JBL GTO1220 User Manual

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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