Patches and discussion for Ensoniq VFX family

On Fri, Apr 24, 2009 at 02:32:39AM -0000, psionic11 wrote:
> Alright, have it all figured out, and here are the results:
> 
> All black keys respond well enough to polypressure.  Most of the white keys also respond ok, many have bad response, and 7 white keys do not respond at all to pressure =(.  I tested by going to the PITCH MOD page, setting MODSRC = PRESS, and set MODAMT = +99, to get a very obvious indicator of how pressing harder affects the pitch.
> 
> So it looks like I will have to take it apart and see if there are some loose screws that can be tightened.  Crossing my fingers.
> 
> Thanks all for the input, it was all very helpful.

When I took my VFX apart, it looked like each of the keys had a piece
of metal in it, and the circuit board running beneath the keys had
different shaped "antenna coils" under each key.  There did not appear
to be any actual electrical contact involved in detecting the keys.

My guess these all work like a metal detector, and the different
shapes to the coils somehow help keep adjacent keys from interfering
with each other.  This would mean all the little microcontroller that
handles the keys can do is detect how close that metal piece is to the
circuit board, and it turns that information into both key down /
velocity and aftertouch messages.

I don't know if this makes any sense at all, this is ALL educated
guesses as to how this stuff works.  But I'm guessing that your keys
that don't work well for aftertouch are either not getting as close to
the keybed as the ones that work well, or maybe they're at one edge of
the calibration range.

If you're going to open it up anyway, you could try swapping two
ocaves worth of keys (I think they're interchangable; someone correct
me if I'm wrong) to see if the problem follows the keys or stays with
the keybed.

I don't know if that will help you at all, but thought I'd send it on
anyway.  Does anyone here have a more thourough understanding of how
the keyboard in these synths actually work?

While I do remember some saying the later keyboards were different,
the keybeds in my (vanilla) VFX and my VFX-SD (not a VFX-SD-II) are
substantially the same.  My guess would be all the changes were in the
mechanics (tolerances, spring strength, etc.), and that everything
about the key sensing stayed the same.

--> Steve

-- 
Steve Wahl    steve@...

Fools ignore complexity.  Pragmatists suffer it.
Some can avoid it.  Geniuses remove it.
-- Perlis's Programming Proverb #58, SIGPLAN Notices, Sept.  1982