Archive of the former Yahoo!Groups mailing list: Yamaha CS80

previous by date index next by date
previous in topic topic list next in topic

Subject: RE: [yamahacs80] Voice allocation ?

From: "Colin f" <colin@...>
Date: 2009-02-18

> They use the same
> ring memory table in the GX-1 and key assigner of the CS 50/60/80.
> There is a somewhat cryptic explanation in the CS service
> guide, pages
> 11 to 19, describing the encoder for 4 voices. JH references the
> service guide on his CS50 page,

You'll find the GX1 KAS schematic here:
http://www.sequentix.com/gx1/GX1-KAS.zip

Are the separate assigner and octave chips used elsewhere ?
Looks like they were combined into a single chip for the CS synths, with a
matrix of keys rather than an input for every single key.

> If you look closely you'll see the actual electrical
> operation of the
> key scanner is ternary, not binary, it uses both -6.5v to 0 and 0 to
> +8.5v to derive logic states.

I'm sure that's not the case on the GX.
It has a +6/-9v supply for the assigner and octave scanning chips, but that
is just to limit the total supply voltage to 15v for the CMOS devices that
are used for the de-mux etc.

Cheers,
Colin f