User Manual
Multichannel Monitoring Tutorial Booklet (M2TB) rev. 3.5.2
Masataka Nakahara : SONA Corporation
©2005 YAMAHA Corporation, ©2005 SONA Corporation
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D. All channels can be given a playback response equivalent to large monitors that reproduce the
ultra-lows starting at 20 Hz.
Most professional sub-woofers are able to reproduce the low range down to about 20 Hz. On the other
hand, virtually no main speakers are able to reproduce the low range down to 20 Hz, with the exception of
only a very few high-quality models. By using bass management, all main speakers can be extended to
allow low-range playback down to 20 Hz.
This is particularly important for studios that produce material for theaters, such as film. In a movie
theater, L, C, and R are reproduced by enormous speakers that are able to play back the ultra-low
frequencies. When creating productions for theaters, it is important to check that the master source does
not contain unwanted ultra-low-frequency noise.
E. The playback result on consumer playback methods can be checked.
DVD-Video players or AV receivers that have Dolby DIGITAL decoding functionality are required to
provide bass redirection functionality equivalent to [Fig. 35], and bass management is performed when
the speaker setting is set to “small.” This functionality is provided to deliver extended low-frequency
response for the “small satellite speakers + subwoofer” playback setups that are common in consumer
listening environments. The bass redirection functionality of consumer equipment was originally provided
as a requirement for Dolby DIGITAL, but is recently being extended to function on a variety of sources
such as DTS, DVD-Audio, Super Audio CD, and digital broadcasts.
Bass management is a process of electrical summation, in which the low-frequency signal of each channel
is combined electrically. In contrast, low-frequency signals played back without using bass management
are combined by acoustical summation as they pass through the space of the room until they reach the
ears of the listener. In comparison to acoustical summation, electrical summation is prone to cause
interference between signals. For example if the same low-frequency signals are recorded on both the
front channels and the surround channels, and if they are being processed so as to be nearly out of phase
with each other, playback via bass management may cause those low-frequency signals to be lost. This
suggests the possibility that low-frequency components that were heard in a production environment not
using bass management can become inaudible in the end-user environment. Using bass management
during production to check the playback sound is an effective way to prevent this type of lost low-
frequency playback.
[Fig.37] is an example of the playback response in a studio that does not have a bass management
controller, while [Fig. 38] is an example of the playback response in a studio that has a bass management
controller.[4] Since both are adjusted for use as a DVD-Video playback environment, it is necessary that
the playback level of the LFE channel maintain +10 dB of gain relative to the main channels.
In the studio that uses a bass management controller, +10 dB of gain is maintained in the entire low-
frequency range, even though there is unevenness in the low-frequency response ([Fig. 38]). In contrast,
in the studio that does not use a bass management controller, this difference is not consistent; some
regions have a +10 dB difference while other regions do not ([Fig. 37]).
[Fig. 37] LFE vs. C; without Bass Management
10dB?
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