
GTO3501 CAR AUDIO SUBWOOFER AMPLIFIER OWNER’S MANUAL
Factory Bolt Ring Connector
Ground Wire
Note: Remove any paint 
below ring connector.
Star Washer
Installation Warnings and Tips:
• Disconnect the negative (–) lead from your vehicle’s 
battery.
• At the installation sites, locate and make a note of 
all fuel lines, hydraulic brake lines, vacuum lines 
and electrical wiring. Use extreme caution when 
cutting or drilling in and around these areas.
• Choose a safe mounting location away from moisture. 
• Make sure there is sufficient air circulation at the
mounting location for the amplifier to cool itself.
• Mount the amplifier, using the supplied hardware.
Specifications
<
• 225W RMS x 1 channel @ 4 ohms and 
1% THD + N*
• 360W RMS x 1 channel @ 2 ohms, 14.4V supply and 
<
1% THD + N*
• Frequency response: 20Hz – 330Hz (–3dB)
• Maximum input signal: 6V*
• Maximum sensitivity: 100mV*
• THD + N: 0.04%
• Signal-to-noise ratio: 85dBA 
(reference 1W into 4 ohms)*
• Signal-to-noise ratio: 104dBA 
(reference rated power into 4 ohms)
* CEA-2006A-compliant
Speaker Output Connectors
• Connect the subwoofer to these terminals, 
observing proper polarity
. Either + or – 
terminal may be used. Minimum total 
impedance is 2 ohms.
Fuses
• Replace only with the same type and rating.
Power Input Connectors 
• +12V: Connect to the positive terminal of the 
vehicle’s battery. 8 AWG wire is recommended. 
Install an appropriate fuse holder and fuse (60A 
minimum) within 18 inches of the battery. Make 
sure the wire is not damaged or pinched during 
installation. Install protective grommets when 
routing wires through the firewall or other sheet 
metal. 
• GND: Connect to the vehicle’s chassis. Refer to 
the picture below. 
DBO (Dynamic Bass Optimization) Variable 
Subsonic High-Pass Filter With V
• For woofers in tuned (vented) enclosures, set 
the Frequency control to a value 10Hz below the 
enclosure’s resonance (tuned) frequency.
• For woofers in sealed boxes, set the control to 
any value you prefer between 30Hz and 50Hz.
• Set the Boost control according to your 
preference, being careful not to apply 
enough boost to damage your woofer(s).
A DBO High-Pass Filter Frequency control,
B DBO Boost control provides up to 
Optional Remote Level Control (RLC) Connector 
• Connect the Remote Level Control (RLC) here, 
using the RJ-11 cable (Supplied with the RLC). 
Power On LED
• Illuminated when the amplifier is on.
Protect LED
• Illuminated under any of the following fault 
conditions: battery over/under voltage, short 
circuit in speaker wires, amplifier is too hot, 
amplifier’ 
is present in the amplifier’s output).
• REM: Connect to the “Remote Out” lead from 
the source unit or to a source of switched 
12V+ (ACC).
Aux Output Connectors (RCA)
• Nonfiltered pass-through output. Connect to the 
input of an additional amplifier. 
Input Connectors (RCA)
• Connect to the RCA outputs from the source unit 
or signal processor.
Input-Level Control
• Used to match the input level of the amplifier 
to the output level of the source unit. 
for the adjustment procedure.
• See 
Low-Pass Filter Frequency Control
• 12dB/octave low-pass filter, 
variable from 32Hz to 320Hz.
• See 
for the adjustment procedure.
Setting Input Level
A Turn Input Level control counterclockwise to
6V (minimim).
B With a dynamic music track playing, turn the
head unit’s volume control to the 3/4 position.
C Turn Input Level control clockwise until the
bass output is proportionate to the output of 
the high-frequency speakers, according to 
your preference.
D Input level is now adjusted correctly.
Setting the Crossover
A Crossover setting for subwoofers.
Note: Acceptable frequency ranges are indicated 
in gray
Remote Level Control (Optional)
The Remote Level Control, if installed, will allow 
you to adjust the level of bass while seated in the 
listening position.
ariable Boost (Q)
variable between 10Hz and 100Hz. See 
above for appropriate settings. 
12dB of boost slightly above the highpass filter’s frequency. See above for 
appropriate settings.
s output circuit has failed (DC voltage
.
This product is designed for mobile applications and is not 
intended for connection to the mains.
A valid serial number is required for warranty coverage. 
Features, specifications and appearance are subject to change
without notice.

www.jbl.com
Harman International, Consumer Division 
8500 Balboa Boulevard, Northridge, CA 91329 USA 
www.jbl.com
© 2009 Harman International Industries, Incorporated. All rights reserved. 
JBL is a trademark of Harman International Industries, Incorporated, 
registered in the United States and/or other countries. 
Part No. GTO3501OM 3/08
Declaration of Conformity
We, Harman Consumer Group, Inc.
2, route de Tours 
72500 Château du Loir 
France
declare in own responsibility that the product described in this owner’s 
manual is in compliance with technical standards: 
EN 55013:2001+A1:2003 
EN 55020:2002+A1:2003
Klaus Lebherz
Harman Consumer Group, Inc.
Château du Loir, France 3/08