GZRA 4HD - Receiver Ground Zero - Free user manual and instructions

Product Type	4-Channel Class D Amplifier
Brand	Ground Zero
Model	GZRA 4HD
RMS Power @ 4Ω (CEA-2006A)	4 x 175 W (1% THD+N)
RMS Power @ 2Ω (CEA-2006A)	4 x 275 W (1% THD+N)
RMS Power @ 4Ω Bridged (CEA-2006A)	2 x 550 W (1% THD+N) / 2 x 700 W (10% THD+N)
Frequency Response	10 Hz – 25 kHz
Signal-to-Noise Ratio (SNR)	-102.3 dB
Total Harmonic Distortion (THD+N)	< 0.1%
Damping Factor	> 200
Input Sensitivity	200 mV – 5.3 V
Low Pass Filter	40 Hz – 4000 Hz (12 dB/oct)
High Pass Filter	40 Hz – 4000 Hz (12 dB/oct)
Stable Impedance (Stereo)	2 Ω per channel
Stable Impedance (Bridged)	4 Ω per channel
Power Supply Voltage	12 V DC (negative ground)
Fuse Rating	3 x 35 A
Recommended Main Fuse	100 A
Dimensions (H x W x D)	52 x 186 x 268 mm (overall) / 2.05 x 7.32 x 10.55"
Input Options	RCA (pre-amp) and High-Level (speaker-level) with auto-on
Protection Features	Thermal protection, short circuit protection, turn-on delay
Status Indicators	Power (green) / Protect (red)
Safety	Disconnect battery before installation; keep away from children; hearing damage risk above 85 dB
Maintenance	Clean with dry cloth; ensure ventilation; replace fuses with identical type/value

Frequently Asked Questions - GZRA 4HD Ground Zero

How do I connect the amplifier using high-level (speaker) inputs?

Connect the speaker output wires from your head unit to the high-level input plug of the amplifier. The amplifier will turn on automatically (auto-on feature). Do not use RCA and high-level inputs simultaneously.

What does the red PROTECT LED mean?

The red PROTECT LED indicates a problem: either the amplifier is overheating, or there is a short circuit on the speaker outputs. Turn off the system, check speaker wiring, and allow the amplifier to cool down before restarting.

Can I run the amplifier at 2 ohms per channel?

Yes, the GZRA 4HD is stable at 2 ohms in stereo mode. It delivers 4x275W RMS at 2 ohms (1% THD+N). For bridged operation, minimum impedance is 4 ohms.

How do I set the crossover filters?

Use the Low Pass and High Pass controls (40-4000 Hz, 12 dB/oct) on the amplifier. For subwoofers, use low pass; for full-range speakers, use high pass. Adjust according to your system's requirements.

What wire gauge should I use for power and ground?

The recommended power wire size is minimum 20 mm² (4 AWG). Speaker wires should be at least 2.5 mm² (13 AWG). Use high-quality copper wire.

How do I bridge two channels?

Connect the positive speaker wire to the positive terminal of one channel, and the negative wire to the negative terminal of the adjacent channel (e.g., CH1+ and CH2- for front pair). Ensure the amplifier is in 2-channel input mode if using 2 RCA inputs.

Why does the amplifier turn off at high volume?

This is typically due to overheating or low impedance. Check that the speaker load is not below 2 ohms per channel (4 ohms bridged). Ensure proper ventilation and reduce volume to let it cool.

What is the auto-on feature and how does it work?

When using high-level inputs, the amplifier detects the speaker signal and turns on automatically. No remote wire is needed. It only works with high-level input; for RCA inputs, you must connect the REM terminal.

How do I replace a blown fuse?

Use only fuses of identical type and rating: 35 A blade fuses. Replace all three if one blows, and check for underlying issues (e.g., short circuit). The main fuse (recommended 100 A) should also be checked.

What is the warranty period for this amplifier?

The warranty is provided by Ground Zero's regional distributors. Terms vary by country. Contact your local retailer or distributor for details. Keep your purchase receipt.

USER MANUAL GZRA 4HD Ground Zero

european mobile media association

www.ground-zero-audio.com

RADIOACTIVE SERIES

4-Channel Amplifier

GZRA 4HD

Owner's manual

(AWV2.0

Main Features

• 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

Thank you for choosing a great GROUND ZERO product! We hope you will enjoy this product from the IRIDIUM series. This owner's manual contains information you need to use this product. Please read it carefully in order to achieve the best possible result. Your car audio specialist or our customer support will answer further questions about the product and its use.

Subwoofers are an important part of your car audio system. Please keep in mind, however, that they can only achieve their full performance if all other components of the entire system are carefully coordinated with one another. It is therefore recommended consulting a car audio specialist dealer or workshop for the assembly of the system and its installation and sound adjustments.

RADIOACTIVE Serie – Advanced Dynamics

The RADIOACTIVE series contains a wide range of exceptional high-efficient loudspeakers and high-power subwoofers for daily use and SPL purpose. GROUND ZERO focused on overall natural and dynamical audio reproduction of each kind of music during the development of every single product. Compact but still powerful amplifiers class D amplifiers complete the line-up.

Terms of warranty

The limited warranty for this product is covered by GROUND ZERO's regional distribution partners and their terms and conditions. For further information contact your local retailer or distributor.

Safety instructions

Safety instructions: Keep all parts of the content and the packaging away from children and pets to avoid accidents and the risk of suffocation. Permanently extreme levels of over 85 dB can lead to irreparable damage to the hearing. Music systems with high amplifier output power can reach levels of 130 dB or more. Extreme levels can also hinder the perception of important traffic noises and distract from what is happening on the road. Ground Zero GmbH and its sales partners expressly assume no responsibility for hearing damage, physical damage or any damage to property or consequential damage resulting from improper or careless use or improper installation of its products. In particular, any claims are forfeited through the use under competitive conditions.

Manufacturer's declaration: Hereby, Ground Zero GmbH declares that this product conforms to the rules of the following EU directives (including all applicable changes): 2011/65 / EU RoHS2 and 2001/95 / EC directive on general product safety.

The full text of the EU declaration of conformity is available at www.ground-zero-audio.com.

Loudspeakers contain magnetized metals and some valuable raw materials and must not be disposed of with normal household waste. Please leave defective or no longer required

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 to 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 NEVER be mounted onto a vibrating part or surface such as a subwoofer 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 it.

Recommended wiring

Speaker wires	min 2.5 mm ^2 / 13 AWG
Power supply wires	min 20 mm ^2 / 4 AWG

GROUND ZERO products are engineered in Germany

GROUND ZERO – international sponsor

EMMA

european mobile media association

1	Power terminal	+12V To be connected to the positive terminal of the batteryREM To be connected to the remote output of the head unit ^* ( ^* not required in high-level input mode)GND To be connected to the vehicle's ground(or directly to the negative terminal of the battery)
2	Fuse(s)	If necessary to replace a defective fuse, it's strongly recommended to use a fuse with identical value
3	Speaker terminal	To connect the speaker wires / min. 2 ohms stereo or 4 ohms bridged
4	Input mode switch (RCA)	To select between 4 channel or only 2 channel input mode according to the quantity of RCA wires available from the head unit
5	Line input (RCA)	Input sockets to connect RCA wiresImportant note: High-level and RCA inputs should never be used simultaneously! This may cause serious damage to the amplifier
6	High-level input	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 unusedImportant note: High-level and RCA inputs should never be used simultaneously! This may cause serious damage to the amplifier
7	Sensitivity control	Controller to adjust the input sensitivity (CH 1/2 & CH 3/4)
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	POWER (green) ok (correct operation)PROTECT (red) error (protection mode)

High-level input wiring

Speaker wiring in stereo mode

Geringste Lautsprecherimpedanz je 2 Ω Minimum speaker impedance 2 Ω each

Speaker wiring in bridged mode

Geringste Lautsprecherimpedanz je 4 Ω Minimum speaker impedance 4 Ω each

Model	GZRA 4HD
Amplifier type	4 channel class D
RMS Power @ 4 ΩCEA Standard CEA-2006-A	4x 175 W (1% THD+N)
RMS Power @ 2 ΩCEA Standard CEA-2006-A	4x 275 W (1% THD+N)
RMS Power @ 4 Ω in bridged modeCEA Standard CEA-2006-A	2x 550 W (1% THD+N)2x 700 W (10% THD+N)
Low pass filter	40 Hz – 4000 Hz (12 dB/oct)
High pass filter	40 Hz – 4000 Hz (12 dB/oct)
Frequency response	10 Hz – 25 kHz
Signal to noise ratio (SNR)	-102.3 dB
Total harmonic distortion(THD+N)	< 0.1%
Damping factor	>200
Input sensitivity	200 mV – 5.3 V
Fuse(s)	3x 35 A
Recommended main fuse	100 A
Dimensionsw x h x l (heatsink / overall)	186 x 52 x 229/268 mm
Dimensionsw x h x l (heatsink / overall)	7.32 x 2.05 x 9.02/10.55"

Trouble shooting guide

Symptoms	Check / Cause	Action
No audible sound	Does the POW LED turn to green?	Check protection fuse(s) of the amplifier (harness)Check remote wire connection (RCA input mode)Check +12 Volt power supply wire connectionCheck ground wire connection
	Did the PROTECT LED turn to red?	Check for speaker short or amplifier overheating
Device does not turn on	Power supply of the amplifier?	Check power wire or connections
	Remote wire powered? (RCA input mode)	Check remote wire connection to the head unit
No sound on one channel	Speaker wiring undamaged?	Check for short circuit or open connections
	Input signal on each RCA lead?	Reverse left and right RCA inputs to check the audio input signal
Device turns off at medium / high volume	Load impedance of each speaker correct?	Check if each speaker load impedance matches the technical specifications of the amplifier
Status LED turned on red	Temperature protection circuit active	Decrease head unit's volume / wait for cooling
	Speaker wires short / speaker damaged	Check speaker / wires and insulate if necessary

Respect the Music

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. [phone] Fax -8310

www.ground-zero-audio.com