KENWOOD KAC-848 / KAC-748 4-Channel Power Amplifier Instruction Manual
Brand: KENWOOD CORPORATION
Models: KAC-848, KAC-748
Introduction
This instruction manual provides essential information for the installation and operation of your KENWOOD 4-channel power amplifier. Familiarity with the procedures outlined herein will help you achieve optimal performance from your new amplifier.
For Your Records: Please record the serial number found on the unit. This information is useful for warranty claims or service inquiries.
Model: KAC-848/748 Serial number: [Space for serial number]
© PRINTED IN USA B64-1350-00 (KM)
Safety Precautions and Warnings
CAUTION: To Prevent Damage to the Machine
- Ensure the unit is connected to a 12V DC power supply with a negative ground connection.
- Do not open the top or bottom covers of the unit.
- Avoid installing the unit in locations exposed to direct sunlight, excessive heat, humidity, dust, or the possibility of water splashing.
- When replacing a fuse, use only a new one with the prescribed rating. Using an incorrect fuse rating may cause malfunction.
- To prevent short circuits when replacing a fuse, disconnect the wiring harness first.
FCC WARNING
This equipment may generate or use radio frequency energy. Modifications not expressly approved in this manual could void the user's authority to operate the equipment.
ACAUTION: Installation Considerations
- Do not install the unit under the carpet, as this can lead to heat build-up and damage.
- Install the unit in a location that allows for easy heat dissipation. Do not place objects on top of the unit after installation.
- The amplifier surface can become hot during use. Install it away from heat-sensitive materials or people.
- When drilling holes, ensure there are no hazardous components (e.g., fuel lines, brake pipes, wiring harnesses) on the opposite side. Be careful not to cause damage.
- Avoid installing near the dashboard, rear tray, or airbag safety components.
- Securely fasten the unit to prevent it from becoming dislodged by shock, which could cause injury or accidents.
- After installation, verify that vehicle electrical equipment (brake lamps, turn signals, wipers) functions correctly.
- Improper speaker wiring, such as shorting speaker wires to the car's metal body, can cause unit failure.
Accessories
| Part name | External View | Number of Items |
|---|---|---|
| Terminal cover (Power terminal) | [Circular terminal cover] | 1 |
| Self-tapping screws (ø4 x 16 mm) | [Screw icon] | 4 |
Protection Function
This unit features a protection function to safeguard itself and your speakers from various issues. When triggered, the Power indicator turns off, and the amplifier stops operating.
Power Indicator
The Power indicator lights when the unit is powered on. If it does not light, the protection function may be active. Check for any signs of trouble.
Situations triggering protection:
- Speaker wire short-circuit.
- Speaker output contacts ground.
- Internal part temperature exceeds 120°C (248°F).
- Improper ground connection for the center unit or this unit to the vehicle's metal chassis (which grounds to the battery's negative terminal).
Installation
The power amplifier can be installed in various locations within the vehicle, such as the trunk, without hindering the driver, as it has no operational parts requiring access.
Mounting
An installation board (15 mm or more in thickness) may be used. Self-tapping screws (ø4 x 16 mm) are used for mounting.
Extension Cables (Optional)
Various lengths of RCA cables are available:
| Type | 0.5m | 1m | 2m | 4m | 5m | 6m |
|---|---|---|---|---|---|---|
| RCA cable | CA-2SL | CA-12SL | CA-22SL | CA-52SL | ||
| RCA cable (ø7mm) | CA-3WL | CA-13WL | CA-23WL | CA-53WL | ||
| RCA cable (ø12mm) | CA-5W | CA-15W | CA-25W | CA-45W | CA-65W |
Connections and Terminals
The amplifier features multiple terminals for power, ground, remote control, audio input, and speaker output.
Terminal Layout (KAC-848 / KAC-748)
Referencing the diagram:
- 1. Fuse (20 A x 2 for KAC-848; 30 A x 1 for KAC-748): Protective fuses for the power input.
- 2. Battery terminal: Connects to the vehicle's battery positive terminal.
- 3. Ground terminal: Connects to the vehicle's metal chassis for grounding.
- 4. Power control (REMOTE) terminal: Connects to the head unit's remote turn-on lead.
- 5. Amplifier A speaker output terminals: For connecting speakers to Amplifier A.
- 6. Amplifier B speaker output terminals: For connecting speakers to Amplifier B.
- 7. Speaker level input terminals (KAC-748 only): For connecting to head units without RCA pre-outs.
- 8. RCA cable ground lead terminal: For connecting the ground lead of RCA cables.
- 9. FUSE(30A): Main fuse.
- 10. POWER IN: Main power input.
- 11. GND: Ground terminal.
- 12. P.CONT(REMOTE): Power control (Remote) terminal.
- 13. INPUT SELECTOR switch: Selects input method (A B or A).
- 14. Amplifier A LINE IN terminal: RCA input for Amplifier A.
- 15. Amplifier B LINE IN terminal: RCA input for Amplifier B.
- 16. LINE OUT terminal: RCA outputs for passing through input signals.
Amplifier Controls
- Input Sensitivity (V): Adjusts input signal level (0.5 - 0.3 V range).
- FILTER switch: Selects High-Pass Filter (HPF) or Low-Pass Filter (LPF).
- FREQUENCY control: Adjusts the threshold frequency for HPF/LPF (50 Hz - 200 Hz).
- OPERATION switch: Selects amplification mode: STEREO or MONO(L+R).
- CONTROL A/B: Controls for Amplifier A and Amplifier B respectively.
Wiring Diagrams
RCA Cable Connections:
Connect RCA cables from the center unit (head unit) to the LINE IN terminals (14, 15). The LINE OUT terminals (16) can pass signals to other amplifiers.
Speaker Level Input Connection (KAC-748 only):
Connect the unit between the genuine-accessory car stereo and speakers using speaker wires.
Speaker Output Connections:
- Standard Connections: Connect speakers to the respective terminals (5, 6). Ensure correct polarity (+/-).
- Bridged Connections: For higher power output to a single speaker, use bridged connections across specific terminals (e.g., A Left output and A Right output for one bridged channel). Refer to the diagram for specific terminal pairings.
Power Wire Connection:
Connect the Battery wire to the battery positive terminal, the Ground wire to the vehicle chassis, and the Power Control (REMOTE) wire to the head unit's remote output. A protective fuse should be installed on the battery wire near the battery.
Diagram Description: The diagrams illustrate how to connect power, ground, remote, RCA inputs, and speaker outputs for both stereo and bridged configurations. They also show the connection of a genuine-accessory car stereo for speaker-level inputs.
System Examples
Full-range 4-channel + Subwoofer System
This example shows a configuration where the amplifier powers front speakers, rear speakers, and a subwoofer. The INPUT SELECTOR and OPERATION switches are set accordingly for each channel/speaker type.
Tri-mode Operation
The tri-mode system allows for flexible speaker configurations, often involving a subwoofer and main speakers. It utilizes a coil (L) for low-pass filtering and a capacitor (C) for high-pass filtering to divide frequency bands.
Principle of Tri-mode: Frequency band division using a coil and capacitor with a 6dB/oct. slope.
- Coil (L): Passes low frequencies and blocks high frequencies (Low pass).
- Capacitor (C): Passes high frequencies and blocks low frequencies (High pass).
Formulas:
C = 159000 / (fc x R) (μF)
L = 159 / fc (mH)
Where: fc = Cut of Frequency (Hz), R = Speaker Impedance (Ω)
Example: To set a crossover frequency of 120 Hz with 4-ohm speakers, a capacitor of approximately 331.25 (μF) and a coil of approximately 5.3 mH are needed.
ACAUTION for Tri-mode:
- When bridge-connecting a speaker, its impedance must be no less than 4 ohms. Connecting a speaker with lower impedance can damage the unit.
- Capacitors must be connected to speakers handling high frequencies to prevent a drop in combined impedance with the subwoofer.
- Ensure the withstand voltage and current ratings of capacitors (C) and coils (L) are sufficient.
Troubleshooting
Problem: The sound quality is bad (The sound is distorted).
- Possible Cause: Speakers are connected with incorrect polarity (⊕/⊗).
- Solution: Connect them properly, checking the ⊕/⊗ of the terminals and wires.
- Possible Cause: A speaker wire is pinched by a screw in the car body.
- Solution: Connect the speaker wire again, ensuring it is not pinched.
- Possible Cause: The switches may be set improperly.
- Solution: Set switches properly by referring to "System examples".
Specifications
Specifications are subject to change without notice.
| Audio Section | KAC-848 | KAC-748 |
|---|---|---|
| Max Power Output (4 Ω) | 100W x 4 | 70W x 4 |
| 3 Channel Mode | 100 W x 2 + 300 W x 1 | 70 W x 2 + 200 W x 1 |
| 2 Channel Mode | 300 W x 2 | 200 W x 2 |
| Rated Power Output (4 Ω) | ||
| 4 Channel Mode (20 Hz ~ 20 kHz, less than 0.08% THD) | 50 W x 4 | 35 W x 4 |
| 3 Channel Mode (1 kHz, 0.08% THD) + (1 kHz, 0.8% THD) | 50 W x 2 + 150 W x 1 | 35 W x 2 + 100 W x 1 |
| 2 Channel Mode (1 kHz, 0.8% THD) | 150 W x 2 | 100 W x 2 |
| Rated Power Output (2 Ω) | ||
| 4 Channel Mode (1 kHz, 0.8% THD) | 75 W x 4 | 50 W x 4 |
| Frequency Response (+0, -1 dB) | 5 Hz ~ 50 kHz | 5 Hz ~ 50 kHz |
| Signal to Noise Ratio | 100 dB | 100 dB |
| Sensitivity (MAX) (rated output) | 0.15 V | 0.15 V |
| (MIN) (rated output) | 4.0 V | 4.0 V |
| Input Impedance | 10 kΩ | 10 kΩ |
| Low Pass Filter Frequency (12 dB/oct.) (Variable) | 50 ~ 200 Hz | 50 ~ 200 Hz |
| High Pass Filter Frequency (12 dB/oct.) (Variable) | 50 ~ 200 Hz | 50 ~ 200 Hz |
| General | KAC-848 | KAC-748 |
| Operating Voltage (11 ~ 16 V allowable) | 14.4 V | 14.4 V |
| Current Consumption (1 kHz, 10 % THD) | 38 A | 28 A |
| Dimensions (W x H x D) | 290 x 56 x 280 mm (11-7/16×2-3/16×11 in.) | 290 x 56 x 230 mm (11-7/16×2-3/16×9-1/16 in.) |
| Weight | 4.3 kg (9.4 lb) | 3.7 kg (8.1 lb) |
