JBL SAM3HA, SAM3VA manual Channel Systems

SPEAKER PLACEMENT

NOTE: It is extremely important to place the tweeter/mid-bass arrays for each of the center, left and right speakers at the same height. The horn array containing the tweeter in the center channel speaker should be no more than two feet (0.6 meter) higher or lower than those in the left and right speakers. This preserves the “localization integrity” of “sound pans,”in which the sound appears to move from left to center to right. If the program material also appears to travel up and down, it can destroy the illusion of panning effects and so should be avoided.

AMBIENT SURROUND SPEAKERS: Although it has been common for many years to use a number of surround speakers in commercial movie houses, until recently, the traditional home theater configuration called for 5.1 channels, i.e., front left, center, front right, surround left and surround right, plus a low-frequency-effects channel. The newer surround formats that are appearing in consumer audio equipment are calling for more complicated 6.1- and 7.1-channel systems. The advantages of using additional speakers are many. Additional channels enable a more versatile use of directionality for a more accurate surround presentation. Also, a higher overall sound-pressure level can be achieved with less energy expenditure from any individual speaker. Placement of the surround speakers remains critical.

5.1-CHANNEL SYSTEMS

The ambient surround speakers work optimally if they are placed as far back from the screen as the viewing chairs are. If there are two rows of chairs, these speakers should be placed between them.

The ambient surround speakers should be placed higher than the seating area, at least two feet (0.6 meter) above (seated) ear level (see Figure 4).

The preferred method to mount the ambient surrounds is to put them directly in the side walls. This lets each speaker radiate to the front and back of the room and to reflect off the side walls.

There are a few instances in which the ambient surrounds would perform better if mounted in the ceiling rather than the walls. If one or both of the walls are “acoustically dead,” due to the presence of windows, fabric, furniture or other absorption, it may be necessary to turn the ambient speakers sideways and, instead of mounting them in a vertical orientation, mount them in the ceiling in a horizontal orientation.

6.1-CHANNEL SYSTEMS

A 6.1-channel system can be thought of as a 5.1-channel system with the addition of a rear center speaker placed midway between the two surround speakers, and further to the rear than the surrounds. It should be placed at the same height as the side surround speakers (see Figure 5).

Min. 2'-0"

Figure 4.

L C R

FLOOR PLAN

Figure 5. 6.1-Channel system

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