My Yamaha EX-2 (a large stage organ that looks a lot like the GX-1,
though it uses a number of different circuits) has touch vibrato on the
upper manual. The keyboard action itself the the same as in the CS-60,
except it has a small plunger that, when the key is pressed, will rest on
a ribbont hat is stretched underneath the entire keyboard. While pressed,
if a key is moved side-to-side it will likewise impart this motion to the
ribbon, which is attched at one end to the shutter of a light source (the
other end of the ribbon is attached to a ballast spring). So, as the key
is wiggled, the shutter will open and close, allowing varying amounts of
light to shine on a photocell, which then with a simple circuit determines
a vibrato voltage. Note that this is not a polyphonic touch action (it
isn't on the GX-1, either).
Here is a photo I took of the upper manual. The touch ribbon is the
sort-of red stripe just visible below the black steel chassis piece and
just above the styrofoam keyboard contact cover. The tiny circuit board
near the right end is the vibrato voltage-deriving circuit.
The little solo manual on a GX-1 is mounted in a sort of springbox; you
wiggle the key and the entire thing moves around a little, operating a
similar shutter.
Crow
/∗∗/
On Mon, 16 Aug 2004, David Rogoff wrote:
> --- In yamahacs80@yahoogroups.com, "kent_spong" <kent_spong@h...> >
> > It would be nice to get the wiggle control
> > onto the keyboard as well like the GX1 has but I don't think that
> is
> > going to happen unless Chris (Old Crow) a synth technician who I
> > respect greatly can give me some insight on how the GX1 does the
> > wiggle on the keyboard :)
>
> Great, insane project! Just a quick note on the wiggle: I think you
> would have to float the keyboard assembly on rubber mounts. Then
> you could just have some kind of strain gauge connected between the
> keyboard frame and the base frame. I don't know how well it would
> work since the CS80's keyboard is much, much heavier than the GX1's,
> which I assume is more like the CS60's (or the solo manual, which is
> even smaller/lighter).
>
> How about adding the knee lever for the ring modulator!
>
> David