Kenwood KAC-745 Instruction Manual

General installation requirements for the Kenwood KAC-745 amplifier include:

• Installation Procedure:

1. Remove the ignition key and disconnect the negative (-) terminal of the battery to prevent short circuits.

2. Connect the input and output cables of the units.

3. Connect the speaker cables.

4. Connect the ground cable and power supply cable in the order listed.

5. Install the unit in the car.

6. Connect the negative (-) terminal of the battery.

• Precautions:
  • If the fuse blows, check cables for shorts, then replace the fuse with one of the same rating.
  • Ensure no unconnected cables or connectors are touching the car body and do not remove caps from them.
  • Connect the speaker cables to appropriate speaker connectors separately; sharing the negative cable or grounding to the car's metal body can cause unit failure.
  • After installation, check that electrical equipment such as brake lamps, winkers, and wipers work properly.
• Installation Location:
  • Do not install the unit under the carpet as heat build-up can occur.
  • It can be installed in a position away from the driver's seat, such as inside the trunk, as it requires no operation.
  • Install the unit in a location which allows heat to easily dissipate.
  • Do not place any object on top of the unit once installed.
  • Install the unit securely in a location that does not interfere with driving.

To correctly wire the Kenwood KAC-745 amplifier to your car's audio system, follow these steps:

• RCA Cable Connections:
  • Connect the Left output (White) and Right output (Red) from your center unit to the amplifier's Left (Mono) input (White) and Right input (Red) terminals, respectively.
  • If using an RCA cable with a ground lead, connect the RCA cable ground lead to the designated terminal.
• Power Control Lead:
  • Connect the amplifier's Power control lead terminal to the power control cord from the center unit.
• Power and Ground Connections:
  • Connect the Power cord and Ground cord to their respective terminals on the amplifier.
  • Connect the ground leads to a metal part of the car chassis that acts as an electrical ground.
  • Use 3mm² (AWG12) or larger automotive grade cable for power supply, memory backup, or ground cables.
  • Connect a fusible link or breaker nearby the battery terminal to prevent fire caused by shorts.
• Speaker Connections:
  • Connect the speaker leads to the appropriate speaker lead terminals on the amplifier for Front Left, Front Right, Rear Left, and Rear Right speakers.

The Kenwood KAC-745 is a 4-channel power amplifier. Its power output specifications are:

• Max Power Output (4 Ω):
  • 4 Channel Mode: 80 W x 4
  • 3 Channel Mode: 80 W x 2 + 160 W
  • 2 Channel Mode: 160 W x 2
• Rated Power Output (4 Ω):
  • 4 Channel Mode: 40 W x 4 (20 Hz-20 kHz, less than 0.08% THD)
  • 3 Channel Mode: 40 W x 2 (1 kHz, 0.08% THD) + 110 W x 1 (1 kHz 0.8%)
  • 2 Channel Mode: 110 W x 2 (1 kHz, 0.8% THD)
• Rated Power Output (2 Ω):
  • 4 Channel Mode: 55 W x 4 (1 kHz, 0.8% THD)

To tune your Kenwood KAC-745 amplifier for optimal sound:

• Adjust the Input sensitivity control according to the pre-out level of your center unit.
• Utilize the FILTER switch to apply a filter to the output signals. You can select:
  • HPF (High-Pass Filter) position (12dB/oct.) for frequencies of 80 Hz or higher.
  • LPF (Low-Pass Filter) position (12dB/oct.) for frequencies of 80 Hz or lower.
• For Low pass filter adjustment, set the switch to ON and the frequency control to the 80 Hz position.

To troubleshoot low or no sound from your Kenwood KAC-745 amplifier, refer to the following:

• Symptom: No sound (No sound from one side.)
  • Cause: A speaker cord has become unconnected.
  • Remedy: Check the speaker cord connections.
• Symptom: The level is too low (or high).
  • Cause: The input sensitivity adjusting knob is not set to the correct position.
  • Remedy: Adjust correctly referring to "Controls".

Recommended audio settings for the Kenwood KAC-745 amplifier include:

• Adjust the Input sensitivity control according to the pre-out level of your center unit.
• Use the FILTER switch to apply filters to the output signals:
  • HPF (High-Pass Filter) for frequencies of 80 Hz or higher.
  • LPF (Low-Pass Filter) for frequencies of 80 Hz or lower.
• For Low pass filter adjustment, set the switch to ON and the frequency control to the 80 Hz position.

The Kenwood KAC-745 amplifier is compatible with speakers that have an overall speaker impedance of no less than 4 ohms. If the impedance is less than 4 ohms, excessive current may flow and the amplifier unit may be damaged.

Your Kenwood KAC-745 amplifier may not be turning on if the ground leads are not connected. Ensure all ground leads are properly connected before attempting to turn on the power.

Yes, the Kenwood KAC-745 amplifier has a built-in crossover feature. It includes a FILTER switch that allows you to apply filters to the output signals. This switch provides:

• HPF (High-Pass Filter) position (12dB/oct.), which outputs frequencies of 80 Hz or higher.
• LPF (Low-Pass Filter) position (12dB/oct.), which outputs frequencies of 80 Hz or lower.

Additionally, the amplifier supports Tri-mode operation for frequency band division using coils and capacitors, allowing for a defined crossover frequency.

Common causes of overheating in the Kenwood KAC-745 amplifier include:

• Installing the unit under the carpet, which can lead to heat build-up.
• Not installing the unit in a location that allows heat to easily dissipate.
• Placing any object on top of the unit once installed.
• Connecting speakers with an overall speaker impedance of less than 4 ohms, which can cause excessive current to flow and potentially damage the amplifier unit.

Wiring schematics for the Kenwood KAC-745 amplifier can be found in the manual under the following sections:

• System connection
• Power and Speakers lead connection