Specifications

5.1-Channel Production Guidelines Production Techniques
5-3
5.3.1 Center/Front Channels
In a stereo program there is only one way to obtain a centrally placed sound image: mix
the signal equally to the L/R channels. In a multichannel system, there are three ways:
•
Create a phantom center just as with stereo.
•
Use the center channel alone.
•
Use all three front channels equally or in varied proportion.
Each approach offers advantages and drawbacks. In use since stereo began, the
phantom center is well understood. The primary disadvantage of this technique is that
the listener must be equidistant from the L/R speakers to achieve proper center
imaging. This is rarely the case in the home, and is nearly impossible in a car.
Another disadvantage is that due to cross-cancellation effects, the timbre is not the
same as from a direct speaker source.
Using the center speaker alone creates a stable center image for every listener no
matter where they sit. To prevent the image from sounding too focused or narrow,
reverb from the center channel can be spread to the L/R channels.
Distributing the center image amongst the three front speakers allows control of the
range of spatial depth and width. A phantom center can be reinforced by some
additional signal in the center channel, or a center channel signal can be enhanced
with some additional signal spread into the L/R pair. The more channels that are used
to carry the same signal, however, the more likely it is that side effects may occur.