SUNBUCK SK-790.4 4-Channel Car Power Amplifier User Manual

1. Introduction

This manual provides detailed instructions for the installation, operation, and maintenance of your SUNBUCK SK-790.4 4-Channel Car Power Amplifier. Please read this manual thoroughly before attempting to install or use the amplifier to ensure proper function and safety.

The SK-790.4 is a high-performance 4-channel Class A/B car power amplifier designed to enhance your vehicle's audio system with powerful and clear sound. It features a slim design, efficient heat dissipation, and comprehensive protection circuits.

Sunbuck SK-790.4 Car Power Amplifier 7900W, a black amplifier unit with a car in the background. — Figure 1.1: SUNBUCK SK-790.4 Car Power Amplifier.

2. Features

4-Channel 7900 Watt Peak Power Output
Class A/B Amplifier Design
Stereo Surround Sound Capability
Designed to power four-door speakers and passive subwoofers
Slim and compact design
Durable Aluminium Alloy casing with drawing process finish
External heat sink and cooling hole design for efficient heat dissipation
Thermal Overload Protection
Speaker Short Protection
Standard safety interface for secure connections
Digital pulse-width-modulated regulated power supply
MOSFET power supply devices
Fully complementary discrete audio stages
Direct coupled output stage
Discrete output transistors
Low overall negative feedback
2 Ohm stable in stereo mode
Bridgeable for mono operation
Simultaneous stereo/mono setup
4-way protection circuit: thermal, current, D.C. MOSFET, and overvoltage
Soft start delayed turn-on
LED power on indicator

Icons representing amplifier features: Strong power, Safe & stable, Efficient heat dissipation, Easy to Install, Hifi sound quality. — Figure 2.1: Key Features of the SK-790.4 Amplifier.

Diagram showing cooling hole design for wider contact surface with air and faster heat dissipation, and a security interface for standard safety. — Figure 2.2: Cooling Hole Design and Security Interface.

Close-up of internal components showing a two-color coil for small size, high power, and short circuit rejection, and a Black King Kong Capacitor for mellow tone and improved sound effect. — Figure 2.3: Internal Component Highlights.

3. Specifications

Attribute	Value
Model	SK-790.4
Material	Aluminium alloy
Channel	4
Working Voltage	DC 12V
Peak Power Output	7900 W
Peak Power Output (2 Ohms)	2000W x 4 Channels
Peak Bridged Power Output (4 Ohms)	3900W x 2 Channels
RMS Power Output (4 Ohms)	120W x 4 Channels
Total Harmonic Distortion (THD) RMS Output	<0.01%
Signal-to-Noise Ratio (SNR)	>95dB
Sensitivity	150mV
Impedance	2Ω~4Ω
Frequency Range (Hz)	20Hz~40KHz
Item Weight	1.9 kg
Dimensions (L x W x H)	31 cm x 22 cm x 4.3 cm (approx.)
Power Fuse	20AX2 or 30AX2 (refer to flank panel text)

Diagram showing the dimensions of the amplifier: 4.3cm/1.7in height, 31cm/12in length, 22cm/8.7in width. — Figure 3.1: Amplifier Dimensions.

Table of specifications for the SK-790.4 amplifier, including model, material, channel, voltage, power output, THD, SNR, sensitivity, impedance, and frequency range. — Figure 3.2: Detailed Specifications Table.

4. Safety Information

Always disconnect the vehicle's battery negative terminal before making any power connections to the amplifier.
Ensure all connections are clean, secure, and properly insulated to prevent short circuits.
Use appropriate gauge wiring for power and speaker connections to handle the amplifier's output.
Install the amplifier in a well-ventilated area, away from direct sunlight, heat sources, and moisture.
Avoid mounting the amplifier in locations where it could interfere with vehicle operation or safety features.
Always use the proper size fusing for both the battery and the amplifier (fuses not supplied with the amplifier).
If the amplifier goes into protection mode (Protection LED illuminates), immediately check all wiring and connections for faults.
For trucks, buses, and other vehicles requiring 24V, a 24V~12V30A converter is necessary.

5. Installation

Proper installation is crucial for optimal performance and safety. If you are unsure about any steps, consult a professional car audio installer.

5.1 General Installation Steps

Take out your car radio.
Connect the radio car tail line using an ISO wiring harness DSP cable (not included).
Insert the terminal to the DSP amplifier.
Finish installation. You can use a computer or phone app to adjust the DSP sound.

Four-step visual guide for amplifier installation: 1. Take out car radio. 2. Connect radio car tail line using ISO wiring harness DSP cable. 3. Insert terminal to DSP amplifier. 4. Finish installation, adjust sound via computer or phone app. — Figure 5.1: Visual Installation Steps.

5.2 Power Connections

Refer to Figure 5.2 for power terminal locations.

B+12V: Connect the +12V power supply directly to the positive terminal of the vehicle's battery.
GND: Connect the GND power supply directly to the negative ground terminal of the vehicle's battery or a solid chassis ground point.
REM (Remote): Connect the "Remote" terminal to an external switch for positive 12V ON/OFF. This can be connected to the power antenna or turn-on lead of your head unit.
Fuse: Ensure proper fusing is used between the battery and the amplifier. Refer to the panel text on the amplifier for specific fuse requirements (e.g., 20AX2 or 30AX2).

5.3 Input Connections (RCA Low Level)

The amplifier uses RCA-type terminals for low-level input. Connect the RCA output from your head unit or pre-amp device to the corresponding input jacks on the amplifier.

5.4 Output Connections (Speaker Terminals)

The amplifier features speaker output terminals for connecting your car speakers. The unit can support an impedance load of 2 ohms per channel or 4 ohms in bridged mode. Bridged mode will require a 4-ohm load.

Stereo Amplifier System: Connect the two pairs of output terminals to the corresponding LEFT and RIGHT speakers.

Mono Amplifier System: For mono operation (e.g., for a subwoofer), bridge two channels. Refer to the wiring diagram for specific bridging instructions. Mono mode is designed for 4-ohm loads and will not support a 2-ohm load in this configuration.

Top view of the amplifier showing power input terminals (GND, REMOTE, B+) on the left, a fuse, and speaker output terminals (CH1, CH2, CH3, CH4) on the right, with bridge mode indicators. — Figure 5.2: Amplifier Power and Speaker Output Terminals.

Detailed wiring diagram showing the internal components and external connections of the amplifier. Labels include: Control line, Left front speaker positive, Left rear horn positive, Negative power supply, +12V Power supply, Double fuse, Right front speaker positive, Right rear horn positive, Audio output/input, Audio adjustment, High frequency adjustment, Gold steel capacitor, Low frequency adjustment, Treble adjustment, Two-color coil, Front and rear speakers positive and negative, Small capacitor. — Figure 5.3: Internal Components and Wiring Diagram.

Diagram illustrating a whole car audio system upgrade solution with the car amplifier at the center, connecting to tweeters, woofers, and coaxial speakers. Subwoofer frequency range is 20Hz~40KHz. — Figure 5.4: Car Audio System Upgrade Solution.

Image stating 'Suitable for 99% models, trucks and buses can also be installed'. Notes that trucks, buses, etc. need to be equipped with 24V~12V30A converters. Lists various car brands. — Figure 5.5: Vehicle Compatibility.

6. Operation and Adjustments

The amplifier provides several controls for fine-tuning your audio experience.

6.1 Input Level Control (LEVEL / GAIN)

This control adjusts the input sensitivity of the amplifier. Set it to match the output level of your head unit. Start with the gain at minimum and slowly increase it until you achieve clear, undistorted sound at your desired volume level.

Close-up of the amplifier's control panel showing RCA input/output jacks and gain controls for CH1/CH2 and CH3/CH4. — Figure 6.1: RCA Input/Output and Gain Controls.

6.2 Bass Boost Control (BASS BOOST OR BASS EQ)

This control allows you to contour the bass response of your system. The bass can be boosted to your preference.

6.3 Crossover/Filter Controls (HPF, LPF, FULL/FLAT)

These controls allow you to direct specific frequency ranges to your speakers, optimizing sound quality and protecting speakers from unwanted frequencies.

HPF (High Pass Filter): Set to the HPF position when the amplifier is used to drive a tweeter/midrange system. Frequencies below the Crossover point will be attenuated at 12dB/octave. Permits adjustment from 50Hz to 100Hz as the crossover point.
LPF (Low Pass Filter): Set to the LPF position when the amplifier is used to drive a subwoofer. Frequencies above the crossover frequency will be attenuated. Rotate the knob to select any frequency between 50Hz to 150Hz as the crossover point.
FULL/FLAT: Set to the FULL/FLAT position when this amplifier will be used for driving full-range speakers. The full frequency bandwidth will be output to the speakers without high or low frequency attenuation.

Side view of the amplifier showing control knobs for HPF (120Hz, 3KHz), LPF (50Hz, 250Hz), and Gain (Min, Max) for CH3/CH4. Also shows a switch for HPF, LPF, and FULL modes. — Figure 6.2: Crossover and Gain Controls.

Another view of the amplifier's control panel, highlighting HPF and LPF settings, gain control, and LED indicators for 'PROTECTION' (red) and 'POWER' (green). — Figure 6.3: Control Panel with LED Indicators.

Video 6.1: Product Overview and Features Demonstration.

7. Maintenance

Keep the amplifier clean and free from dust and debris. Use a soft, dry cloth for cleaning.
Ensure adequate ventilation around the amplifier to prevent overheating. Regularly check that cooling fins are not obstructed.
Periodically inspect all wiring connections to ensure they remain tight and free from corrosion.
Avoid spilling liquids on the amplifier.

8. Troubleshooting

Problem	Possible Cause	Solution
No Power / Power LED Off	Blown fuse, loose power connection, no remote turn-on signal.	Check amplifier and battery fuses. Verify B+12V, GND, and REM connections are secure and receiving power.
Protection LED On (Red)	Short circuit in speaker wiring, impedance too low, overheating, DC offset.	Check all speaker wires for shorts to ground or each other. Ensure speaker impedance is within specifications (2-4 ohms). Allow amplifier to cool down. Check for DC voltage on speaker outputs.
No Sound Output	Loose RCA input cables, incorrect gain setting, speaker wires disconnected.	Verify RCA cables are securely connected. Adjust gain control. Check speaker wire connections at both amplifier and speakers.
Distorted Sound	Gain set too high, incorrect crossover settings, poor ground connection.	Reduce gain level. Adjust HPF/LPF settings appropriately for your speakers/subwoofer. Ensure a solid ground connection.

9. User Tips

Cable Considerations: The amplifier package typically does not include connection cables. Ensure you purchase appropriate power, ground, remote, RCA, and speaker cables separately.
Tuning Flexibility: The amplifier offers flexible tuning options with its HPF, LPF, and gain controls, allowing you to customize the sound profile for different speakers (e.g., high frequencies for front, mid/low for rear/subwoofer).
Subwoofer Compatibility: This amplifier is capable of driving passive subwoofers. When connecting subwoofers, ensure the impedance matches the amplifier's specifications, especially in bridged mode (4 ohms recommended for bridged).
Installation Check: Double-check all wiring connections during installation. Loose or incorrect wiring can cause the amplifier to enter protection mode.

10. Warranty and Support

For warranty information, technical support, or service inquiries, please contact the seller or manufacturer directly. Keep your purchase receipt as proof of purchase.

Sunbuck SK-790.4