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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6. Measurement and adjustment
In two-channel playback, placing the L and R speakers at the left and right of the listening point and
playing them back at the same power will allow both L and R to be received at the same power and the
same timing. However for multi-channel playback, simply powering all speakers equally is not usually
enough to ensure that all channels including LFE are received at the appropriate level balance and the
same timing.
This means that in most cases, a process of measurement and adjustment is required when setting up a
multi-channel listening environment.
To measure the monitor response and make adjustments, we need pink noise as a source signal, and a
sound level meter to measure the playback sound pressure level of the speakers.
In addition, a 1/3 octave analyzer (RTA; Real-Time Analyzer) is usually necessary when making the
actual measurements..
[Fig. 48] Measurement and tuning for DVD-Video
6-1. Test signal
Broad-band pink noise of (20 Hz) - 20 kHz is used as the signal for measurement.
The level (dBrms) of pink noise used as the sound source shall be the reference for the headroom setting
(0 VU) of the studio. In other words, -20 dBrms pink noise is used for a studio in which the headroom is
set at 20 dB, and -18 dBrms pink noise is used for a studio in which the headroom is set to 18 dB.
Pink noise changes significantly in amplitude, and it is difficult to determine its input level by using the
level meters of the console. (In the case of -20 dBrms pink noise, there will be intensive change in the
region of approximate -14 dBFS.)
For this reason, it is necessary that the actual value of the pink noise used for detection be known
beforehand.
If -20 dBrms pink noise is to be used for a studio in which the headroom is set to 18 dB, the playback
level from each speaker must be adjusted so that it is 2 dB (20 dBrms - 18 dBrms) lower than the target
level.
RTA
SPL meter
Pinknoise
(-14)
…
70
80
MAIN
LFE
85dBC
20 80 12512.5 31.5 50 10k 20k
Band level [dB]
1/3oct. band center frequency [Hz]
Pinknoise
-20dBrms
(-20dB=0VU)
Mixing Console
LPF
+10dB
95dBC
(89dBC)
To
Recorder
LFEMAIN
dB
LFEMAIN
LFE
MAIN
0
〜
1.5dB
VU