Emu XL-7 & MP-7 User's Group

On 10/29/02 11:40 AM, "pocketd@..." <pocketd@...> wrote:

> Key velocity is aftertouch? Then it´s called pressure in the patchcord, do
> the XX-7 pads have
> that possibility, hmmm...
> But if that´s Key velocity, why is it a own point in the manuals?
> 

No aftertouch is different. And yes the XX7 pads can produce both velocity
and pressure control signals.

Velocity is normally measured on standard mechanical keyboard controllers by
measuring the time between two switch closures (or a switch break before the
next break).  Since the physical distance is known this is a good first
order approximation of the travel speed of the key.  The resulting value is
then scaled to 0-127.

On the XX7 you are dealing with pads that actually sense the pressure or
force being exerted on them.  So there is no 'trick' like there is with
mechanical keyboards.  The likely way it is done is to measure the change in
pressure over a short period of time and use the rate of change as an
indication of velocity.  This is how I believe the XX7 does this but only
the Emu wizards would know for sure.

Having both velocity and pressure as control sources is useful.  Velocity is
used to general affect the entire entire note event solely based on how fast
or slow it was played. Since it is only measured at the start of the musical
event its value is held through the whole event so velocity offers no
further potential for articulation while the note is playing.

pressure on the other hand (or  would that be finger :-) ) can be measured
and updated throughout the life of the music event.  So it is possible to
modulate one or more aspects of a sustained not or notes simply by varying
the force exerted on the pads.

Aftertouch is shown as "pressure" in the modulation source list of the patch
cords menu.  Velocity is Vel+, Vel+-, and Vel< which were discussed in
detail in my post yesterday.


drk

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