Apple Logic Pro 8 - Manual (Page 821)

Chapter 35 Working With Surround 821
 A number of speaker icons, that surround the circular grid. You can change the
channel surround format directly in the Surround Panner window by clicking on the
speaker icons. This will activate or deactivate the respective channels. Blue speakers
indicate active channels, and gray speaker icons denote inactive channels.
 The blue dot controls the routing of the signal to the speaker outputs. You can drag
the blue dot in the surround field.
The movement of the surround position (indicated by the blue dot) is made easier with
these functions:
 Hold Command to lock diversity.
 Hold Command-Option to lock the angle.
 Option-click the blue dot to reset angle and diversity.
Level Controls
The Center Level slider, and field, determine the volume relationship of the (front)
center channel—typically used for dialog in film and TV productions.
The LFE Level slider, and field, control the volume of the LFE output. The abbreviation
stands for Low Frequency Enhancement or Low Frequency Effects, as the LFE output is
most commonly sent to a subwoofer channel. The use of a subwoofer speaker is not a
must.
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Tip: If you only want low frequency signals to reach the output, insert a multi mono
surround EQ into the surround master channel. Use this to set the LFE (or subwoofer)
output. A cutoff frequency of 120 Hz is standard for most surround applications.
Separation Controls
The sliders in the lower section of the Surround Panner window determine the amount
of separation between various channels. As you alter these parameters away from
values of 1.00, the separation square will change (to a trapezoid or rectangle) in the
surround field, providing visual feedback on how the channel is being affected.
 Separation XF: Applies to the Left and Right (front) channels. Reducing Separation
from 1.00 down to 0.00 mixes the right signal into the left channel, and vice versa,
until both channels output a mono signal.
 Separation XR: Applies to the Left and Right Surround (rear) channels. Works as
above, for the surround speakers.
 Separation Y: Affects the mix relationship of the front and rear channels (in front or
behind the listening position, in other words). It mixes the Left/Left Surround and
Right/Right Surround channels. When Separation Y is set to 0.00, the front and rear
channels will output in mono.