How Many Subwoofers - Niles Subwoofer PSW800 Installation & Operation Manual

How Many Subwoofers?

For most applications a single PSW800's is
appropriate. However, in large rooms, high
performance listening rooms or in home
theaters, an array of two or more PSW800
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 PSW800s 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 in volume
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
1 Sub 95dB
2 Subs 100dB
VLSA of 4 Subs 103dB
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 PSW800 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 settings of the switch-
es on the front panel. A single stereo sub-
woofer is compatible with any 4 ohm stable
amplifier. Eight ohm stable amplifiers may
be used with a Niles IM volume control (see
Impedance section on Page 7)
Dual Subwoofer Systems
Using two PSW800 subwoofers in a sys-
tem raises the maximum attainable volume
of the system by 3dB. Additionally, at
lower volumes, excursion — and therefore
distortion 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 PSW800 paralleled.
This requires a multi-channel amplifier or
an amplifier capable of driving the 2 to 2.6
ohm load of the overall system.
VLSA Installations
A Very Large Subwoofer Array (VLSA)
installation lowers the amount of excur-
sion required to achieve a high sound
100
Watts
pressure level. Lowering excursion dra-
101dB
matically improves the quality of the
106dB
sound. VLSA installations are most appro-
109dB
priate when the listener appreciates detail
and bass extension, but must have a con-
cealed installation. A VLSA of four sub-
woofers must have a multi-channel ampli-
fier with one channel assigned to each
subwoofer. (See Figure 7).
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