[sdiy] SSM2164 base for Doepfer sdiy synth kit.

[David G. Dixon]

> One more 2164 app.

Damn copycats!  ;o)

> 
> 1:Doepfer diy synth kit are apparently based on the SSM2164.(One side Expo
> other SVF).
> 2:According to Doepfer a oven heats up the 2164.
> 3:As seen in the block diagram the VCO core have Lin FM Sync,Saw, PWM.
> 4:That suggest he uses a traditional Saw (we can see a BF245)core with
> the expanded Roman Sowa expo(expanded by D Dixon/Huoysama and Co.)
> 5:But since expo already temp compensated why go the extra mile to heat
> it.

Maybe because using it as a self-tempco involves fairly precise voltages,
and therefore, a reference and an expensive trimmer...?  But it does seem
kinda stoopud.

> 6:The picture of the PCB shows us the oven either piggybacked over the
> 2164 or replaced by a SO 2164 who plugs into the DIP 2164 socket.
> 7:In either case there must be plenty of package mass to create gradients
> between the oven and the actual 2164 who makes heating slow.
> 8:Doepfer verifies that with a heat up period of 20minutes.
> 9:Doepfer says temp sensor are set just above room temp?!

This oven business makes me nervous.

> 10:The VCA seams to be a CA3080.

Why not use ... (wait for it) ... 2164?!?!?  It is a VCA after all!

> One idea i got was to to use a small heating filament under the DIP2164.

I'm contemplating writing a little book (in the spirit of Thomas Henry) on
how to build an entire 2164-based synthesizer (like mine).  The only "main"
module in my modular now which isn't centred around 2164 is the my custom
dual MFOS ADSR.