[sdiy] MIDI velocity

[Richie Burnett]

Some actual transit times measured from my Fatar velocity keybed:

Hard hits average around 1.5ms to 2ms,
Medium hits average 15ms to 20ms,
Soft hits anywhere from around 150ms to 250ms,

These are the times between the first closure of the "early" set of contacts 
at the top of the key's travel (Fatar calls them "break" even though they 
are actually normally open contacts,) and the first closure of the "late" 
set of contacts at the bottom of the key's travel (Fatar calls them "make".) 
I found it impossible to get transit times below 1.5ms without hitting the 
keys much harder than I would feel comfortable doing.

Looking at those figures it does seem that a logarithmic relationship is a 
good fit, as the time goes up by roughly one decade from "hard" to "medium", 
and up another decade from "medium" to "soft".

Polling the complete keybed every 1ms is fast enough to capture even the 
hardest hits, but it doesn't look like it gives much timing resolution at 
the top end of the velocity range.  I wouldn't be surprised if some velocity 
sensitive MIDI keyboards don't output all of the 127 possible velocity 
values if their timing resolution is quite coarse at the high-velocity end 
of the scale.

-Richie,

PS. Nantonos, I've tried to contact you off-list but not sure if you got my 
Email.