KAC-728
KAC-628
KAC-528
POWER AMPLIFIER
INSTRUCTION MANUAL
B64-1360-00 (EM)
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.
Power indicator
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.
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.
3
Controls
Operations of the following control and switches are required in accordance with the center
unit and speakers connected with this unit.
SPEAKER LEVEL INPUT
LEFT
RIGHT
OPERATION
STEREO MONO(Lch)
FILTER
OFF LPF
LINE IN
L
R
0.5 0.3
KAC-728
1.0
GND
MIN
INPUT
SENSITIVITY(V)
MAX
1
2
3 4
5
6
SPEAKER LEVEL INPUT
LEFT RIGHT
OPERATION
FILTER
OFF
L+R
LINE IN
HPF
LPF
STEREO MONO(Lch)
L
R
0.5 0.3
1.0
KAC-628
KAC-528
GND
MIN
INPUT
SENSITIVITY(V)
MAX
1
2
3 4
5
6
SPEAKER LEVEL INPUT
LEFT RIGHT
OPERATION
STEREO MONO(Lch)
FILTER
OFF
LPF
LINE IN
L
R
0.5 0.3
1.0
GND
MIN
INPUT
SENSITIVITY(V)
MAX
1
2
3 4
5
6
POWER IN
GND
BRIDGED
LEFT
FUSE(20A
x
2)
BATT
P.CON(REMOTE)
RIGHT
SPEAKER OUTPUT
KAC-728
KAC-628
POWER AMPLIFIER
7
8 9 0
!
POWER IN
BRIDGED
LEFT
GND
P.CON(REMOTE)
RIGHT
SPEAKER OUTPUT
FUSE(25A)
BATT
POWER AMPLIFIER
7
8 9 0
!
POWER IN
BRIDGED
LEFT
GND
P.CON(REMOTE)
RIGHT
SPEAKER OUTPUT
FUSE(15A)
BATT
KAC-528
POWER AMPLIFIER
7
8 9 0
!
4
1 RCA cable ground lead terminal
5 LINE IN terminal
2 FILTER switch
6 Speaker level input terminals
These switches allow filtering of the
speaker output signals.
7 Fuse (20 A × 2 : KAC-728)
Fuse (25 A × 1 : KAC-628)
Fuse (15 A × 1 : KAC-528)
KAC-628
KAC-728/528
FILTER
OFF
FILTER
OFF LPF
HPF
LPF
8 Battery terminal
9 Ground terminal
0 Power control (REMOTE) terminal
• HPF (High Pass Filter) position
(KAC-628 only)
Only frequencies of 150 Hz or higher are
output. (Frequencies below 150 Hz are cut.)
! SPEAKER OUTPUT terminals
• 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.
• 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.
3 OPERATION switch
This switch allows selection of the
amplification method of input signals.
KAC-628
KAC-728/528
OPERATION
STEREO MONO(Lch)
OPERATION
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.
2CAUTION
The rated input of the speakers should be
no less than the maximum output of the
amplifier. Otherwise malfunction may
result.
• 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.
10
0.5 0.3
15
NOTE
1.0
For the pre-output level or
the maximum power output,
refer to the “Specifications”
MIN
MAX
25
(W)
in the instruction manual of the center unit.
5
Connection
■ RCA cable connection
2CAUTION
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
SPEAKER LEVEL INPUT
LEFT RIGHT
OPERATION
STEREO MONO(Lch)
FILTER
OFF LPF
LINE IN
D
N
G
L
R
0.5 0.3
1.0
GND
MIN
INPUT
SENSITIVITY(V)
MAX
To Power control
(REMOTE) terminal
RCA cable
(Commercially
available part)
Left output (White)
Right output (Red)
CENTER UNIT
(Cassette receiver,
CD receiver, etc.)
RCA cable ground terminal
When using an RCA cable with a ground lead attached, connect the ground lead to this
terminal.
2CAUTION
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
Connect the unit by inserting it in the connection between the genuine-accessory car stereo
and speakers.
2CAUTION
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
T
H
IG
R
SPEAKER LEVEL INPUT
LEFT RIGHT
T
F
SPEAKER LEVEL INPUT
LE
OPERATION
STEREO MONO(Lch)
FILTER
OFF LPF
LINE IN
L
R
0.5 0.3
GND
MIN
INPUT
SENSITIVITY(V)
MAX
Lead terminal
(Commercially available parts)
To Power control
(REMOTE) terminal
Left output
Genuine-accessory
car stereo
Right output
Battery
2CAUTION
• 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.
6
■ Speakers cable connection
(Stereo Connections)
Left output
Right output
T
H
IG
R
POWER IN
BRIDGED
T
F
E
L
GND
BRIDGED
LEFT
BATT
P.CON(REMOTE)
RIGHT
SPEAKER OUTPUT
POWER AMPLIFIER
Lead terminal
(Commercially available parts)
Right
speaker
Left
speaker
(Bridged Connections)
T
H
IG
R
POWER IN
BRIDGED
T
F
E
L
GND
BRIDGED
LEFT
BATT
P.CON(REMOTE)
RIGHT
SPEAKER OUTPUT
POWER AMPLIFIER
Lead terminal
(Commercially available parts)
■ 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
KAC-728
KAC-628
KAC-528
Stereo Connections (4Ω)
Bridged Connections (4Ω)
200 W or greater
100 W or greater
70 W or greater
600 W or greater
300 W or greater
200 W or greater
200W
(2Ω)
100W
200W
100W
(8Ω)
200W
200W
200W
(4Ω)
(8Ω)
(4Ω)
(4Ω)
(4Ω)
200W
(2Ω)
4 Ω
4 Ω
4 Ω
Maximum output of
the amplifier
Combined
impedance
Rated input power and
impedance of the speakers
7
Connection
■ Power cable connection
2WARNING
To prevent fire caused by a short in the wiring, connect a fusible link or breaker nearby the
battery’s positive terminal.
POWER IN
GND
BRIDGED
LEFT
BATT
P.CON(REMOTE)
RIGHT
SPEAKER OUTPUT
POWER AMPLIFIER
Power terminal
Round terminal (Small)
Round terminal (Medium)
Terminal cover
CENTER UNIT
Car fuse box
Power control cable
(Commercially available parts)
ACC
Battery cable
(Commercially available parts)
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 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.
8
Example: One Power Amplifier Is Used
Model
Maximum Current
Drawn
Protective Fuse
Cross-sectional Area of Wiring
Cable (AWG)
2
KAC-728
KAC-628
KAC-528
28 A
19 A
16 A
50 A × 1 [25 A × 2]
30 A × 1
5 mm (AWG 10) or greater × 1
2
3 mm (AWG 12) or greater × 1
2
25 A × 1
3 mm (AWG 12) or greater × 1
25 A
25 A
50 A
25 A
25 A
Installation
Self-tapping screw
(ø4 × 16 mm)
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 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.)
Length
0.5m
1m
2m
4m
5m
6m
Type
RCA cable
RCA cable (ø7mm)
RCA cable (ø12mm)
CA-2SL
CA-12SL CA-22SL
CA-52SL
CA-53WL
CA-3WL CA-13WL CA-23WL
CA-5W CA-15W CA-25W
CA-45W
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.
9
System examples
■ Full-range 2-channel system
KAC-728/528
Left speaker
L
L
OPERATION
FILTER
OFF
LPF STEREO MONO(Lch)
CENTER UNIT
R
R
Right speaker
KAC-628
OPERATION
L+R
FILTER
OFF
HPF
LPF STEREO MONO(Lch)
Switch setting
■ High-power full-range 2-channel system
L
KAC-728/528
L
L
Left speaker (Bridged)
Right speaker (Bridged)
OPERATION
FILTER
OFF
LPF STEREO MONO(Lch)
R
R
CENTER UNIT
Switch setting
L
L
KAC-628
R
OPERATION
L+R
FILTER
R
R
OFF
HPF
LPF STEREO MONO(Lch)
■ Full-range 2-channel + Subwoofer system
KAC-728/528
Left speaker
OPERATION
FILTER
CENTER UNIT
OFF
LPF STEREO MONO(Lch)
Right speaker
KAC-628
L
L
Subwoofer
(L + R)
(Bridged)
OPERATION
L+R
FILTER
OFF
HPF
R
R
LPF STEREO MONO(Lch)
Switch setting
■ Tri-mode
L
C
C
KAC-728/528
Subwoofer
(L + R)
(Bridged)
OPERATION
L
L
FILTER
High
pass
OFF
LPF STEREO MONO(Lch)
CENTER UNIT
Switch setting
R
R
KAC-628
OPERATION
L+R
FILTER
OFF
HPF
LPF STEREO MONO(Lch)
●Principle of Tri-mode
Method of frequency band division using a coil and capacitor•••in case of 6dB/oct. slope
Coil (L): Passes low frequencies and blocks high
Crossover Frequency
frequencies. (Low pass)
0 dB
-3 dB
Capacitor (C): Passes high frequencies and blocks low
frequencies. (High pass)
159000
L
C
C=
L=
(µF)
fc=Cut of Frequency (Hz)
fc x R
159 x R
fc
R=Speaker Impedance (Ω)
Frequency
(mH)
●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).
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.
10
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) cables are
disconnected.
• Connect the input (or output)
cables.
• Protection circuit may be
activated.
• Check connections by referring
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 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 cable are
connected with wrong + / -
polarity.
• Connect them properly checking
the + / - of the terminals and
cables well.
• A speaker cable is pinched by a • Connect the speaker cable again
screw in the car body.
so that it is not pinched by
anything.
• The switches may be set
improperly.
• Set switches properly by
referring to "System examples".
11
Specifications
Specifications subject to change without notice.
Audio Section ..............................................KAC-728
Max Power Output (4 Ω)
KAC-628
KAC-528
Normal..............................................................200 W × 2
Bridge ..............................................................600 W × 1
Rated Power Output (4 Ω)
100 W × 2
300 W × 1
70 W × 2
200 W × 1
Normal (DIN45324, +B=14.4 V) ......................100 W × 2
Bridge (1 kHz, 0.8 % THD) ..............................300 W × 1
Rated Power Output (2 Ω)
50 W × 2
150 W × 1
35 W × 2
100 W × 1
Normal (1 kHz, 0.8 % THD)..............................150 W × 2
75 W × 2
50 W × 2
5 Hz ~ 50 kHz
100 dB
0.2 V
Frequency Response (+0, –1 dB) ........................5 Hz ~ 50 kHz 10 Hz ~ 45 kHz
Signal to Noise Ratio............................................100 dB
Sensitivity (MAX) (rated output) ..........................0.2 V
Sensitivity (MIN) (rated output) ............................5.0 V
Input Impedance ..................................................10 kΩ
Low Pass Filter (12 dB/oct.) ................................80 Hz
High Pass Filter (12 dB/oct.) ................................
100 dB
0.15 V
4.0 V
10 kΩ
80 Hz
150 Hz
5.0 V
10 kΩ
80 Hz
General..........................................................KAC-728
Operating Voltage (11 ~ 16 V allowable)..............14.4 V
Current Consumption (1 kHz, 10% THD) ............28 A
KAC-628
14.4 V
KAC-528
14.4 V
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
12
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