KAC-728 KAC-628 KAC-528

POWER AMPLIFIER

INSTRUCTION MANUAL

B64-1360-00 (EM)

Safety precautions

2WARNING 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.
To prevent injury and/or fire, take the following precautions: When extending the battery or ground cables, make sure to use automotive-grade cables or other cables with an area of 5 mm 2 (AWG10) or more to prevent cable deterioration and damage to the cable coating. To prevent short circuits, never put or leave any metallic objects (e.g., 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.

2CAUTION

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. 2CAUTION 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.

Accessories

Part name
Round terminal (Large) Round terminal (Medium) Round terminal (Small) Terminal cover (Power terminal) Self-tapping screws (mm)
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 short circuits when replacing a fuse, first disconnect the wiring harness.

External View

Number of Items

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.

s 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. Power indicator
s The protection function activates in the following situations:
When a speaker cable may be short-circuited. When a speaker output contacts ground. When the unit malfunctions and a DC signal is sent to the speaker output. When the temperature of internal parts exceeds 120C (248F). When a ground cable 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.

Installation procedure

1. Remove the ignition key and disconnect the negative - terminal of the battery to prevent short circuits. 2. Set the unit according to the intended usage. 3. Connect the input and output cables of the units. 4. Connect the speaker cables. 5. Connect the power cable, power control cable and grounding cable following this order. 6. Install the unit in the car. 7. Connect the negative - terminal of the battery. 2CAUTION Be sure to turn the power off before changing the setting of any switch. If the fuse blows, check cables for shorts, then replace the fuse with one of the same rating. Check that no unconnected cables or connectors are touching the car body. Do not remove caps from unconnected cables or connectors to prevent short circuits. Connect the speaker cables to appropriate speaker connectors separately. Sharing the negative cable of the speaker or grounding speaker cables 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.

Controls

Operations of the following control and switches are required in accordance with the center unit and speakers connected with this unit.

FILTER

OFF LPF

OPERATION

STEREO MONO(Lch) 0.5 1.0 0.3
SPEAKER LEVEL INPUT LEFT RIGHT LINE IN L R

KAC-728

INPUT SENSITIVITY(V)

OFF HPF LPF

L+R STEREO MONO(Lch) 0.5 0.3

KAC-628

SPEAKER LEVEL INPUT LEFT RIGHT

KAC-528

LINE IN L R

POWER IN

BRIDGED

FUSE(20A x 2)

P.CON(REMOTE)

RIGHT SPEAKER OUTPUT

FUSE(25A)

FUSE(15A)

GND P.CON(REMOTE)

SPEAKER OUTPUT

POWER IN BATT
1 RCA cable ground lead terminal 2 FILTER switch
These switches allow filtering of the speaker output signals. KAC-628 KAC-728/528 FILTER

OFF LPF OFF HPF LPF

HPF (High Pass Filter) position (KAC-628 only)
Only frequencies of 150 Hz or higher are output. (Frequencies below 150 Hz are cut.)
LPF (Low Pass Filter) position
Only frequencies of 80 Hz or lower are output. (Frequencies above 80 Hz are cut.) The Lch and Rch will be mixed before output even if the operation switch is set to STEREO.
5 LINE IN terminal 6 Speaker level input terminals 7 Fuse (20 A 2 : KAC-728) Fuse (25 A 1 : KAC-628) Fuse (15 A 1 : KAC-528) 8 Battery terminal 9 Ground terminal 0 Power control (REMOTE) terminal ! 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 2 or greater. When multiple speakers are to be connected, ensure that the combined impedance is 2 or greater for each channel.

OFF position

The original sound without filtering is output.

Bridged Connections:

When you wish to use the unit as a highoutput 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 4 or greater. When multiple speakers are to be connected, ensure that the combined impedance is 4 or greater. 2CAUTION The rated input of the speakers should be no less than the maximum output of the amplifier. Otherwise malfunction may result.

3 OPERATION switch

This switch allows selection of the amplification method of input signals. KAC-728/528

STEREO MONO(Lch)

L+R STEREO MONO(Lch)

STEREO position

The amplifier can be used as a stereo amplifier.
L+R position (KAC-628 only)
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.)
4 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 10 0.5 0.3 right as a guide. NOTE

15 1.0

For the pre-output level or MIN MAX the maximum power output, 25 (W) refer to the Specifications in the instruction manual of the center unit.

Connection

s RCA cable connection
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. Right input Left input RCA cable ground terminal
To Power control (REMOTE) terminal CENTER UNIT (Cassette receiver, CD receiver, etc.) Left output (White)
RCA cable (Commercially available part)

Right output (Red)

RCA cable ground terminal When using an RCA cable with a ground lead attached, connect the ground lead to this terminal.
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.
s Speaker level input connection
Connect the unit by inserting it in the connection between the genuine-accessory car stereo and speakers.
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. Left input
EAT SP LEF ER K P IN L IGHT VE R LE T U

Right input

Lead terminal (Commercially available parts) Genuine-accessory car stereo
To Power control (REMOTE) terminal Left output Right output Battery
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. 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.

s Speakers cable connection (Stereo Connections)

Left output

Right output

ED IDG BR

BATT P.CON(REMOTE)

LE RIGHT SPEAKER OUTPUT

Lead terminal (Commercially available parts) Right speaker Left speaker

(Bridged Connections)

Lead terminal (Commercially available parts)

s 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 2 or greater (for stereo connections), or 4 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 KAC-728 KAC-628 KAC-528

200W (4)

Stereo Connections (4) 200 W or greater 100 W or greater 70 W or greater

200W (2) 200W (2)

Bridged Connections (4) 600 W or greater 300 W or greater 200 W or greater

100W (8) 100W (8)

Maximum output of the amplifier Combined impedance
Rated input power and impedance of the speakers

s Power cable connection

2WARNING
To prevent fire caused by a short in the wiring, connect a fusible link or breaker nearby the batterys positive terminal.

Power terminal

Round terminal (Small) Round terminal (Medium) Terminal cover CENTER UNIT Car fuse box Power control cable (Commercially available parts) Battery cable (Commercially available parts) ACC
Ground cable (Commercially available parts)
Round terminal (Large) Protective Fuse

Battery

Power terminal Connect to their respective terminals the power control cable, power supply cable, and ground cable, all of which pass through the associated terminal cover. Once the connections are complete, place the cover on the terminal section. 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 cable. Do not allow the cord to directly contact the edge of the iron plate by using Grommets. Connect the ground cable to a metal part of the car chassis that acts as an electrical ground passing electricity to the batterys negative - terminal. Do not turn the power on if the ground cable is not connected. Be sure to attach a protective fuse into the battery cable 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 cable for the battery cable and the ground cable. The current capacity of the power supply wiring cable 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 cable 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 28 A 19 A 16 A

Protective Fuse

50 A 1 [25 A 2] 30 A A 1
Cross-sectional Area of Wiring Cable (AWG) 5 mm2 (AWG 10) or greater mm2 (AWG 12) or greater mm2 (AWG 12) or greater 1

25 A 50 A 25 A 25 A 25 A

Installation

Self-tapping screw (mm)

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Installation board, etc. (thickness : 15 mm or more)
Since the power amplifier has no parts which require operation, it can be installed at a position away from the drivers seat without any hindrances. As generally accepted positions for its installation, places such as inside the trunk, etc. can be considered. Use the extension cables. (Optional.) Length 0.5m 1m 2m 4m 5m 6m Type RCA cable CA-2SL CA-12SL CA-22SL CA-52SL RCA cable (7mm) CA-3WL CA-13WL CA-23WL CA-53WL RCA cable (12mm) CA-15W CA-45W CA-5W CA-25W CA-65W 2CAUTION 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.

System examples

s Full-range 2-channel system

KAC-728/528

MONO(Lch)

LPF STEREO

CENTER UNIT
Left speaker Right speaker

FILTER OPERATION

L+R OFF HPF LPF STEREO MONO(Lch)

Switch setting

s High-power full-range 2-channel system

L R L R

Left speaker (Bridged) Right speaker (Bridged)
s Full-range 2-channel + Subwoofer system
Subwoofer (L + R) (Bridged)

s Tri-mode

High pass
qPrinciple of Tri-mode Method of frequency band division using a coil and capacitorin case of 6dB/oct. slope Crossover Frequency 0 dB -3 dB

Frequency

qExample: 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 (F) and the coil rating should be as close as possible to 5.3 (mH). 2CAUTION 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.
Coil (L): Passes low frequencies and blocks high frequencies. (Low pass) Capacitor (C): Passes high frequencies and blocks low frequencies. (High pass) 159000 C= (F) fc=Cut of Frequency (Hz) fc x R R=Speaker Impedance () 159 x R L= (mH) fc

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

No sound. (No sound from one side.)

POSSIBLE CAUSE

SOLUTION
Input (or output) cables are Connect the input (or output) disconnected. cables. Protection circuit may be Check connections by referring activated. to "Protection function". The fuse may be blown because Replace the fuse with a new the volume was too high. fuse and use a lower volume. The input sensitivity adjusting control is not set to the correct position. The speakers cable are connected with wrong + / polarity. A speaker cable is pinched by a screw in the car body. The switches may be set improperly. Adjust the control correctly referring to Controls. Connect them properly checking the + / - of the terminals and cables well. Connect the speaker cable again so that it is not pinched by anything. Set switches properly by referring to "System examples".

The output level is too small (or too large). The sound quality is bad. (The sound is distorted.)

Specifications

Specifications subject to change without notice.

Audio Section...KAC-728

Max Power Output (4 ) Normal..200 W 2 Bridge..600 W 1 Rated Power Output (4 ) Normal (DIN45324, +B=14.4 V)..100 W 2 Bridge (1 kHz, 0.8 % THD)..300 W 1 Rated Power Output (2 ) Normal (1 kHz, 0.8 % THD)..150 W 2 Frequency Response (+0, 1 dB).5 Hz ~ 50 kHz Signal to Noise Ratio..100 dB Sensitivity (MAX) (rated output).0.2 V Sensitivity (MIN) (rated output)..5.0 V Input Impedance..10 k Low Pass Filter (12 dB/oct.)..80 Hz High Pass Filter (12 dB/oct.)..
100 W W W W W Hz ~ 45 kHz 100 dB 0.15 V 4.0 V 10 k 80 Hz 150 Hz
70 W W W W W Hz ~ 50 kHz 100 dB 0.2 V 5.0 V 10 k 80 Hz

General...KAC-728

14.4 V 16 A 160 1.8 kg
Operating Voltage (11 ~ 16 V allowable).14.4 V 14.4 V Current Consumption (1 kHz, 10% THD).28 A 19 A Dimensions (W H D)[mm]..220 56.220 56.Weight...3.6 kg 2.7 kg