Apple Logic Pro 8 - Manual (Page 94)

94 Chapter 4 Setting Up Your System
Not only does this allow you to play up to 64 different sounds simultaneously through
your tone generators, it also allows full MIDI control for each channel of each device.
This becomes increasingly important when arranging and orchestrating such a large
number of instrument parts.
If your computer offers several MIDI inputs, you can connect the MIDI outputs of other
MIDI expanders and controllers to it.
USB MIDI Keyboards
If using a MIDI keyboard fitted with a USB connector, you don’t require a separate MIDI
interface, as it is already built into the keyboard. Just be sure to install the driver, if
needed, and connect the keyboard to your computer with a USB cable. Some modern
USB keyboards and controllers are automatically recognized by Mac OS X.
Separating a MIDI Keyboard From Its Sound Generator
If your MIDI keyboard has an internal sound source, it is important that you stop the
keyboard from generating sounds directly from its own keyboard.
To explain: If you buy a new keyboard that is to be used without a sequencer, and
connect it to an amplifier, you would expect the device to make a sound when you
press its keys—in other words, the keyboard is directly connected to the sound
generator.
When using the MIDI keyboard with Logic Pro, however, this is not desirable. In this
situation, the keyboard is used as a computer input device, and Logic Pro will pass the
incoming performance information back to the keyboard’s sound generator (or to an
internal software instrument or another connected sound module, if you wish).
If the direct connection between the keyboard and its tone generator isn’t cut, this will
result in a doubling of each note—one played directly from the keyboard to the
internal tone generator, and another sent through Logic Pro back to the tone
generator.
Not only does this cause a phased sound, but it also halves the polyphony of the
keyboard’s tone generator. In situations where you want to control or record another
sound module or software instrument with your keyboard, you would hear both the
keyboard sound (due to the direct keyboard to tone generator connection) and the
sound of the software or MIDI instrument. This is why the keyboard must be separated
from its own internal sound generator.
This function is known as Local Off, and is set directly on your keyboard. Don’t worry
about losing the ability to use the tone generator of your keyboard. Logic Pro will still
be able to communicate with your keyboard tone generator just like any other
connected, keyboardless, sound module or software instrument.