KAC-648
4-CHANNEL POWER AMPLIFIER
INSTRUCTION MANUAL
B64-1364-00 (EM)
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.
Installation
Self-tapping screw
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.
3
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.
5
SPEAKER LEVEL INPUT
BRIDGED
LEFT
SPEAKER OUTPUT
A
POWER IN
FUSE(25A)
LEFT
RIGHT
RIGHT
A
B
GND
SPEAKER LEVEL INPUT
BATT
P.CON(REMOTE)
A
B
L
R
B
1
2 3 4
6
7
8
9
0 !
FILTER
OFF
LPF
OPERATION
(Lch)
MONO
FILTER
OFF
OPERATION
INPUT SELECTOR
LINE IN
LINE OUT
A
B
A
A
B
A
+
B
STEREO
MONO(Lch)
STEREO
HPF
LPF
HPF
1.0
1.0
0.5
MONO
L
L
0.5
0.3
GND
0.3
MIN
MAX
MIN
INPUT
SENSITIVITY(V)
MAX
4 CHANNEL
POWER AMPLIFIER
INPUT
SENSITIVITY(V)
R
R
CONTROL
A
CONTROL
B
@
mA
mA
#
$
%
When multiple speakers are to be
connected, ensure that the combined
impedance is 4Ω or greater.
1 Fuse (25 A × 1)
2 Battery terminal
3 Ground terminal
2CAUTION
4 Power control (REMOTE) terminal
The rated input of the speakers should be
no less than the maximum output of the
amplifier. Otherwise malfunction may
result.
5 Amplifier A speaker output
terminals
6 Amplifier B speaker output
7 Speaker level input terminals
terminals
8 INPUT SELECTOR switch
This switch selects the input method of the
signals to be amplified by amplifiers A and
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.
A
B
A
INPUT SELECTOR
• 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.
• 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.
9 Amplifier A LINE IN terminal
0 Amplifier B LINE IN terminal
4
independently according to the setting of
this switch.
• STEREO position:
The amplifier can be used as a stereo
amplifier.
! 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.
• MONO (Lch) position:
@ RCA cable ground lead terminal
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.
% FILTER switch
The sensitivities of amplifiers A and B can
be adjusted independently regardless of the
position of the input selector switch.
These switches allow filtering of the
speaker output signals.
• HPF(High Pass Filter) position:
Only frequencies of 150Hz or higher are
output. (Frequencies below 150Hz are cut.)
• LPF(Low Pass Filter) position:
Only frequencies of 80Hz or lower are
output. (Frequencies above 80Hz are cut.)
The Lch and Rch will be mixed before
output even if the operation switch is set to
STEREO.
Use the diagram on
15
10
1.0
the right as a guide.
1.0
0.5
2.0
3.0
0.5
0.3
0.3
MAX
MIN
(V)
25
4.0
(W)
0.2
NOTE
For the pre-output level or the maximum
power output, refer to the “Specifications”
in the instruction manual of the center unit.
• OFF position:
The original sound without filtering is
output.
$ OPERATION switch
The amplification methods of the signals
input to amplifiers A and B can be selected
System examples
■ Full-range 4-channel + Subwoofer system
1.0
0.5
L
L
Front
FILTER
OPERATION
STEREO MONO(Lch)
LPF
A
B
OFF
R
HPF
0.3
MAX
INPUT
SENSITIVITY(V)
speaker
R
CENTER UNIT
Switch setting
MIN
INPUT SELECTOR
CONTROL
CONTROL
A
B
L
A
B
A
L
1.0
0.5
Rear
speaker
R
FILTER
OFF
OPERATION
(Lch)
MONO
HPF
LPF
R
STEREO
0.3
L
LINE
OUT
MIN
INPUT
SENSITIVITY(V)
MAX
R
L
Subwoofer
R
Power amplifier
5
System examples
■ High-pass + Subwoofer system
1.0
0.5
L
L
FILTER
OFF
OPERATION
STEREO MONO(Lch)
A
B
(High pass)
HPF
LPF
R
0.3
MAX
INPUT
SENSITIVITY(V)
MIN
R
CENTER UNIT
Switch setting
INPUT SELECTOR
CONTROL
CONTROL
A
B
L
A
B
A
1.0
0.5
R
Subwoofer
(L + R)
(Bridged)
FILTER
OFF
OPERATION
(Lch)
MONO
HPF
LPF
STEREO
0.3
L
LINE
OUT
MIN
INPUT
SENSITIVITY(V)
MAX
R
■ High-power 2-channel system
1.0
0.5
L
L
Left
FILTER
OFF
OPERATION
STEREO MONO(Lch)
A
B
HPF
LPF
R
0.3
MAX
INPUT
SENSITIVITY(V)
CENTER UNIT
Switch setting
speaker
MIN
INPUT SELECTOR
CONTROL
CONTROL
A
B
L
A
B
A
R
1.0
0.5
Right
speaker
R
FILTER
OFF
OPERATION
(Lch)
HPF
LPF
STEREO
MONO
0.3
L
LINE
OUT
MIN
MAX
INPUT
SENSITIVITY(V)
R
■ Tri-mode
(High pass)
L
L
C
C
1.0
0.5
FILTER
OFF
HPF LPF
OPERATION
L
L
STEREO
MONO(Lch)
A
B
0.3
R
MIN
MAX
CENTER UNIT
Switch setting
R
INPUT
SENSITIVITY(V)
INPUT SELECTOR
CONTROL
CONTROL
A
B
A
B
A
L
1.0
0.5
FILTER
OFF
OPERATION
R
(Lch)
MONO
HPF
LPF
STEREO
0.3
L
MIN
INPUT
SENSITIVITY(V)
MAX
L
LINE
OUT
R
R
Subwoofer
(L + R) (Bridged)
●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
Capacitor (C): Passes high frequencies and blocks low
-3 dB
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.
6
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.
SPEAKER LEVEL INPUT
BRIDGED
LEFT
SPEAKER OUTPUT
A
POWER IN
FUSE(25A)
LEFT
RIGHT
RIGHT
A
B
GND
SPEAKER LEVEL INPUT
BATT
P.CON(REMOTE)
A
B
L
R
B
Round terminal (Small)
Round terminal (Medium)
Power terminal
Terminal cover
Battery cable
Power control cable
Ground cable
CENTER UNIT
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.
Example: One Power Amplifier Is Used
Model
Maximum Current
Drawn
Protective Fuse
Cross-sectional Area of Wiring
Cable (AWG)
3 mm (AWG 12) or greater × 1
2
KAC-648
22 A
30 A × 1 [15 A × 2]
15 A
15 A
30 A
15 A
15 A
7
Connection
■ Speakers cable connection
(Stereo Connections)
Front Left speaker
Front Right speaker
Lead terminal
(Commercially
available parts)
T
H
IG
R
BRIDGED
T
F
E
L
A Right output
A Left output
SPEAKER LEVEL INPUT
LEFT RIGHT
BRIDGED
LEFT
SPEAKER OUTP
A
POWER IN
FUSE(25A)
RIGHT
A
B
GND
SPEAKER LEVEL INPUT
BATT
P.CON(REMOTE)
B
L
R
B
Speaker terminal polarity
BRIDGED
B Right output
A
B
B Left output
L
R
Rear Right speaker
Rear Left speaker
(Bridged Connections)
Lead terminal
(Commercially
available parts)
Speaker (Bridged)
T
H
IG
R
BRIDGED
T
F
E
L
A Bridged output
SPEAKER LEVEL INPUT
LEFT RIGHT
BRIDGED
LEFT
SPEAKER OUTPUT
A
POWER IN
FUSE(25A)
RIGHT
A
B
GND
SPEAKER LEVEL INPUT
BATT
P.CON(REMOTE)
B
L
R
B
Speaker terminal polarity
BRIDGED
A
B
B Bridged output
L
R
Speaker (Bridged)
■ 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.
8
Examples:
Model
Stereo Connections (4Ω)
Bridged Connections (4Ω)
KAC-648
50 W or greater
140 W or greater
50W
(2Ω)
25W
50W
25W
(8Ω)
50W
(4Ω)
50W
50W
(4Ω)
(8Ω)
(4Ω)
(4Ω)
50W
(2Ω)
4 Ω
4 Ω
4 Ω
Maximum output of
the amplifier
Combined
impedance
Rated input power and
impedance of the speakers
■ 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.
B Left input
A Left input
RCA cable ground terminal
D
N
OPERATION
FILTER
OFF
LPF
G
FILTER
OFF
OPERATION
STEREO MONO(Lch)
INPUT SELECTOR
LINE IN
LINE OUT
(Lch)
A
B
A
A
B
A
+
B
STEREO
MONO
HPF
LPF
HPF
1.0
1.0
0.5
MONO
L
L
0.5
0.3
GND
0.3
MIN
MAX
MIN
INPUT
SENSITIVITY(V)
MAX
4 CHANNEL
POWER AMPLIFIER
INPUT
SENSITIVITY(V)
R
R
CONTROL
A
CONTROL
B
B Right input
A Right input
RCA cable
(Commercially available part)
To Power control
(REMOTE) terminal
Front output
Rear output
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.
9
Connection
■ 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.
To Power control
(REMOTE) terminal
A Left input
A Right input
SPAKER LEVEL INPT
LEFT IGHT
BRIDGED
LEFT
SPEAKER OUTPUT
A
POWER IN
FUSE(25A)
RIGHT
A
B
GND
SPEAKER LEVEL INPUT
BATT
P.CON(REMOTE)
A
B
L
R
B
ACC
B Right input
T
H
IG
R
Car fuse
box
B Left input
Front Right
Battery
T
F
SPEAKER LEVEL INPUT
LE
Front Left
Rear Left
Rear Right
Genuine-accessory
car stereo
Lead terminal
(Commercially available parts)
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.
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
Max Power Output (4 Ω)
4 Channel Mode.................................................................................................................50 W × 4
3 Channel Mode............................................................................................50 W × 2 + 140 W × 1
2 Channel Mode...............................................................................................................140 W × 2
Rated Power Output (4 Ω)
4 Channel Mode ..........................................................................25 W × 4 (DIN45324, +B=14.4 V)
3 Channel Mode ............................25 W × 2 (1 kHz, 0.08 % THD) + 70 W × 1 (1 kHz, 0.8 % THD)
2 Channel Mode.................................................................................70 W × 2 (1 kHz, 0.8 % THD)
Rated Power Output (2 Ω)
4 Channel Mode.................................................................................35 W × 4 (1 kHz, 0.8 % THD)
Frequency Response ...............................................................................10 Hz ~ 45 kHz (+0, –1 dB)
Signal to Noise Ratio................................................................................................................100 dB
Sensitivity (MAX) .................................................................................................0.2 V (rated output)
Sensitivity (MIN) ..................................................................................................4.0 V (rated output)
Input Impedance........................................................................................................................10 kΩ
Low Pass Filter .......................................................................................................80 Hz (12 dB/oct.)
High Pass Filter.....................................................................................................150 Hz (12 dB/oct.)
General
Operating Voltage...................................................................................14.4 V (11 ~ 16 V allowable)
Current Consumption ....................................................................................22 A (1 kHz, 10% THD)
Dimensions (W × H × D) ...................................................................................260 × 56.5 × 209 mm
Weight.......................................................................................................................................3.0 kg
12
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