APPENDIX
MIDI FOR PERCUSSION
The world of Percussion has some special needs that affect how MIDI is generally used for Percussion
and Drum Sounds. These special differences include how Note Offs (Gate Time) are handled, how
Notes and Program Changes are used, and sensitivity to time delay and polyphony.
Keyboardists, guitarists, string, and horn players are all used to dynamically controlling the length of
the Sounds they produce. This is not generally true for drummers and percussionists. Generally, once
a drum is struck, it plays its sound out on its own. (Of course there are exceptions like cymbal
choking and damping mallet or drum sounds - but often the sounds do play out on their own.)
Because of this, it is not unusual for a drum machine to not pay any attention to Note Off Commands.
This means that generally, even if a drum machine is told to turn off a Sound after only a few
milliseconds, most will play the Sound out until it is done on its own anyway. Because of this, you can
choose on the trapKAT not to send any Note Off Commands - because often, for drum Sounds, they are
not needed and simply fill up space in sequencers and waste the time of the Receiving Sound Source.
Another difference for Percussion is that different Note Numbers are more likely to stand for totally
different Sounds - (not just different pitches of the same Sound). There are exceptions to this, but a
keyboard player is more likely to think of MIDI Notes correlating to Pitch and a drummer is more
likely to think of MIDI Notes as referring to totally different Sounds.
For a keyboard player, a Program Change Command is typically thought of as selecting some specific
Sound which the MIDI Notes access different Pitches of. For a drummer, a Program Change is
generally thought of as selecting a specific collection of individual sounds which specifies which
different Sounds can be accessed through MIDI Note On Commands.
Because drummers and percussionists have a highly developed sense of time, they are more sensitive to
time delays. A drummer is very sensitive to where a Sound is played with respect to the beat. This
brings us to MIDI Delay. The MIDI time delay for a Note On Command is 1 millisecond (one
thousandth of a second). It is imperceptible! (5 milliseconds (mS) is where you start to notice, 10 mS is
noticeable and 20 mS is obnoxious.) (1 mS = .001 Second)
So why do we hear all this talk about MIDI Delay? Because they are really talking about Sound
Source Delay when they talk about MIDI Delay. So what is Sound Source Delay? It is the time that it
takes a Sound Source to respond to a MIDI Note On Command it has received and start to make a
Sound. Sound Source delay typically ranges from 1/2 mS to 15 mS. The Sound Sources with 1/2 mS to
3 mS delay are the ones worth owning.
So if you want to avoid “MIDI Delay”, avoid Sound Source Delay! Call us and we’ll tell you how the
current Sound Sources rate.
Interestingly enough, there is also Sound Travel Delay! It actually takes sound a noticeable time to
travel through the air. Hence echoes. Hence you see lighting, then hear thunder seconds later.
Specifically, sound travels 1 foot in just a bit less than 1 mS. This means that a monitor placed 10
feet from your ears will cause around 10 mS of delay - Sound Travel Delay! (There is about a 2mS
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