Kenwood KA-907 User manual

HIGH
SPEED
DC
INTEGRATED
AMPLIFIER
KA-907
INSTRUCTION MANUAL

INTRODUCTION
The purpose of this manual is to acquaint you
with the operating features of your new amplifier.
You will notice that in every detail of planning,
engineering, styling, operating convenience, and
adaptability, we have sought to anticipate your
needs and desires.
We suggest that you read this manual carefully.
Knowing how to set up your amplifier to the best ad-
vantage will enhance your listening pleasure right
from the start. You will also become aware of the
ease with which you can adjust your amplifier to
meet your special requirements.
FOR YOUR RECORDS
Record the serial number, found on the back of
the unit, in the spaces designated on the warranty
card, and in the space provided below. Refer to the
model and serial numbers whenever you call upon
your Kenwood dealer for information or service on
this product.
Model KA-907 Serial number
AFTER UNPACKING
After unpacking, we recommend you inspect and
examine the unit for any possible shipping damage.
If your unit is damaged or fails to operate, notify your
dealer immediately. If your unit was shipped to you
directly, notify the shipping company without delay.
Only the consignee (the person or company receiv-
ing the unit) can file a claim against the carrier for
shipping damage.
We recommend that you retain the original car-
ton and packing materials to prevent any damage
should you transport or ship your unit in the future.
INSTALLATION PRECAUTIONS
a) Avoid locations subject to direct sunlight.
b) Avoid high or low temperature extremes.
c) Keep the unit away from heat radiating sources.
d) Choose a location that is relatively free of vibra-
tion or excessive dust.
e) Make sure power is off before making any system
connections.
WARNING:
TO PREVENT FIRE OR SHOCK
HAZARD, DO NOT EXPOSE THIS
APPLIANCE TO RAIN OR MOISTURE.
KA-907(K)
IMPORTANT!
U. s. A AND. CANADA o
‘Units shipped to the U.S.A. and Canada are
3 designed for operation on 120 volts AC on-
ly. These units are not equipped with an AC
= Voltage Selector switch and the discussion __
ef such a switch that follows should be —
5 disregarded. ee .
ALL OTHER COUNTRIES
Units shipped to countries other than ‘he
U.S.A. and Canada are equipped with an AC.
Voltage Selector switch on the bottom plate.
Refer to the following paragraph for the. Pie:
per setting of this switch,
AC VOLTAGE SELECTION
This unit operates on 110-120 volts or 220-240
volts AC.The AC Voltage Selector Switches on the
bottom plate is set to the voltage that prevails in the
area to which the unit is shipped. Before connecting
the power cord to your AC outlet, make sure that the
setting position of these switches match your line
voltage. If not, it must be set to your voltage in ac-
cordance with the following direction.
Note:
Our warranty does not cover damage caused by excessive line
voltage due to improper setting of the AC Voltage Selector
Switch.
110-120V~ qp220-240V~ 110-120V~ <¢p220-240V~
This shows switch
levers locked in the
110-120V~
position.
This shows switch
levers locked in the
220-240V~
position.
!
Move switch levers to match your line
voltage with a small screw driver or
other pointed tool.
AC VOLTAGE SELECTOR SWITCH

CONTENTS
SYSTEM CONNECTION DIAGRAM .................00cc eee eees 4
SYSTEM CONNECTIONS..................0068 ttadeeccals a1 akereaee 5
CONTROLS, INDICATORS AND CONNECTORS _.......... 6
OPERATING INSTRUCTIONS ................ccceceeeeeeeeeee eens 8
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PPECIRIGATIONS © Ctadsd.ty waasvuasnadastesueseereiececut seed 15
THE MEANING OF ‘‘HIGH SPEED’’
FEATURES
5.
HIGH-PERFORMANCE
MC
HEAD
AMPLIFIER
WITH
SIGNAL-
in the continuing search for perfect sound, recent research
has focused on a form of distortion that occurs when sound tran-
sients force the amplifier to deliver very large changes in voltage
in
less
than
a
millionth
of
a
second.
To
counter
this
cause
of
distortion,
Kenwood
engineers
have
incorporated
a
new
high
speed amplifier design. The result is an amplifier that can respond
to a change in output from a very low value to near maximum (the
specification called rise time) in 0.8 microseconds. The voltage
rate-of-change, called slew rate, is an unprecedented 230 volts
per microsecond in both the positive and negative directions.
These values of rise time and slew rate represent an improvement
factor
of
4
to
10
over
conventional
amplifiers.
The
result
is
preser-
vation of tonal quality through the most complex of musical
crescendos.
2. ULTIMATE DC AMPLIFIER “‘DC COUPLED”
Listening
tests
have
shown
that
low-frequency
phase
shift
can
be
detected
as
a
change
in
tonal
timbre.
To
prevent
phase
shift
and
preserve
low-frequency
tonal
quality
the
amplifier
employs
DC
coupling
throughout
the
amplifier
chain
from
the
tuner,
tape,
and
aux
inputs
to
the
speakers.
Kenwood's
leadership
and
experience
with
DC
design
techniques
ensures
perfect
and
stable
operation
right
down
to
zero
Hertz.
The
phono
input
employs
one
AC
coupling
device
(a
capacitor)
but
this
does
not
af-
fect
the
follow,
since
magnetic
phono
cartridges
do
not
respond
to
static
stylus
pressure.
For those program sources that produce unwanted sound in
the extreme low-frequency range, such as rumble, DC coupling
can be switched out at the tuner, tape and aux inputs.
3. TWO INDEPENDENT POWER SUPPLIES
The KA-907 operates as two independent monophonic
amplifiers, one for each stereo channel and each powered by its
own individual power supply. This eliminates a form of distortion
known as dynamic crosstalk when the power demands in one
channel act to lower power to the other. By maintaining complete
power independence, this notable form of distortion is avoided. In
addition, extra solid-state regulators supply power to the preamps
to that low-level signal processing is unaffected by the large
power demands at the output stages.
4. HIGH PERFORMANCE PHONO EQUALIZER
A newly-designed DC equalizer employing dual-gate FETs
achieves precision equalization to match RIAA record
characteristics an moving-magnet cartridges. DC coupled inter-
nally, and using a single input coupling capacitor, the equalizer
achieves an outstanding 90 dB signal-to-noise ratio while distor-
tion is reduced to the vanishing point.
TO-NOISE
RATIO
OF
70
DB
(IHF
A)
AT
100
zV
INPUT
The
KA-907
has
an
extra-wide
range
DC
head
amplifier,
all
stages
of
which
are
made
up
of
completely
symmetrical
push-pull
circuits
to
ensure
optimum
performance
for
MC
cartridges.
6. PHONO SELECTOR MATCHES CARTRIDGE NEEDS
At
PHONO
1,
MM
and
MC
type
cartridges
can
be
used
without
reconnecting
the
pin
jacks.
For
the
MM
type,
any
of
the
three
input
impedances
—
33
kilohms,
47
kilohms,
and
100
kilohms
—
can
be
selected
so
that
various
brands
of
commercial
cartridges
can
be
accommodated.
Input
impedance
for
MC
car-
tridges
is
100
ohms.
At
PHONO
2,
only
MM
type
(47
kilohms)
cartridges
may
be
used.
The
PHONO
pin
jacks
are
gold-plated
to
reduce
contact
resistance.
7. TONE CONTROL WITH TURNOVER SELECTOR
Turnover
frequency
selection
can
be
made
(150
Hz
or
400
Hz
for
bass;
3
kHz
or
6
kHz
for
treble)
to
subtly
compensate
for
the
acoustic
characteristics
of
the
program
source
or
your
listening
room,
and
thus
provide
the
desired
tone.
In
addition,
the
tone
defeat
permits
the
tone
circuit
to
be
bypassed
completely
for
flat
response.
8. LOUDNESS CONTROL WITH 3-LEVEL AND 2-FREQUENCY
POSITIONS
Fine
adjustments
can
be
made
to
compensate
for
sound
field,
aural sensitivity, and the speakers’s low range.
9. SPECIAL TAPE-THROUGH SYSTEM
For
maximum
convenience
the
tape
switching
circuits
have
been
set
up
to
provide
normal
tape
operations
using
a
pair
of
tape
decks.
The
unique
tape-through
feature
permits
tape
dubbing
from
one
deck
to
the
other
without
tying
up
the
entire
system.
Tuner,
phono
or
other
sources
can
drive
the
speakers
while
tape
dubbing
is in
progress.
10. SPEAKER SWITCHING
The
speaker
switching
circuit
is
wired
for
minimum
resistance
using with 3 relays. This maintains a high damping factor.
11. DUAL SPEAKER OPERATION
The
KA-907
will
drive
one
or
two
pairs
of
speakers.
Each
pair
can
be
selected
for
individual
use
or
they
can
be
driven
simultaneously.
KA-907(K)

SYSTEM CONNECTION DIAGRAM
TURNTABLE 1 TAPE DECK A SPEAKER SYSTEM A SPEAKER SYSTEM B
LEFT RIGHT
LINE OUT) LINE IN
REL REIL
AorB:4~160,AandB:8~160
SWITCHED UNSWITCHED
TOTAL200W MAX TOTAL 260W MAX ial
5) = = &
=) = = =
—
TO AC OUTLET
a: 1S
LINE OUT
Cea) 5.
7 weeeee cE Ou:
TURNTABLE 2 TUNER TAPE DECK B
AC OUTLETS
The AC outlets on the rear panel of the unit may 2. UNSWITCHED outlets: These outlets provide
be used to supply power to other components in the power when the unit is plugged into an active AC
system, such as a turntable, tape deck, etc. Never wall outlet, regardless of the setting of the
connect equipment whose power consumption ex- POWER switch. lts maximum total capacity is
ceeds the maximum value shown at each outlet. 280 watts.
1. SWITCHED outlets: These outlets supply power Note:
only when the KA-907 is turned on. Its max- Units shipped to European countries are not equipped with AC
imum total capacity is 200 watts. OUHEES:
KA-907(K)

SYSTEM CONNECTIONS
SPEAKERS
If
only
one
set
of
speakers
is
to
be
connected,
make
connections
to
the
terminals
marked
SPEAKERS
A,
as
shown
on
page
4.
Connect
the
speakers
to
the
RIGHT
and
LEFT
terminals
in
accor-
dance
with
the
location
selected
for
each
speaker.
To
ensure
correct
speaker
phasing,
observe
polarity
marks;
connect
terminals
marked
+
on
the
amplifier
to
similarly-marked
speaker
terminals.
Do
the
same
for
amplifier
and
speaker
terminals
marked
with
a
minus
sign.
Reversal
of
speaker
leads
will
result
in
loss
of
bass
tones
and
poor
stereo
separation.
if
a
second
set
of
speakers
is
to
be
used,
make
connections
at
the
right
set
of
terminals,
marked
B.
Note:
If
a
single
pair
of
speakers
is
to
be
used,
each
speaker
must
be
rated at 4 ohms or more.
When
two
pairs
of
speakers
are
connected
(A+B)
each
speaker
must
be
rated
at
8
ohms
or
more.
WARNING
Particular attention must be given to making
good electrical contact at the amplifier-output and
speaker terminals. Poor or loose connections can
cause sparking or burning at the terminals because
of the very high power that the amplifier can deliver.
Follow these steps carefully.
1. Strip 10 mm (3/8 inch) of insulation from the
ends of the speaker cable. Twist the bare strands
of wire together and solder the ends to keep the
strands from separating.
white cae
b——
10mm (3/8 inch)
2. Back the caps of the SPEAKER
terminals on the amplifier all
the way out by turning them
counterclockwise as far as
they will go.
3. Insert one end of the red cable
into the hole in the +terminal
as shown at right.
4. Turn the cap clockwise and
tighten securely to ensure a
firm contact.
5. Connections at your speakers will vary depending
upon the type of terminals used. Check the
manufacturer’s instructions and make sure that a
good, tight, metal-to-metal contact is made.
6.
Check
all
connections.
Make
sure
all
are
tight,
and
that
there
are
no
loose
strands
of
wire
touching
the
wrong
terminals,
meta!
cabinet
or
trim.
TURNTABLES
Your stereo turntable has two audio cables that
are terminated with phono plugs. PHONO 1 for an
MM or MC cartridge and PHONO 2 for an MM car-
tridge. Plug the left channel plug into the ‘‘LEFT”’
and the right channel plug into the ‘‘RIGHT’’ PHONO
1 INPUT jacks as shown on page 4.
lf an additional turntable is to be used, make
similar connections at the PHONO 2 jacks.
If the turntable has a ground wire, connect it to the
unit's GND terminal to avoid hum.
TUNERS
Use the TUNER terminals for connection to an
FM stereo or AM-FM stereo tuner.
Connect the left channel of the tuner to the
“LEFT’’ TUNER input jack and the right channel of
the tuner to the ‘‘RIGHT’’ TUNER input jack.
AUX JACKS
INPUT AUX jacks are used to connect other high-
level signal sources, such as tuners, extra tape decks
(equipped with preamps), TV or VTR sound output
mic preamps, etc.
TAPE DECKS
If only one tape deck is to be connected to the
system it is recommended that it be connected to
the jacks marked TAPE A.
Tape deck input and output cables are normally
terminated with phono plugs.
Playback
Plug the left and right output cables of the tape
deck into the ‘‘LEFT’’ and ‘‘RIGHT’’ TAPE A PLAY
jacks.
Record
Plug the left and right input cables of the tape
deck into the ‘‘LEFT”’ and “‘RIGHT’’ TAPE A REC
jacks.
DIN Connector
\f your tape deck is equipped with a DIN connec-
tor, connect it to the TAPE B REC/PLAY connector
with the DIN connecting cord. The DIN connection
makes both input and output connections with a
single cord, and the signal must be controlled with
the TAPE MONITOR switch on the front panel.
Note —£ —@@ -—@-@—_—______—__
lf connections are made with a DIN connecting cord, the TAPE B
PLAY and REC jacks should not be used.
Second Tape Deck
Plug the input and output cables from the
second tape deck into the REC and PLAY jacks
marked TAPE B.
KA-907{K)

CONTROLS, INDICATORS AND CONNECTORS
SPEAKERS TREBLE
("7 FILTER —
SUBSONIC HIGH
od
TURNOVER
DEFEAT
oc
COUPLED
@
ON = QOFF
INPUT SELECTOR
TUNER
aoKe Sone
mc PHONO 2
47K
Re
BALANCE [~ LOUDNESS —
Soda
tare!
FREQUENCY LEVEL,
s
OFF
nz 100H 2 °
de
SAME QUAL POWER SUPPLY
°
OQ
s
verr
x
2
3
«
5
RIGHT
@ POWER switch/POWER indicator (orange)
Set to ON, to turn power on. The power indicator
(orange) will flash for about ten seconds. When the
indicator stops flashing, and remains lit, the set is in
normal operating condition. Set the switch to OFF to
remove power. If the DC COUPLED switch is ON, the
DC COUPLED indicator (green) 43 also flashes, and
then lights simultaneously with the power switch.
@ SPEAKERS switch
OFF — This position silences all speakers to permit
private use of headphones.
A — Activates speakers connected to the
SPEAKERS A terminals on the rear panel.
B— Activates speakers connected to the
SPEAKERS B terminals on the rear panel.
A+B — Activates speakers connected to the
SPEAKERS A and B terminals simultaneously.
@ TONE controls
The BASS and TREBLE controls adjust bass and tre-
ble response. Each knob controls both left and right
channels equally.
Turning the knobs clockwise increases bass and tre-
ble response and counterclockwise decreases bass
and treble response.
You can select the bass and treble TURNOVER fre-
quencies (150 Hz or 400 Hz for bass control, 3 kHz
or 6 kHz for treble control) with the TURNOVER
switches. The DEFEAT position provides completely
flat frequency response with the tone control circuit
deactivated.
Switch positions and functions are as follows:
150 Hz: +7.5 dB at 75 Hz
400 Hz: +7.5 dBat 150 Hz
3 kHz: +7.5 dB at 10 kHz
KA-907(K)
14)
6 kHz: +7.5 dB at 20 kHz
@ VOLUME control
This control adjust left- and right-channel volume
simultaneously. Set it for the desired listening level.
The scale is provided with dB graduations to indicate
attenuation when maximum output level cor-
responds to O dB.
@® ATTENUATOR switch
—o — Turns OFF all sound. The sound volume
can be temporarily reduced to zero when
changing the cartridge, record, or tape.
O — Keep the control at this position for normal
listening. Sounds will not be attenuated at this
position.
-—20 dB — When temporarily lowering the
sound volume, for example, when answering
the telephone, set the control to it lowers
volume to 1/10 of the level set by the VOLUME
control.
© TAPE DUBBING switch
Facilitates the making of copies (dubs) of taped pro-
grams. Two tape decks are required, one to playback
the tape, the other to record the copy.
A > B — To dub from a tape deck connected to the
TAPE A jacks into a tape deck connected to the
TAPE B jacks.
B > A — To dub from a tape deck connected to the
TAPE B jacks into a tape deck connected to the
TAPE A jacks.
@ TAPE MONITOR switch
SOURCE — The signal applied to the record ter-
minals of a tape deck is heard.

CONTROLS,
INDICATORS
AND
CONNECTORS
A — To monitor a recording in progress or to play
back a tape from a tape deck connected to the
TAPE A jacks.
B —~— To monitor a recording in progress or to play
back a tape from a tape deck connected to the
TAPE B jacks.
PHONO selector
PHONO 1 — Selects the source connected to the
PHONO 1 input jacks on the rear panel. At
these positions, MM and MC type cartridges
can be used without reconnecting the input
cables. Any of the input impedances of 33, 47
and 100 kilohms can be selected as required
when using MM cartridges. Select the im-
pedance specified in the instruction manual for
the turntable or cartridge. The input impedance
for MC cartridges is 100 ohms.
PHONO 2 — Selects the turntable (MM type 47
kilohm cartridges only) connected to the
PHONO 2 input jacks.
@ INPUT SELECTOR switch
This switch selects the desired program source.
TUNER — Selects the tuner connected to the TUNER
input jacks.
PHONO — Selects the turntable connected to the
PHONO 1 or PHONO 2 input jacks.
AUX — Selects the program source connected to the
AUX input jacks.
(® FILTER switches
SUBSONIC
—
Press
the
switch
in
to
attenuate
signals
below
18Hz
(6
dB
per
octave).
Although
such
signals
are
inaudible,
they
can
cause
intermodulation
distortion
products
in
the
audible
range.
It
is
recommended
that
this
switch
be
depressed
(latched
in)
at
all
times,
even
if
no
turntable
rumble
is
apparent.
Press
the
switch
again
to
release
the
latch.
It
will
pop
out
removing
the
subsonic
filter.
HIGH
—
Pressing
this
switch
in
(latched)
reduces
signals
above
8
kHz
at
the
rate
of
12
dB
per
oc-
tave.
Press
this
switch
in
to
lessen
the
effects
of
tape
hiss,
record
scratch,
etc.
Press
to
unlatch
(switch
out)
in
all
other
cases.
@ PHONES jack
Plug
stereo
headphones
into this
jack
for
private
listening.
@® DC COUPLED switch
When this switch is set to OFF a single coupling
Capacitor is inserted at the preamp input circuits.
This breaks the DC coupling path between the signal
source and the speaker, and should be used if the
signal sources connected to the TUNER, TAPE, or
AUX jacks introduce unwanted DC leakage. The OFF
setting may also be used to eliminate very low-
frequency audio, which while inaudible, may cause
intermodulation distortion.
A single capacitor is always in the PHONO input cir-
cuits. Thus, two capacitors are in the signal path
when phono operation is selected and the DC
COUPLED switch is OFF.
When the switch is set ON the input capacitors to
the preamps are removed and true DC coupling ex-
ists between the TUNER, TAPE and AUX jacks and
the speakers (the single coupling capacitor remains
at the PHONO inputs). This provides a flat response,
down to DC (zero Hz) for the ultimate in amplitude
and phase response at the extreme low range of
human hearing. Overall phono response is not af-
fected by the single coupling capacitors at the phono
inputs.
@3 +=DC COUPLED indicator (Green)
If
the
DC
COUPLED
switch
is
on
when
power
is
ap-
plied,
the
green
indicator
will
flash
for
about
ten
seconds
while
the
circuits
stabilize.
At
the
end
of
this
period
the
indicator
will
glow
steadily,
indicating
full
stabilization
and
perfect
balance.
If
the
indicator
flashes
continuously,
an
imbalance
exists
due
to
DC
leakage
from
the
signal
source
or
a
possible
malfunction.
Turn
off
power,
and
consult
the
table
on
page
13
for
appropriate
corrective
measures.
BALANCE control
This
control
permits
balancing
of
left
and
right
chan-
nels
when
an
imbalance
exists
from
the
sound
source,
or
to
correct
acoustic
imbalance
due
to
room
conditions.
Turn
it
to
the
left
from
the
zero
position
to
boost
the
left
channel;
turn
it
to
the
right
of
zero
to
raise
the
level
of
the
right
channel.
@} LOUDNESS control
The LOUDNESS control compensates for a natural
loss of human aural sensitivity in the bass range at
low volume levels. In the KA-907, additional correc-
tion is available to compensate for small speakers or
the effects of room acoustics. Low-frequency cor-
rection may be applied at 30 or 100 Hz and boosts
of 3, 6 or 9 dB selected. The boost values apply at a
VOLUME setting of —50 dB; the larger values
signify greater intensification.
MODE switch
Switch positions and functions are as follows:
STEREO — This provides stereophonic reproduction
of any stereo program source. The left channel
is heard from the left speaker, and the right
channel is heard from the right speaker.
REVERSE — Stereophonic reproduction with revers-
ed channels: left channel to right speaker, right
channel to left speaker.
MONO — Monophonic reproduction. The left and
right channels are mixed together and heard
from both speakers.
KA-807(K}

OPERATING INSTRUCTIONS
INITIAL SETUP
MODE
Set controls and switches as follows:
VOLUME
TURNOVER
BASS, TREBLE, BALANCE
LOUDNESS, DC COUPLED
ATTENUATOR ———- 0
TAPE DUBBING, TAPE MONITOR
Unplug headphones from the PHONES jack.
Turn POWER ON.
Fully counterclockwise (oo)
DEFEAT
Center (zero)
OFF
STEREO
SOURCE
TUNER
1 . Set the INPUT SELECTOR switch to TUNER.
2. Operate the tuner as usual.
3. Turn up VOLUME to the desired listening level.
4. Adjust tone controls to suit your taste.
TURNTABLES
1. Set the INPUT SELECTOR switch to PHONO.
2. Set the PHONO selector to PHONO 1 or
PHONO 2 to select audio from turntables con-
nected to the PHONO 1 and/or PHONO 2 jacks
respectively.
3. Operate the selected turntable.
4. Adjust volume and tone controls for your
preference.
AUX
1. Set the INPUT SELECTOR switch to AUX.
2. Operate the component or accessory connected
to the AUX jacks.
3. Adjust volume and tone for your preference.
TAPE DECKS
Tape Playback
1. Set the TAPE MONITOR switch to A or B to select
output from tape decks connected to the TAPE A
or B jacks (The setting of the INPUT SELECTOR
switch affects speaker output only when the
TAPE switches are set to SOURCE).
2. Operate the tape deck.
3. Adjust volume and tone for your preference.
KA-807(K)
Monitoring
If your tape deck is equipped with three heads,
you can compare the sound quality of the recording
in progress with that of the source material by
switching the TAPE MONITOR switch between
SOURCE and A (or B) while the recording is being
made.
Recording (one tape deck)
1. Set the INPUT SELECTOR switch to the desired
program source. Set the TAPE DUBBING switch
to SOURCE. To monitor the recording, set the
TAPE MONITOR switch to A or B depending on
the set of jacks to which your tape deck is con-
nected.
2. Set up your tape deck for recording and set
recording levels with the controls on your tape
deck. The volume control and tone controls on
the amplifier do not affect the signal applied to
the tape deck for recording purposes.
3. Adjust listening level and tone at the amplifier for
your preference in monitoring the signal; these
settings will not affect the recording.
Recording (two tape decks)
1. Set the INPUT SELECTOR switch to the desired
program source.
2. Set the TAPE DUBBING switch to SOURCE.
3. Recordings can now be made on both tape decks
simultaneously. Either recording can be
monitored by setting the TAPE MONITOR switch
to Aor B.
4. Recording levels should be set using the controls
on the individual tape decks.

OPERATING INSTRUCTIONS
Tape-to-Tape Dubbing
Tape
recordings
may
be
duplicated
easily
using
one
tape deck to play the prerecorded tape and another
tape
deck
to
record
the
copy.
Set
the
TAPE
DUBB-
ING switch as follows:
A
>
B
—
To
record
a
copy
on
tape
deck
B
from
a
tape
played
on
tape
deck
A.
B
>
A
—
To
record
a
copy
on
tape
deck
A
from
a
tape
played
on
tape
deck
B.
Note:
The
setting
of
the
INPUT
SELECTOR
switch
does
not
affect
this
operation. Adjust record levels on the deck that is making the
copy using that decks operating controls. Start both decks (play
and record) simultaneously.
THE THROUGH CIRCUIT
This unit permits listening to other program
sources, such as FM broadcasts or records while
tape
dubbing.
Other
combinations
can
be
set
up
as
follows:
* FM broadcasts can be tape recorded while
simultaneously listening to records as follows:
1. Connect the tuner to the ‘‘PLAY”’ jacks of the
TAPE A group on the rear panel of this unit and
the tape deck to the TAPE B jacks.
2. Connect the turntable to PHONO 1 jacks on the
rear panel and set the PHONO selector switch to
PHONO 1.
3. FM broadcasts can be recorded when the TAPE
DUBBING switch is then set to A > B and the
tape deck is operated in recording mode.
4. Phono sound is reproduced when the TAPE
MONITOR switch is set to SOURCE.
5. FM broadcasts are reproduced when the TAPE
MONITOR switch is set to A. The recorded sound
of FM broadcasts are reproduced and can be
monitored when the TAPE MONITOR switch is
set to B.
¢ Phono sources can be tape recorded while
simultaneously listening to FM broadcasts as
follows:
1.
Connect
the
tuner
to
the
‘‘PLAY”’
jacks
of
the
TAPE
A
group
on
the
rear
panel
of
this
unit
and
the
tape
deck
to
the
TAPE
B jacks.
2. Connect the turntable to PHONO 1 jacks on the
rear panel and set the PHONO selector switch to
PHONO 1.
3. Set the TAPE MONITOR switch to A and tune in
FM broadcasts.
.
Set
the
TAPE
DUBBING
switch
to
SOURCE
and
the
tape
deck
to
recording
mode.
The
sound
from
the
disc
record
can
then
be
recorded.
.
The
FM
broadcasts
are
reproduced
when
the
TAPE
MONITOR
switch
is
then
set
to
A.
When
it
is
set
to
SOURCE,
the
sound
of
the
disc
record
will
be
reproduced.
When
it
is
set
to
B,
the
tape
recorded
sound
of
the
disc
record
can
be
monitored.
TURNTABLE 1 STEREO TUNER
TAPE.
REC-A-PLAY REC-B-PLAY
weeaaw G0 Oa!
TAPE DECK B
KA-907(K)

OPERATING INSTRUCTIONS
PRE OUTPUT/POWER IN JACKS PRE OUT POWER IN
Independent Preamplifier and Power Amplifier Sections
The preamplifier and power sections are tied LEFT
together by short jumpers at the PRE OUT/POWER
IN jacks. These major sections may be separated for
independent operation by removing the short
jumpers. This permits the KA-907 preamps to drive RIGHT
another set of power amplifiers for test or com-
parison purposes. In addition, an external preamp
may be connected to the POWER IN jacks to drive ; .
a . When not using these jacks, be sure to
the
power
amplifier
section
of
the
KA-907.
Turn
off
keep
the
short
jumpers
in
place.
power when removing or replacing the jumpers.
SHORT JUMPER
RIGHT
PROGRAM SPEAKER
SOURCE KA-907
A Multi-amplifier system
O00 _ tO &
a age ooo ¢
By adding an electronic crossover network and
one or two additional power amplifier, a high-grade
multi-amplifier system can be built in the following
manner.
1. Connect the PRE OUT jacks to the input jacks of
the crossover network (adaptor).
2. Connect the POWER IN jacks to the low-range
output jacks of the crossover network. ~
3. Connect the high range output jacks of the = ) LEFT
crossover network to the input jacks of a lad ide Promminllee Syeierh SPEAKER
separate power amplifier for the high-frequency seein P ¥
range: RIGHT
4. Connect the speakers for the lower frequencies PROGRAM SPEAKER
aa : SOURCE
to the amplifier, and those forthe higher frequen- a
cies to the separate amplifiers. OOO HO &
Note: As 32° 66°O) 000 t
For further details on connections, etc, see the instruction manual
supplied with the adaptor.
Precautions when using the POWER IN jacks
e The power amplifier in the KA-907 is fully DC
coupled. if a DC voltage is applied at the POWER
IN jacks it will be amplified and appear as a large
direct current into your speakers (the speaker
cones will show a static displacement). To pro-
tect your speakers, make sure that there is no
steady-state DC voltage applied from the equip-
ment connected to the POWER IN jacks.
¢ Ifa DC voltage in excess of 200 mV is applied to
the POWER IN jacks the protection circuit will ac-
tivate to prevent speaker or circuit damage and
the power indicator will flash to indicate a fault.
Note:
There are no level controls in the power amplifier section. Make
sure power is off before making any connections to the POWER IN
jacks.
CROSSOVER
POWER
INPUTTNETWORK
[|
amp.
HIGH INPUT
A Multi-amplifier System
KA-907(K)}

SAFETY PRECAUTIONS
CLEANING
Do not use volatile solvents such as alcohol,
paint
thinner,
gasoline,
benzine,
etc.
to
clean
the
cabinet. Use a silicon cloth or a clean dry cloth.
VENTILATION HOLES
The case top is slotted to allow ventilation. Never
block these holes with ornamental cloths, books or
other objects. Make sure that metal objects such as
hairpins, or needles do not enter the unit through the
ventilation
holes.
The
result
could
be
a
serious
malfunction
or
a
possible
shock
hazard.
Make
sure
that children do not insert foreign objects into the
ventilation holes.
MODIFICATIONS AND SERVICE
Each unit is shipped after it has been carefully ad-
justed and tested to provide optimum performance.
The unit must not be modified internally. Unauthoriz-
ed modifications will void the terms of the warranty.
High voltages are used in some of the internal cir-
cuits. Therefore, do not remove the cabinet or touch
internal parts. Refer all service to qualified service
personnel.
POWER CORD
Always insert or remove the power plug from the
AC outlet by grasping the plug body. Never pull or
stretch the cord. Take care that the cord is not sub-
ject to traffic or bent sharply around furniture. Keep
heavy objects off the cord; never route it under rugs,
and avoid the use of extra extension cords. Atten-
tion to these precautions will avoid fire or shock
hazards.
PROTECTION OF SPEAKER SYSTEM
Your amplifier is capable of supplying very high
power to yopur speakers. To prevent speaker
damage due to accidental surges, such as may be
caused by inadvertently dropping the stylus onto a
record, make it a habit to reduce volume before
changing records, switching between program
sources or turning power ON.
Check the power-handling ability of your
speakers and make sure that the power supplied is
within their limits. Excessive power can permanently
damage your speakers.
ACOUSTIC FEEDBACK
Occasionally a disturbing howling sound caused
by acoustic feedback, may be heard. This is general-
ly caused by the relative positions of the turntable
and speaker enclosures. The sound pressure
radiated from the speaker surrounds and vibrates the
turntable.
This vibration is picked up by the cartridge, sent
to the unit as an electrical signal, and returned to the
speaker. This again causes the speakers to radiate
vibration which induces sympathetic vibrations in
the turntable and cartridge. Sympathetic vibrations
are reinforced with each repeating cycle and result in
an undesirable sound called oscillation or
““howling’’. To prevent it, keep your turntable away
from your speakers. Also mounting your turntable on
shock-absorbing pads may help.
HEXAGONAL KEY
Be sure to keep the hexagonal wrench since it is
necessary for repair by your service technician.
KA-907(K)

IN CASE OF DIFFICULTY
AM, FM, PHONO or Tape playback
If your unit should not perform as expected, consult
the table below to see if the problem can be corrected
before seeking help from your Kenwood dealer or service
technician.
Pilot lamp out, no sound, power on.
Pilot lamp lights but no sound from
left or right.
CAUSE REMEDY
a) Power cord not plugged in. a) Check plug contact.
b) Poor connection at wall outlet. b) Check outlet using a lamp or other ap-
Power outlet inactive. pliance (outlet may be controlled by a
wall switch).
—
c) Fuse blown. c
Replace fuse. If it blows again, trou-
ble must be corrected.
a) Speaker cords disconnected. a) Check speaker connections.
b) Speakers switched off. b) Check speaker switch.
c) Volume control fully CCW. c) Adjust volume.
d) TAPE MONITOR or DUBBING d) Set to SOURCE except when tape
switches set to A or B. decks are in use.
Sound from left or right, but not
both.
Noise when POWER is switched on
or volume is adjusted immediately
after.
Phono level differs from FM or AM
level.
PHONO playback only
a) Check connections at both ends of
speaker cord.
b) Reverse speakers, if problem stays
with speaker have speaker checked.
c) Check setting of BALANCE control.
a) Poor speaker connections.
b) Defective speaker.
c) BALANCE set to one extreme or
the others.
a) Insufficient warmup. a) Allow 10 seconds for warmup before
adjusting volume.
b) Low or high output from phono
cartridge.
b) May be normal;
accordingly.
adjust volume
CAUSE REMEDY
No sound from both or one speaker.
Loud hum drowns out sound.
a) Turntable output disconnected.
b) Poor ground connection at phono
cable connections.
a) Check phono cables.
b) Check phono plugs, particularly
Low background hum.
Background buzz.
TV signal picked up by phono cable
outershell connections.
Keep cables away from power cords.
Twist left and right cables together.
Reverse AC plug of turntable. Connect
ground wire between turntable and GND
connector.
Hum Picked up in turntable or turn-
table cables.
Route phono cables to minimize buzz.
(especially near transmitter).
Howling noise at maximum volume
settings.
| Acoustic pickup from speaker.
Increase distance between speaker and
turntable. Choose speaker locations
carefully. Check turntable suspension.
KA-907{K)

IN CASE OF DIFFICULTY
POWER INDICATOR AND DC COUPLED INDICATOR
The
POWER
indicator
and
the
DC
COUPLED
indicator
flash
in
case
of
some
malfunction
of
the
unit.
In
such
a
case,
locate
the
cause
of
the
trouble,
and
take
corrective
measures
by
referring
to
the
following
chart.
*When another equipment is
connected to the power
amplifier of this unit.
For example, when a pre-
amplifier or adaptor is con-
nected to the POWER IN
jacks.
Disconnect the equip-
ment connected to
the POWER IN jacks.
®The POWER switch is turn-
ed ON when the DC
COUPLED switch is OFF,
Turn the POWER
switch to OFF
beforehand.
¢The POWER switch is turn- i
ed ON when the DC
COUPLED switch is ON.
*SELECTOR
TUNER or AUX.
*TAPE MONITOR
switch at A or B.
Set the DC COUPL-
ED switch to OFF.
: The indicator stops flashing after about 10 seconds, the speaker relays operate, and sound normal.
: The indicator keeps flashing after 10 seconds and no sound.
at
*The unit functions when the
DC COUPLED switch is
OFF, but ceases to
reproduce sound when the
DC COUPLED switch is set
to OFF, and the indicator
begins to flash.
Set the AT-
TENUATOR at
— oO,
xO
Normal operation.
DC leakage exists at the output
of the equipment connected to
the POWER IN jacks.
DC leakage occurs from the
output of the equipment con-
nected to the TUNER, AUX, or
TAPE PLAY jacks.
Caution: If DC leakage occurs
from the output of equipment
connected to the unit, it is audi-
ble when the DC COUPLED
switch is OFF, provided that its
voltage is very low, e.q., incase
of output capacitor leakage. If a
high DC voltage leakage occurs
due to some malfunction, it
may damage the circuitry of the
unit. Great care must be exer-
cised in this respect.
Power amplifier section is faul-
Equalizer section is faulty.
(Probable faulty locations)
NORMAL
FAULTY
HANDLE INSTALLATION
The unit is provided with a pair of handles. When
mounting the handles, take the four screws off each
of both sides of the unit, and put them aside. Then,
mount the handles to the unit with the supplied
longer ornamental screws driven with a Phillips
screwdriver.
KA-307(K)

BLOCK DIAGRAM
PHONO SELECTOA
‘
Ss ,” EQUALIZER
PHONO |
MUTING
TAPE
PHONO 2 MON MODE
TUNER
OC COUPLED POWER AMP
O—o A SPEAKERS
——
TAPE PLAY A@
TAPE PLAY B@
AUX
TAPE DUBBING
°
TAPE
REC
A
@
LOUCNESS
TAPE REC B @
TO PRE AMP
ree
Fo FLAT ane fran arn f $e T)
pe —
REGULATOR
Fae = 0
SUBSONIC
iS
POWER IN ‘
' O—o B SPEAKERS
PHONES
PROTECTION
Meco gee See
- eral
oes
ie
POWER
-B
5 AC
GND
+B
TECHNICAL DESCRIPTION
DC Power Amplifier
In many ways the direct current (DC) amplifier is
the ideal amplifier for audio use.
Kenwood audio engineers have taken up the
challenge of producing this ideal amplifier. The result
has been success in producing a power amplifier
which makes this concept a reality.
Characteristics of DC Amplifier
1. They make reproduction of low frequencies
down to subsonic and DC levels possible.
The result is to give a greater sense of power in
the audio reproduction which greatly increases
enjoyment of music and reproduces the low-
frequency high-energy sounds of a live perform-
ance as only a DC amplifier can.
. There is zero phase difference between input and
output.
Because there are no capacitors in the signal
path to cause phase rotation, phase distortion is
absent.
. Output waveform is a faithful duplication of the
input waveform. Although this would seem to be
a natural prerequisite for a hi-fi amplifier, it is a
fact that only a DC amplifier makes this duplica-
tion possible.
The performance of a DC amplifier depends upon
the stability of each individual circuit within it. In the
input stage, special dual FETs are used, intended for
the most demanding electronic computer applica-
tions {in packs of perfectly balanced pairs). This is
followed by a three-stage differential amplifier
operating in Class A, in which the open loop gain is
high, and in which a predetermined degree of
negative feedback is applied. The pre-driver load cir-
cuit includes a power transistor for which bias is
stabilized by a constant current supply. This circuit
configuration gives excellent stability and extremely
wide frequency response.
KA-SO7(K}

SPECIFICATIONS
POWER OUTPUT
150
watts*
per
channel
minimum
RMS,
both
channels
driven,
at
8
ohms
from
20
Hz
to
20,000
Hz
with
no
more
than
0.01%
total
harmonic
distor-
tion.
Both
Channels
Driven
.................00.
000.
cece
150+
150
watts
8
ohms
at
1,000
Hz
180+ 180 watts 4 ohms at 1,000 Hz
Total Harmonic Distortion
(20 Hz to 20,000 Hz)
AUX
input
to
SPEAKER
output
..................
0.01%
at
rated
power
into
8
ohms
0.006%
at
1/2
rated
power
into
8
ohms
PHONO
input
to
SPEAKER
output
...............
0.01%
at
rated
power
with
VOLUME
—
20
dB
Intermodulation
Distortion
.....................00..
0.0045%
at
rated
power
into
8
ohms
(60
Hz:
7
kHz=4:
1)
Damping
Factor..............
0.0.00.
ccc
cece
eee
eaee
100,
DC
~
20,000
Hz
into
8
ohms
Transient
Response
Rise Times clic ecacee nde naa beni See eok 0.8 us
Slew
Rate
.............
0.0.0
c
cece
eee
eee
eae
+230
Vius
Power
Bandwidth..............0.0.
0.0.
cc
ceeeeceeee
5
Hz
to
100
kHz
at
0.03%
T.H.D.
Frequency
Response
(DC
COUPLED
at
ON)..........
DC
to
400
kHz,
+0
dB,
—3
dB
(DC COUPLED at OFF) ......... 1 Hz to 400 kHz, +O dB, —3 dB
Speaker
Impedance
............0..
00...
c
ccc
eeeeeee
Accept
4
ohms
to
16
ohms
Power
IN
Sensitivity/Impedance....................
1
V,
50
kohms
Input
Sensitivity/Impedance
Phono
1
(MM)...............
00000
ccc
cece
cease
2.5
mV/33
kohms,
47
kohms
and
100
kohms
Phono
2
(MM)..............0..00
ccc
cece
cece
ane
2.5
mV/47
kohms
Phono
1
(MC)
....
0...
ccc
cee
eee
eee
nee
0.1
mV/100
ohms
Tuner,
AUX,
Tape
A,B.....
6...
eee
eee
ee
150
mV/50
kohms
Signal
to
Noise
Ratio
(IHF.
A)
Phono
1&2(MM)...................
cee
cece
ee
90
dB
for
2.5
mV
input
96 dB for 5.0 mV input
102 dB for 10 mV input
Phono
1
(MC)
..............
00
ccc
cece
cence
aes
70
GB
for
0.1
mV
input
76
dB for
0.2
mV
input
Tuner
AUX,
Tape
A,
B.............0
cc
eee
105
dB
for
150
mV
input
Maximum
Input
Level
for
Phono
1
&
2(MM)
.........
230
mV
(RMS),
T.H.D.
0.01%
at
1,000
Hz
for
Phono
1
(MC)
.............
9
mV
(RMS),
T.H.D.
0.01%
at
1,000
Hz
Output
Level/lmpedance
Tape
REC
(Pin)
.........0..
0.00
cece
eee
eee
eae
150
mV/180
ohms
UDIND
cies
sips
e
ecoe
ica
earekoe
viet feat
ohare
30
mV/80
kohms
PRE
OUT
(Maximum)
......................000-
9
V/750
ohms
Frequency
Response
for
Phono...................-.
RIAA
standard
curve
+0.2
dB
(20 Hz to 20,000 Hz)
Bas
tiioinsse.
coe,
potece:
Habs
ivan
apo
toe
cae
od
ae
meets
+
7.5
dB,
Crossover
Freq.
150
Hz
and
400
Hz
We
DI
6!
2
oye
ie
and
setae
hehe
a
Sivas
ooetaleehe
econ
+
7.5
dB,
Crossover
Freq.
3
kHz
and
6
kHz
Loudness
Control
................0
0c.
cece
eee
eeeee
+3
dB,
+6
dB,
+9
dB
at
30
Hz
or
at
100
Hz
(at —50 dB VOLUME Level)
Subsonic
Filter.........0.00.0000
00000.
c
cece
eee
eeaee
18
Hz,
6
dB/oct
High
Filtet
ics
os.
Siy
can
Can
ainncenSagln:
Bevin
iniucen
8
kHz,
12
dB/oct
GENERAL
Power
Consumption
.................
000
..c0
cee
eee
1,000
watts
at
full
power
A.C.
Outlets:is
6
ig
652
bites
vain
cows
ba
suudeensa
Switched
2,
Unswitched
2
DIM@NSIONS
2.5
605545
eselapcpeou
gee
sh
velveteen
ee
Lane
W
460
mm
(18-1/87’)
H 161 mm (6-11/32"}
D 463 mm (18-7/32"')
Net
Weight
(less
handles)
.......................04,
25.8
kg
(56.9
Ibs)
*
Measured
pursuant
to
Federal
Trade
Commission’s
Trade
Regulation
rule
on
Power
Output
Claims
for
Amplifier
in
U.S.A.
Note:
Kenwood
follows
a
policy
of
continuous
advancements
in
developments.
For
this
reason
specifications
may
be
changed
without
notice.
KA-9O07(K}