Kenwood KAC 8403 Manual

The Kenwood KAC 8403 is a high-performance 4-channel car amplifier designed to deliver exceptional audio quality with 50W RMS x 4 channels at 4 ohms, 75W RMS x 4 channels at 2 ohms, and 150W RMS x 2 channels in bridged mode. Features include MOSFET power supply, variable high-pass/low-pass filters, bass boost, speaker-level inputs, and comprehensive protection circuits. Below are key sections for safety, features, installation, setup, operation, and troubleshooting.

1. Features at a Glance 2. Installation 3. First-Time Setup 4. Specifications 5. Controls and Settings 6. Connecting Devices 7. Operation Modes 8. Protection Features 9. Care & Maintenance 10. Regulatory Information 11. Troubleshooting

Features at a Glance

Key components: MOSFET power supply, variable electronic crossover, bass boost, speaker-level inputs, protection circuits.

Feature	Description
Power Output	50W x 4 (4Ω), 75W x 4 (2Ω), 150W x 2 (4Ω bridged)
MOSFET Power Supply	Efficient and reliable power delivery
Variable Crossover	High-pass/low-pass filters (50-200Hz)
Bass Boost	0-12dB boost at 50Hz
Speaker-Level Inputs	Connect directly to factory head units
Protection Circuits	Thermal, overload, and short circuit protection
RCA Inputs	Gold-plated for optimal signal transfer
Remote Turn-on	Remote wire connection for automatic power control
Fuse Rating	25A x 2 for power protection

Installation

Unpack and inspect contents. Choose suitable mounting location.

Disconnect negative battery terminal before installation.
Mount amplifier: Secure to solid surface with proper ventilation.
Connect power: Run 4-gauge power wire from battery to amplifier.
Connect ground: Use short 4-gauge wire to clean metal chassis point.
Connect remote: Run remote turn-on wire from head unit.
Connect speakers: Use appropriate gauge speaker wire.
Connect audio inputs: Use RCA cables or speaker-level inputs.

WARNING! Ensure proper fuse rating and secure all connections. Do not run power wires near audio cables.

First-Time Setup

Reconnect battery; power on system and configure settings.

Set input level: Adjust gain control for optimal signal matching.
Configure crossover: Set high-pass/low-pass filters based on speaker setup.
Adjust bass boost: Set to desired level (start with minimum).
Test all channels: Verify proper operation of each speaker.
Fine-tune settings: Make final adjustments while playing music.

CAUTION! Set gain properly to avoid distortion and speaker damage.

Specifications

Power Output: 50W RMS x 4 (4Ω), 75W RMS x 4 (2Ω), 150W RMS x 2 (4Ω bridged)
Frequency Response: 10Hz - 50kHz (+0, -1dB)
Signal-to-Noise Ratio: 100dB
THD: 0.08%
Crossover: High-pass/low-pass (50-200Hz, 12dB/octave)
Bass Boost: 0-12dB at 50Hz
Input Sensitivity: 200mV - 4V (RCA), 0.5V - 10V (speaker level)
Fuse Rating: 25A x 2
Dimensions: 10-1/16" W x 2-3/8" H x 9-1/16" D

Controls and Settings

Access controls via front panel controls and switches.

Front Panel: Power indicator, Protection indicator, Input level controls, Crossover controls, Bass boost control.

Input Level: Adjust gain for each channel pair. Crossover: Select high-pass/low-pass/off; adjust frequency (50-200Hz). Bass Boost: 0-12dB boost at 50Hz. Input Select: Choose between RCA and speaker-level inputs.

Connecting Devices

RCA Inputs: For aftermarket head units. Speaker-Level Inputs: For factory head units.

Turn off vehicle and disconnect battery before connections.
Match input type to head unit (RCA or speaker-level).
Connect speakers observing proper impedance (2Ω minimum per channel).
Connect remote turn-on wire to head unit remote output.

Tip: Use high-quality cables and keep power wires separated from audio cables.

Operation Modes

Supports stereo, bridged, and mixed operation modes.

Stereo Mode: Standard 4-channel operation for front/rear speakers.
Bridged Mode: Combine two channels for higher power to single speaker.
Mixed Mode: Use some channels for full-range, others for subwoofers.
Crossover Settings: Configure based on speaker capabilities and installation.
Input Level Matching: Set gain to match head unit output voltage.

WARNING! Do not bridge channels to impedance less than 4Ω. Observe minimum impedance requirements.

Protection Features

Thermal Protection: Automatically reduces output if overheating detected. Overload Protection: Protects against excessive current draw. Short Circuit Protection: Safeguards against speaker wire shorts. DC Offset Protection: Prevents DC voltage from reaching speakers.

Care & Maintenance

Keep amplifier clean and free of dust. Ensure proper ventilation. Check connections periodically for corrosion or looseness.

CAUTION! Do not block ventilation openings. Keep away from moisture and extreme temperatures.

Regulatory Information

FCC Part 15: Class B digital device; complies with interference limits. Copyright © Kenwood Corporation. All rights reserved. For support, visit www.kenwood.com or contact authorized Kenwood service centers.

Troubleshooting

Symptom	Possible Cause	Corrective Action
No power	Power/ground connections	Check battery connection; verify ground; check fuses.
Protection mode active	Short circuit/overheating	Check speaker wires for shorts; allow amplifier to cool.
Distorted sound	Gain setting/input level	Adjust gain control; check head unit output level.
No sound from channels	Input connections/settings	Verify RCA/speaker-level connections; check crossover settings.
Amplifier overheating	Insufficient ventilation	Improve airflow; check impedance load; reduce gain.

Reset: Disconnect power for 30 seconds to reset protection circuits.

Service: Contact authorized Kenwood service center; www.kenwood.com