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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comb filtering could cause highs to be attenuated in the playback sound.
In musical productions, signals that are highly correlated between the front channels and surround
channels are sometimes used to create phantom sound images in a variety of directions. In such cases, it is
desirable that the distance from each speaker to the listening point be identical so that loss of highs does
not occur in the playback response. In addition, in order to obtain a good surround playback sound field, it
is necessary that all speakers be placed at the same height. This means that “A” is ideal as a playback
environment for musical productions, but if for various reasons the height of the surround speakers must
differ from the height of the front speakers, you must decide whether the surround playback sound field or
the playback response are of greater importance, and choose either “B” or “C” as the playback
environment.
For post-productions such as DVD-Video and film on the other hand, it is customary to place the surround
speakers higher than the front speakers, and in this case it is best to construct environment “C” in which
priority is given to the naturalness of the surround sound field. In post-productions, it is usually the case
that the acoustical roles can be divided between the three categories of L/R, C, and LS/RS, and it is
seldom the case that signals are highly correlated between these. Thus, even if the actual distance to the
front channels differs slightly from the distance to the surround channels, it is not likely that comb
filtering effects between the two signals will cause problems in the playback response such as a loss of
highs. This means that we should give preference to environment “C,” since the surround sound field will
be well-formed and gestures such as flyovers can be performed. However if the distance difference
between the front channels and surround channels is so great that the Haas effect results, we need to
consider an environment that falls between “B” and “C.”
The Yamaha DM2000, DM1000, and 02R96 digital consoles allow a delay in 0.02 ms steps (0 - 30
msec) and a gain adjustment in 0.1 dB steps (-12db - +12 dB) to be applied to each speaker output.
This allows precise adjustments to be made to eradicate comb filtering effects in the audible band
( <20 kHz).
3-9. THX pm3 Certified Studios
At present, there is a profusion of multi-channel playback environments.
When deciding which playback environment you will ultimately construct, you must
take into account overall considerations such as the media you will be producing, and
the state of your room.
It is also important that the level balance and frequency response of each speaker in
your multi-channel monitoring system be adjusted according to the media you are producing.
Announced by THX Ltd. in 1999, THX pm3 is a program for designing this type of small to medium size
multi-channel studio, and is currently the only design program that provides a total solution.
The THX pm3 Certified Studio program allows the design of a multi-channel studio according to the
following guidelines.
1. Achievement of room acoustic performance that meets standards for soundproofing, NC values, and
reverberation time etc.
2. Consideration of the ideal speaker placement as appropriate for the purpose of the studio and the room
environment.
3. Monitor adjustments and certification measurements performed by a specialized THX engineer.
4. If the room acoustics and monitoring response satisfies the THX pm3 reference values, certification as
a THX pm3 Certified Studio.
5. Following certification, certification measures are performed at yearly intervals, and monitor response
is re-adjusted if necessary. This ensures that a monitoring environment in compliance with the
regulations is maintained.