Apple Logic Pro 7 - Manual (Page 302)

302 Chapter 6 Logic’s Mixing Facilities
Bus Objects
The Bus Objects can be used in several ways:
They can be used to route audio signals to external devices via the individual outputs
of the audio hardware, allowing you to change their level and pan settings, and apply
plug-ins, if you wish.
They can be used as subgroup channels, which control the level of several audio
channels at once. As an example, all drum tracks or all different vocal takes could be
routed to one stereo bus for control of their overall level—while still retaining the
relative differences between the individual channels.
As busses can also be routed to other busses, several effect returns can be routed to
the same subgroup, in order to adjust the level of all effects in the mix at once. This
approach makes it much easier to handle the mixdown (particularly if automated).
To record the signal of a particular subgroup (for later use as a stereo track in the
arrangement), route it to an unused Output Object, and use the Bounce function (see
“Bounce” on page 285).
The Bus Objects can be used as effect returns: in this case the plug-ins serve as internal
effect processors.
Effects such as reverb and delay are generally used as bus inserts. These Bus Objects
are usually addressed with the send knobs of the audio channels, and act as effect
returns.
These busses can be routed to other busses, or to an Output Object.
In the default song, the pre-set Bus Objects have been named “Returns”.