™
GTO SERIES
Automotive Subwoofers Owner’s Manual GTO1020 GTO1020D GTO1220 GTO1220D
Connecting Your Subwoofer to Your Amplifier JBL GTO 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 GTO Series subwoofers
are available in two different
configurations: as a single 2-ohm
voice coil or as dual 2-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
2. You may connect the coils of a
dual-voice coil woofer in series,
but we recommend that you
avoid connecting separate
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 GTO Series
GTO1020
GTO1020D
GTO1220
GTO1220D
10" Automotive
subwoofer
10" Automotive subwoofer,
dual-voice coil
12" Automotive
subwoofer
12" Automotive subwoofer,
dual-voice coil
Power handling (RMS)
Power handling (Peak)
300 Watts
300 Watts
300 Watts
300 Watts
1200 Watts
1200 Watts
1200 Watts
1200 Watts
Sensitivity (2.83V/1m)
Frequency response
89dB
92dB
91dB
94dB
25Hz – 500Hz
25Hz – 500Hz
20Hz – 450Hz
20Hz – 450Hz
Impedance
2 Ohms
Dual 2 Ohms
2 Ohms
Dual 2 Ohms
Mounting depth
Cut-out diameter
6-1/16" (154mm)
9" (229mm)
6-1/16" (154mm)
9" (229mm)
6-13/16" (174mm)
10-7/8" (277mm)
6-13/16" (174mm)
10-7/8" (277mm)
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:
©2002 JBL, Incorporated • JBL is a registered trademark of JBL, Incorporated
Part No. GTO1020-D/GTO1220-DOM
EN 50081-1:1992
EN 50082-1:1997
Emmanuel Millot
Harman Consumer International
FRANCE. 2/02
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