[sdiy] Another 2164 project

[David G. Dixon]

> I've just finished another SSM2164-based PCB.  This time its 
> a 3- channel VC mixer: three inputs, each with their own CV 
> input, signal presence LED and buffered output, then all feed 
> into a fourth 'master' channel, again with CV control, LED 
> and buffered output.  I didn't quite have room for mute, so 
> there are two headers for a daughter card (currently being 
> worked on!) that will give 3-channel VC mute.
> 
> Details here:
>    http://www.milton.arachsys.com/nj71/index.php? 
> menu=2&submenu=0&subsubmenu=4

Very nice!  Anything with 2164 warms the cockles of my heart (and all my
other cockles too!).

Two (impertinent) design questions, if I may:

1.  Are the multiple input resistors just a matter of saving PCB real
estate, or for some other reason?

2.  Why do you buffer outputs which are already buffered?  Is it something
to do with driving capacitance?