Yamaha CS80

A PIC EG runs on 5V which I obtain using a local regulator.  The 
output of the EG is a 10-bit PWM signal that is integrated into an 
usable voltage.  The phase accumulator outputs samples (curves are 
interpolated from lookup tables) at a rate of 20KHz.  Tom Wiltshire of 
SDIY is the one who did the grunt work on this kind of  retrofit EG; he 
has examples at his web site, electricdruid.net

  I designed a KAS replacement, which I need to build one of these 
days.  It uses discrete DACs and my favorite sneaky way of doing level 
shifting of bipolar logic: RS232 chips.  (The venerable MC1488, MC1489).

Crow
/**/


David Rogoff wrote:
>
>>   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?
>
>