Yamaha CS80

Scott Rider wrote:
>   I have no plan for designs beyond the standard M board at this time.  
> I need to proof and verify that the basic voice card works "as 
> advertised" so that actually using it to replace broken cards means the 
> machine still sounds like a CS-50/60/80.  
Seems very reasonable!
>
>   The EGs btw are (lowers voice to a mumble) *digital*, using  PICs and 
> calculated rate tables similar to the EG-S chip of a DX voice engine.  
A couple of questions here.  How fast are the envelope samples?  What
kind of digital/analog interpolation/smoothing are you using?  Also,
I've thought many times about replacing most of the KAS and KBC boards
with one, cheap FPGA.  The problem is that the CS80 runs all the digital
logic off +8.5v/-6.5v (= 15volt supply) to interface with the analog
stuff and modern digital chips will fry at any anything over 3.3v.  How
do you handle the PIC?  Outboard DAC?  A billion level shifters?

Thanks & good work!

 David