optical pots

[xeon at freemail.nl]

|Hello everybody, I've changed my emailadress because of a few nasty |          
|problems Hotmail (it seems that mICro$oft can't get anything right).|
|So now you'll see xeon but the name is still Paul.                  | 

I'm still thinking of a way to improve the way those VA synts are 
interfaced. MIDI is 16 years old and it's 7 bits quantization is just
mediocre. 

>From an advertisement;

The NUMARK PRO-SM1, a pro DJ-mixer, uses optical faders, so no 
crackling. The faders can be adjusted in a few ways that their 
respondse will differ, this all made possible by the optical VCA 
technique used. The mixer costs about Hfl 1500,- that's plusminus $750.
So that technique is quite costly.

I was thinking about a digital emulation synth with high resolution 
infinite rotary knobs. The knobs would work just as a computer mouse 
does but with far better accuracy. Put a special "FOCUS" mode into the
software. 
So imagine yourself tweaking your VA synth, everything goes 
smooth and than you think "Oh this parameter is difficult to adjust 
precisely with that knob without an editor let's take focus and 
limit the range of the knob, 2x push focus (now the knob doesn't change 
say osc frequency 20000 Hz with 360 degrees but just 200 Hz with 360 
deg = far better accuracy) and done"

Question; Does anyone know of such technique used? And maybe has 
got/knows literature about this subject?


Thanks a lot,


Paul (aka Mr XeoN Freemail ;-> )