Kenwood KAC 748 Manual

The Kenwood KAC 748 is a high-performance car amplifier designed to deliver exceptional audio quality with robust power output. This 4-channel amplifier features MOSFET power supply, variable high-pass/low-pass filters, bridgeable channels, speaker-level inputs, and comprehensive protection circuits. Below are key sections covering specifications, installation, setup, operation, and troubleshooting.

Features at a Glance

Key components: 4-channel amplifier, MOSFET power supply, variable crossover controls, bridgeable outputs, speaker-level inputs, comprehensive protection circuits.

Feature	Description
MOSFET power supply	For efficient power delivery and thermal stability
Variable high-pass/low-pass filters	Adjustable crossover frequencies for precise sound control
Bridgeable channels	Combine channels for higher power output
Speaker-level inputs	Direct connection to factory head units
Protection circuits	Thermal, short-circuit, and DC offset protection
RCA inputs	For line-level audio signals
Gain controls	Adjustable input sensitivity for each channel
Bass boost	Enhanced low-frequency response
Remote turn-on	Automatic power on/off with head unit
LED power indicator	Visual status indication

Installation

Unpack and inspect contents. Choose suitable mounting location in vehicle.

1. Disconnect negative battery terminal before installation.
2. Mount amplifier: Secure to stable surface with proper ventilation.
3. Connect power: Run power cable from battery positive terminal with fuse.
4. Connect ground: Secure ground wire to clean metal chassis point.
5. Connect remote turn-on: Connect to head unit's remote output.
6. Connect audio inputs: Use RCA cables or speaker-level inputs.
7. Connect speakers: Wire speakers to appropriate amplifier outputs.

WARNING! Ensure all connections are secure and insulated. Do not route power cables near audio cables to avoid noise.

First-Time Setup

After installation, configure amplifier settings for optimal performance.

1. Set gain controls: Start at minimum, adjust while playing music at normal listening level.
2. Configure crossover: Set high-pass/low-pass filters based on speaker capabilities.
3. Adjust bass boost: Use sparingly to avoid distortion.
4. Test all channels: Verify proper operation of each speaker.
5. Check protection circuits: Ensure all safety features are functional.

CAUTION! Do not set gain levels too high to prevent speaker damage.

Specifications

• Channels: 4
• RMS Power: 50W x 4 (4Ω), 75W x 4 (2Ω), 150W x 2 (4Ω bridged)
• Peak Power: 100W x 4
• Frequency Response: 10Hz - 50kHz
• Signal-to-Noise Ratio: >100dB
• THD: <0.08%
• Crossover: Variable 50Hz - 200Hz
• Input Sensitivity: 200mV - 4V
• Power Supply: MOSFET
• Operating Voltage: 14.4V DC (11-16V range)

Controls and Settings

Access controls via front/rear panel adjustments.

Front Panel: Power LED, Protection indicator.

Rear Panel: Gain controls, Crossover frequency, Bass boost, Input selectors, Speaker outputs, Power/ground terminals, RCA inputs.

Gain: Adjust input sensitivity for each channel. Crossover: Set high-pass for front/rear speakers, low-pass for subwoofers. Bass Boost: +12dB boost at 45Hz. Input Select: Choose between RCA or speaker-level inputs.

Connecting Devices

Multiple connection options for various audio setups.

1. RCA connection: Use RCA cables from head unit preamp outputs.
2. Speaker-level connection: Connect to factory speaker wires.
3. Bridge mode: Combine two channels for higher power output.
4. Multiple amplifier setup: Use RCA pass-through outputs.

Tip: Use high-quality cables and ensure proper grounding for best performance.

Operation Guide

Proper operation procedures for daily use.

1. Power on: Amplifier turns on automatically with head unit via remote wire.
2. Volume control: Adjust at head unit, fine-tune with amplifier gain.
3. Crossover adjustment: Match crossover settings to speaker specifications.
4. Bridging channels: Use for powering subwoofers or high-power speakers.
5. Multiple source setup: Configure for different audio sources.

WARNING! Do not operate with loose connections or damaged wiring.

Protection Features

Comprehensive protection circuits ensure safe operation.

• Thermal Protection: Automatically shuts down if temperature exceeds safe limits
• Short-Circuit Protection: Protects against speaker/output shorts
• DC Offset Protection: Prevents DC voltage from reaching speakers
• Over-Voltage Protection: Guards against voltage spikes
• Under-Voltage Protection: Prevents operation at dangerously low voltages

Care & Maintenance

Keep amplifier clean and properly ventilated for optimal performance.

Regular maintenance: Check connections for corrosion, ensure mounting is secure, clean ventilation areas, inspect wiring for damage.

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 for residential use. Copyright © Kenwood Corporation. All trademarks are property of their respective owners. For technical support, visit www.kenwood.com or contact 1-800-536-9663.

Troubleshooting

Symptom	Possible Cause	Corrective Action
No power	Power/ground connections	Check power cable fuse; verify ground connection; ensure remote wire connected.
Protection mode active	Short circuit/overheating	Check speaker wires for shorts; allow amplifier to cool; verify proper impedance.
No sound	Input connections/settings	Verify RCA/speaker-level connections; check gain settings; ensure head unit output.
Distorted sound	Gain settings/clipping	Reduce gain settings; check input levels; verify speaker impedance compatibility.
Overheating	Insufficient ventilation/load	Improve ventilation; check speaker impedance; reduce volume levels.

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

Service: 1-800-536-9663; www.kenwood.com