How Many Subwoofers?
For most applications a single CM8SW is appropriate. However, in large rooms, high performance listening rooms or in home theaters, an array of two or more CM8SW will deliver astounding results. Unlike other subwoofer systems, a Niles Subwoofer Array is concealed. Consider the distance between the subwoofer(s) and the listener, the size of the amplifier and the desired quality and volume of sound when deciding how many CM8SWs to install in your home.
| Decibels and Power |
65dB | Conversation at three feet. |
75dB | Sewing Machine at three feet. |
85dB | Vacuum Cleaner at 10 feet. |
95dB | Subway Train entering a station |
| at 20 feet. |
3dB | The smallest difference of sound |
| the human ear can easily detect. |
10dB | Perceived as twice as much loud- |
| ness if it is an increase (half as |
| much if it is a decrease). |
Any speaker requires twice as much amplifier power to increase 3dB and ten times as much power to increase 10dB.
Comparison of 1, 2 or 4 Subwoofers
16’ x 18’ x 8’ Room @ 12’
| 25 Watts | 100 Watts |
1 Sub | 95dB | 101dB |
2 Subs | 100dB | 106dB |
VLSA of 4 Subs | 103dB | 109dB |
2 x Watts = 3dB Increase in Volume.
2 x Subs = 3dB Increase in Volume.
2 x Subs = 1/2 the subwoofer excursion for the same volume.
If you double the distance from the sub- woofer to the primary listening position you decrease the volume by 4 to 6dB.
Single Stereo Subwoofer
One CM8SW can produce the bass sound from both the left and the right channels because of its unique dual voice coil design. One voice coil powers the left chan- nel and the other powers the right channel. A stereo crossover divides the signal and fil- ters it according to the position of the switches on the front panel. A single stereo subwoofer is compatible with any 4 ohm stable amplifier. Eight ohm stable amplifiers may be used with a Niles IM volume con- trol (see Impedance section on Page 7)
Dual Subwoofer Systems
Using two CM8SW subwoofers in a system raises the maximum attainable volume of the system by 3dB. Additionally, at lower volumes, excursion — and therefore distor- tion levels — are reduced. In a large room, or a home theater system, the effect on bass quality is extremely desirable. Another 2dB increase is possible if the voice coils of each are CM8SW paralleled. This requires a
VLSA Installations
A Very Large Subwoofer Array (VLSA) installation lowers the amount of excursion required to achieve a high sound pressure level. Lowering excursion dramatically improves the quality of the sound. VLSA installations are most appropriate when the listener appreciates detail and bass exten- sion, but must have a concealed installa- tion. A VLSA of four subwoofers must have a multichannel amplifier with one channel assigned to each subwoofer.
How Many Subwoofers?
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