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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3-6. SUB
When placing the sub-woofer, we must take the acoustics of the room into account.
For example, placing the sub-woofer in the corner of the room will produce good results in terms of
power, but may produce problems in the frequency response due to disruptions caused by standing waves.
[Fig. 29] shows an example of the measured relationship between the sub-woofer location in the listening
room and the frequency response [4]. It can be seen that the frequency response changes in various ways
depending on the location of the sub-woofer.
When placing the sub-woofer, we must consider both the playback power and the frequency response.
[Fig. 29] Placement of the subwoofer and Frequency responses : Measured examples
[3]
In some cases, placing two sub-woofers in appropriate locations can stabilize the playback environment.
[Fig. 30] shows an example[6] of calculations performed to simulate the differences in sound pressure
distribution between one sound source and two sound sources. You can see that playback using two sound
sources produces less variance of sound pressure distribution across the width (W-axis) of the room than a
case in which only one sound source is used. If two sub-woofers are placed across the width of the room
in this way, changes in sound pressure level will be mainly limited to the depth (D-axis) of the room. In
this case, design methods for conventional two-channel studios can easily be applied, such as applying
sufficient acoustical treatment to the rear wall. Using two sub-woofers placed across the front of the room
will also contribute to the quality of the playback by improving the connection between L/R when bass
management playback (discussed below) is used.
[Fig. 30] Low frequency response reproduced by the single source / the double source (80Hz) :
Examples of numerical calculations
[6]
The Yamaha DM2000, DM1000, and 02R96 digital consoles allow the phase of the sub-woofer output
to be reversed, making it possible to manage the phase of the sub-woofer appropriately for the
placement location.
60
65
70
75
80
85
16
20
25
31.5
40
50
63
80
100
125
160
200
250
1/3oct. band frequency [Hz]
Relative SPL [dB]
P2
P4
P1
P3
6.7m
7.6m
6.4m
6.2m
P4
P3
P1
P2
Measured position
Sub-woofer
Frequency responses
Room plan
D = 7m
W = 5m
1.3m
1.3m
D = 7m
W = 5m
1.3m
1.3m
1.2m
Single source (80Hz)
Double source (80Hz)