"><span class="ydp772113dayiv3960329954893392018-15122020"></span></font> </div>
<div class="ydp772113dayiv3960329954"><font class="ydp772113dayiv3960329954" size="2" face="Arial"><span class="ydp772113dayiv3960329954893392018-15122020">Would this response
suffice as an "equal power" panner?</span></font></div>
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