Apple Logic Express 9 User Manual
Page 39
If the keyboard can generate its own sounds, you should also connect the MIDI Out port
of the MIDI interface to the keyboard MIDI In port. If your MIDI interface offers more than
one MIDI output, connect any other tone generators (or other MIDI devices, such as
control surfaces that require bidirectional MIDI communication) to these.
Computer
MIDI interface
Tone generator
Out port
Out port
Keyboard
In port
In port
In port
If the MIDI interface connected to your computer only offers one MIDI output, you need
to connect the MIDI In of the second tone generator to the keyboard MIDI Thru port. A
third device can be connected to the MIDI Thru of the second unit, and so on.
Computer
MIDI interface
Out port
Out port
Keyboard
In port
In port
In port
In port
MIDI Thru port
Tone generator 2
Tone generator 3
The MIDI Thru port replicates the signals coming into the MIDI In port of the device. It is
preferable to use a direct connection from the computer MIDI Out to a device, rather
than chaining too many units, one after the other. Doing so can cause timing problems
in the chain, if numerous MIDI commands are sent quickly. This is due to the slight delays
introduced by each MIDI In to MIDI Thru transaction. As such, a multi input/output MIDI
interface is recommended in studios with several MIDI tone generators and controllers.
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Chapter 2
Setting Up Your System