MIDI-CV converters (was: Building my first synth...)

[Mikko H.]

>      Any thoughts on this? How should it be connected to the PC? If it's 
>      built on a card that fits into a slot in the PC, there may be 
>      connector density problems as well as EMI pickup from nearby spikey 
>      digital stuff. Maybe an external box, attached through the parallel 
>      port? How about using the serial port? Now it has a UART in it, but 
>      now it only has to decipher D/A setup data instead of MIDI traffic.
How about serial D/A convertor on printer port, there are some 4 channel
12 bit DACs made by Analog Devices (and even octal ones), but it will be
cheaper and better to use single DAC with analog switches and S/H's.
Optoisolators between parallel port and DAC thing would reduce noise and
help with grounding problems. Paia Fatman uses voltage dividers and multiplexor
to select an octave and the DAC08 for the notes inside octave, but it generates
exponential CV for linear CV inputs.

Btw. I haven't ever understood why exponential CV inputs are so important,
what is the point, as CV's are now mostly generated by computers. Is it
so difficult to build an analog exponential EG, or what is the reason?

-Mikko