Specifications

5.1-Channel Production Guidelines Production Environment
3-11
3.3 Bass Management
Stereo requires the reproduction of signals from 20 Hz to 20 kHz. This is done with
multi-way speaker systems, which utilize a combination of woofers and tweeters to
achieve full range response. These speakers are connected via a crossover network to
route the appropriate frequencies to the various speakers in the system. This may be a
two-way, three-way, four-way, or even-five way system, but in each case, the goal is
to reproduce 20 Hz to 20 kHz evenly.
The introduction of Dolby Surround home theater systems added three speakers to the
stereo system, a full range center speaker and two limited-range surround speakers.
The bandwidth of the surround channel is 100 Hz to 7 kHz. This results in the ability
to use small bookshelf speakers for the surround channel.
Although the center channel is full bandwidth, most consumer applications will not
allow a full-sized center speaker as would be typical for the left and right speakers.
Because of this, a bass management system is included in the Dolby Surround Pro
Logic consumer decoder to cross over the center channel low frequencies below
100 Hz and redirect them to the left and right speakers. The bass signal is now
reproduced by speakers capable of handling the information without overloading the
smaller, center speaker.
Dolby Digital consumer decoders also include a bass management system. Just as
with the stereo and Dolby Surround systems, the goal is to be able to reproduce all