Harman JBL MS-15SD2 - Manual (Page 2)

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Thank you for purchasing an MS Series subwoofer. Subwoofer
installation requires woodworking skills and some experience in
disassembling and reassembling automotive interiors. If you lack
the tools or necessary skills, have your subwoofer installed by an
authorized JBL ® dealer.
warning: Playing loud music in an automobile can permanently
damage your hearing as well as hinder your ability to hear traffic. We
recommend listening at low levels while driving. We accept no liability
for hearing loss, bodily injury or property damage resulting from use or
misuse of this product.
CHOOSING AN ENCLOSURE
MS Series subwoofers are optimized to perform best in small, sealed
and vented enclosures. While infinite-baffle mounting of MS subwoofers
is possible, power handling will be greatly compromised because there
will be no enclosed volume of air to prevent the speaker’s cone from
moving past its limit. For this reason, we do not recommend infinite-
baffle mounting for MS subwoofers.
You should choose the enclosure you will use based on the type of
music you listen to, how much amplifier power you will use for the
subwoofer and how much space inside the vehicle you can devote to
a subwoofer enclosure.
Because a sealed enclosure provides the most control over the
woofer’s movement, a woofer mounted in a sealed enclosure will
handle more power than a woofer mounted in another enclosure
type. Sealed enclosures provide more accurate sonic reproduction
than other enclosure types when mounted inside a vehicle, so they
are well suited to all types of music. Sealed-enclosure construction is
straightforward, and there are many prefabricated sealed enclosures
available. An optimum sealed enclosure is always smaller than other
types of enclosures optimized for a particular speaker, so they require
the smallest amount of space inside the vehicle.
Vented enclosures provide better efficiency in the 40Hz – 50Hz range,
but this efficiency comes at the expense of sound in the lowest octave
(below 40Hz) and at the expense of some control and power handling
at the lowest frequencies. If you are using a small amplifier, a vented
box will provide more perceived bass output from less power. Vented
enclosures are also well suited to a variety of music types. Because
vented enclosures require the volume of the enclosure and the size
of the port to have a specific relationship with the characteristics of
the woofer, the enclosure must be built exactly to the specifications
provided. While there are some prefabricated vented boxes available,
matching a prefabricated box to a particular woofer is difficult. If you
wish to use a vented enclosure, we strongly recommend having your
authorized JBL dealer build it or verify that your design is correct if you
wish to build it yourself. An optimum vented enclosure is always larger
than the optimum sealed box for the same woofer and will require more
space inside the vehicle.
CONNECTING YOUR SUBWOOFER TO YOUR
AMPLIFIER
JBL MS Series subwoofers are available in two different configurations:
a dual two-ohm voice coil or dual four-ohm voice coils. You may
use MS subwoofers in singles or multiples to maximize the power
available from your amplifier(s). To achieve the maximum amplifier
output possible, you should design a speaker system that provides the
lowest impedance that your amplifier will drive safely. When designing a
subwoofer system, consider the following rules:
Do not mix different subwoofers or enclosure types in the same 1.
system. Subwoofers being used in the same enclosure or powered
by the same amplifier should be identical models. Mismatched
woofers and enclosures can result in poor performance from your
subwoofer system.