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It cannot be stressed enough that the vast majority of loudspeaker problems turn out to be acoustical
or cabling problems. PLEASE CHECK THESE FIRST, then contact the local Genelec distributor for
advice.
3
Practical Installation Considerations
3.1
Main Loudspeaker Positioning
The ideal loudspeaker placement is often compromised when working within the client's wishes and room
design restrictions. Often sound quality is third on the list after the room aesthetics and video require-
ments, however, with some attention to detail, it can be close rather than distant third.
DVD's are normally mixed in studios that conform to the ITU standard ITU-R BS.775-1 "Multichannel
stereophonic sound systems with and without picture" (Geneva, 1992-94). The closer a Home Theater
can get to this standard the better the audio result will be. A few of the more important recommendations
found in this international standard are presented and discussed below:
3.1.1 Angles
ITU Recommendation:
Left and right are positioned 30º from the center and the rears are positioned 110º ± 10º from the
center. The loudspeakers should then be angled so that they point towards the optimum listening
position - see Figure 6.
In Practice:
These angles are generally not respected in Home Theaters. The center loudspeaker is usually
in the correct place but the left and right loudspeakers are positioned according to the size of the
screen (a practice inherited from the movie theater 'standards'). Multiple loudspeakers are used for
the rear channels to increase coverage in the listening area and are positioned wherever is most
convenient on the side and/or rear walls.
3.1.2 Distance
ITU Recommendation:
All loudspeakers should be equidistant from the "sweet spot."
In Practice:
In Figure 6, it can be seen that it is difficult to place the left, center and right loudspeakers equi-
distant front the "sweet spot" as the loudspeaker enclosures are normally positioned in the same
plane, i.e. against a wall or in some cabinetry. The resulting timing differences are then electroni-
cally compensated using the processor. Unfortunately, this results in a compromise that is rarely
referred to in most literature. The polar pattern of the loudspeaker is different at different listening
distances and this cannot be compensated for in a simple digital delay.
3.1.3 Height
ITU Recommendation:
The front loudspeakers should ideally be placed at a height approximately equal to that of the
listener's ears (1.2 m / 4 ft from the floor). If the loudspeakers are to be placed higher or lower than
the listeners' ears, the loudspeakers should be angled vertically to point towards the listening posi-
tion.
In Practice:
Genelec recommends that its loudspeakers be positioned at least 1.2 m (4 ft) off the floor so the floor
reflection does not dominate the frequency response. If the loudspeaker is placed close to the floor,
for example, below a screen, two things happen: a deep and wide notch occurs in the bass (typically
18
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