GTi SERIES
W10GTi MkII
W12GTi MkII
W15GTi MkII
automotive subwoofer owner’s manual
THANK YOU
for choosing a JBL® GTi Series subwoofer. GTi subwoofers are designed to
provide maximum sound output in a variety of enclosure types while maintaining the superb sound quality associated with JBL. To ensure the best subwoofer performance, we strongly
recommend that installation be entrusted to a qualified professional. Although these instructions explain how to install a GTi Series subwoofer in
a general sense, they don’t show the specific installation procedures that may be required for your particular vehicle. If you feel you don’t have the necessary tools or experience, don’t attempt the installation yourself; rather, ask your authorized JBL dealer about professional-installation options.
INSTALLATION WARNINGS AND TIPS
WARNING |
YOUR CAR AND BASS |
POWER-HANDLING |
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Playing loud music in an automobile can |
REPRODUCTION |
LIMITATIONS |
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hinder your ability to hear traffic, as well |
Depending on the size of the vehicle’s |
The power-handling capacity of any |
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as permanently damage your hearing. |
interior listening space, reproduced |
subwoofer is related to the excursion |
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We recommend listening at low levels |
frequencies below 80Hz may be boosted |
limit of its suspension and its ability to |
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while driving. JBL accepts no liability for |
by nearly 12dB per octave as frequency |
dissipate heat. A speaker reaches its |
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hearing loss, bodily injury or property |
decreases. This effect, commonly known |
excursion-limited power-handling |
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damage resulting from use or misuse of |
as transfer function, or cabin gain, plays |
capacity when its suspension is |
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this product. |
an important role in defining the in-car |
stretched to its limit. The excursion |
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frequency response of your subwoofer. |
curve shown on the Enclosure Design |
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It is displayed graphically, along with |
Sheet (included with your woofer) |
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freespace response, on the enclosed |
displays cone excursion at the input |
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data sheet for your GTi subwoofer. |
power level required to drive the woofer |
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to maximum linear excursion (Xmax). |
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The input power shown may be used |
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as instantaneous input only. |
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Thermal power handling is determined by the amount of heat that may be dissipated by the driver’s voice coil. The power-handling rating assigned to your GTi Series subwoofer is its thermal-power-handling rating. This rating assumes a clean (unclipped) signal. A clipped waveform has much
higher average power, due to the longer duty cycle at the top and bottom of the waveform; it will heat the woofer’s voice coil faster than a clean signal and may damage the voice coil. A square wave has a 100% duty cycle and is extremely dangerous for any speaker. Audible distortion in the output of your woofer is an indication that your amplifier may be clipping, which could damage your speakers over time.
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CHOOSING AN ENCLOSURE
GTi Series subwoofers are optimized to perform best in small sealed, vented and bandpass enclosures. While infinitebaffle mounting of GTi Series subs is possible, power handling will be compromised since there will be no enclosed volume of air to help the speaker’s suspension control the motion of the woofer’s cone. For this reason, we do not recommend infinite-baffle mounting for high-power applications. You should choose the enclosure you’ll use based on the type of music you listen to, how much amplifier power you’ll use to drive the subwoofer, and how much space inside the vehicle you can devote to a subwoofer enclosure. If you’ll be using your GTi Series subwoofer for SPL competition, please see the document titled “GTi as SPL Competition Subwoofers” (included with your woofer).
Because a sealed enclosure provides the most control over the woofer’s movement, a woofer mounted in a sealed enclosure will handle more power at low frequencies than a woofer mounted in another enclosure type. Sealed enclosures provide more accurate sonic reproduction than other enclosure types, so they are
well suited to all types of music. Sealed-enclosure construction is straightforward. An optimum sealed enclosure is always smaller than other types of enclosures that are optimized for a particular speaker, so they require the least space inside the vehicle.
Vented enclosures provide better |
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efficiency in the 40Hz – 60Hz range, |
the |
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but this efficiency comes at the expense |
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of sound output in the lowest octave |
at |
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(below 40Hz) and at the expense of |
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some control and power handling below |
what |
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box tuning. If you are using a small |
or |
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amplifier, a vented box will provide |
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more bass output from less power. |
aid |
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Vented enclosures are also well suited |
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to a variety of music types. Because |
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vented enclosures require the volume |
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of the enclosure and the size of the |
must |
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port to have a specific relationship with |
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the characteristics of the woofer, the |
quite |
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enclosure must be built exactly to the |
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specifications provided. If you wish to |
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use a vented enclosure, we strongly |
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recommend having your authorized JBL |
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dealer build it; or verify that your design |
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is correct if you wish to build it yourself. |
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An optimum vented enclosure is always |
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larger than the optimum sealed box for |
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the same woofer, and will require more |
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space inside the vehicle. |
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