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3.3
Bass Management
The bass response of a Home Theater can even be more important than the visual image right from
the first note. Client satisfaction depends upon the quality and quantity of bass energy, therefore careful
attention is required for the lower frequencies. Unfortunately, simply putting many big subwoofers into the
room will probably not ensure the client's happiness. Overblown and distorted bass can sound impressive
at first but the quality and quantity can quickly become tiring.
The most important aspect to consider for a good bass response is the room shape and dimensions.
Low frequency absorption will help reduce the effect of standing waves but this is usually difficult to fully
accomplish due to the large depth required to absorb long wavelengths at low frequencies - see Section
5.1 Treating the Room for Good Acoustical Performance. If a room is reverberant at longer wavelengths,
less energy will be required for the low frequency reproduction. However, this has to be balanced against
the listening position, as many times a standing wave in either the length, height or width dimension will
have a negative effect, especially if the listener is in the middle of the room. The general rule is to specify
the right size devices into the room volume with additional consideration given to the listening distance.
It is generally the case that if a room is small, say less than 125 m
well. In addition, it is also a good idea to band pass all five main loudspeakers so that the lowest two octaves
(20-80 Hz) are reproduced by the subwoofer. The logic behind this is that when the room dimensions are
small and the room becomes resonant at specific frequencies, it is advantageous to be able to physi-
cally locate the source of the low frequencies to optimize the room mode excitation for a smooth bass
response.
The bass management crossover frequency should be carefully selected to optimize the performance
of the individual system. This is a trade-off between sharing the bandwidth between the subwoofer and
the main loudspeakers and the possibility to localize the subwoofer. If the crossover is too high (>80 Hz),
the subwoofer will be localized more easily. If the crossover is too low, the benefit of adding it will not be
seen in the SPL output performance of the whole system. See Table 5 for the recommended crossover
frequencies for different models. These frequencies are good starting values and may be adjusted to suit
different rooms and set-ups.
In some (usually less expensive) processors, the LFE channel information above the crossover fre-
quency may not be reproduced, so be careful when setting a lower crossover frequency than 80 Hz on
these units. Well designed processors generally route the LFE information above the crossover to the
Front
Loudspeakers
6020A
HT205 / AIW25
HT206B / AIW25
HT208B / AIW26
HT210B
HT312A / AOW312
HT315A / HT320AC
HT324A / HT324AC
HT330A
1035B / 1036A
Table 5. - Active Home Theater System Recommended Crossover Frequencies
* If the subwoofer is positioned far away from the front loudspeakers, for example, on one side of the room or at the
rear of the room, it may be necessary to lower the crossover frequency from 80 Hz down to 60 Hz in the bi-amplified
systems to avoid localizing the subwoofer.
** Consult Genelec for subwoofer solutions for this sized installation
20
Side and Rear Loudspeakers
(per channel)
6020A
HT205 / AIW25
HT205 / HT206B / AIW25
HT206B / HT208B / AIW26 / AIW25
HT208B / HT210B / AIW26 / 2x AIW25
HT208B / HT210B / AIW26
HT210B / 2x AIW26
HT312A / AOW312 / 3x AIW26
HT315A / 2x AOW312 / 4x AIW26
HT315A / 2x AOW312 / 4x AIW26
(4400 ft
), a single subwoofer will work
3
3
Subwoofer
Recommended Crossover
Frequency*, Hz
5050A
HTS3B
HTS3B
HTS4B
60 - 80*
2x HTS4B
60 - 80*
2xHTS4B
60 - 80
HTS6
2x HTS6
2x HTS6
40 - 60
3x HTS6**
80
80
80
60
60
**
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