1. Introduction
This manual provides comprehensive instructions for the installation, operation, and maintenance of your WAPUNO SK-790.4 4-Channel Car Power Amplifier. Designed for enhanced car audio, this Class A/B amplifier delivers up to 7900W peak power, offering stereo surround sound for an immersive listening experience. Please read this manual thoroughly before installation and use to ensure proper function and safety.
Figure 1: WAPUNO SK-790.4 Car Power Amplifier Overview
2. Features
The WAPUNO SK-790.4 Car Power Amplifier is equipped with advanced features for superior audio performance and reliability:
- 4-Channel 7900 Watt Car Power Amplifier (Peak Power)
- Amplifier Class: Class A/B
- Digital pulse-width-modulated regulated power supply
- MOSFET power supply devices
- Fully complementary discrete audio stages
- Direct coupled output stage with discrete output transistors
- Low overall negative feedback for clear sound
- 2 ohm stable in stereo mode
- Bridgeable to mono operation
- Supports stereo/mono setup simultaneously
- 4-way protection circuit: thermal, current, D.C.MOSFET, and overvoltage
- Soft start delayed turn-on
- Increased surface area and mass for continuous heat dissipation (Aluminium alloy casting drawing process with external heat sink and cooling hole design)
- LED power on indicator (Green) and Protection LED (Red)
- Gold plated RCA terminals for Low Level Input and Speaker Terminals for high conductivity
- Adjustable Bass Boost Control (up to +12dB)
- Selectable Crossover/Filter: High-Pass Filter (HPF), Low-Pass Filter (LPF), and Full/Flat modes (50Hz to 150Hz adjustment range)
Figure 2: Visual representation of amplifier features
3. Specifications
| Specification | 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 (Speaker Impedance: 2-16 Ω) |
| Frequency Range | 10Hz-40,000Hz ±1dB |
| Bass Boost | 12dB |
| Power Fuse | 20AX2 or 30AX2 (refer to flank panel) |
| Dimensions (LxHxW) | 310x253x55mm (approx. 12.2 x 9.96 x 2.17 inches) |
| Item Weight | 1.9kg |
Figure 3: Amplifier Dimensions (Length: 31cm/12in, Width: 22cm/8.7in, Height: 4.3cm/1.7in)
4. Safety Warnings
Please observe the following safety precautions to prevent injury or damage to the amplifier and your vehicle:
- Always disconnect the vehicle's battery positive (+) terminal before making any power connections to the amplifier.
- Ensure all wiring connections are clean, secure, and properly insulated to prevent short circuits.
- Use appropriate gauge wiring for power and speaker connections as recommended.
- Install a proper size fuse at the battery and near the amplifier (fuses are not supplied with the unit, refer to the flank panel text for required fuse ratings).
- Avoid routing power cables near signal cables to prevent noise interference.
- Do not expose the amplifier to moisture or extreme temperatures.
- Professional installation is recommended for optimal performance and safety.
5. Installation
Follow these steps for proper installation of your WAPUNO SK-790.4 Car Power Amplifier:
5.1 General Installation Steps
- Remove Car Radio: Carefully take out your existing car radio from the dashboard.
- Connect Radio Tail Line: Connect the car radio's tail line using an ISO wiring harness DSP cable.
- Insert Terminal to Amplifier: Insert the appropriate terminals into the DSP amplifier.
- Finalize Installation & Adjust: Once physically installed, you can adjust the DSP sound using a computer or a phone application.
Figure 4: Visual guide for general installation steps
5.2 Power Connections
The amplifier is provided with high current barrier strip terminals for robust connections:
- B+/+12V: Connect the +12V pole of the power supply directly to the positive (+) terminal of your vehicle's battery.
- GND: Connect the GND pole of the power supply directly to the negative (-) ground battery terminal of the car chassis. Ensure a clean, secure ground point.
- REM (Remote): Connect the "Remote" pole to an external switch for positive 12V ON/OFF. This is typically connected to the power antenna or turn-on lead of your head unit, allowing the amplifier to power on/off with your car stereo.
- FUSE: Refer to the amplifier's flank panel text for the correct fuse rating (e.g., 20AX2 or 30AX2). Always use the proper size fusing.
Important: Improper wiring connections can seriously damage amplifiers, accessories, or speakers. Follow instructions carefully. Disconnect the battery positive (+) before making any power connections. Use grommets when routing wires through the firewall and other metal bodywork.
5.3 Input Connections
Connect the pre-amp (low-level) outputs from your source unit (car stereo or crossover) to the RCA jacks labeled "INPUT" on the amplifier. Use high-quality RCA cables to ensure better signal transfer and avoid noise.
- Stereo Mode: Connect the left and right RCA plugs from the source unit to their appropriate input jacks.
- Mono/Bridged Mode: Connection can be made to the right, left, or both input jacks.
- Line Out: The "OUT" RCA terminals can be used to connect to another power amplifier.
5.4 Output Connections
High current barrier strip terminals are provided for connection to your loudspeaker system:
- Stereo Mode: Connect the left speaker leads to the left terminal and the right speaker leads to the right terminal. Ensure correct polarity (+ to + and - to -). Stereo mode supports 2, 4, or 8 ohm speaker loads. The minimum recommended speaker load is 2 ohms per channel.
- Bridged/Mono Mode: Connect the speaker (+) lead to the R+ terminal and the speaker (-) lead to the L- terminal. Bridged mode is designed for 4-8 ohm loads and will not support a 2 ohm load. The minimum recommended speaker load is 4 ohms for each bridged channel.
Caution: Operating the amplifier below the recommended impedance load can damage both the amplifier and your speakers, and will void your warranty.
Figure 5: Detailed wiring diagram for power, input, and speaker connections
Figure 6: Diagram illustrating a whole car audio system upgrade solution with the amplifier
6. Operation
Familiarize yourself with the amplifier's controls and indicators:
- POWER ON LED (Green): Illuminates when the unit is properly grounded, has correct power, and is receiving its remote power signal.
- PROTECTION LED (Red): Illuminates when the unit detects a fault condition (e.g., short circuit, overheating).
- Input Level Control (LEVEL): Adjusts the input sensitivity to match the output of your source unit. This can increase or decrease the sound response output.
- Bass Boost Control (BASS BOOST or BASS EQ): Allows you to add extra bass response to your system, adjustable up to +12dB.
- Crossover/Filter (X-OVER or FILTER):
- HPF (High-Pass Filter): Set to this position when driving tweeters/midrange speakers. Frequencies below the crossover point (adjustable from 50Hz to 150Hz) will be attenuated at 12dB/octave.
- LPF (Low-Pass Filter): Set to this position when driving a subwoofer. Frequencies above the crossover point (adjustable from 50Hz to 150Hz) will be attenuated.
- FULL/FLAT: Set to this position for full-range speakers. The full frequency bandwidth will be output without high or low frequency attenuation.
Figure 7: Side view of the amplifier showing HFP, LPF, and Gain controls
Figure 8: Internal component layout with labels for audio adjustments
7. Maintenance
To ensure the longevity and optimal performance of your amplifier:
- Cleaning: Periodically clean the exterior of the amplifier with a soft, dry cloth. Do not use harsh chemicals or abrasive cleaners. Ensure cooling fins and holes are free from dust and debris to maintain efficient heat dissipation.
- Connection Checks: Regularly inspect all power, ground, input, and output connections to ensure they are secure and free from corrosion. Loose connections can lead to poor performance or damage.
- Fuse Replacement: If a fuse blows, replace it only with a fuse of the exact same type and rating as specified on the amplifier's flank panel. Using an incorrect fuse can cause serious damage.
8. Troubleshooting
If you experience issues with your amplifier, refer to the following common problems and solutions:
- No Power / Amplifier Not Turning On:
- Check the power (B+/+12V) and ground (GND) connections for tightness and proper contact.
- Verify the remote (REM) wire is connected to a switched 12V source from your head unit.
- Check the fuses on the amplifier and at the battery. Replace any blown fuses with the correct rating.
- Ensure the vehicle's battery has sufficient charge.
- Protection LED is On (Red):
- This indicates a fault. Check all speaker wires for short circuits (e.g., bare wire touching chassis or other wires).
- Ensure the speaker impedance is within the recommended range (2 ohms minimum for stereo, 4 ohms minimum for bridged).
- The amplifier may be overheating. Ensure adequate ventilation and that cooling fins are not blocked. Allow the unit to cool down.
- No Sound Output:
- Verify all RCA input cables are securely connected to both the source unit and the amplifier.
- Check speaker wire connections for proper polarity and tightness.
- Ensure the head unit's volume is up and not muted.
- Adjust the amplifier's input level (GAIN) control.
- Distorted Sound:
- Reduce the input level (GAIN) control if it's set too high.
- Check for proper crossover settings (HPF/LPF) for your speakers.
- Ensure speaker impedance matches the amplifier's capabilities.
- Inspect speaker wires for damage or loose connections.
9. User Tips
Based on common user inquiries and experiences, here are some tips for getting the most out of your WAPUNO SK-790.4 amplifier:
- RMS vs. Peak Power: While the amplifier boasts a 7900W peak output, always consider the RMS power (120W x 4 Channels at 4 Ohms) when matching with speakers and subwoofers. RMS is a more accurate measure of continuous power handling.
- Subwoofer Compatibility: This 4-channel amplifier can power subwoofers. For example, it can drive two 400 RMS Pioneer 308 subwoofers when bridged, but ensure the impedance matches the bridged mode requirements (minimum 4 ohms).
- Sound Quality: Users report good sound quality. Proper tuning of the gain, bass boost, and crossover settings (HPF/LPF) is crucial for optimizing the sound for your specific car audio setup.
- Heat Dissipation: The aluminum alloy design with cooling holes is effective. Ensure the amplifier is installed in a location with good airflow to prevent overheating, especially during prolonged high-volume use.
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.
11. Documents and Media
11.1 User Manual (PDF)
A detailed user manual in PDF format is available for download. This document contains additional information and diagrams.
11.2 Product Video
Watch this official product video for a visual overview of the WAPUNO SK-790.4 Car Power Amplifier and its features.
Video: WAPUNO SK-790.4 Car Power Amplifier Overview
