[sdiy] Using MIDI internally in a polysynth

[Tom Wiltshire]

Hi All,

I'm looking for a bit of advice:

I'm currently working on an updated version of my PIC-based VCADSR  
envelope generator. The new version has an input for a velocity CV,  
and bipolar controls to alter how this affects the envelope time and  
the envelope level ('velocity time amount' and 'velocity level  
amount'). I've also included an input for the keyboard voltage, and a  
bipolar control to alter how that affects the envelope time  
('envelope key follow').

However, having done all this, I realised that if I were just to use  
the serial port on the chip to receive MIDI input directly, I could  
get rid of both of these CV inputs, along with the digital Gate and  
Trigger inputs. It does seem a bit silly to do a MIDI-CV conversion  
and then send a control voltage to my PIC chip, where I then do an  
A2D conversion to get the original MIDI data out again - why not just  
use the digital data directly?!

I can see that for a monosynth, it isn't a bad idea to send the MIDI  
to the elements of the voice directly.

However, for a polysynth, I can't have every envelope generator  
responding to every note, so I'd need another processor to read the  
incoming MIDI stream, and assign certain messages to individual  
voices inside the synth. Essentially, there'd be one chip acting as a  
MIDI router and doing the voice assignment.

What I want to know is: What do people think of using MIDI internally  
this way? Has anyone tried anything similar, or does anyone know of  
any synths that do something similar? Would this scheme be too laggy?

Thanks!

Regards,
Tom