CHAPTER 17. INSTRUMENT, DRUM AND EFFECT RACKS
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17.5.1
Signal Flow through Zones
To understand how zones work, let's examine the signal ow in a MIDI Effect Rack. Our
MIDI Effect Rack resides in the device chain of a MIDI track, and therefore processes MIDI
signals. We will assume that it contains four parallel device chains, each containing one
MIDI effect.
1. All MIDI data in the track is passed to its device chain, and therefore into the
input of the MIDI Effect Rack.
2. Our MIDI Effect Rack has four device chains, all of which receive the same MIDI
data at the same time.
3. Before any MIDI data can enter a device chain, it must be able to pass through
every
zone in that chain. Every chain in a MIDI Effect Rack has three zones: a
key zone, a velocity zone and a chain select zone.
4. An incoming MIDI note gets compared to a chain's key zone. If the MIDI note lies
within the key zone, it is passed to the next zone for comparison; if it does not,
then we already know that the note will not be passed to that chain's devices.
5. The same comparisons are made for the chain's velocity and chain select zones.
If a note also lies within both of these zones, then it is passed to the input of the
rst device in that chain.
6. The output of all parallel chains is mixed together to produce the MIDI Effect
Rack's nal output. If there happened to be another device following after
the Rack in the track's device chain, it would now receive the Rack's output for
processing.
