[sdiy] Emulating Hammond keyboard contacts, was:MIDI isn

[Ingo Debus]

jhaible at debitel.net wrote:
> The old Korg CX-3, while not using Midi, uses an internal serial data stream
> from its keyboard scanner to th etone generator section. And a single
> contact for all drawbars, too. This is a limitation, but I can live with it
> for the few organ parts I include in my music. But there's no doubt that
> the real thing, B3, offers more means of expression to the player,
> and thus can be called "more musical".

Just took the chance and fired up my Hammond M-101 after a long time.
Lovely instrument, the upper manual has the same drawbars as the B3 (but
only 3 1/2 octaves).
I used to own an old Korg CX-3 too, but it was stolen before I got my
Hammond so I could never compare them side by side. Although the Korg
too has the B3 type drawbars, its sound is completely different. It's a
good drawbar organ, but it is not a Hammond clone. This is mostly not
because of the multiple key contacts. I think what contributes most to
the Hammond sound (opposed to the Korg) are the tubes and the tonewheels.

harry wrote:
> 
> In the Hammond case... I would think that velocity could be used to synthesize
> or multi-sample the various speeds of key closure. They close in the same order
> 
> (unless bent beyond recognition...) and the bounce should be a function of the
> velocity as well...
> 
> And 99.5% of people cannot hear the difference...
> 
> H^) harry  (who can.... ssometimes....)

With normal playing style the effect of the multiple key contacts is
very subtle, and then it's different for each key (at least on my
organ). I don't even think that it's required to use velocity at all to
get a good emulation.
But what Juergen refers to, I think, is a more experimental style,
pressing the keys *very* slow, so that the drawbars come in one by one
audibly. This can't be modeled with one velocity parameter only.  
I'd love to have a keyboard that senses the key travel. Someone here on
the list suggested building one a while ago. This could emulate the
multiple contact thing very well and do much more. In MIDI, the key
travel could be transmitted via polyphonic aftertouch.

Ingo