Kenwood KAC-848 / KAC-748 4-Channel Power Amplifier
Instruction Manual
Model Numbers: KAC-848, KAC-748
Product Type: 4-Channel Power Amplifier
Manufacturer: Kenwood Corporation
Take the time to read through this instruction manual. Familiarity with installation and operation procedures will help you obtain the best performance from your new power amplifier.
For your records: Record the serial number, found on the back of the unit, in the spaces designated on the warranty card, and in the space provided below. Refer to the model and serial numbers whenever you call upon your KENWOOD dealer for information or service on the product. Model KAC-848/748 Serial number: ________
Safety Precautions
WARNING
To prevent injury or fire, take the following precautions:
- When extending the ignition, battery, or ground wires, make sure to use automotive-grade wires or other wires with a 5mm² (AWG10) or more to prevent wire deterioration and damage to the wire coating.
- To prevent a short circuit, never put or leave any metallic objects (such as coins or metal tools) inside the unit.
- If the unit starts to emit smoke or strange smells, turn off the power immediately and consult your Kenwood dealer.
- Do not touch the unit during use because the surface of the unit becomes hot and may cause burns if touched.
CAUTION
To prevent damage to the machine, take the following precautions:
- Be sure 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.
- Do not install the unit in a spot exposed to direct sunlight or excessive heat or humidity. Also avoid places with too much dust or the possibility of water splashing.
- When replacing a fuse, only use a new one with the prescribed rating. Using a fuse with the wrong rating may cause your unit to malfunction.
- To prevent a short circuit when replacing a fuse, first disconnect the wiring harness.
NOTE
- If you experience problems during installation, consult your Kenwood dealer.
- If the unit does not seem to be working right, consult your Kenwood dealer.
Cleaning the Unit
If the front panel gets dirty, turn off the power and wipe the panel with a dry silicon cloth or soft cloth.
CAUTION
Do not wipe the panel with a hard cloth or a cloth dampened by volatile solvents such as paint thinner and alcohol. They can scratch the surface of the panel and/or cause the indicator letters to peel off.
FCC WARNING
This equipment may generate or use radio frequency energy. Changes or modifications to this equipment may cause harmful interference unless the modifications are expressly approved in the instruction manual. The user could lose the authority to operate this equipment if an unauthorized change or modification is made.
Protection Function
This unit is equipped with a protection function for protecting this unit and your speakers from various accidents or problems that can occur. When the protection function is triggered, the Power indicator goes off and the amplifier stops operating.
Power Indicator
When the power is turned on, the Power indicator lights. If the Power indicator does not light when the power is turned on, the protection function may be activated. Check whether there is any indication of trouble.
The protection function activates in the following situations:
- When a speaker wire may be short-circuited.
- When a speaker output contacts ground.
- When the temperature of internal parts exceeds 120°C (248°F).
- When a ground wire of the center unit (cassette receiver, CD receiver, etc.) or this unit is not connected to a metal part serving as an electrical ground passing electricity to the battery's negative terminal.
Accessories
| Part name | External View | Number of Items |
| Terminal cover (Power terminal) | [Diagram of terminal cover] | 1 |
| Self-tapping screws (ø4 x 16 mm) | [Diagram of screws] | 4 |
Installation Procedure
- Remove the ignition key and disconnect the negative terminal of the battery to prevent short circuits.
- Set the unit according to the intended usage.
- Connect the input and output cables of the units.
- Connect the speaker wires.
- Connect the power wire, power control wire and grounding wire following this order.
- Install the unit in the car.
- Connect the negative terminal of the battery.
CAUTION
- Be sure to turn the power off before changing the setting of any switch.
- If the fuse blows, check wires for shorts, then replace the fuse with one of the same rating.
- Check that no unconnected wires or connectors are touching the car body. Do not remove caps from unconnected wires or connectors to prevent short circuits.
- Connect the speaker wires to appropriate speaker connectors separately. Sharing the negative wire of the speaker or grounding speaker wires to the metal body of the car can cause this unit to fail.
- After installation, check that the brake lamps, winkers, and wipers work properly.
Installation Location
Since the power amplifier has no parts which require operation, it can be installed at a position away from the driver's seat without any hindrances. As generally accepted positions for its installation, places such as inside the trunk, etc. can be considered.
[Diagram showing a car, an installation board (thickness: 15 mm or more), and a self-tapping screw (ø4 x 16 mm)]
Extension Cables (Optional)
| 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 |
CAUTION
- Do not install the unit under the carpet. Otherwise heat build-up occurs and the unit may be damaged.
- Install this unit in a location which allows heat to easily dissipate. Once installed, do not place any object on top of the unit.
- The surface temperature of the amplifier will become hot during use. Install the amplifier in a place where people, resins, and other substances that are sensitive to heat will not come into contact with it.
- When making a hole under a seat, inside the trunk, or somewhere else in the vehicle, check that there is nothing hazardous on the opposite side such as a gasoline tank, brake pipe, or wiring harness, and be careful not to cause scratches or other damage.
- Do not install near the dashboard, rear tray, or air bag safety parts.
- The installation to the vehicle should securely fasten the unit to a place in which it will not obstruct driving. If the unit comes off due to a shock and hits a person or safety part, it may cause injury or an accident.
- After installing the unit, check to make sure that electrical equipment such as the brake lamps, turn signal lamps and windshield wipers operate normally.
Controls
This is a 4 channel amplifier including 2 stereo amplifiers in a body. One amplifier is referred to as amplifier A and the other is amplifier B. This unit is compatible with a large variety of systems by combining the switches and functions described in the following.
[Diagram of the rear panel of the KAC-848 and KAC-748 amplifiers, showing terminal layout. Numbered terminals include: 1. Fuse (20 A x 2 for KAC-848, 30 A x 1 for KAC-748), 2. Battery terminal, 3. Ground terminal, 4. Power control (REMOTE) terminal, 5. Amplifier A speaker output terminals, 6. Amplifier B speaker output terminals.]
[Diagram of the front panel controls for Amplifier A and Amplifier B. Controls include: 7. FREQUENCY (Hz) adjustment for HPF/LPF, 8. FILTER switch (HPF/LPF), 9. OPERATION switch (STEREO, L+R, MONO Lch), 10. INPUT SENSITIVITY control (V), 11. INPUT SELECTOR switch (A B, A), 12. LINE OUT terminal, 13. LINE IN terminal (Amplifier A), 14. LINE IN terminal (Amplifier B).]
Speaker Output Terminals
Stereo Connections
When you wish to use the unit as a stereo amplifier, stereo connections are used. The speakers to be connected should have an impedance of 2Ω or greater. When multiple speakers are to be connected, ensure that the combined impedance is 2Ω or greater for each channel.
Bridged Connections
When you wish to use the unit as a high-output monaural amplifier, bridged connections are used. (Make connections to the LEFT channel (+) and the RIGHT channel (-) SPEAKER OUTPUT terminals.) The speakers to be connected should have an impedance of 4Ω or greater. When multiple speakers are to be connected, ensure that the combined impedance is 4Ω or greater.
CAUTION
The rated input of the speakers should be no less than the maximum output of the amplifier. Otherwise malfunction may result.
Controls Detailed
FREQUENCY control
When the FILTER switch is set to the HPF (High-Pass Filter) or LPF (Low-Pass Filter) position, the threshold frequency can be adjusted with this control.
FILTER switch
High-pass or low-pass filtering can be applied to the speaker output according to the setting of this switch.
OPERATION switch
The amplification methods of the signals input to amplifiers A and B can be selected independently according to the setting of this switch.
STEREO position
The amplifier can be used as a stereo amplifier.
L+R position
The input left and right signals are combined before being amplified. Use this position when the unit is used for subwoofer speakers or the L+R (monaural) sound is required.
MONO (Lch) position
Amplifies the signal input from the left side only. Set to this position and make bridged connections to use as a high-power monaural amplifier. (The input right signal is not output.)
INPUT SENSITIVITY control
Set this control according to the pre-output level of the center unit connected with this unit, or to the maximum power output of the genuine-accessory car stereo. Use the diagram on the right as a guide.
[Diagram showing a dial with markings 0.3, 0.5, 1.0, 1.5, 2.5 (V) and MIN/MAX, with a note indicating to refer to center unit specifications for pre-output level or max power output. This diagram is noted as KAC-748 only.]
RCA cable ground lead terminal
Used for connecting the ground lead of an RCA cable.
INPUT SELECTOR switch
This switch selects the input method of the signals to be amplified by amplifiers A and B.
A B position
Amplifies both of the signals input to amplifiers A and B.
A position
Amplifies only signal input amplifier A with both amplifiers A and B.
Amplifier A LINE IN terminal / Amplifier B LINE IN terminal
These are the input terminals for amplifier A and amplifier B, respectively.
LINE OUT terminal
These jacks output respectively the signals input to amplifiers A and B. They always output the stereo signals regardless of the position of the OPERATION switch.
Connection
RCA cable connection
CAUTION
Do not connect cables and leads to both RCA cable input jacks and the speaker input terminals simultaneously, for this may cause malfunction or damage.
[Diagram showing connection of RCA cables from a CENTER UNIT (Cassette receiver, CD receiver, etc.) to the amplifier's Left and Right inputs, and to the RCA cable ground terminal. Also indicates connection to the Power control (REMOTE) terminal.]
RCA cable ground terminal
When using an RCA cable with a ground lead attached, connect the ground lead to this terminal.
CAUTION
Do not use this terminal for power source grounding. This unit will be damaged if the power source grounding wire is connected to this terminal.
Speaker level input connection (KAC-748 only)
Connect the unit by inserting it in the connection between the genuine-accessory car stereo and speakers.
[Diagram showing connection from a Genuine-accessory car stereo (Front Left, Front Right, Rear Left, Rear Right speaker outputs) to the amplifier's speaker level input terminals. Also shows connection to ACC and Battery via fuse box, and to Power control (REMOTE) terminal.]
CAUTION
- The genuine-accessory car stereo shall have a maximum power output of no more than 25 W.
- Do not connect the speaker output leads from a power amplifier (Optional) to the speaker input terminals of this unit, for this may cause malfunction or damage.
- Do not connect cables and leads to both RCA cable input jacks and the speaker input terminals simultaneously, for this may cause malfunction or damage.
- Connect the power control lead to a power supply which can be turned ON/OFF by the ignition key switch (ACC line). With this connection, shock noise may be generated when the power of the genuine-accessory car stereo is switched ON/OFF.
Speakers wire connection
Stereo Connections
[Diagram showing connection of Front Left, Front Right, Rear Left, and Rear Right speakers to Amplifier A and B speaker output terminals respectively, using '+' and '-' polarity.]
Bridged Connections
[Diagram showing connection of speakers to the bridged outputs of Amplifier A and B, using '+' and '-' polarity.]
Speaker Selection
The rated input power of the speakers that are going to be connected should be greater than the maximum output power (in Watts) of the amplifier. Use of speakers having input power ratings that are less than the output power of the amplifier will cause smoke to be emitted as well as damage.
The impedance of the speakers that are going to be connected should be 2Ω or greater (for stereo connections), or 4Ω or greater (for bridged connections). When more than one set of speakers are going to be used, calculate the combined impedance of the speakers and then connect suitable speakers to the amplifier.
Examples:
| Model | Stereo Connections (4Ω) | Bridged Connections (4Ω) |
| KAC-848 | 100 W or greater | 300 W or greater |
| KAC-748 | 70 W or greater | 200 W or greater |
[Diagram illustrating amplifier output, combined impedance, and speaker input power/impedance for stereo and bridged connections.]
Power Wire Connection
WARNING
To prevent fire caused by a short in the wiring, connect a fusible link or breaker nearby the battery's positive terminal.
Wiring
- If a buzzing noise is heard from the speakers when the engine is running, connect a line noise filter (optional) to each of the battery wire.
- Do not allow the cord to directly contact the edge of the iron plate by using Grommets.
- Connect the ground wire to a metal part of the car chassis that acts as an electrical ground passing electricity to the battery's negative terminal. Do not turn the power on if the ground wire is not connected.
- Be sure to attach a protective fuse into the battery wire close to the battery. Use a protective fuse having a capacity that is about 10 A higher than the maximum current drawn by the amplifier.
- Use vehicle-type (fire-resistant) power supply wiring wire for the battery wire and the ground wire. The current capacity of the power supply wiring wire should be about 10 A higher than that of the protective fuse capacity (which means about 20 A higher than the maximum current drawn by the amplifier).
- When more than one power amplifier are going to be used, use a power supply wiring wire and protective fuse of greater current-handling capacity than the total maximum current drawn by each amplifier.
Example: One Power Amplifier Is Used
| Model | Maximum Current Drawn | Protective Fuse | Cross-sectional Area of Wiring Wire (AWG) |
| KAC-848 | 38 A | 50 A x 1 [25 A x 2] | 5 mm² (AWG 10) or greater x 1 |
| KAC-748 | 28 A | 40 A x 1 [20 A x 2] | 5 mm² (AWG 10) or greater x 1 |
[Diagram showing connection of Battery wire, Power control wire, and Ground wire to the amplifier terminals (BATT, P.COM, GND) and Battery, including a Protective Fuse.]
System Examples
Full-range 4-channel + Subwoofer system
[Diagram showing a CENTER UNIT connected to the Amplifier. Amplifier outputs are connected to Front speaker, Rear speaker, and Subwoofer. Switch settings are indicated.]
High-pass (100 Hz) + Subwoofer (100 Hz) system
[Diagram showing system configuration with specific switch settings for high-pass and subwoofer. Subwoofer is shown as (L+R) (Bridged).]
High-power 2-channel system
[Diagram showing system connection to Left and Right speakers.]
Tri-mode
[Diagram showing system connection to Left speaker, Right speaker, and Subwoofer (L+R) (Bridged).]
Principle of Tri-mode
Method of frequency band division using a coil and capacitor...in case of 6dB/oct. slope
[Diagram showing a crossover frequency graph with lines for low-pass (Coil L) and high-pass (Capacitor C).]
Coil (L): Passes low frequencies and blocks high frequencies. (Low pass)
Capacitor (C): Passes high frequencies and blocks low frequencies. (High pass)
Formulas:
fc = 159000 / (C x R) [Cut of Frequency (Hz)]
L = (159 x R) / fc [Inductance in mH]
Where: fc = Cut of Frequency (Hz), R = Speaker Impedance (Ω)
Example:
When it is required to set a crossover frequency of 120 Hz using speakers with an impedance of 4 ohms.
Prepare commercially-available coil and capacitor with the closest ratings to the results calculated from the formula above. The capacitor rating should be as close as possible to 331.25 µF and the coil rating should be as close as possible to 5.3 mH.
CAUTION
- If you wish to bridge-connect a speaker, the speaker impedance must be no less than 4 ohms. Connecting a speaker with an impedance lower than 4 ohms may damage the unit.
- Be sure to connect capacitors to speakers to which high frequencies will be passed. Failure to do so will result in a drop of the combined impedance with the subwoofer.
- Ensure that the withstand voltage and current ratings of the capacitors (C) and coils (L) are sufficient.
Troubleshooting Guide
What might appear to be a malfunction in your unit may just be the result of slight misoperation or miswiring. Before calling service, first check the following table for possible problems.
| PROBLEM | POSSIBLE CAUSE | SOLUTION |
| No sound. (No sound from one side.) | Input (or output) wires are disconnected. | Connect the input (or output) wires. |
| Protection circuit may be activated. | Check connections by referring to "Protection function". | |
| The fuse may be blown because the volume was too high. | Replace the fuse with a new fuse and use a lower volume. | |
| The output level is too small (or too large). | The input sensitivity adjusting control is not set to the correct position. | Adjust the control correctly referring to "Controls". |
| The sound quality is bad. (The sound is distorted.) | The speakers wire are connected with wrong polarity. | Connect them properly checking the +/- of the terminals and wires well. |
| A speaker wire is pinched by a screw in the car body. | Connect the speaker wire again so that it is not pinched by anything. | |
| The switches may be set improperly. | Set switches properly by referring to "System examples". |
Specifications
Specifications subject to change without notice.
Audio Section
| KAC-848 | KAC-748 | |
| Max Power Output (4 Ω) | 100 W x 4 | 70 W x 4 |
| 4 Channel Mode | 100 W x 2 + 300 W x 1 | 70 W x 2 + 200 W x 1 |
| 3 Channel Mode | 300 W x 2 | 200 W x 2 |
| 2 Channel Mode | ||
| 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 (11-7/16x2-3/16x11 in.) | 290 x 56 x 230 mm (11-7/16x2-3/16x9-1/16 in.) |
| Weight | 4.3 kg (9.4 lb) | 3.7 kg (8.1 lb) |
