Harman Kardon STRATOPHONIC Series User manual

AMES COURT, PLAINVIEW, L. I., N.Y.
fait kardon |
A SUBSIDIARY OF THE JERROLD CORPORATION
90722322
INSTALLATION AND OPERATION MANUAL
STRATOPHONIC SERIES
MODEL SR9YODOB
arigest-la Kardon |
SOLID-STATE STEREOPHONIC RECEIVER

SPECIFICATIONS FOR SRSOOB STRATOPHONIC RECEIVER
A. Amplifier
Music Power Output
at 4 ohms
Full Power
Bandwidth
Harmonic Distortion
20--20KC
Mrequency Response
* {db
Damping Factov
Square Wave
Rise ‘Lime
{Yuin and Noise
Input Sensitivity
Phono
Tape Head
Auk,
Tone Controls
Speaker Inipedanice
High Cut Filter
Low Cut Hilter
100 watts
5-60 KC
Jess than 0.2%
2-100 KC
AQti
22 us
945 db
2.5 Vv
2.9 TON
200 tiv
+14 db, ---L0 db
4.16 olims
-— 6 db at LO KC
--- 10 db at 50 cps
B. Tuner
Useable Sensitivity
Image Rejection
better than
Spurious Response
Rejection better
than
Frequeney Response
Distortion beiter
(hai
Multiplex Separation
Antenna bapedance
C. General
Input Receptacles:
Mapnetic Phono
Tape Head
Ceramic Phono
Auxiliary
Tape Monitor
Output Receptacles
Tape Out
1.85 uv
710 db
85 db
#O.S db
0.3%
AQ db
300 ohing
~
I “
Yniroduction
YOUR NEW STRATOPHONIC RECEIVER
We know how anxious you are to try your new Stratophonic Recciver. But
a
few
cxtra
moments
of
paticnce
spent
in
carefully
reading
this
instruction
book
will
pay
vast
dividends
in
the
ultimate
enjoyment
of
your
component,
It
is
customary,
at
this
time,
to
congratulate
you
on
the
wise
decision
you
have
made
in
the
purchase
of
your
new
Stratophonic
Solid-State
Receiver.
This,
we
most
certainly
do.
You should also know that it is the culmination of several years of intensive
research
in
solid-state
technology.
Your
Stratophonic
Receiver
is
literally
born
of space-age development,
Thus, you have invested in the finest stereophonic integrated music center
available.
It
truly
represents
the
state-of-the-art
in
its
ability
to
reproduce
life-like
music,
And,
because
of
advanced
solid-state
reliability
and
construction,
your
new
Stratophonic
Receiver
will
continue
to
provide
the
ultimate
subteltics
of
every musical nuance.
But,
this
alone
is
not
enough.
Your
new
Stratophonic
Receiver
has
also
been
designed
for
maximum
versatility.
The
simple
movement
of
a-switch
or
control
makes
you
master
of
every
program
source---tape,
disc
and
FM—mono
and
stereo,
And,
Harman-Kardon
designers
have
endeavored
to
make
your
Strato-
phonic
Recciver
a
major
asset
to
home
decor.
Now,
go
on
to
a
new
cxpericnce—Stratophonic
Sound—the
experience
of
hearing
music
as
you
have
never
heard
it
before.
KEEP
THIS
BOOK
AVAILABLE
AT
ALL
TIMES
FOR
IT
CONTAINS
INDISPENSABLE
TECHNICAL
AND
SERVICE
INFORMATION,
J

General Information
UNPACKING
After
unpacking
the
SR900,
inspect
it
carefully
for
signs
of
transit
damage.
The
receiver
was
subjected
to
numerous
rigid
quality
control
inspections
and
therefore
should
be
in
perfect
operating
condition.
If
damage
1s
visible,
notify
your
dealer
at
once.
If
the
receiver
was
shipped
to
you,
notify
the
transportation
company.
Harman-Kardon
will
cooperate
with
you
in
such
instances,
but
please
note
that
only
you
can
recover
from
the
carrier
for
damages
incurred
during
shipment.
WARRANTY POLICY
We
urge
you
to
fill
in
your
warranty
card
and
mail
it
to
the
factory
without
delay
to
protect
your
rights
under
warranty,
The
Haman-Kardon
warranty
is
not
valid
unless
we
have
your
card
on
file.
WARRANTY
We
warrant
each
$R900
to
be
free
from
defects
in
material
and
workman-
ship
under
normal
use
and
service,
and
in
accordance
with
the
conditions
herein
below
set
forth,
for
a
period
of
2
years
from
date
of
delivery
to
the
original
pur-
chaser,
and
agree
to
replace
or
repair
any
part
or
parts,
returned
to
us
within
said
2
years,
with
transportation
prepaid
and
which
our
examination
shall
disclose
to
our
satisfaction
to
have
been
thus
defective,
This
warranty
does
not
include
free
labor,
nor
is
it
applicable
to
any
instrument
which
shall
have
been
repaired
or
altered
in
any
way
so
as
in
our
judgment
to
affect
its
stability
or
reliability
nor
which
has
been
subject
to
neglect,
misuse,
abuse,
negligence
or
accident
-nor
which
has
had
the
serial
number
altercd,
effaced,
or
removed.
Neither
shall
this
warranty
apply
to
any
instrument
which
has
been
connected
otherwise
than
in
accordance
with
instructions
furnished
by
us.
os
This
warranty
is
expressly
in
lieu
of
all
other
warranties,
express
or
implied,
and
of
all
other
obligations
or
liability
on
our
part,
and
we
neither
assume
nor
authorize
any
representative
or
other
person
to
assume
for
us
any
other
liability
in
connection
with
the
sale
of
this
instrument.
SERVICE POLICY
Harman-Kardon
has
established
a
special
consumer
division
to
answer
all
questions
pertinent
to
the
installation
and
operation
of
your
unit.
Please
feel
free
to
Z
write us at any time and we will endeavor to offer prompt and complete advice.
If your problem cannot be resolved through our combined efforts we may
wish to refer you to one of our authorized warranty stations, The unit must be
shipped via Railway Express, Prepaid to the station designated, accompanied by a
brief note describing the exact nature of the difficulty. Under no circumstances
should the set be shipped directly to the factory without prior authorization.
Ynstallation Preece
VENTILATION
Sufficient space must be allowed around the SR900 to permit unrestricted
air flow for maximum circulation. This will insure low operating temperatures
which will result in extended component life.
The SR900 chassis is constructed of steel together with a heavy gauge
aluminum rear panel which acts as a heat sink (a device which dissipates heat)
for the output transistors, This area will become hot under normal use. This is
normal and should not be cause for concern. Do not place books or other objects
on the cage or in the immediate vicinity of the receiver.
When mounting your SR900 into an equipment cabinet the following
precautions must be observed.
1. Allow at least 3 inches above the top cover of the unit.
2. Allow at least 1 inch on each side of the chassis.
3, Cut the mounting shelf in accordance with the instructions on the mounting
template.
4, Leave the back of your equipment cabinet open to insure proper venti-
lation.
POWER REQUIREMENTS
Connect the AC line cord into any outlet furnishing 117 volts, 50 or 60
cycle AC current. The voltage may vary between 105 and 125 volts. An AC
convenience outlet is located on the rear panel of the recciver. This outlet is
“switched” and is controlled by the on/off switch on the front panel. Any auxiliary
equipment may be plugged into this outlet. The rating of this equipment should
not exceed 200 watts,

CONNECTING THE SPEAKERS FOR STEREO OPERATION (1 SYSTEM)
Your two speakers should be identical, if possible, to obtain optimum results.
Experts agree that a perfectly matched system offers the best stereophonic repro-
duction, The speakers should be placed along the same wall approximately 8 to
10 feet apart depending upon room size and furniture placement. It may be
necessary to experiment with speaker placement until best results are obtained.
Use any type of wire to connect your speakers to the SR900, Lamp cord
“Zin cord” is excellent and may be easily dressed around the molding for an
inconspicuous and neat installation. Do not drive the staples or tacks through the
center of the wire for this may short out the two sections and will decrease the
overall volume or short out the speakers entirely. It is permissible to use approxi-
mately 50 feet of speaker connecting wire for each speaker without loss of volume.
CONNECT SPEAKERS WITH CARE. AVOID SHORTS-—-RECEIVER HAS
BEEN DESIGNED TO PREVENT DAMAGE FROM ACCIDENTAL SHORT-
ING; HOWEVER, REPETATIVE SHORTING CAN DAMAGE TRANSIS-
TORS.
1, Connect one length of lamp cord to the left speaker. (This is the speaker
on your left as you face the speakers. This speaker will now be referred to as
Channel A.)
2. Attach the other end of the lamp cord to the terminals marked SYSTEM
1 CHAN A located on the rear of the SR900.
3, Similarly connect another length of lamp cord to your right speaker. (This
speaker will now be referred to as Channel B.)
en
|
CONNECT
SPEAKERS
WITH
A
6
CARE—AVOID
ACCIDENTAL
SHORTS
DIAGRAM A
H907ZO6504
4. Attach the other end of the lamp cord to the terminals marked SYSTEM
| CHAN B.
5. Your receiver is now connected for | system stereo operation and is opera-
tive when the speaker selector switch on the front panel is in the System 1 or
System 1 & 2 position.
SPEAKER PHASING
When more than one speaker is used in any music reproducing system the
speakers
must
be
connected
in
a
manner
to
work
together
rather
than
work
out
of
phase. If one speaker is pushing air out while the other is moving in the opposite
‘direction this will result in diminishing bass response. Checking for proper phase
and correcting if necessary is quite simple.
1. Place a stercophonic recording on your record player.
2. Pull the “Stereo-Mono” switch on the BALANCE control to its “Out”
position for monophonic playback.
3. Play the record. The sound should emerge from approximately the center
area between the two speakers.
4. While the record is playing push the “Stereo-Mono” switch “In” to the
stercophonic position.
5. The sound should now move across the wall of the room and should
appear to come from both speakers as well as the center.
6. If your speakers are out of phasc, the sound source will not pinpoint itself
between the two speakers when the Sterco-Mono switch is in the monophonic
position. Instead it will appear to come from both sides.
If the speakers are out of phase, turn off the receiver and disconnect both leads
from either the left or right speaker and reverse them. Your system will now be
in phase.
This completes your speaker connections. The SR900 is a solid state device
which does not contain audio output transformers, It is therefore not necessary
to match the impedance of your speakers to the receiver. The SR900 will per-
form perfectly with any speaker which has an impedance of 4, 8 or 16 ohms.

CONNECTING THE SPEAKERS FOR STEREO OPERATION (2 SYSTEMS)
{. Connect all 4 speakers for your two system operation as shown in
Diagram B.
2. You may now select either system 1, system 1 and 2 or system 2 by the
use of the “Speaker Selector Switch” on the front panel.
CONNECT SPEAKERS WITH
CARE—AVOID ACCIDENTAL
SHORTS
\ |
DIAGRAM B \ OC
SYSTEM }
A
H90720649A
NOTE: WHEN ALL THE SPEAKERS USED IN YOUR 2 SYSTEM CON.
NECTION ARE 4 OHMS, CONNECT A 2 OHM, 10 WATT RESISTOR IN
SERIES WITH THE HOT SIDE OF EACH OF THESE SPEAKERS, (IF TWO
OF THE SPEAKERS ARE 4 OHMS AND 2 OF THE SPEAKERS ARE ANY
HIGHER IMPEDANCE THIS PRECAUTION IS NOT NECESSARY.)
CONNECTING THE SPEAKERS FOR MONOPHONIC OPERATION (1 SYSTEM)
If the SR900 is to be used monophonically and stereo is to be added at
a later date, it is essential that both speaker output terminals are terminated into
a propcr load to prevent damage to the output stage of the receiver. Refer to Dia-
gram C for proper installation of the loading resistor.
At no time should the output terminals be paralleled for monophonic operation!
THIS IS THE ONLY CORRECT METHOD FOR
CONNECTING ONE SPEAKER TO THE SR900
a
CONNECT
SPEAKERS
WITH
CARE—AVOID ACCIDENTAL
SHORTS
DIAGRAM C es HOO7Z065IA

CONNECTING THE SPEAKERS FOR MONOPHONIC OPERATION (2 SYSTEMS)
If the SR900 is to be used monophonically and stereo is to be added at
a later date, it is essential that both speaker output terminals are terminated into
a proper load to prevent damage to the output stage of the receiver. Refer to Dia-
gram D for proper installation of the loading resistors.
At no time should the output terminals be parelleled for monophonic operation!
THIS IS THE ONLY CORRECT METHOD FOR
CONNECTING TWO SPEAKERS MONOPHONICALLY TO THE SR900
CONNECT SPEAKERS WITH
CARE—AVOID ACCIDENTAL
SHORTS
SYSTEM |
\
DIAGRAM D
HS0720652A
CONNECTING THE SPEAKER FOR STEREOPHONIC OPERATION (SYSTEM 1)
AND MONOPHONIC OPERATION (SYSTEM 2)
CONNECT SPEAKERS WITH
CARE—AVOID ACCIDENTAL
SHORTS
\
SYSTEM 2
H9O0S20653A
STEREO HEADPHONE RECEPTACLE
The stereo headphone receptacle located on the front panel will accept any
headphone with any impedance rating, To activate the headphone receptacle, the
Speaker Selector switch must be in the “Phones” position. For speaker operation,
throw the Speaker Selector switch to cither the system 1, 1 and 2 or 2 positions,
depending on the number of speakers connected in your system,

CONNECTING THE FM ANTENNA
Due to the exceptionally high sensitivity of the SR900 the folded dipole
supplied with the receiver is sullicient for all but the most difficult locations, ‘The
balanced antenna input is designed to accept a 300 ohm antenna, indoor or
outdoor type.
When using the antenna supplied, spread the dipole so that it forms a “I”
shape,
The
stem
of
the
“IT”
ends
in
two
screw
terminal
connections,
and
these
should be connected to the 300 ohm and GND terminals on the Antenna Terminal
Strip. Horizontal placement of the antenna offers maximum polarization for
optimum reception. The antenna may be tacked to the back of your hi-fi cabinet,
to the molding behind the equipment or to the shelf you use, Use ordinary tacks
through the center portion of the antenna leads to avoid shorting out the antenna.
In more remote locations, an outside Yagi, folded di-pole or omni-directional
antenna is recommended (Jerrold/Taco FMP 8, FMP 10, FMP 16, CM677). For
the greatest gain, an 8 to 14 element Yagi designed for the FM band is suggested.
A Yagi, however, is very directional and it may be desirable to use an antenna rotor
if a full 360° coverage is required. For reception in the suburbs, an outside folded
di-pole or omni-directional di-pole is recommended.
CONNECTING A STEREO RECORD PLAYER — (MAGNETIC PICKUP)
Connect both leads from your record player to the CHAN A and CHAN B
PHONO LO input receptacles on the rear of the SR900 chassis. If your record
player has a special ground wire emerging with the two input leads, conncct this
ground wire to the special GND terminal on the rear panel.
CONNECTING A STEREO RECORD PLAYER — (CRYSTAL OR
CERAMIC PICKUP)
Connect both leads from your record player to the CHAN A and CHAN B
PHONO HI input receptacles. There is usually no ground lead emerging from
the record player when a ccramic or crystal cartridge is uscd. However, if your
record player does use a ground lead, connect it to the special GND terminal
located on the rear panel.
CONNECTING A MONOPHONIC RECORD PLAYER
Connect the single lead from your monophonic record player to either the A
or B PHONO LO input if your player uscs a magnetic pickup, or to the A or B
PHONO HI input if it uses a ceramic or crystal pickup.
10
CONNECTING A STEREO TAPE DECK
A stcreophonic tape deck has two output leads. Connect these leads to the
CHAN A and CHAN B TAPE HEAD input receptacles on the rear of the
receiver. Should you desire to play back a monophonic tape on your stereophonic
tape
deck,
throw
the
VUNCTION
SWITCH
to
the
TAPE
HEAD
MONO
position.
CONNECTING A MONOPHONIC TAPE DECK
Connect the shielded lead from your tape deck to the CHAN A ‘TAPE HEAD
input receptacle on the rear of the rceciver and throw the FUNCTION switch to
the TAPE HEAD MONO position.
CONNECTING A STEREO TAPE RECORDER
Since most stereo tape recorders include their own record and playback
pre-amplificrs, it is not desirable to connect the output of the recorder into the
TAPE HEAD or any of the other low level input receptacles. This will result in
overloading of the low level stage and cause distortion.
Connect the two tape recorder output leads to the CHAN A and CHAN B
AUX receptacles on the rear panel of the receiver. ‘This will enable you to play
back your stereo tapes.
To make a recording, connect the inputs of your recorder to the CHAN A
and CHAN B TAPE OUT receptacles. This will enable you to make a stcreo-
phonic recording with the proper recording cqualization as determined by your
recorder, while simultancously listening to the program material through your
speaker system. The recording signals from the TAPE OUT receptacles are
unaffected by the tone controls or volume setting of the SR900 to insure an abso-
lutely flat response.
CONNECTING A MONOPHONIC TAPR RECORDER
If a monophonic tape recorder is to be used with the SR900, connect the
recorder output to either the CHAN A or CHAN B AUX input receptacle located
on the rear pancl. This will enable you to play back your monophonic tapes.
If your recorder is sterco playback but records monophonically, connect
the output as described in the previous section on connecting a sterco tape
recorder. Connect the input for recording monophonically as described betow.
Connect the input of your recorder to either the CHAN A or CHAN B
TAPE OUT receptacle, This will enable you to record monophonically while
simultancously listening to the program through the recciver and speakers.
TO MONITOR YOUR TAPES WHILE RECORDING
Connect the monitoring head of your tape recorder to the TAPE MON recep-
tacles on the rear of the recciver chassis, Connect in accordance with the instruc-
‘tions supplied by the recorder manufacturer.
11

Opera tion Procedure
kivery control on this receiver serves a specific useful function and is im-
portant for the proper operation of your sterco system. Jt is important to note
that under no circumstances should this receiver be operated without either a
speaker or resistive load across both the output terminals,
ON/OFF SWITCH
The illuminated push-button power switch is located in the lower left hand
corner of the receiver. Depress the amber button to turn the receiver on, Depress
sv to turn the receiver off. When the receiver is on, the push-button will glow
softly,
TUNING CONTROL
‘The TONING CONTROL is located directly to the right of the dial glass
and is used to select the desired FM station.
TUNING METER
_ The SR900 incorporates a D’Arsonval movement tuning meter for precise
tuning. The TUNING METER is used to tune to the center of the station channel
and proper tuning is achicved when you are on a station and the TUNING METER
is at maximum.
VOLUME CONTROL
The VOLUME CONTROL on the $R900 is essentially two controls in one,
mechanically tied together, to be operated by onc knob. The volume control varies
both channels simultaneously and is used to adjust the volume level of program
material
fed
into
the
sterco
system.
Its
effect
can
be
modificd
by
the
special
Harman-Kardon CONTOUR switch.
12
BALANCE CONTROL
The nature of stereophonic reproduction is such that it requires two identical
channels
to
attain
the
highcst
degree
of
faithfulness
and
spatial
distribution.
Any
variation
in
the
cfliciency
of
one
channel
as
compared
to
the
other
will
disturb
this
relationship.
As
there
may
be
slight
differences
between
the
two
speakers,
tape heads, cartridge coils, ctc., the SR9O0 includes a special control to balance
one
channel
against
the
other,
Suflicient
range
is
covered
by
this
contro]
to
permit
rebalancing of the overall system even in extreme cases where unbalance exists.
It should be noted that the BALANCE control may be set anywhere within
its range of adjustment to attain system balance.
BASS AND TREBLE TONE CONTROLS
The BASS and TREBLE tone controls on the SR900 provide the full range
of
tonal
adjustment
necessary
for
stereo
high
fidelity
listening.
The
tone
control
range is considerable and can adequately adjust the low and high frequencies in
accordance with your listening preference, speaker characteristics and room
acoustics.
FUNCTION SELECTOR SWITCH
The FUNCTION SELECTOR switch selects the desired type of prograin
source, The switch on the $R900 has six switching positions,
i. TAPE HD MONO. This position selects your tape deck for monophonic
playback, and includes NARTB equalization,
2. TAPE HD STEREO. This position sclects your tape deck for sterco-
phonic playback and also includes NARTB equalization.
3, PHONO. This position selects your record player (magnetic, crystal .or
ceramic pickup) for playback and includes RIAA equalization,
4. FM MONO/STEREOLOGIC, This is the normal listening position for
all monophonic and stereophonic FM broadcasts. In this position the Stereo
{ndicator Light and the automatic switching circuit built into your receiver are
operative. |
5. FM STEREO. This position selects FM stereo without the automatic
switching circuit, |
6. AUX. This position selects any high level equipment, such as an AM
tuner, the output of your television sct or any other high level signal which is
connected to the AUX receptacles on the rear of the receiver.
{3

SPEAKER SELECTOR SWITCH
The Speaker Selector Switch is a 4 position switch which selects between
headphone or speaker operation. It permits the connection of 2 complete speaker
systems (system 1, system | and 2, or system 2).
For additional information sce the paragraphs on speaker connections.
CONTOUR SWITCH
One of the limitations of human hearing is its tendency to lose sensitivity to
the very low pitched sounds as the program sound level is reduced. It is this
characteristic (known as the Fletcher-Munson cffect) which causes one to play
inusic programs at high listening levels in order to experience the full rich tone
available from fine modern recordings.
The Harman-Kardon CONTOUR switch compensates for this effect; thereby
eliminating high listening levels as a requisite for full enjoyment of reproduced
music, For warm, full-bodied reproduction at low listening Icvels, throw the
CONTOUR switch “IN”, At high levels, the contour switch nas no effect.
TAPE MONTFOR SWITCH
If your tape recorder has a special monitoring head, throwing this switch to
the “IN” position will enable you to listen to your tapes a second altcr they are
recorded. When not in use this switch must be in the “OUT” position,
LOW CUT SWITCH
At times, record changers, turntables and even some I'M stations produce
an objectionable low frequency signal that is strong enough to be introduced into
the playback system. This is knowa as rumble and can be cancelled out by the
cal low frequency cut off filter network included in this receiver, Whenever
rumble is present throw the LOW CUT switch “IN”.
HIGH GUT SWITCH
In the event of objectionable high frequency scratch, throw the HIGH CUT
switch located on the front panel “IN.” ‘This will roll off the higher frequencies
and will clear up the program material considerably,
‘This switch may also be used when listening to FM reception. It may be
useful when listening to a stereophonic FM broadcast which 1s slightly noisy,
Throwing the FUGH CUT switch “IN” will eliminate the noise.
14
TONE CONTROL SWITCH
This switch, when in the “OUT” position completely defeats the tone control
circuit to provide absolutely flat response. When activated the tone controls are
“IN” the circuit and can be adjusted to your own listening preference.
MUTING SWEPCH
The purpose of the muting circuit is to reduce audible noise when tuning from
station to station. Since very weak signals may be muted at the same time, the
front panel MUTING switch may be used to defeat the muting circuit on weak
signals.
To reduce interstation noise, throw the MUTING ‘switch “ON”, To defcat
the circuit, throw the switch “OFF”.
STEREO-MONO SWITCH
The STEREO-MONO switch is physically located as a “PUSH-PULL”
function on the “BALANCE” control.
When the switch is in the “IN” position the reeciver is operating stereo-
phonically. When the switch is pulled to the “OUT” position the receiver is
operating monophonically, This position may be used when listening to monophonic
records, or when it is desired to reproduce a stereo program, such as an FM
stereo broadcast, monophonically,
SELECTING MONOPHONIC OR FIM STEREO BROADCASTS
Under normal use, the FUNCTION selector switch should be placed in the
FM MONO/STEREOLOGIC position.
If the recciver is tuned to a monophonic FM broadcast, the special STEREO
LOGIC circuit will automatically defeat the multiplex circuitry and the tuner will
reproduce monophonic sound through both channels. Should this station begin
to transmit sterco, the logic circuit will automatically switch in the multiplex
section and you will receive the broadcast in full stereophonic sound. Should the
station conclude broadcasting in sicreo, your SR900 recciver will automatically
switch back to monophonic reception.
The exclusive Harman-Kardon logic circuit is always operative —--cven as
you tune across the FM dial. As you tune to a stcreophonic broadcast, the logic
circuit automatically switches your reeciver to the stereophonic mode of operation
-— and back to monophonic as the sterco station is passed.
15

Should you receive a weak stereo signal whose quality has been degraded by
noise or excessive multipath, the special STEREO LOGIC circuit will auto-
matically change the mode of operation of the recciver to monophonic enabling it to
reproduce an undistorted signal. Should you desire to listen to this stereo broad-
cast in spite of noise and degraded tone quality, place the function sclector switch
in the FM STEREO position, ‘This defeats the STEREOLOGIC circuit.
STEREO INDICATOR LIGHT
A sterco indicator light is located directly behind the FM dial glass and
operates
in
conjunction
with
the
STEREOLOGIC
circuit.
The
light
visually
indi-
cates the reproduction of stereo through your receiver.
AUTOMATIC STEREO ADJUST CONTROL
This control, located on the rear panel, has been factory adjusted and should
not require further readjustment. It adjusts the level at which the automatic logic
circuit will switch your receiver from stereophonic to monophonic operation.
If it is necessary to re-adjust this control the following procedure should be
followed. Tune to the weakest stereo station which you desire to hear stereo-
phonically. Slowly rotate the automatic stereo adjust control counter-clockwise to
the point at which the sterco indicator light on the front panel gocs out. Then,
slowly rotate the control clockwise to the point at which the light gocs on, This
is the point at which the control should be set.
INTERCHANNEL MUTING THRESHOLD ADJUSTMENT
This control is located on the rear of the chassis and should be adjusted as
follows:
Tune
in
the
weakest
station
in
your
arca
with
the
front
panel
FM
Muting
switch
in
the
“OFF”
position.
Tune
off
the
station
and
throw
the
FM
Muting
Switch
“ON”,
Rotate
the
“Muting
Adjustment”
clockwise.
Then
rotate
counter-
clockwise
until
only
a
faint
hiss
is
heard.
Tune
in
again
to
the
weak
signal.
If
it
still can be heard, and noise present off station is negligible, the adjustment. can
be considered satisfactory. NOTE: Maximum sensitivity is obtained with the
FM Muting Switch in the “OFF” position.
16
Special Sechn teat Ynformat (On
DIAL SCALE
The SR900 Dial Scale is marked with two scales, a frequency scale (88-
108 MC), and a logging scale (0-100). Since most FM stations operate on fre-
quencies which are not whole numbers (such as 96 MC as compared to 96.3)
ideally each megacycle division on the frequency scale should be divided into 10
parts to cnable the user to pinpoint the location of the station, This wouid require
a dial scale which would be longer than the front panel.
The logging scale which is divided into 100 equal parts provides a means of
finding your favorite station, once you have noted its position on the logging scalc.
For example, in New York City, WOXR operates on 96.3MC. After locating this
station through the use of the frequency scale (between 96 and 98 MC), you find
that the pointer falls on 46 on the logging scale. Make a note of this setting and
when you next want to tunc to WOXR, all that is necessary is to set the pointer to
46 on the logging scale.
EQUALIZATION
In order to achieve good reproduction of the wide range of frequencies in
music and to make necessary adjustments for the limitations of the recording
technique, record manufacturers have found it necessary to modify the actual
frequency response of the music while it is being recorded. ‘Thus, to avoid over-
cutting and consequent distortion, a measured and deliberate reduction is effected
in low frequency response by selecting a “turnover frequency” and by recording
attenuated response below that point. To assure optimum signal to noise at the
high frequency end when the record is played at home, the highs are dcliberately
exaggcrated during the recording process. A measured and deliberate boost is
effected above a certain frequency. This combination of deliberate exaggeration
at the low and high ends of the frequency response can be expressed in a recording
curve, When the record is played a mirror image of that curve should be available
so that the ideal “flat” response may be achieved,
The TAPE HD and PHONO positions of the Function Selector automatically
select the proper equalization that is required.
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