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RADIOACTIVE SERIES
4-CHANNEL
AMPLIFIER
GZRA 4HD
• High-performance class D amplifier
• 2 ohms stable in stereo mode
• 4 ohms stable in bridged mode
• High-level input with auto-on feature
• Adjustable wide band active crossover
• Adjustable input sensitivity
• Turn-on delay
• Thermal protection circuit
Owner´s Manual
Features
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GROUND ZERO GZRA 4HD
RADIOACTIVE SERIES
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GROUND ZERO GZRA 4HD
RADIOACTIVE SERIES
Speaker wires
Power supply wires
Mounting instructions
• As a precaution, it is recommended to disconnect the vehicles battery before mounting the amplifier.
Note: For new vehicles, disconnecting the battery might cause various errors in your vehicle´s electric
system that can be cleared only by authorized service partners of your vehicle´s manufacturer! Please
ask your service partner first before disconnecting the battery!
• The power supply wire (+12 V) has to be protected within max. 20 cm / 8” by a main fuse holder with
a fuse value matching the recommendation for your amplifier
Note: If there is more than one amplifier connected using this power wire, the main fuse value must be
equal to the sum of the recommended fuses of all connected devices. However, make sure the
diameter of your power wire will be enough for the required current!
• If necessary, replace a defective fuse by a fuse with identical quality and value
• Never drill holes to the vehicle´s gas tank, brake lines, to wirings or any other important vehicle parts!
• Never pass wires over sharp edges or vehicle parts due avoid any kind of damage
• Keep the wiring away from the antenna and electronic devices contributing to radio reception
• Lay the power supply wiring always separated from speaker wiring to avoid disturbance
• The amplifier contains a temperature protection circuit that turns the device off in case of overheating.
After a certain cooling time, it will turn on automatically. To avoid heat build-up, enough air supply for
cooling must be provided. Never cover the surface of the amplifier´s heatsink entirely
• The amplifier should
enclosure. This might lead to malfunction due to loosened electrical parts inside the amplifier.
• Some amplifiers offer a high-level input option, however if a pre-amplified output (RCA) is available (at
the head unit), it is strongly recommended to make use of them.
NEVER be mounted onto a vibrating part or surface such as a subwoofer
The limited warranty for this product is covered by GROUND ZERO´s regional distribution partners and their
Terms of warranty
terms and conditions. For further information contact your local retailer or distributor.
Recommended wiring
min 2.5 mm² / 13 AWG
min 20 mm² / 4 AWG
GROUND ZERO products are engineered in Germany
GROUND ZERO – international sponsor
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GROUND ZERO GZRA 4HD
RADIOACTIVE SERIES
1
Power terminal
2
Fuse(s)
If necessary to replace a defective fuse, it´s strongly recommended to
use a fuse with identical value
3
Speaker terminal
4
Input mode switch
(RCA)
5
Line input (RCA)
never
6
High-level input
never
7
Sensitivity control
8
Low pass filter
To adjust the required crossover point. Frequencies above the selected
crossover point will be filtered (40 Hz to 4000 Hz) (CH 1/2 & CH 3/4)
9
High pass filter
To adjust the required crossover point. Frequencies below the selected
crossover point will be filtered (40 Hz to 4000 Hz) (CH 1/2 & CH 3/4)
10
Status indication
Controls & Features
+12V To be connected to the positive terminal of the battery
REM To be connected to the remote output of the head unit*
GND To be connected to the vehicle´s ground
To connect the speaker wires / min. 2 ohms stereo or 1 ohm bridged
To select between 4 channel or only 2 channel input mode according
to the quantity of RCA wires available from the head unit
Input sockets to connect RCA wires
Important note: High-level and RCA inputs should
simultaneously! This may cause serious damage to the amplifier
Head units without RCA pre-amplifier output signal can be connected
using the high-level input to connect the speaker output of the head
unit directly.
If used, the amplifier turns on automatically (auto-on feature)
The remote input of the power supply terminal remains unused
Important note: High-level and RCA inputs should
simultaneously! This may cause serious damage to the amplifier
Controller to adjust the input sensitivity (CH 1/2 & CH 3/4)
(*not required in high-level input mode)
(or directly to the negative terminal of the battery)
be used
be used
POWER (green) ok (correct operation)
PROTECT
(red) error (protection mode)
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GROUND ZERO GZRA 4HD
RADIOACTIVE SERIES
4-channel mode RCA input wiring
4-channel mode high-level input wiring
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GROUND ZERO GZRA 4HD
RADIOACTIVE SERIES
4-channel mode speaker wiring
2-channel mode (bridged) wiring
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GROUND ZERO GZRA 4HD
RADIOACTIVE SERIES
Model
GZRA 4HD
Amplifier type
RMS Power @ 4 Ω
CEA Standard CEA-2006-A
RMS Power @ 2 Ω
CEA Standard CEA-2006-A
RMS Power @ 4 Ω in bridged mode
CEA Standard CEA-2006-A
Low pass filter
High pass filter
Frequency response
Signal to noise ratio (SNR)
Total harmonic distortion (THD+N)
Damping factor
Input sensitivity
Fuse(s)
Recommended main fuse
Dimensions
w x h x l (heatsink / overall)
Dimensions
w x h x l (heatsink / overall)
Symptoms
Check / Cause
Action
Check protection fuse(s) of the amplifier (harness)
Check ground wire connection
Did the PROTECT LED turned to red?
Check for speaker short or amplifier overheating
Power supply of the amplifier?
Check power wire or connections
Remote wire powered? (RCA input
mode)
Speaker wiring undamaged?
Check for short circuit or open connections
Reverse left and right RCA inputs to check the
audio input signal
Device turns off at
volume
Temperature protection circuit active
Decrease head unit’s volume / wait for cooling
Speaker wires short / speaker
damaged
Specifications
4 channel class D
4x 175 W (1% TH D+N)
4x 275 W (1% TH D+N)
2x 550 W (1% T HD+N)
2x 700 W (10% THD+N)
40 Hz – 4000 Hz (12 dB/oct)
40 Hz – 4000 Hz (12 dB/oct)
10 Hz – 25 kHz
-102.3 dB
< 0.1%
> 200
200 mV – 5.3 V
3x 35 A
100 A
186 x 52 x 229/268 mm
7.32 x 2.05 x 9.02/10.55“
Trouble shooting guide
No audible sound
Does the POW LED turn to green?
Device does not
turn on
No sound on one
channel
medium / high
Input signal on each RCA lead?
Load impedance of each speaker
correct?
Status LED turned
on red
Check remote wire connection (RCA input mode)
Check +12 Volt power supply wire connection
Check remote wire connection to the head unit
Check if each speaker load impedance matches
the technical specifications of the amplifier
Check speaker / wires and insulate if necessary
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GROUND ZERO GZRA 4HD
RADIOACTIVE SERIES
Listening to music can be emotional, impressive, relaxing or enjoyable. At that, it doesn´t really
matter what kind of music is the personal favorite, whether it´s Instrumental, Jazz, Electro,
Latin, Classic, Rock or any other music direction. However, audio reproduction quality at each
desired volume is elementary. Some music styles require higher levels while others prefer the
soft tones.
GROUND ZERO considers all the different wishes of customers during the development of
new products. Along with this, the target is to create the most realistic sound, to transfer the
soul of the music and the intention of the performer. Summarized to one phrase: RESPECT THE
MUSIC!
Ground Zero GmbH
Erlenweg 25, 85658 Egmating, Germany
Tel. +49 (0)8095/873 830 Fax -8310
www.ground-zero-audio.com
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