™
GT SERIES
Automotive Subwoofers Owner’s Manual GT100 GT100D GT120 GT120D GT150 GT150D
Connecting Your Subwoofer to Your Amplifier JBL GT Series
Figure 1. Parallel connection
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:
JBL GT Series subwoofers
2. You may connect the coils of a
dual-voice coil woofer in series,
but we recommend that you
avoid connecting separate
are available in two different
configurations: as a single 4-ohm
voice coil or as dual 4-ohm voice
coils. Depending on the amplifiers
you are using, you may use either
single-voice coil or dual-voice coil
subwoofers in singles or multiples
to maximize the power available
from your amplifiers. To achieve
the maximum amplifier output
possible, 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:
1. Don’t mix different subwoofer
or enclosure types in the same
system (use all single-coil
BLACK
RED
STRIPE
NEG ( – )
STRIPE
POS ( + )
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. You must use both coils of a
dual-voice coil woofer connected
either in series or in parallel.
4. Most amplifiers deliver exactly
the same amount of power
bridged into a 4-ohm load
POS ( + )
NEG ( – )
1
1
w2
Impedance=
1
w1
1
w3
. . .
Figure 2. Series connection
+
+
BLACK
RED
STRIPE
NEG ( – )
STRIPE
POS ( + )
where w is the nominal
impedance of the woofer.
2. The total system impedance
of voice coils (or woofers) in
series can be calculated using
the formula:
POS ( + )
NEG ( – )
Impedance = w1 + w2 + w3 . . .
The diagrams at right show parallel
and series speaker connections.
woofers or all dual-coil woofers).
as they do running a 2-ohm
stereo load.
03
Specifications JBL GT Series
GT100
GT100D
10" Dual-voice coil
GT120
12" Automotive
GT120D
12" Dual-voice coil
automotive subwoofer subwoofer
GT150
15" Automotive
GT150D
15" Dual-voice coil
automotive subwoofer
10" Automotive
subwoofer
automotive subwoofer subwoofer
Power handling (RMS) 250 Watts
Power handling (Peak) 1000 Watts
250 Watts
250 Watts
250 Watts
250 Watts
250 Watts
1000 Watts
1000 Watts
1000 Watts
1000 Watts
1000 Watts
Sensitivity (2.83V/1m)
Frequency response
90dB
90dB
93dB
93dB
95dB
95dB
28Hz – 500Hz
28Hz – 500Hz
23Hz – 450Hz
23Hz – 450Hz
20Hz – 400Hz
20Hz – 400Hz
Impedance
4 Ohms
Dual 4-ohm voice coils 4 Ohms
Dual 4-ohm voice coils 4 Ohms
Dual 4-ohm voice coils
6-3/4" (172mm)
Mounting depth
Cut-out diameter
5-3/4" (147mm)
9-1/8" (232mm)
5-3/4" (147mm)
9-1/8" (232mm)
6-1/4" (159mm)
11-1/8" (283mm)
6-1/4" (159mm)
11-1/8" (283mm)
6-3/4" (172mm)
14-1/4" (362mm)
14-1/4" (362mm)
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
Features, specifications and appearance are subject to change without notice.
declare in own responsibility, that the products described in this owner’s manual are in
compliance with technical standards:
©2002 JBL, Incorporated • JBL is a registered trademark of JBL, Incorporated
Part No. GTSUBSEROM
EN 50081-1:1992
EN 50082-1:1997
Emmanuel Millot
Harman Consumer International
Chateau-du-Loir, FRANCE. 7/02
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