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User's Manual
5
Your Sunfire Subwoofer is designed to
give you the best possible low-frequency
sound quality for your home theater
experience. It incorporates a tremen-
dously powerful built-in amplifier and a
pair of drivers to produce tight, floor-
rumbling bass down to 18 Hz, that you
can feel as well as hear.
The subwoofer has an adjustable high
cut filter and a choice of speaker-level or
line-level inputs for easy incorporation
into existing systems, or as part of a
subwoofer/satellite speaker combination.
The Woofer
To have lots of bass requires moving
lots of air. Your Sunfire Subwoofer
incorporates two drivers that can move
back and forth approximately five times
more than a normal subwoofer. This
gives it a lot of air moving capacity
which allows for majestic bass perfor-
mance.
Two drivers share the acoustic output.
Sometimes one driver appears to be
moving more than the other. They both
move the same amount only when
operating at the limit of their excursion
and power output, or when bass
requirements and music requirements
demand maximum output from the
system. Otherwise, the power is shared
between the two drivers in a way that
depends on the momentary amplitude
and the momentary musical spectrum. It
is normal for one or the other to move
more or less than its mate during
operation.
On the driver to the left of the control
panel there is a slight bump, under
which is a pressure cap. The bump is
normal. The driver on the right is
absolutely flat and very rugged. The one
with the slight bump is not quite as
rugged, and modest care should be
taken with it, though it is still very strong.
During installation, you should position
the driver with the bump towards a
protected side.
The Amplifier
The large movement range of the
drivers creates greater air pressure
inside the box than a conventional
woofer. Therefore, the drive amplifier
must be much more powerful than an
ordinary woofer amplifier. In fact, it has
to be so powerful that it is almost hard to
believe.
The power amplifier within your Sunfire
Subwoofer is capable of delivering over
2,700 watts into a 3.3 ohm resistor (the
voice coil resistance of the subwoofer’s
driver). When the same full output is
applied to the driver, however, the
enormous back-electromotive force
generated as a consequence of its large
motion and giant magnet causes the
current flow to be much less than if it
were a 3.3 ohm resistor. It is this singular
property of the driver that allows the
woofer to be approximately ten times
more efficient than a woofer this size
would normally be. Hence, the actual
average input power is substantially less
than 2,700 watts, and is approximately
270 watts for most musical material on
the loudest passages.
A compressor circuit kicks in automati-
cally if the input signal level reaches a
level that would overload the driver. This
maintains a ceiling on the output without
clipping.
If the input signal is driven even
further, a ‘soft clipping’ circuit is enabled.
This allows the woofer to put more sound
into the room to satiate the power hungry
user, but without distortion or damage to
the woofer. Thus, for explosive scenes in
movies, this produces extremely high
sound pressure levels (SPL) in your
room without the woofer banging against
its mechanical stops.
If you would like more detailed
information regarding the subwoofer
design, please call us and we will send
you a copy of our subwoofer technical
white paper, or you can view it on our
website: www.sunfire.com.
Overview