Kenwood KAC-728 User manual

KAC-728
KAC-628
KAC-528
POWER AMPLIFIER
INSTRUCTION MANUAL
B64-1360-00 (EM)

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 mm2
(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.
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.
• 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.
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
2CAUTION
NOTE
2CAUTION
2WARNING
2
Safety precautions
Part name Number of
Items
External
View
Round terminal
(Large) 1
Round terminal
(Medium) 2
Round terminal
(Small) 1
Terminal cover
(Power terminal) 1
Self-tapping screws
(ø4 ×16 mm) 4

3
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 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 120°C (248°F).
• 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.
Power indicator
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.
• 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.
2CAUTION

4
Controls
Operations of the following control and switches are required in accordance with the center
unit and speakers connected with this unit.
FUSE(15A)
POWER IN
BATT P.CON(REMOTE)
GND
LEFT
BRIDGED RIGHT
SPEAKER OUTPUT
POWER AMPLIFIER
15
LPF
FILTER
OFF MONO(Lch)
STEREO
OPERATION
GND INPUT
SENSITIVITY(V)
MAXMIN
0.30.5
1.0
LR
LINE IN
LEFT RIGHT
SPEAKER LEVEL INPUT
FUSE(25A)
POWER IN
BATT P.CON(REMOTE)
GND
LEFT
BRIDGED RIGHT
SPEAKER OUTPUT
POWER AMPLIFIER
25
LPF
FILTER
HPF MONO(Lch)
STEREO
OFF L+R
OPERATION
GND INPUT
SENSITIVITY(V)
MAXMIN
0.30.5
1.0
LR
LINE IN
LEFT RIGHT
SPEAKER LEVEL INPUT
LPF
FILTER
OFF MONO(Lch)
STEREO
OPERATION
GND INPUT
SENSITIVITY(V)
MAXMIN
0.30.5
1.0
LR
LINE IN
LEFT RIGHT
SPEAKER LEVEL INPUT
FUSE(20A x 2)
POWER IN
BATT P.CON(REMOTE)
GND
LEFT
BRIDGED RIGHT
SPEAKER OUTPUT
POWER AMPLIFIER
20 20
1
!0987
!0987
!
6
0987
5432
1 65432
1 65432
KAC-628
KAC-528
KAC-728
KAC-628
KAC-528
KAC-728

5
1 RCA cable ground lead terminal
2 FILTER switch
These switches allow filtering of the
speaker output signals.
• 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.
• OFF position
The original sound without filtering is
output.
3 OPERATION switch
This switch allows selection of the
amplification method of input signals.
• 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
right as a guide.
For the pre-output level or
the maximum power output,
refer to the “Specifications”
in the instruction manual of the center unit.
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 2Ωor 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 4Ωor greater. When
multiple speakers are to be connected,
ensure that the combined impedance is 4Ω
or greater.
The rated input of the speakers should be
no less than the maximum output of the
amplifier. Otherwise malfunction may
result.
2CAUTION
NOTE
MAXMIN
0.30.5
1.0
(W)
25
15
10
LPF
FILTER
OFF
KAC-728/528
LPF
FILTER
HPF
OFF
KAC-628
MONO(Lch)
STEREO
OPERATION
KAC-728/528
MONO(Lch)
STEREO
L+R
OPERATION
KAC-628

6
LPF
FILTER
OFF MONO(Lch)
STEREO
OPERATION
GND INPUT
SENSITIVITY(V)
MAXMIN
0.30.5
1.0
LR
LINE IN
LEFT RIGHT
SPEAKER LEVEL INPUT
LEFTRIGHT
SPEAKER LEVEL INPUT
LPF
FILTER
OFF MONO(Lch)
STEREO
OPERATION
GND INPUT
SENSITIVITY(V)
MAXMIN
0.30.5
1.0
L R
LINE IN
LEFT RIGHT
SPEAKER LEVEL INPUT
GND
■ 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.
2CAUTION
CENTER UNIT
(Cassette receiver,
CD receiver, etc.)
RCA cable
(Commercially
available part)
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.
2CAUTION
Left output (White)
Right output (Red)
Left input Right input
• 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.
2CAUTION
Genuine-accessory
car stereo
■ 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.
2CAUTION
Left output
Right output
Lead terminal
(Commercially available parts)
Left input Right input
Connection
RCA cable ground terminal
To Power control
(REMOTE) terminal
To Power control
(REMOTE) terminal
Battery

7
POWER IN
BATT P.CON(REMOTE)
GND
LEFT
BRIDGED RIGHT
SPEAKER OUTPUT
POWER AMPLIFIER
LEFT
BRIDGED
RIGHT
■ Speakers cable connection
(Stereo Connections)
Left
speaker
Right
speaker
(Bridged Connections)
Lead terminal
(Commercially available parts)
Left output Right output
POWER IN
BATT P.CON(REMOTE)
GND
LEFT
BRIDGED RIGHT
SPEAKER OUTPUT
POWER AMPLIFIER
LEFT
BRIDGED
RIGHT
Lead terminal
(Commercially available parts)
Examples:
■ 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 2Ωor greater (for
stereo connections), or 4Ωor 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.
Model Stereo Connections (4 Ω ) Bridged Connections (4 Ω )
KAC-728 200 W or greater 600 W or greater
KAC-628 100 W or greater 300 W or greater
KAC-528 70 W or greater 200 W or greater
200W
(4Ω)
4 Ω
200W
(4Ω)200W (4Ω)200W (4Ω)
4 Ω4 Ω
200W
(2Ω)100W
(8Ω)100W (8Ω)
200W
(2Ω)
Maximum output of
the amplifier Combined
impedance Rated input power and
impedance of the speakers

8
POWER IN
BATT P.CON(REMOTE)
GND
LEFT
BRIDGED RIGHT
SPEAKER OUTPUT
POWER AMPLIFIER
■ Power cable connection
To prevent fire caused by a short in the wiring, connect a fusible link or breaker nearby the
battery’s positive terminal.
2WARNING
Terminal cover
Battery
Ground cable
(Commercially available parts)
Battery cable
(Commercially available parts)
Protective
Fuse
Power control cable
(Commercially available parts)
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 battery‘s 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.
Connection
CENTER UNIT
ACC
Round terminal (Large)
Round terminal (Small)
Power terminal
Round terminal (Medium)
Car fuse box

9
Installation
• 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.
• Use the extension cables. (Optional.)
• 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.
2CAUTION
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Installation board, etc.
(thickness : 15 mm or more)
Self-tapping screw
(ø4 ×16 mm)
CA-2SL CA-12SL CA-22SL CA-52SLRCA cable
CA-3WL CA-13WL CA-23WL CA-53WLRCA cable (ø7mm)
CA-5W CA-15W CA-25W CA-45W CA-65W
RCA cable (ø12mm)
0.5m 1m 2m 4m 5m 6m
Type Length
Model
KAC-728
KAC-628
KAC-528
Maximum Current
Drawn
28 A
19 A
16 A
Protective Fuse
50 A ×1 [25 A ×2]
30 A ×1
25 A ×1
Cross-sectional Area of Wiring
Cable (AWG)
5 mm2(AWG 10) or greater ×1
3 mm2(AWG 12) or greater ×1
3 mm2(AWG 12) or greater ×1
Example: One Power Amplifier Is Used
50 A 25 A 25 A
25 A
25 A

10
System examples
● Principle of Tri-mode
Method of frequency band division using a coil and capacitor•••in case of 6dB/oct. slope
LC
0 dB
-3 dB
Coil (L): Passes low frequencies and blocks high
frequencies. (Low pass)
Capacitor (C): Passes high frequencies and blocks low
frequencies. (High pass)
Crossover Frequency
Frequency
159000
C= (µF)
fc x R
159 x R
L= (mH)
fc
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).
• 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.
2CAUTION
L
R
L
R
L
R
L
R
L
R
L
R
L
R
L
R
L
R
L
R
L
R
L
C
C
MONO(Lch)
STEREO
OPERATION
MONO(Lch)
STEREO
L+R
OPERATION
KAC-728/528
KAC-628
LPF
FILTER
OFF
LPF
FILTER
HPF
OFF
MONO(Lch)
STEREO
OPERATION
MONO(Lch)
STEREO
L+R
OPERATION
KAC-728/528
KAC-628
LPF
FILTER
OFF
LPF
FILTER
HPF
OFF
MONO(Lch)
STEREO
OPERATION
MONO(Lch)
STEREO
L+R
OPERATION
KAC-728/528
KAC-628
LPF
FILTER
OFF
LPF
FILTER
HPF
OFF
MONO(Lch)
STEREO
OPERATION
MONO(Lch)
STEREO
L+R
OPERATION
KAC-728/528
KAC-628
LPF
FILTER
OFF
LPF
FILTER
HPF
OFF
CENTER UNIT
CENTER UNIT
CENTER UNIT
CENTER UNIT High
pass
Subwoofer
(L + R)
(Bridged)
■ Full-range 2-channel system
■ Full-range 2-channel + Subwoofer system
■ Tri-mode
■ High-power full-range 2-channel system
Switch setting
Switch setting
Switch setting
Switch setting
Right speaker
Left speaker
Right speaker (Bridged)
Left speaker (Bridged)
Right speaker
Left speaker
Subwoofer
(L + R)
(Bridged)

11
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.)
The output level is too
small (or too large).
The sound quality is bad.
(The sound is distorted.)
• Input (or output) cables are
disconnected.
• Protection circuit may be
activated.
• The fuse may be blown because
the volume was too high.
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.
• Connect the input (or output)
cables.
• Check connections by referring
to "Protection function".
• Replace the fuse with a new
fuse and use a lower volume.
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".

12
Specifications
Specifications subject to change without notice.
Audio Section ..............................................KAC-728 KAC-628 KAC-528
Max Power Output (4 Ω)
Normal..............................................................200 W ×2 100 W ×2 70 W ×2
Bridge ..............................................................600 W ×1 300 W ×1 200 W ×1
Rated Power Output (4 Ω)
Normal (DIN45324, +B=14.4 V) ......................100 W ×2 50 W ×2 35 W ×2
Bridge (1 kHz, 0.8 % THD) ..............................300 W ×1 150 W ×1 100 W ×1
Rated Power Output (2 Ω)
Normal (1 kHz, 0.8 % THD) ..............................150 W ×2 75 W ×2 50 W ×2
Frequency Response (+0, –1 dB) ........................5 Hz ~ 50 kHz 10 Hz ~ 45 kHz 5 Hz ~ 50 kHz
Signal to Noise Ratio ............................................100 dB 100 dB 100 dB
Sensitivity (MAX) (rated output) ..........................0.2 V 0.15 V 0.2 V
Sensitivity (MIN) (rated output) ............................5.0 V 4.0 V 5.0 V
Input Impedance ..................................................10 kΩ10 kΩ10 kΩ
Low Pass Filter (12 dB/oct.) ................................80 Hz 80 Hz 80 Hz
High Pass Filter (12 dB/oct.) ................................ 150 Hz
General..........................................................KAC-728 KAC-628 KAC-528
Operating Voltage (11 ~ 16 V allowable)..............14.4 V 14.4 V 14.4 V
Current Consumption (1 kHz, 10% THD) ............28 A 19 A 16 A
Dimensions (W ×H ×D)[mm] ..............................220 ×56.1 ×300220 ×56.1 ×228 220 ×55 ×160
Weight..................................................................3.6 kg 2.7 kg 1.8 kg