<html><head></head><body><div style="font-family: Verdana;font-size: 12.0px;"><div>Ah, I see :-D <br/>
<br/>
Just some funny thought, maybe it's not practical because of noise...<br/>
If you use 32x LM13700s as 64 VCAs, each of them has a huge* capacitor with simple voltage-to-current amplifier feeding into the OTA control imput, and you use one DAC and some mux ICs to switch which capacitor you will be feeding, then perhaps one could refresh all those capacitors in a circular manner.<br/>
As if it's DRAM but for analog purposes, keeping the caps on some voltage level which represents the volume of that mixer "channel".<br/>
(for an MCU with more than one DAC output, maybe use more, and fewer mux ICs, some groups of mux ICs then working in parallel, for better speed)<br/>
<br/>
* huge cap: As it's just a mixer, it can be slow as hell, right?<br/>
<br/>
Could something like that possibly work? I have no idea :D<br/>
<br/>
Steve
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<div style="margin:0 0 10px 0;"><b>Von:</b> "Vladimir Pantelic" <vladoman@gmail.com><br/>
On 28.06.2016 10:16, Steve wrote:<br/>
><br/>
> is there a limit...<br/>
> Well I just wonder what kind of a monstrous circuit would have 64 digi pots.<br/>
> Sounds like something that's non-modular (design wise, not necessarily<br/>
> synth rack mount "modular"), so that's no-no land I will not enter ^^<br/>
> But then again it might be a kind of circuit that just isn't occurring<br/>
> to me know, nothing of the sort I ever planned to use digi pots for, so<br/>
> I was curious for an example.<br/>
<br/>
I have a design with 64 analog switches:<br/>
<a href="https://www.muffwiggler.com/forum/viewtopic.php?t=138964" target="_blank">https://www.muffwiggler.com/forum/viewtopic.php?t=138964</a><br/>
<br/>
if I replace the ON/OFF switches with digipots I'll have an 8 into 8<br/>
mixer with individual gain. TI PGA4311 is nice (and chainable), but I'd<br/>
need 16 at $15 a piece...<br/>
<br/>
and yes, it's in my modular rack :)<br/>
<br/>
and yes, maybe it makes more send to just use 8 ADCs and 8 DACs and do<br/>
it all in digital....<br/>
<br/>
<br/>
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