<html><head></head><body><div style="color:#000; background-color:#fff; font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:16px"><div id="yui_3_16_0_ym19_1_1484021342000_3290"><span>Tom,</span></div><div id="yui_3_16_0_ym19_1_1484021342000_3289"><span><br></span></div><div id="yui_3_16_0_ym19_1_1484021342000_3057" dir="ltr"><span id="yui_3_16_0_ym19_1_1484021342000_3069">I think you are on the right track with the microcontroller version. I've been simulating the THAT AN120, which is just a simple diode breakpoint generator. But the amplitudes never match up for the given circuit, with differences of 50% or greater depending on the setting and the left or right channel. In reality I think this circuit will need multiple trimmers to get everything right. Considering it is modifying CVs that go into an exponential control circuit, just small errors can be significant.</span></div><div id="yui_3_16_0_ym19_1_1484021342000_3057" dir="ltr"><span><br></span></div><div id="yui_3_16_0_ym19_1_1484021342000_3057" dir="ltr"><span>John</span></div> <div class="qtdSeparateBR" id="yui_3_16_0_ym19_1_1484021342000_3597"><br><br></div><div class="yahoo_quoted" id="yui_3_16_0_ym19_1_1484021342000_3704" style="display: block;"> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;" id="yui_3_16_0_ym19_1_1484021342000_3703"> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;" id="yui_3_16_0_ym19_1_1484021342000_3702"> <div dir="ltr" id="yui_3_16_0_ym19_1_1484021342000_5500"><font size="2" face="Arial" id="yui_3_16_0_ym19_1_1484021342000_5499"> On Monday, January 9, 2017 7:34 PM, Tom Wiltshire <tom@electricdruid.net> wrote:<br></font></div> <br><br> <div class="y_msg_container" id="yui_3_16_0_ym19_1_1484021342000_3701">Hi Laurie,<br clear="none"><br clear="none">Thanks for the reply. Yes, I have looked at the Serge equal power panner, but I'd discarded it for the following reasons:<br clear="none"><br clear="none">1) I don't understand it fully. The schematic is spread across three modules (CGS102A, CGS102B, CGS108) plus a mixer board to plug them all into, which makes it somewhat difficult to get a grip on. The CGS108 Serge Gain Cell is a proprietary design for which we aren't given a schematic. I don't want to tread on illustrious toes, so I'm not interested in trying to find a schematic if people don't wish me to know. The parts remind me of the discrete OTA Jürgen Haible designed for his discrete SSM2040 filter, which would make sense.<br clear="none">2) All those parts! Isn't there a simpler way?! Ok, I accept that the image on Ken's site is a dual version, but nonetheless - it's not straightforward:<br clear="none"><br clear="none"> <a shape="rect" href="http://www.cgs.synth.net/modules/pic/photo_cgs101v10_upap.jpg" target="_blank">http://www.cgs.synth.net/modules/pic/photo_cgs101v10_upap.jpg</a><br clear="none"><br clear="none">The THAT Corp solution is similarly involved.<br clear="none"><br clear="none">Currently the easiest way (by far) is to do as Richie suggested and generate the required pan law (*any* required pan law, or even the user's favourite law) with a uP and a DAC, fed to a pair of your VCAs of choice. It's a pity since I'd hoped for an analog solution to avoid the default "throw a micro at it" answer, but in this case, it really does seem like the sensible way. <br clear="none"><br clear="none">Thanks,<br clear="none">Tom<br clear="none"><br clear="none"><br clear="none"><div class="yqt2428526090" id="yqtfd13130"><br clear="none">On 9 Jan 2017, at 22:13, Laurie <<a shape="rect" ymailto="mailto:elby_designs@ozemail.com.au" href="mailto:elby_designs@ozemail.com.au">elby_designs@ozemail.com.au</a>> wrote:<br clear="none"><br clear="none">> Have you looked at the Serge Equal Power Panner?<br clear="none">> Go to my site or Ken Stones CGS site and look at CGS102.<br clear="none">> PCB and Component Kits available to DIY it<br clear="none">> <br clear="none">> Best Regards<br clear="none">> Laurie Biddulph<br clear="none">> Mobile: +61 0400 257 645<br clear="none">> Phone.: +61 02 4340 0938<br clear="none">> Web...: www.elby-designs.com<br clear="none">> Skype.: widgetoz<br clear="none">> <br clear="none">> Elby Designs<br clear="none">> 9 Follan Close<br clear="none">> Kariong<br clear="none">> NSW 2250<br clear="none">> Australia<br clear="none">> <br clear="none">> ABN: 70 022 727 605<br clear="none">> <br clear="none">> Happy New Year<br clear="none">> <br clear="none">> <br clear="none">> On 10/01/2017 8:29 AM, <a shape="rect" ymailto="mailto:microtonalsynthesis@yahoo.com" href="mailto:microtonalsynthesis@yahoo.com">microtonalsynthesis@yahoo.com</a> wrote:<br clear="none">>> Like many app notes, the THAT AN120 is something of a DIY project in itself.<br clear="none">>> <br clear="none">>> The control voltage inputs are reversed. U1 should use EC+ pin 2 and U2 should use EC- pin 3.<br clear="none">>> <br clear="none">>> The breakpoint generator is very sensitive to offsets and the circuit as given has unequal volumes for left and right sides. Adjustment of all resistors going to -15V is needed. I estimate about 130.5K for the 133K. Of course, if you adapt this circuit to 12V supplies then you need to adjust some more.<br clear="none">>> <br clear="none">>> John<br clear="none">>> <br clear="none">>> <br clear="none">>> On Sunday, January 1, 2017 6:24 PM, Richie Burnett <<a shape="rect" ymailto="mailto:rburnett@richieburnett.co.uk" href="mailto:rburnett@richieburnett.co.uk">rburnett@richieburnett.co.uk</a>> wrote:<br clear="none">>> <br clear="none">>> <br clear="none">>> You could always generate the two VCA control signals with the appropriate pan law using a micro... Low cost pic with dual output PWM perhaps? Pre-calculated values in lookup table on a low end micro, or use quadratic fit approximation if you're already using a dspic.<br clear="none">>> <br clear="none">>> -Richie,<br clear="none">>> <br clear="none">>> Sent from my Xperia SP on O2<br clear="none">>> <br clear="none">>> ---- Tom Wiltshire wrote ----<br clear="none">>> <br clear="none">>> >That's a fairly involved circuit, but I don't think I've ever seen an analog panner with a switch to select different pan laws. Very impressive!<br clear="none">>> ><br clear="none">>> >I'll have a look over it and see if I couldn't use the gist of it in a simpler way.<br clear="none">>> ><br clear="none">>> >On 1 Jan 2017, at 20:14, Tom Bugs <<a shape="rect" ymailto="mailto:admin@bugbrand.co.uk" href="mailto:admin@bugbrand.co.uk">admin@bugbrand.co.uk</a> <mailto:<a shape="rect" ymailto="mailto:admin@bugbrand.co.uk" href="mailto:admin@bugbrand.co.uk">admin@bugbrand.co.uk</a>>> wrote:<br clear="none">>> ><br clear="none">>> >> Not LM13700 based, but the details within the THAT app note here may be some use:: <a shape="rect" href="http://www.thatcorp.com/datashts/dn120.pdf" target="_blank">http://www.thatcorp.com/datashts/dn120.pdf </a>(VCAs in pan pot apps)<br clear="none">>> >><br clear="none">>> >><br clear="none">>> <br clear="none">>> >>>>> -----Ursprüngliche Nachricht-----<br clear="none">>> >>>>> Von: Synth-diy [mailto:<a shape="rect" ymailto="mailto:synth-diy-bounces@synth-diy.org" href="mailto:synth-diy-bounces@synth-diy.org">synth-diy-bounces@synth-diy.org</a> <mailto:<a shape="rect" ymailto="mailto:synth-diy-bounces@synth-diy.org" href="mailto:synth-diy-bounces@synth-diy.org">synth-diy-bounces@synth-diy.org</a>>] Im Auftrag von Tom<br clear="none">>> >>>>> Wiltshire<br clear="none">>> >>>>> Gesendet: Sonntag, 1. Januar 2017 18:07<br clear="none">>> >>>>> An: <a shape="rect" ymailto="mailto:Synth-diy@synth-diy.org" href="mailto:Synth-diy@synth-diy.org">Synth-diy@synth-diy.org</a> <mailto:<a shape="rect" ymailto="mailto:Synth-diy@synth-diy.org" href="mailto:Synth-diy@synth-diy.org">Synth-diy@synth-diy.org</a>><br clear="none">>> >>>>> Betreff: [sdiy] Panning with LM13700<br clear="none">>> >>>>><br clear="none">>> >>>>> Hi All,<br clear="none">>> >>>>><br clear="none">>> >>>>> Happy New Year to everyone! Here's hoping you all have a great year with<br clear="none">>> >>>>> many (completed) synth projects.<br clear="none">>> >>>>><br clear="none">>> >>>>> I've got quick question - what's the best way to do equal power panning (-<br clear="none">>> >>>>> 3dB in the centre) with the LM13700? I'm assuming that such a thing has<br clear="none">>> >>>>> been done already, so it's seems silly to reinvent the wheel, but I can't<br clear="none">>> >>>>> find anything that isn't a simple linear crossfade (which is ok for<br clear="none">>> >>>>> crossfading, but not so good for panning).<br clear="none">>> >>>>><br clear="none">>> >>>>> Any tips/pointers appreciated.<br clear="none">>> >>>>><br clear="none">>> >>>>> Thanks,<br clear="none">>> >>>>> Tom<br clear="none">>> <br clear="none">>> <br clear="none">>> <br clear="none">>> <br clear="none">>> <br clear="none">>> _______________________________________________<br clear="none">>> Synth-diy mailing list<br clear="none">>> <a shape="rect" ymailto="mailto:Synth-diy@synth-diy.org" href="mailto:Synth-diy@synth-diy.org">Synth-diy@synth-diy.org</a><br clear="none">>> <a shape="rect" href="http://synth-diy.org/mailman/listinfo/synth-diy" target="_blank">http://synth-diy.org/mailman/listinfo/synth-diy</a><br clear="none">> <br clear="none">> <br clear="none"></div><br><br></div> </div> </div> </div></div></body></html>