Automotive Subwoofers Owner’s Manual P1040 P1042 P1240 P1242
Connecting Your Subwoofer to Your Amplifier JBL Pro Power GTp Series
Figure 2. Series 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 = 1/(1/w1 +
1/w2 + 1/w3...), where w is the
nominal impedance of the
woofer.
JBL GTp subwoofers are available
in two different configurations:
single 4-ohm voice coil and dual
4-ohm voice coils. Depending on
the amplifier 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
amplifier. 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:
2. You may connect the coils of a
dual-voice-coil woofer in series,
but NEVER connect separate
woofers in series. Because 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, 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
BLACK
RED
STRIPE
NEG ( – )
STRIPE
POS ( + )
POS ( + )
NEG ( – )
2. The total system impedance
of voice coils (or woofers) in
series = w1 + w2 + w3...
The diagrams below and at right
show parallel and series speaker
connections.
Figure 1. Parallel connection
1. Don’t mix different subwoofer
or enclosure types in the same
system (use all single-coil
BLACK
RED
STRIPE
NEG ( – )
STRIPE
POS ( + )
woofers or all dual-coil woofers).
POS ( + )
NEG ( – )
as they do running a 2-ohm
stereo load.
03
Specifications JBL Pro Power GTp Series
P1040
P1042
P1240
P1242
10" Automotive subwoofer
10" Automotive subwoofer,
dual voice coil
12" Automotive subwoofer
12" Automotive subwoofer,
dual voice coil
Power handling (peak)
Power handling (RMS)
1400 Watts
350 Watts
1400 Watts
350 Watts
1400 Watts
350 Watts
1400 Watts
350 Watts
Sensitivity (2.83V/1m)
Frequency response
92dB
92dB
93dB
93dB
20Hz – 500Hz
20Hz – 500Hz
18Hz – 500Hz
18Hz – 500Hz
Impedance
4 Ohms
2 or 8 Ohms
4 Ohms
2 or 8 Ohms
Mounting depth
Cut-out diameter
5-1/8" (131mm)
9-1/8" (232mm)
5-1/8" (131mm)
9-1/8" (232mm)
5-11/16" (145mm)
11-1/8" (283mm)
5-11/16" (145mm)
11-1/8" (283mm)
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
declare in own responsibility, that the products described in this owner’s manual are in
compliance with technical standards:
©2000 JBL, Incorporated • JBL is a registered trademark of JBL, Incorporated
EN 50081-1:1992
EN 50082-1:1992
Made in USA Printed in USA 3/00
Part No. P1040-42/P1240-42OM
Lutz Uphoff
Harman Consumer International
FRANCE. 2/00
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