™
GT4 SERIES
Owner’s Manual
Einbauanleitung
Guide d’utilisation
Manual del propietario
Gebruikershandleiding
Manuale utente
Bruksanvisning
Omistajan käsikirja
Manual do utilizador
Automotive Subwoofers Owner’s Manual GT4-10 GT4-12 GT4-15
Connecting Your Subwoofer to Your Amplifier JBL GT4 Series
Figure 1. Parallel connection
JBL GT4 Series subwoofers are
single 4-ohm voice coil. Depending
on the amplifiers you are using, you
may want to use either one or sev-
eral subwoofers in the same enclo-
sure to maximize the power avail-
able from your amplifiers. To achieve
the maximum amplifier output possi-
ble, you should design a speaker
system that provides the lowest
impedance that your amplifier is
rated to drive safely. When designing
a subwoofer system, consider the
following rules:
2. We recommend that you avoid
connecting separate woofers in
series. The amplifier-damping
factor (the amplifier’s ability to
control the motion of the woofer)
is expressed as a ratio of terminal
impedance (the sum of speaker
impedance, wire resistance and
the D.C. resistance of any
crossover coil connected to the
woofer) to amplifier-output
impedance. Therefore, connecting
separate woofers in series
reduces the damping factor of
the amplifier to a value less
than 1. This will result in poor
transient response.
3. Most amplifiers deliver exactly the
same amount of power bridged
into a 4-ohm load as they do
running a 2-ohm stereo load.
To design a subwoofer system
that maximizes available amplifier
power, keep the following rules
in mind:
1. The total system impedance
of woofers in parallel can be
calculated using the formula:
BLACK
RED
STRIPE
NEG ( – )
STRIPE
POS ( + )
POS ( + )
NEG ( – )
1
Impedance=
1
1
1
. . .
Figure 2. Series connection
+
+
w1
w2
w3
BLACK
RED
where w is the nominal
impedance of the woofer.
2. The total system impedance
of woofers in series can be calcu-
lated using the formula:
STRIPE
NEG ( – )
STRIPE
POS ( + )
POS ( + )
1. Don’t mix different subwoofer
or enclosure types in the same
system.
NEG ( – )
Impedance = w1 + w2 + w3 . . .
The diagrams at right show parallel
and series speaker connections.
2
Specifications JBL GT4 Series
GT4-10
GT4-12
GT4-15
10" Automotive
subwoofer
12" Automotive
subwoofer
15" Automotive
subwoofer
Power handling (RMS)
Power handling (Peak)
250 Watts
250 Watts
250 Watts
1000 Watts
1000 Watts
1000 Watts
Sensitivity (2.83V/1m)
Frequency response
90dB
93dB
91dB
28Hz – 500Hz
23Hz – 450Hz
20Hz – 400Hz
Impedance
4 Ohms
147mm
232mm
4 Ohms
159mm
283mm
4 Ohms
172mm
362mm
Mounting depth
Cut-out diameter
Features, specifications and appearance are subject to change without notice.
Declaration of Conformity
We, Harman Consumer International
2, route de Tours
72500 Chateau-du-Loir
FRANCE
JBL Consumer Products • 250 Crossways Park Drive, Woodbury, NY 11797
Europe: 2, route de Tours. 72500 Chateau-du-Loir
declare in own responsibility, that the products described in this owner’s manual are in
compliance with technical standards:
©2003 JBL, Incorporated • JBL is a registered trademark of JBL, Incorporated
Part No. GT4SUBSEROM
EN 50081-1:1992
EN 50082-1:1997
Emmanuel Millot
Harman Consumer International
Chateau-du-Loir, FRANCE. 2/03
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