System examples L
R
L
R
A
B
A
B
L
R
L
R
A
B
L
R
L
R
A
B
L
R
L
R
A
B
L
R
L
R
A
B
L
R
L
R
A
B
L
R
L
R
ON
OFF
BASS BOOST(B.CH)
LPF
HPF
OFF
A.CH
FILTER
LPF
HPF
OFF
B.CH
ON
OFF
BASS BOOST(B.CH)
LPF
HPF
OFF
A.CH
FILTER
LPF
HPF
OFF
B.CH
ON
OFF
BASS BOOST(B.CH)
LPF
HPF
OFF
A.CH
FILTER
LPF
HPF
OFF
B.CH
OPERATION
INPUT SELECTOR
MONO(Lch)
STEREO
A.CH
MONO(Lch)
STEREO
B.CH
A AB
7
#
$%
OPERATION
INPUT SELECTOR
MONO(Lch)
STEREO
A.CH
MONO(Lch)
STEREO
B.CH
A AB
$%
OPERATION
INPUT SELECTOR
MONO(Lch)
STEREO
A.CH
MONO(Lch)
STEREO
B.CH
A AB
$%
OPERATION
F
R
INPUT SELECTOR
MONO(Lch)
STEREO
A.CH
MONO(Lch)
STEREO
B.CH
A AB
$%
@
7
#@
7
#@
200
200
50
50
LPF
HPF
150
80 150
100
80
A.CH B.CH
FILTER FREQUENCY(Hz)
100
200
200
50
50
LPF
HPF
150
80 150
100
80
100
200
200
50
50
LPF
HPF
150
80 150
100
80
A.CH B.CH
FILTER FREQUENCY(Hz)
100
200
200
50
50
LPF
HPF
150
80 150
100
80
100
200
200
50
50
LPF
HPF
150
80 150
100
80
A.CH B.CH
FILTER FREQUENCY(Hz)
100
200
200
50
50
LPF
HPF
150
80 150
100
80
100
40
LEFT
BRIDGED
SPEAKER
POWER IN
P.CONBATT.FUSE(40A) OUTPUT RIGHT
A
B
POWER AMPLIFIER
GND
432
L
A
A
R
L
R
B
A
B
B
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.
1Fuse
40 A ×1 : KAC-849
30 A ×1 : KAC-749S
If you can’t find the specified capacity fuse at your
store etc., consult your Kenwood dealer.
2Battery terminal
3Ground terminal
4Power control terminal
5Amplifier A/B SPEAKER OUTPUT
terminals
•Stereo Connections:
When you wish to use the unit as a stereo
amplifier, stereo connections are used.
•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.)
6INPUT 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.
The sensitivities of amplifiers A and B can be
adjusted independently regardless of the position
of the input selector switch.
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.
7FILTER FREQUENCY control
When the FILTER switch is set to the HPF (High-
Pass Filter) or LPF (Low-Pass Filter) position, the
threshold frequency can be adjusted with this
control.
8RCA cable ground lead 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.
9Amplifier A/B LINE IN terminals
0LINE 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.
!Speaker level input terminals
@BASS BOOST switch
When the switch is in “ON” position, the bass is
boosted by 6 dB.
The bass boost applies only to the B amplifier.
#FILTER switch
This switch allows to apply high-pass or low-pass
filtering to the speaker outputs.
•HPF (High-Pass Filter) position:
The filter outputs the band of higher frequencies
than the frequency set with the FILTER
FREQUENCY control.
•OFF position:
The entire bandwidth is output without filtering.
•LPF (Low-Pass Filter) position:
The filter outputs the band of lower frequencies
than the frequency set with the FILTER
FREQUENCY control.
The speaker output is automatically turned
monaural (L+R).
$OPERATION switch
The amplification methods of the signals input to
amplifiers A and B can be selected independently
according to the setting of this switch.
•STEREO position:
The amplifier can be used as a stereo amplifier.
•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.)
%INPUT SELECTOR switch
This switch selects the input method of the signals
to be amplified by amplifiers A and B.
•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.
Power indicatorWhen 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 is activated
in the following situations:
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.
•When a speaker wire 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 internal temperature is high and unit
won’t operate.
•When a ground wire 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.
2CAUTION
NOTE
NOTE
Controls6
40
ON
OFF
BASS BOOST(B.CH)
LPF
HPF
OFF
A.CH
A.CH
FILTER
OPERATION
INPUT SELECTOR
LINE IN LINE OUT
SPEAKER LEVEL INPUT
MONO(Lch)
STEREO
A.CH
MONO(Lch)
STEREO
B.CH
LPF
HPF
OFF
B.CH
B.CH
LEFT
BRIDGED
SPEAKER
POWER IN
P.CONBATT.FUSE(40A) OUTPUT RIGHT
A
B
POWER AMPLIFIER
0.2(MAX)
(MIN)5
0.3
0.5
1
2
3
4
0.2(MAX)
(MIN)5
0.3
0.5
1
2
3
4
80
INPUT SENSITIVITY(V)
GND
A AB A
L
R
A+B B
A
B
LR
0.2(MAX)
(MIN)5
0.3
0.5
1
2
3
4
INPUT SENSITIVITY(V)
ON
OFF
BASS BOOST(B.CH)
LPF
HPF
OFF
A.CH
FILTER
OPERATION
INPUT SELECTOR
MONO(Lch)
STEREO
A.CH
MONO(Lch)
STEREO
B.CH
LPF
HPF
OFF
B.CH
A AB
200
200
50
50
LPF
HPF
150
80150
100
A.CH B.CH
FILTER FREQUENCY(Hz)
100
200
200
50
50
LPF
HPF
150
80150
100
80
100
GND
1 02 3 4 85 !6
@$ %
MAXIMUM POWER
4
/
3
/
2 CHANNEL AMPLIFIER
KAC
-
749S
MAXIMUM POWER
9
#
7
4
/
3
/
2 CHANNEL
AMPLIFIER
KAC-849
(W)
25
40
15
10
Power indicator
KAC-849 KAC-749S
Terminal cover
Battery
Ground wire*
Battery wire*
Protective Fuse*
Power control wire*
■Power wire connection
L
C
C
L
C
C
ON
OFF
BASS BOOST(B.CH)
LPF
HPF
OFF
A.CH
FILTER
LPF
HPF
OFF
B.CH
OPERATION
INPUT SELECTOR
MONO(Lch)
STEREO
A.CH
MONO(Lch)
STEREO
B.CH
A AB
$%#@
L
R
L
R
L
R
L
R
A
B
Connection For safe installation, read "Installation procedure" before starting work.
NOTE
40
ON
OFF
BASS BOOST(B.CH)
LPF
HPF
OFF
A.CH
A.CH
FILTER OPERATION
INPUT SELECTOR
LINE IN LINE OUT
SPEAKER LEVEL INPUT
MONO(Lch)
STEREO
A.CH
MONO(Lch)
STEREO
B.CH
LPF
HPF
OFF
B.CH
B.CH
LEFT
BRIDGED
SPEAKER
POWER IN
P.CONBATT.FUSE(40A) OUTPUT RIGHT
A
B
POWER AMPLIFIER
40
LEFT
BRIDGED
SPEAKER
POWER IN
P.CONBATT.FUSE(40A) OUTPUT RIGHT
A
B
POWER AMPLIFIER
0.2(MAX)
(MIN)5
0.3
0.5
1
2
3
4
0.2(MAX)
(MIN)5
0.3
0.5
1
2
3
4
INPUT SENSITIVITY(V)
GND
A AB A
L
R
A+B B
A
B
LR
ON
OFF
BASS BOOST(B.CH)
LPF
HPF
OFF
A.CH
A.CH
FILTER OPERATION
INPUT SELECTOR
LINE IN LINE OUT
SPEAKER LEVEL INPUT
MONO(Lch)
STEREO
A.CH
MONO(Lch)
STEREO
B.CH
LPF
HPF
OFF
B.CH
B.CH
0.2(MAX)
(MIN)5
0.3
0.5
1
2
3
4
0.2(MAX)
(MIN)5
0.3
0.5
1
2
3
4
INPUT SENSITIVITY(V)
GND
A AB A
L
R
A+B B
A
B
LR
LL
A
A
L
A
A
B
R
B
R
LR
RL
R
AR
B
B
L
A
R
L
R
B
L
B
200
200
50
50
LPF
HPF
150
80150
100
80
A.CH B.CH
FILTER FREQUENCY(Hz)
100
200
200
50
50
LPF
HPF
150
80150
100
80
100
200
200
50
50
LPF
HPF
150
80150
100
80
A.CH B.CH
FILTER FREQUENCY(Hz)
100
200
200
50
50
LPF
HPF
150
80150
100
80
100
GND GND
4
4
LEFT
BRIDGED
RIGHT
A
B
BRIDGED
RL
LEFT
BRIDGED
RIGHT
A
B
BRIDGED
RL
8
55
GND
CENTER UNIT(Cassette receiver,
CD receiver, etc.)
Power control wire*
RCA cable*
Genuine-accessory
car stereo (No line
output center unit
etc.)
ACC
Battery
Car fuse box
Lead terminal* Lead terminal*
■4-channel ■4-channel
■3-channel
■2-channel
■2ch + woofer
■2-channel
■RCA cable connection ■Speaker level input connection
■Speaker stereo connection ■Speaker bridge connection
CENTER
UNIT
CENTER
UNIT
CENTER
UNIT
■2-channel
CENTER
UNIT
■Tri-mode
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 frequencies. (Low pass)
Capacitor (C): Passes high frequencies and
blocks low frequencies. (High pass)
Example:
When it is required to set a crossover
frequency of 120 Hz using speakers with an
impedance of 4 ohms.
fc=Cut of Frequency (Hz)
R=Speaker Impedance (Ω)
•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
LC
0 dB
-3 dB
Crossover Frequency
Frequency
CENTER
UNIT
High pass
Subwoofer
(L + R)
159000
C= (µF)
fc x R
159 x R
L= (mH)
fc
159000
= = 331.25 µF
120Hz x 4Ω
159 x 4Ω
= = 5.3 mH
120Hz
Front left speaker
Front right speaker
Rear left speaker
Rear right speaker
Left speaker
Right speaker
Left speaker
Right speaker
Subwoofer
Lead terminal*
Bridge
Bridge
White
White/Black
Gray
Gray/Black
Green
Green/Black
Purple
Purple/Black
Left
Front left
Front right
Right
Rear left
Rear right
Front
Rear
Cable Color of the
connector
F
R
*Commercially available
parts
Description of markings in the figure.
KAC-8_749(KE)1En 02.12.16 11:28 AM Page 2