[sdiy] MIDI volume to volts formula

Hugh Blemings hugh at blemings.org
Fri Jun 8 06:59:04 CEST 2018

On 8/6/18 14:47, MTG wrote:
> Actually I guess it was always possible, you just had to hit the keys
> so hard you were just short of breaking them. ]

My recollection is that an unmodified original DX7 would top out at a 
MIDI velocity value of 105 or so - clipped in firmware I guess for want 
of a better way to describe it.

Regrettably the KX76 of the same era did the same thing somewhat
limiting it's utility as a controller for other modules.  I'm not sure
if the KX88 had the same limitation though - it was basically the same 
electronics and ROMs

I recall it being explained at the time that this was done so that a DX7 
(and TX7 module) would "sound right" if played from a KX76

There was I think a MIDI solutions black box that would do the relevant
math to expand the 0-105 range to 0-127.  I recall doing a similar tweak
with a Yamaha MEP-4 MIDI event processor in my rig during that era.

I did some vaguely related exploring of Velocity to MIDI mapping with
one of my '76s a couple of years ago -


> He must have modified the table(s) to make it more sane (I'm
> guessing). Is Robin around? Is that ROM available for purchase/trade?
> :-o

I think Robin has posted here from time to time in the last few years.

HTH :)


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