Marantz 4270 User manual

~
Model 4270
Stereo 2+ Quadradial 4
R Receiver
MARANTZ CO., INC.·P.O . BOX 99·SUN VALLEY, CALIFORNIA·91352
A WHOLLY·OWNED SUBSIDIARY OF SUPERSCOPE INC., SUN VALLEY, CALIFORNIA 91352

WA R A
All parts of MARAN TZ produ cts are fully
guaranteed for a period
of THREE YEARS from
date of purchase, exce pt for tubes which are
guaranteed for NINETY DAYS from
date of
purchase,
and except for spe aker pr oducts. Speaker
produ cts are guaranteed.as f ollow s: all speaker and
electron ic compo nents are fully guaranteed for a
period of
THRE E YEARS from date of purchase;
the cabinetry Is guara
ntee d against manufacturing
defects on ly, for a period of TWO YEARS from
dat e of purchase.
In
the event that service is requ ired, all
necessary
par ts and labo r will be furnished free of
charge during the above stated periods. The
conditions of th is Warranty, and t he
exte nt of the
responsibilitY
of MARA NTZ COMPANY, INC.
under this War;anty,
are as follows:
1,
The purchase must have been made from
an authorized MARANTZ dealer.
2,
The Warranty extends only in favor of
the original, registered
owner of the prod uct.
3.
The Warranty Registration Card must be
transmitted to MARAN IZ COMPANY, INC., P. O.
Box 99, Sun Valley, California 91 352, no t later
than TEN DAYS from date of purchase..
4.
The Warranty will become void if repairs
are
effected by anyone other than an authorized
MARANTZ Service Station.
5. If it becomes necessary to send this
product or any defective part to MARANTZ
COMPANY, INC., or
to an aut horized MARANTZ
Serv
iceStet ion, all shipping charges must be fullv
prepaid.
If the ent ire inst rume nt is sent, it must be
shipped in its original package. No accessories
should be shipped
with the product. If any
accessories are s hipp ed with the product.
MARANTZ COMPANY, INC. shall have no
liability whatsoever for loss of
or damage to any
such accessories,
nor for the safe-return thereof.
6. This Warranty shall be valid only if
the
purchase was made within the United States of
America.
The Warr anty shall not apply unless
shipment is made by
the pur chaser to the
MARANTZ Service
Station from a point within
the United Stat es. If the requested repairs an d/ or
parts exchange are
within the t erm s of this
Warranty , MARAN TZ COMPANY. INC. will
prepay return shi pping charges, provided that such
return shipment is to be made to an address
located
wit hin the United States.
7. This Warranty is void if the Serial
Nunt>er has been
altered or removed. This
W
arranty shall not apply if the product has not
been co nnec ted or operated in accordance with th e
instru
ctions furn ished by MARANTZ COMPANY,
INC. This Warranty shall also be void if the
prod uct has been altered or repaired in any way
which MARANTZ COMPANY, INC. believes has
affected the stability or reliability of the product.
8. MARANTZ COMPANY, INC. shall have
no liability whatsoever for consequential da mages.
The sole responsibility of MARANTZ COMPANY,
INC.
under this Warranty sha ll be limited to the
repair of the prod uct, or rep lacement thereo f, in
the sole discretion of MARANTZ COMPANY,
INC.
9. This Wa
rranty does not include the
furnishings of labor or par ts for user mainte nance,
as the same is described in the instructi on
manu al
or
handbook furnished with this pro duct,
10. This Warranty is valid only with respect
to repairs effected by an author ized MARANTZ
Service
Station .
11. EXCEPT TO THE EXTENT THAT
APPLICABLE LAW PRECLUDES A
DISCLAIMER OF WARRANTY,
THERE IS NO
IMPLI ED WARRANTY O F
MERCHANTABILITY OR FITNESS WITH
RESPECT TO THIS PRODUCT, NOR ARE
THERE ANY O THER WARRANTIES WHICH
EXTEND BEYOND THE PROVISIONS OF
THIS WARRANTY. ORDINAR Y PERIODIC
CHECK·UPS ARE
NOT INCLUDED IN THIS
WARRANTY.
12 . MARANTZ COMPANY, INC. reserves
the right to
make chariges .ln design and/or
i mprovements upon its prod uct s without any
obligation to include these changes in any
products theretofore manufac tured.
TO
PROTECT YOUR RIGHTS UNDER
THIS WARRANTY. FILL OUT AND MAIL THE
WARRANTY REGISTRATION CARD TO
MARANTZ COMPANY, INC., P.O. BOX 99,
SUN VALLEY,
CALIFORNIA 91352 , NOT
LATER THAN TEN DAYS FOLLOWING THE
DATE OF PURCHASE.
Should there be any questions, please contact the
Marantz National Service Manager, Marantz Company, Inc.
P.O. Box 99, Sun Valley, California
91352
~
PURCHASE 'S RECD 0
REGISTRATION FOR MARANTZ 3-YEAR GOLDEN
WARRANTY
Model: Marantz Model 4270
Serial No. _
Purchaser's Name _
Purchased From (Name) _
Address _
Price Paid $
------
Date Purchased - _
Date Warranty Reply Card Mailed _
The above information becomes
your permanent record of
a valuable purchase. It should be promptly filled in at the
same
time that you fill in and mail the warranty registration
reply card to Marantz. This information provides a valuable
insurance record and must also be referred to should you
have any correspondence with Marantz.

•
•
•
TABLE OF CONT EN TS
Connecting the 4270 2
Source Devices 4
Remote Speakers 4
Speaker Phasing 5
Speaker Placement 5
Front Panel Features 7
Mode Switch 7
Dimension 8
SQ Decoder 8
Balance Controls 8
Selector Switch 8
Bass, Mid and Treble Controls 8
Monitor Switch for Tape 1!Tape 2 8
Monitor Switch for Tape/Source 8
Main and Remote Spkr Switches 9
Power Switch 9
Front and Rear PhonesJacks 9
Loudness 9
Hi
Filter Switch 9
Tuning Meter 9
Tuning 9
FM Muting Switch 10
Volume 10
Dolby Switch 10
Record Level
(L) (R) 10
Play Cal.
(L) (R) 10
400Hz Tone Switch 10
Rear
Panel Features 11
Phono Jacks
11
CD-4/
AUX Jacks 11
Tape
Monitor In and Tape Monitor
Out Jacks 11
FM Antenna Terminals
11
AM Antenna Terminal 11
FM Quadradial
Output Jack 12
FM De-EmphasisSwitch 12
Dolby FM Preset Level Controls 12
Muting Level Control 12
Power Mode Switch 12
Pre Out, Main In Jacks 12
Connecting an External
Amplifier for
Rear Channels 12
Connecting an External
Amplifier for
Front Channels 12
Chassis Ground Binding Post 12
Main and Remote Speakers 12
Connection
to AC Outlet
13
AC Convenience Outlets 13
Remote Control 13
External Decoder Connection 13
Tape Recording 13
Basic
Dolby Process
14
Dolby Calibration 14
Procedure
for Playback Calibration 14
Procedure
for Record Calibration 15
Use
of the Dolby System on FM
Broadcasts 16
FM De-Emphasis Switch 16
Dolby Mode Chart 16
Technical Description 18
General 18
Functional Description 18
Frond End 18
IF
Stages
18
Limiter
18
FM Stereo Demodulator 18
Muting
Circuit
18
AM Tuner 18
Phono
Amplifiers
19
Selector Switch 19
Monitor (Tape/Source) Switch 19
Monitor (Tape 1 or 2) Switch 19
Tone Control 19
Power
Amplifier
19
General Requirements 19
Installation
of Walnut Cabinet 20
Service Notes 20
LIST F ILL USTRA TI ONS
1. Rear Panel Connection
Facilities and Adjustments 2
2. Loudspeaker System Connections 3
3. Connection Diagram 4
4. Speaker Placement 6
5. Mono Mode Sound Dispersion 7
6. 2-channel Mode Sound Dispersion 7
7. Discrete Mode Sound Dispersion 7
8. Vari-Matrix Mode Sound Dispersion 7
9. Front Panel Controls and Jacks 8
10. Stereophone Plug 9
11. FM/AM Antenna Connections 11
12. AM Ferrite-rod Antenna 11
13. Quick-Connect Speaker Terminal 13
14. Block Diagram 17
15. Packing Instructions 20
TABLE
1. Dolby Mode Chart 16

GEN ERA LD ESCRIPTION
Your Marantz Model 4270 is a high-quality Stereo
2 + Quadradial 4 Receiver developed by Marantz,
a name famous for quality in the audio com-
ponent industry. The Model 4270 incorporates
Marantz' exclusive Vari-Matrix circuit which sim-
ulates 4-channel sound from normal 2-channel
stereo programs, and is capable of reproducing
4-channel sound from any matrix-encoded source.
The 4270 will also reproduce any discrete 4-
channel program as well as regular stereo and
monaural programs. An optional plug-in decoder
adapts the 4270 for any specific matrix system
such asColumbia's SQ.
The FM tuner section employs an FET for the
RF amp and Mixer stage. The IF tuning circuit
employs ceramic filters of wide bandwidth and
high selectivity to provide high sensitivity and
unparalleled interference-free operation. The
4270 incorporates a switchable 2-channel DOLBY
system to reduce noise, inherent in recording
music from records, tape, FM broadcasts and TV.
The FM multiplex circuitry includes aphase locked
loop Stereo-Monaural Automatic switching circuit,
stereo indicator circuit and a buffer amplifier to
obtain output at low impedance. Low pass filters
for 19KHz and 38KHz rejection are incorporated.
Moreover, the Model 4270 unit has a muting cir-
cuit that permits pleasant FM broadcast reception
by completely eliminating inter-station inter-
ference which is usually generated at the time of
selecting FM stations.
FORE WO RD
To obtain opt imum performance and enjoyment
from the Model 4270, please study these instruc-
tions carefully. Follow the step-by-step instruc-
tions to obtain maximum performance.
The manual is divided into two parts. The first
covers installation and operation in simple, non-
technical language. The second describes the
Model 4270 in more detail with technical specifi-
cations and functional explanations.
For quick identification of the controls and
connections, references are printed in bold face
type.
AFT ER UNPAC KI NG
It is advisable to save all original packing material
to prevent damage shouId you wish to transport
or ship the Receiver (refer to Figure 15 for pack-
ing instructions). Please inspect your Model
4270 carefully for any signs of damage in transit.
It has undergone stringent quality control inspec-
tion and tests prior to packing, and left the
factory in perfect operating condition . If the
unit is damaged, notify the carrier without delay.
Only the consignee may institute a claim with
the carrier for damage during shipment. How-
ever, the Marantz Company will co-operate fully
in such an event. Save the damaged carton as
evidence for inspection by the carrier.

CONN E CTING THE 4270
The 4270 can be used as a stereo or 4-channel
Receiver. When using
the 4270 as a stereo unit,
the POWER MODE Switch on the rear panel
should be placed in
the 70Wx2 mode. The
instructions contained in this manual are to be
followed
for both stereo or 4-channel operation;
however, for stereo operation,
the front channels
alone will apply.
1. Using a balanced and shielded
300 Ohm cable,
connect an FM antenna to the 4270 as shown
in Figure 11.
2. Using No. 18,
or heavier, lamp cord (zip cord),
connect main speakers to the 4270 as follows:
LEFT FRONT SPEAKER
4270
- or GND or NEG or
COMM or 0 to MAIN
SPEAKERS
FRONT L-
+ or HOT or POS or 1 to MAIN
SPEAKERS
FRONT L+
RIGHT FRONT SPEAKER
4270
- or GND or NEG or
COMM or 0 to MAIN
SPEAKERS
FRONT R-
+ or HOT or POS or 1 to MAIN
SPEAKERS
FRONT R+
LEFT REAR SPEAKER
4270
- or GND or NEG or
COMM or 0 to MAIN
SPEAKERS
REAR L-
+ or HOT or POS or 1 to MAIN
PSEAKERS
REAR L+
Figure 1. Rear Panel Connection Facilities and Adjustments
RIGHT REAR SPEAKER
4270
- or GND or NEG or
COMM or 0 to MAIN
SPEAKERS
REAR R-
+ or HOT or POS or 1 to MAIN
SPEAKERS
REAR R+
CAUTION: When using the 4270 in the 70 Wx 2
mode, do not use 4 Ohm speakers -
use 8 Ohms or higher.
3. Using shielded
audio cables with phono plugs,
connect your record player to the 4270 as
follows:
RECORD PLAYER
4270
LEFT OUTPUT
to PHONO L
RIGHT OUTPUT
to
PHONO R
4. If a discrete 4-channel playback device (0-8
cartridge player, 4-channel reel-to-reel player,
CD-4 discrete disc demodulator, etc.), is to be
engaged in the system, make connections be-
tween
the device and the 4270 using shielded
audio cables with phono plugs.
DISCRETE 4·CHANNEL
4270
PLAYBACK DEVICE
LEFT-FRONT or LF or
CHANNEL 1 or TRACK 1 to
FRONT CD·4/AUX L
LEFT ·REAR or LR or
CHANNEL 2 or TRACK 2 to REAR CD-4/AUX L
RIGHT-FRONT or RF or
CHANNEL 3 or TRACK 3 to
FRONT CD ·4/AUX R
RIGHT-REAR or RR or
CHANNEL 4 or TRACK 4 to
REAR CD-4/AUX R
2

I
II
II
REAR SPEAKER SySTEM
R{PEAT WIRIN G
AS FOR FRONT sPEAKER SYSTEM
LEFT
Figure 2. Loudspeaker System Connections
5. Using shielded audio cables with
phono plugs,
connect a discrete 4-channel
tape recorder to
the 4270 as follows:
DISCRETE 4-CHANNEL 4270
TAPE RECORDER
LEFT-FRONT OUTPUT
or LINE OUT
to FRONT TAPE MONI-
TOR IN L
LEFT-REAR OUTPUT
or LINE OUT
to REAR TAPE MONI-
TOR IN L
RIGHT-FRONT OUTPUT
or LINE OUT
to FRONT TAPE MONI·
TOR IN R
RIGHT-REAR OUTPUT
or LINE OUT
to REAR TAPE MONI-
TOR IN R
LEFT-FROIH
INPUT
or LINE IN to
FRONT TAPE MONI-
TOR OUT L
LEFT-REAR INPUT
to LINE IN to
REAR TAPE MONI-
TOR OUT L
RIGHT-FRONT INPUT
or LINE IN to FRONT TAPE MONI-
TOR OUT R
3
RIGHT-REAR INPUT
or LINE IN to REAR TAPE MONI-
TOR OUT R
6. Pull the AM ferrite-rod antenna out as shown
in Figure 12.
7.
Set the controls and switches as follows:
FRONT L-R BALANCE
REAR L-R BALANCE
FROI\lT·REAR BALANCE
MODE
DIMENSION
BASS and TREBLE Controls
VOLUME
MAIN SPKR
REMOTE SPKR
FM MUTING
MONITOR (TAPE/SOURCE)
HI FILTER
LOUDNESS
DOLBY
400Hz TONE
POWER
8. Plug
the 4270 into the AC wall outlet.
9. Turn
the POWER Switch ON.
10. Select
the desired program source by setting
the SELECTOR Switch to appropriate posi-
tion.
Mid
position
Mid position
Mid position
VARI·MATRIX
Mid
position
Mid position
Minimum (fully counter-
clockwise)
ON (in)
OFF (out)
ON (in)
SOURCE (out)
OFF (out)
OFF (out)
OFF
OFF (out)
OFF (out)

I
I FRONT
RIGHT
REAR
I lEFT
REAR
RIGHT
IIFRONT
LEF T
f RONT
11. If phono is selected, put on a stereo record.
If FM is selected,
tune to a stereo broadcast.
12. Increase
the VOLUME control to a comfort-
able listening level.
Your
complete 4-channel or stereo system is now
operative, and you may experiment with the vari-
ous controls to discover
their effects.
The remainder
of this manual explains how to use
your system most effectively.
SOURCE DEVICES
2-channel
A stereo record player may be
connected to the
PHONO jacks.
High level 2-channel playback devices (tuner,
tape player, record player with equalized high
level
output, etc.) may be connected to the
FRONT TAPE MONITOR and CD·4/AUX IN-
PUTS.
~
00 IS:] lS5 00
2·CHANNEL
TAPE RECORDER
2·CH TAPE RECOR.DE~ MAT8£
CONNECTED TO THE
Ff ~Or4 T lUT
,o\HD RIGHT CHANNEL TERM.lMAl S
TAPE t
@) ,@
~ I
00 1D 1D00
OO !SJ ISJOo
4·CHANNEL
TAPE RECOROER
TAPE 2
.
~
RIGHT
1l£J lS:l 1 1£S5 EB I
000000
I IREAR
LEFT
REAR
TAPE DECK
4·CHANNEL RIGHT
4-channel
Discrete 4-channel playback devices (0-8 cartridge
player, 4-channel reel-to-reel player, CD-4 discrete
disc demodulator, etc.) may be connected to
the
CD-4/AUX, TAPE MONITOR 1 or TAPE MONI-
TOR 2
input jacks.
REMOTE SPEAKERS
The 4270 can accommodate both main and
remote speaker systems. A second group of
four speakers may be set up in another room.
Connect these
four remote speakers to the RE-
MOTE SPEAKERS terminals as you did
the
main speakers.
The MAIN and REMOTE SPKR Switches on the
front panel now permit activation of MAIN and/
or REMOTE groups of loudspeakers.
NOTE: Do
not use 4-0hm speakers if main and
remote speakers are to be used simulta-
neously. Use 8- or
16-0hm speakers only.
@l
r RIGHT
OUTPUT ®l
RECORD PlAYER
I
10 a 'I
2-CHANNEL
8 .TRAC~
TAPE PLAYER
1001SJ 1S300
~~ LD IDI
2·CHANNEL
I,
'000
TAP1: PLAYER
0.8 TAPE
PlAYER 2·C"1 DEVICi. MAYBE
CONNECTED
TO THEfRONT LEFTANDRIGHT
CHANNEL TERMINAlS
~
00 1SJ rs:300
00 ISJ IS:l 00
4-CHANNEL
TAPE PLAYER
00 ?!
CO·.. DEMODULATOR
Figure 3. Connection Diagram
FRONT
LEFT
FRONT
RIGHT
REAR
LEFT
REAR
4

SPEAKER PHASING
To assure
the best 4-channel or Stereo separation
and frequency response,
the following tests will
verify
that all four speakers are correctly phased.
1. After the speakers are connected to the 4270,
place all four speakers in the center of the
room.
2.
Set MODE Switch at MONO. Play a record
(or radio or tape) with strong bass tones,
at a
low volume level. Center
the FRONT L-R
and REAR L-R BALANCE controls.
Set
FRONT-REAR BALANCE control at extreme
FRONT position.
3. Position the front (left and right) speakers
about six inches apart, face-to-face. Listen,
particularly
to the apparent loudness of the
bass tones.
4. Next,
turn off all power, but do not disturb
the volume, tone or balance settings. Reverse
connections on
the right-front speaker only.
Turn on the power, and listen again. If the
bass tones now seem louder than in (3), you
have corrected the phasing between the front
(left and right) speakers. If the bass tones
now
sound softer, then turn off all power and
re-connect
the right-front speaker as you first
had it
connected .
5. Now check phasing between the two left (front
and rear) speakers. Set both FRONT L-R and
REAR L-R BALANCE controls at extreme L
position, and
set FRONT-REAR BALANCE for
equal loudness from
the two speakers. Posi-
tion the two speakers face-to-face, about six
inches
apart , and listen for bass as in (3).
6. Turn off power. Experimentally reverse con-
nections only on
the left-rear speaker. Use the
connection which gives the "best" bass, as
in (4).
7. Last, check phasing between
the two rear
(left
and right) speakers. Center both FRONT
and REAR BALANCE controls. Set FRONT-
REAR BALANCE control
at extreme REAR
position. Position
the two rear speakers face-
to-face as before. Listen for bass.
8. Turn
off power. Experimentally reverse con-
nections
only on the right-rear speaker. Listen
again
to determine the "best " bass method of
connecting
the right-rear speaker. All speakers
will
then be in phase, and you may use all
controls normally.
9. Once having phased
your four speakers, you
need
not repeat the procedure in the future if
you now
code the speaker connections and/or
the speaker cables. Any method of coding is
satisfactory, provided it enables
you, in the
future, to duplicate your now-correct hookup
between speakers and amplifiers.
SPEAKER PLACEMENT
Experimentation will reveal
the best speaker
locations in
your room. The placements are
shown in Figure 4.
5

LF
RF
LR RR
LF
RF RF
RR
LF
RF
RF
RF
RR
LR
RR
LR LF
LF
RF
RF
RR
LR
RR
Figure 4. Speaker Placement
6

FRONT PANEL FE lURES
MODE SWITCH
MONO
When
the MODE Switch is in the MONO position,
all input signals are summed. Speakers are driven
as
shown in Figure 5.
Use the MONO position for A) phasing speakers
and B) playing a monaural source such as TV
audio, AM radio or monaural records through
all four channels.
2 CH
When
the MODE Switch is in the 2 CH position,
left-front and left-rear inputs are summed. Right-
front and right-rear inputs are summed. Speak-
ers are driven as
shown in Figure 6.
Use
the 2 CH position for playing regular stereo
records without synthesizing rear channels.
DISCRETE
When the MODE Switch is in the DISCRETE
position, each input signal goes to its respective
output channel. Speakers are driven as shown
in Figure 7.
Use
the DISCRETE position for A) playing dis-
crete 4-channel sources such as 0 -8 cartridges or
CD-4 records, and B) playing 2-channel stereo
programs through front speakers only .
VARI-MATRIX
When the MODE Switch is in the VARI-MATRIX
position, rear input signals are internally discon-
nected. Left-front and right-front inputs feed
left-front and right-front speakers, as in the DIS-
CRETE MODE. Rear channel signals are "syn-
thesized" or derived from the left-front and right-
front input signals. The characteristics of the
LEFT FRONT RIGHT FRONT
SPEAKER SPEAKER
<, ",~'
"
..... '"'" ,
\ LF + RF+ "~(''''LF + RF + I
\ LR + RR '" -.LR + RR '
\ '
,\ I '
\ ' \,
,,' \I
I "\
/\
:\
I ,
,\
I LF + RF + ..... "'LF + RF +'
I LR + RR '> ~ LR + RR \
I ... ........ \
~,. ....................
... .....
," """
LEFT REAR RIGHT REAR
SPEAKER SPEAKER
,NPUT SI GNAL OESIGNA. TlONS ;
lFo<lEfT fRONT . Rf-RIOHT fRONT
LA-lEn REAR . RR-RIGHT REAR
Figure 5. Mono Mode Sound Dispersion
rear channel signals are varied by the DIMENSION
control. Speakers are driven as shown in Figure 8.
LEFT FRONT
SPEA
KER
,,"
....................... ". ,.
<, ,""" I
" LF + LR ..... " RF.+ RR I
, .,." <, I
\ , I '
\ I \ ,I
, I \I
"
" I 1\,
I \ ,
I ,
I \
I ..... '" ,
I
,>" . \
, LF + LR ",'" ..... RF + RR \
'" "",'" ...................
.-
LEFT REAR RIGHT REAR
SPEAKER SPEAKER
INPUT SI GNA L D ESIQN A,n ON S:
IF -L EFT fRONT , RF - RIGH T FRONT
LA-LEFT R fA R. RR"RI GHT REAR
Figure 6. 2- channel Mode Sound Dispersion
,
I
I
. I
I
I
\ I
\I
1\
I ,\,
\
RR " \
LEFT REAR RIGHT REAR
SPEAKER SPEAKER
LEFT FRONT RIGHT FRONT
SPEAKER SPEAKER
\\ \ \ ,
\ \ '
,,'
I'
I \
I
I
I
I LR
I
IHf"VT SIQNAl DESIGNATIOHS :
Lf-lEfT FRONT , AF-RIGHT FRONT
l R- l EFT REAR , Aft-RIGHT REAR
Figure 7. Discrete Mode Sound Dispersion
LEFT FRONT
SPEAKER
.. ","
'"
'"
\ '...... "'" I
\ LF .. ~(", RF I
\ '" ~/
\ I
, I
\ , \ I
, I \I
't 1\
" I
1\\
I \
,'DERIVED '" DERIVED\
I FROM LF ... ,>~ FROM LF \
I AN DR E"'''' ......... ANDRF \
"."/' <;
. ... .....
.-" ...
LEFT REAR RIGHT REAR
SPEAKER SPEAKER
INPlIT SIGNAL DESIGNATIOJlIS :
V-LEFT FRONT , RF-RIGHT fRONT
lA-lEfT AEAA , nA-HIGHT REAR
Figure 8. Vari·Matrix Mode Sound Dispersion
7

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DIMENSION
The DIMENSION control is operative only when
the MODE Switch is set to the VARI-MATRIX
position. This control optimizes the 4-channel
VARI -MATRIX effect.
SO DECODER
With the MODE Switch on sa DECODER, any
rear input signals to the 4270 are internally dis-
connected. The rear channel outputs are, in-
stead, derived from front channel signals which
have been processed by the plug-in decoder. The
characteristics of these derived rear channel out -
puts are determined by the type of plug-in
decoder.
UseSO DECODER position only with an optional
plug-in decoder installed. Without this opt ional
decoder, there will be no output when the MODE
Switch is set to the SO DECODER position.
BALANCE CONTROLS
The Model 4270 has three BALANCE controls:
FRONT L-R, REAR L-R and FRONT-REAR.
The FRONT L-R slide knob adjusts the balance
between the front channels. The REAR L-R
slide knob adjusts the balance between the rear
channels. The FRONT-REAR slide knob adjusts
the balance between the rear and front pairs of
channels. Balance adjustments must be carried
out in the MONO mode. To balance the front
channels, first set the FRONT-REAR control all
the way to the FRONT to silence the rear speakers
while you adjust the FRONT L-R BALANCE
control. To balance the rear channels, move the
FRONT-REAR control all the way to REAR,
and then adjust REAR L-R BALANCE. Now you
are ready to adjust the FRONT-REAR control
for the most pleasing overall balance.
_ ~ "' '1 _~ ~
I. .. .... t'n.d 'r.b'.
...01 ........
p .........
•
Figure 9. Front Panel Controls
-
and Jacks
SELECTOR SWITCH
The SELECTOR Switch selects the program
source for listening or recording. The switch
can select any of six sources: AM, FM, PHONO,
CD-4/ AUX, TAPE 1 and TAPE 2.
BASS, MID AND TREBLE CONTROLS
These controls are used to adjust the tonal
balance of program material to suit your indi-
vidual listening preference. The bass, midrange
and treble responses are adjusted by dual-con-
centric, friction -coupled controls. With BASS,
MID and TREBLE controls set at the center posi-
tion, frequency response of the amplifier becomes
flat.
The smaller (outer) knob adjusts the response of
the front audio channels, while the larger (inner)
knob adjusts the rear audio channels.
Turn the knobs clockwise to boost, or counter-
clockwise to attenuate its respective frequency
range.
MON ITOR SWITCH FOR TAPE 1/TAPE 2
This switch assigns the TAPE/SOURCE MONI·
TOR Switch to either TAPE 1 or TAPE 2.
MONITOR SWITCH FOR TAPE/SOURCE
When the MONITOR (TAPE/SOURCE) Switch is
placed in "TAPE" (in) position, the signals con-
nected to the tape input jacks (asselected by the
MONITOR TAPE 1, 2 Switch) will be played
back.
To play the tape recorder connected to the
TAPE MONITOR 1 or TAPE MONITOR 2 jacks,
8

or to monitor the tape on a three-head recorder
during recording, place the MONITOR (TAPE/
SOURCE) pushswitch in the "TAPE" (in) posi-
tion.
During recording, the MODE Switch should be
in the DISCRETE,
VARI-MATRIX or SO DE-
CODER positions. This applies the source signal
unchanged, directly
to the tape outputs. '
To record a discrete 4-channel source on a 2-
channel recorder,
put the MODE Switch in the
2 CH position.
Leave the TAPE/SOURCE button
in the SOURCE (out) position while recording.
This
will feed the sum of the left-front and left-
rear inputs to the left-front TAPE MONITOR
OUT jack, and the sum of the right-front and
right-rear inputs to the right-front TAPE MONI-
TOR OUT jack.
To record any type
of source on a monaural
recorder,
put the MODE Switch in the MONO
position.
Leave the TAPE/SOURCE button in
the SOURCE (out) position while recording.
MAIN AND REMOTE SPKR SWITCHES
These switches select the loudspeaker terminals
to which audio power is fed. The
MAIN and
REMOTE groups
of loudspeakers may be operat-
ed separately or simultaneously. With both
speaker switches in the
"out" position, all loud-
speakers are disconnected. The signal at the
FRONT and REAR PHONES jacks is
not affected
by the
MAIN and REMOTE SPKR Switches.
NOTE: When using hoth
MAIN and REMOTE
speakers simultaneously, the combined
impedance of all the speakers should not
be less than 4 Ohms.
POWER SWITCH
This pushswitch turns the Power on or
off. When
the POWER Switch is
"in", the dial lamp illumi-
nates. Be sure
to turn the POWER pushswitch
off before plugging or unplugging the power cord.
FRONT
AND REAR PHONES JACKS
These jacks accept a standard 3-conductor phone
plug employed
with standard stereo or 4-channel
headphones. When using 2-channel headphones,
insert the plug
into the FRONT PHONES jack.
When using 4-channel headphones, insert the
front plug into the FRONT PHONES jack and
the rear plug
into the REAR PHONES jack.
Either high- or low-impedance headphones may
be used.
LOUDNESS
When listening at low levels, set this switch "in" .
The LOUDNESS Switch boosts
bass and treble
tones to compensate for the human ear's lack of
response to those frequencies at low volume
levels.
HI
FILTER SWITCH
With this pushswitch set
"in", the High Fre-
quency Filter
suppresses high frequency noise,
such
as "scratch" from worn phonograph records
and tape "hiss". The
filter will also slightly
reduce high frequencies in the program material.
When the program does not have high frequency
noise, the HI
FILTER pushswitch should be
"out" .
TUNING METER
The Model 4270 is equipped
with two meters,
aSIGNAL-STRENGTH Meter and anFM
TUNING
Meter. The SIGNAL-STRENGTH Meter indicates
the signal-strength of any AM or FM broadcast.
The FM
TUNING Meter operates on FIVI only and
indicates correct station tuning. The
SIGNAL-
STRENGTH Meter acts as a Dolby Calibration
Meter when the
DOLBY Switch is in any position
other than "OFF".
TUNING
AM: For optimum AM reception, tune to the
desired station. Then, rock the
TUNING knob
slightly back and
forth until the maximum
reading is obtained on the SIGNAL-STRENGTH
Meter. The FM
TUNING Meter is not used for
AM.
FM: Set
the SELECTOR Switch to "FM" and
tune to the desired station. Then, slowly rock
the
TUNING knob back and forth until the FM
TUNING Meter points to the center scale posi-
tion.
,.-- --- -- LEFT CHANNEL
COM MON
L..-.----RIGH T CHAN NEL
Figure 10. Stereophone Plug
9

FM MUTING SWITCH
When tuning
to FM broadcasts with the FM MUT-
ING Switch in its "in" position, the muting circuit
will eliminate inter -station noise. To prevent
muting
of very weak stations along with the
noise, the
muting function may be turned off by
releasing the FM
MUTING pushswitch to the
"out" position.
VOLUME
This control regulates volume of all four channels
simultaneously.
DOLBY SWITCH
This switch sets the Dolby noise-reduction circuit
for record or playback and also switches the
Meter Mode
from AM or FM SIGNAL-STRENGTH
to
DOLBY CAL LEVEL, or vice-versa. With the
DOLBY Switch placed in "OFF" position, the
Meter
will be used as a SIGNAL-STRENGTH
Meter; in all other positions, as a DOLBY CAL
LEVEL METER.
DOLBY FM: This position is used for listening
to Dolbyized FM broadcasts. The Dolby FM
level has been pre-adjusted at the factory.
PLAY: This position is used to play back a
Dolbyized source (except FM).
OFF: With this position, the Dolby circuit IS
by-passed and the input signals are directly
applied to both TAPE MONITOR OUT jacks
and amplifiers.
RECORD I: For making a Dolbyized recording
from an in-coming "flat" (non-Dolbyized) signal.
When the
MONITOR Switch is in the SOURCE
(out) position, the
"flat" signal will be heard.
When the
MONITOR Switch is in the TAPE (in)
position, the Dolbyized signal
from the tape will
be heard.
RECORD
II: For making a "flat" (non-Dolbviz-
ed) recording
from an in-coming Dolby ized signal.
Regardless of the position of the MONITOR
SWitch, a "flat" signal will be heard.
Refer to the
Dolby Mode Chart on page 16.
RECORD LEVEL (L) (R)
These knobs control the record level of the signals
to be recorded through the
Dolby unit. Adjust
the knobs so that the Level Meter pointers of
the tape recorder do not exceed the OVU level.
PLAY CAL. (L) (R)
These knobs adjust the playback
outputs from a
tape deck
to the proper Dolby level.
400Hz
TONE SWITCH
This is used for calibration of the record input
level of the tape deck. When the switch is
depressed, the
built -in oscillator operates and a
sine wave signal
output of 580mV will be applied
to the four TAPE MOI\IITOR OUT jacks.
10

R ARPA E FEATUR
ES
PHONO JACKS
These
two jacks are intended for use with
magnetic cartridges requiring a
standard 47,000
Ohm resistive load. If a hum is heard when
playing a record,
try reversing the polarity of
the turntable power plug. If this is ineffective,
connect a separate ground wire from the turn-
table or record changer
to the CHASSIS GROUI\ID
binding post of
the 4270.
CD-4/AUX JACKS
These jacks are for
connection of any 4-channel
high level
equipment source. Manufacturers may
use
different terminology for the four channels,
and care should be exercised to avoid confusing
the signal channel terminations. The following
are examples of 4-channel
nomenclature equiva-
lents:
LEFT FRONT LF-LF-CHANNEL - 1
TRACK 1
LEFT REAR
LR-LB-CHANNEL - 2
TRACK 2
RIGHT FRONT
RF-RF-CHANNEL - 3
TRACK 3
RIGHT REAR
RR-RB-CHANNEL - 4
TRACK 4
TAPE MONITOR IN AND TAPE MONITOR
OUT JACKS
These jacks are for
the connection of a 2-channel
or 4-channel
tape recorder.
(Refer
to "SOURCE DEVICES", page 4.)
1\", ANTENNA FM
ANfENaA
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,,
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300 0 UNSHI ElDED ~
TRAN SMISSIO N lI UE • ,
( TW I N L.EAD ) ::
SINGLE WIRE
n .1 ANTENNJl.. f M ANTENNA
[iii]
,,
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·, , .
.,:
-
.... _ SHIELD 750 COAX.
~SHIElO
3 00 0 SHIELDED TRANSMISSfON
TRANSMISSION LINE LINE
~
FM ANTENNA TERMINALS
These terminals
connect to an FM antenna. For
best FM reception, Marantz recommends a Log-
Periodic
antenna mounted on a good quality
rotor system. For rural areas, it is recommended
that a local dealer be consulted about antenna
installation and lightning arrestor protection. A
master
antenna system is not recommended for
use with
your Model 4270; such systems are
usually designed expressly for television reception
and frequently suppress FM signals
before distri-
bution. In addition, master
antenna systems
often severely limit quality FM reception. Where
outdoor antennas are prohibited or inconvenient,
use a simple form
of 300 Ohm TV " rabbit ear"
antenna or the simple ribbon-type folded dipole
antenna supplied with the 4270. Both are prac-
tical and will give satisfactory resuIts in primary
signal areas.
Your Model
4270 will accept either a 75 Ohm or
300 Ohm antenna. (See Figure 11.)
The 300 Ohm antenna cable should be connected
to the two terminals marked FMon the ANTENNA
terminal. When using 75
Ohm coaxial antenna
cable,
connect its shield to the " G" terminal, and
its inner or
center conductor to either of the FM
terminals.
AM ANTENNA TERMINAL
This terminal
connects to an AM antenna. The
4270 is equipped with a ferrite-rod antenna for
AM reception
and it will give satisfactory results
in primary signal areas. However, an
outdoor
Figure 11. FM/AM Antenna Connections
Figure 12. AM Ferrite-rod Antenna
11

antenna will provide better reception. Two single
wires are required
to make an AM outdoor
antenna. First, connect one end of a single
wire
to the AM ANTENNA terminal on the rear
panel, and the
other end at a very high position
outdoors. Next, connect the
other single wire
between the "G" terminal and an earth ground
(such as a water pipe).
(Refer
to Figure 11.)
FM
QUAD RADIAL OUTPUT JACK
In antic ipat ion of discrete 4-channel stereo broad-
casts,
your Model 4270 is equipped w ith an FM
QUAD RADIAL OUTPUT jack. The signal avail-
able at this jack is the unequalized
output of the
FM
discriminator . It's frequency response cha-
racteristics and signal level are ideal
to drive any
4-channel adaptor. This jack can also be used as
a simple white-noise generator for frequency
response check
of loudspeakers or amplifiers.
For
this application, release FM MUTII\lG Switch
of the Model 4270 in FM mode and tune off
from any FM signal.
FM DE-EMPHASIS SWITCH
Selects
75J.LS or 25J.LS FM DE-EMPHASIS for
accurate reception of Dolbyized FM signals.
DOLBY FM PRESET LEVEL CONTROLS
These factory -adjusted controls govern FM out-
put level to the DOLBY circuit. These controls
are
for the use of a qualif ied technician only.
MUTING LEVEL CONTROL
Adjusts the threshold of the inter-station muting
circuit. Turning this control counter -clockwise
w
ill lower the threshold to permit reception of
weak signals.
POWER
MODE SWITCH
Switches
from 25 watts x 4 operation to 70 watts
x 2. In
the 2-channel mode, only the front
speaker terminals are used.
BE
CERTAIN THAT THE UNIT'S POWER
SWITCH IS
OFF BEFORE OPERATING THE
POWER MODE SWITCH.
NOTE: When operating
the unit in the 70W x 2
mode, all speaker terminals are "above
ground".
Consequently, the use of any switching or testing
system
which employs a common ground will
activate the l imiting circuits and should therefore
be avoided.
PRE
OUT, MAIN IN JACKS
For normal operation, these jacks are inter-
connected
with the supplied jumpers. When
connecting an external
unit (equalizer, reverbera-
tion unit, etc.), remove the jumpers and connect
the PRE
OUT jacks to the external unit's inputs.
In
turn, connect the external unit's outputs to the
MAIN IN jacks.
It is possible to create a higher powered 4-channel
system by adding an external
amplifier. If the
external
amplif ier has less than 70 watts x 2, it
should be used to drive the rear speakers. If the
external
amplifier has more than 70 watts x 2, it
should be used to drive the front speakers. In
each
case, the rear panel POWER MODE Switch
should be set
to the 70Wx2 position.
CONNECTING AN EXTERNAL AMPLIFIER
FOR REAR CHAI\II\IELS
To use an external
amplifier for the rear chan-
nels, connect the
REAR PRE OUT jacks to
the inputs of the external amplifier. In turn,
connect the rear speakers to the output terminals
on the external
amplifier. The 4270 will then
supply
the power for the front speakers and the
external
amplifier will supply the power for the
rear speakers.
CONNECTING AN EXTERNAL AMPLIFIER
FOR FRONT CHANNELS
To use an external amplifier for the front chan-
nels, connect
the REAR PRE OUT jacks to the
FRONT MAIN IN jacks. Connect the rear speak-
ers
to the FRONT speaker terminals on the 4270 .
Then, connect the
FRONT PRE OUT jacks to the
inputs
of the external amplifier. In turn, connect
the front speakers to the output terminals on the
external
amplifier. The 4270 will then supply
the power
for the rear speakers and the external
amplifier will supply the power for the front
speakers.
CHASSIS
GROUND BINDING POST
Permits connection of the ground wire from a
turntable or other component to reduce hum.
MAIN AND REMOTE SPEAKERS
Sixteen
quick -connect terminals are provided
eight
for main speakers and eight for remote
speakers. (Refer
to "CONNECTING THE 4270"
and "REMOTE SPEAKERS".)
12

Terminals work as shown in Figure 13.
1)
Press terminal in
2) Insert speaker wire
3)
Release terminal
CONNECTION TO AC
OUTLET
With the front panel POWER pushswitch "OUT",
plug the line cord into an electrical outlet supply-
ing the proper voltage.
CAUTION: DO NOT PLUG YOUR MODEL
4270 INTO A DC OUTLET, AS
SERIOUS
DAMAGE WI LL OCCUR.
AC CONVENIENCE
OUTLETS
Two AC outlets, one switched and one unswitch-
ed, are provided on the rear panel
to supply
power
to associated components of the system
(tape recorder, record player, etc.), The maxi-
mum power available
from the SWITCHED and
UNSWITCHED AC
OUTLETS is 100 Watts and
200 Watts, respectively.
REMOTE
CONTROL
The REMOTE CONTROL connector and switch
are intended
for use only with the optional
Model RC-4 Remote Control. The REMOTE
CONTROL Switch assigns control of loudness,
balance and volume
to the optional RCA Remote
Control. WHEN
THE RC-4 IS NOT USED,
THE REMOTE CONTROL SWITCH MUST BE
IN
THE LOCAL POSITION.
EXTERNAL DECODER CONNECTION
A pocket on the
bottom of the chassis will ac-
commodate Marantz 4-channel decoders, such as
the Model SQA-1. For use,
follow the instruc-
tions supplied
with the optional decoder.
TAPE RECORDING
Instructions
for connecting a recorder and playing
back a tape are given in "SOURCE DEVICES",
page 4.
To record, select the desired program source,
using the SELECTOR Switch. Put the recorder
connected
to the TAPE MONITOR OUT jacks
"1
or 2" in the record mode.
For additional
information, refer to MODE
SWITCH on page 7, and
MONITOR SWITCH
on page 8.
3. RELEASE THE
TERMINAL
Figure 13. Quick-Connect Speaker Terminal
2. INSERT SPEAKER WIRE
INTO TERMINAL
1. P RESS ENDOF
TERMINAL IN
13

BASIC DOLBY PROCESS
The Dolby system increases the level of low-level,
mid - and high-frequency signals during recording
and reduces the level of these signals by an
identical amount during playback. As a result,
the playback signal is identical to the original
source signal, but the level of background noise
generated by the tape recorder is greatly reduced.
A Dolbyized FM broadcast has already been
subjected to the first phase of the noise reduction
process before it is transmitted. When these
signals pass through the Dolby playback circuitry,
the mid- and high-frequency noise, is greatly
reduced.
OLBV CAL IBRATI ON
The purpose of the following adjustments is to
achieve the proper Dolby levels by calibrating
the recording and playback signals being applied
to the Dolby processors to a standardized level
of 580mV.
The Model 4270 is capable of processing Dolby
signals from sources other than a tape recorder
(AUX, PHONO, FM, ETC.).
NOTE: It is possible to use the Dolby system for
recording and playing back tapes through your
system without using a standard alignment tape.
Procedures for making your own Dolby Align-
ment Tape are asfollows:
1. Thread a blank tape onto your recorder
(or insert a cassette).
2. Set the 400Hz TONE Switch to the "ON"
(in) position.
3. Set your recorder's monitor switch to the
source position.
4. Set your recorder's record levels to 0 VU.
5. Commence recording. Record about 45 se-
conds of the tone. This tape you have just
made is used to calibrate the Marantz Dolby
circuit with the recorder.
However, a Dolby recording made on your re-
corder using the calibrated tape you have just
made may not necessarily be compatible with the
Dolby circuits in a different recorder or systems.
Therefore, for universal compatibility, Marantz
offers a Dolby standard alignment tape which
will make all of your Dolby recordings universal
with any other Dolby system. These tapes are
available in the standard reel-to-reel, cassette and
8-Track formats. If you desire one of these tapes,
enclose a check or money order for $4.95 for
each tape desired (California residents add 5%
sales tax). Be sure to specify which format is
desired. Mail to:
MARANTZ NATIONAL PARTS
P. O. Box 99
Sun Valley, California 91352
NOTE: The Dolby system can be used with
most types of tape recorders. However, it can-
not be used with a recorder utilizing Automatic
Recording Level system (A LC).
PROCEDURE FOR PLAYBACK CALIBRATION
1. Turn on the Model 4270 and your recorder.
2. Set the DOLBY function switch on the
Model 4270 to the PLAY position.
3. If your recorder has a SOURCE!TAPE
(MONITOR) Switch, set it to "TAPE".
4. Load the Dolby standard alignment tape.
5. Play the Tape.
6. If your recorder does not have output
level controls, proceed to step 9.
7. When your recorder has output level controls
and the meters on the recorder read play-
back level, adjust the controls until the
meters read "OVU". Then proceed to step 9.
8. If neither 6 nor 7 apply to your recorder,
set the output level controls to about 2/3
of full output.
9. Adjust the PLAY CAL controls (left and
right) on the 4270 to the DOLBY LEVEL
reference on the SIGNAL-STRENGTH Me-
ter. To adjust the left PLAY CAL control,
place the METER Switch to the "OUT"
position. To ad just the right PLAY CAL
control, place the METER Switch to the
"IN" position.
10. You have now properly calibrated the Dolby
Playback Level. From this point on, do not
change your recorder's output level contro ls
or the Model 4270's PLAY CAL controls.
14

Since the calibration is extremely stable and
should not have to be repeated (except to period-
ically check it), we suggest that you mark the
settings of your recorder's output level controls
with a felt-tipped pen. Doing so will enable
you
to easily reset the controls if they are
inadvertantly moved.
PROCEDURE FOR RECORD
CALIBRATION
Before proceeding with the record calibration,
be certain
that the playback adjustments have
been performed. DO
NOT CHANGE TH E POSI-
TIONS OF THE RECORDER'S
PLAYBACK
LEVEL CONTROLS (if any) OR THE 4270's
PLAY CAL CONTROLS.
In
the event a record calibration is performed by
the use
of TAPE MOI\IITOR 1 IN and OUT Jacks
of Model 4270, shift the SELECTOR switch to
TAPE 2 after turning on a 400Hz TONE knob.
On the other hand, when the record calibration is
conducted by the use of TAPE MONITOR 2 IN
and
OUT Jacks, shift the SELECTOR switch to
TAPE 1. Home-position the SELECTOR switch
after the calibration.
For Recorders
with Three Heads
1. Thread a blank tape onto your recorder (or
insert a cassette).
2. Put the 4270's
DOLBY Switch in the
"PLAY" position.
3. Put both the 4270's and the recorder's moni-
tor switches in the "Tape" position.
4. Put the 400Hz TONE Switch in the "ON"
(in) position.
5. Commence recording.
6. Adjust the recorder's record level controls
so the tone will deflect the 4270's SIGNAL-
STRENGTH lVIeter to the "DOLBY LEVEL"
mark.
For Recorders
with Two Heads
1. Thread a blank tape
onto your recorder (or
insert a cassette).
2. Put the 4270's
DOLBY Switch in the "OFF"
position.
3. Put the 400Hz TONE Switch in the "ON"
(in) position.
4. Commence recording.
5. Adjust
the recorder's record level controls
to deflect the recorder's meters to OVU.
6. Record the tone for approximately 15 sec-
onds. I
7. Stop the recorder and rewind
it to the begin-
ning of the tone recording. I
8. Put the 4270's DOLBY Switch in the
"PLAY" position. I
9. Put the recorder in the play mode and play
back the tape.
10. Note the level reading on the 4270's SIG-
NAL-STRENGTH Meter. To check the left •
channel level, put the METER Switch in the
"OUT" position. To check the right chan-
nel level,
put the METER Switch in the
"1 N" position. The object is to adjust the
recorder's record level controls so the play-
back level achieved indicates "DOLBY-LEV-
EL" on the 4270's SIGNAL-STRENGTH
Meter.
11.
If the Meter indicates "DOLBY LEVEL" ,
calibration is completed.
12. A)
If the Meter indication is above the
"DOLBY LEVEL", repeat steps 2 - 11,
but decrease the record level in step 5
to slightly below OVU on the recorder's
VU Meters.
B)
If the Meter indication is below the
"DOLBY LEVEL", repeat steps 2 - 11,
but increase the record level in step 5
to slightly above OVU on the recorder's
VU Meters.
For all Recorders
After the "DOLBY LEVEL" has been achieved
on the SIGNAL-STREI\lGTH Meter, DO NOT
change the recorder's
input or output level con-
trols or the 4270's
PLAY CAL controls.
Utilizing the recorder's VU Meters, proper Dolby
recording levels are adjustable by using the RE-
CORD
LEVEL controls on the front panel of the
4270. This
only applies when making a Dolby
recording.
Setting the level slightly
lower than OVU will
increase the Dolby effect.
CHANGING THE RECORDER'S RECORD OR
PLAYBACK LEVELS OR THE 4270's PLAY
CAL CONTROLS WI LL AFFECT THE DOLBY
CALIBRATION .
15

Mark the calibration positions on the recorder's
record and playback level controls
to avoid the
necessity
of re-calibrating after making a non-
Dolby recording.
IMPORTANT:
It will be necessary to re-calibrate the Dolby
levels when a change in tape
speed has been made
or when a
different brand or type of tape is used.
When the
Dolby process is not desired on a re-
cording, record in the normal manner - adjusting
the record levels
with the recorder's record level
controls. DO NOT change the 4270's
PLAY
CAL controls.
USE OF
THE DOLBY SYSTEM ON FM BROAD-
CASTS
Your Model 4270 is equipped to receive Dolbyiz-
ed FM broadcasts.
Most FM broadcasts do
not currently use the
Dolby Noise-Reduction system.
To receive these
broadcasts, leave the
DOLBY Switch in the
"OFF" position. However, if a local station is
broadcasting a Dolbyized FM signal,
full advan-
tage
of the increase in signal-to-noise ratio may
be obtained by
putting the DOLBY Switch in
the
"DOLBY FM" position. The rear panel
DOLBY FM PRESET LEVEL controls are fac-
tory -adjusted. Do not change the position of
these controls.
FM DE-EMPHASIS SWITCH
This rear panel switch operates
only when the
front panel DOLBY Switch is in the "DOLBY
FM" position. It alters the frequency response
of the FM signal. Normally, this switch should
be
left in the 7511S position. However, if the
station is broadcasting the Dolbyized signal using
a 2511S pre-emphasis, put this switch in the
"25I1S" position to obtain flat FM frequency
response. If in doubt, call the station.
DOLBY MODE CHART
This chart indicates the correct DOLBY Switch
positions
for various types of input material.
The
input format is indicated in the left column
and the appropriate
DOLBY Switch position,
together
with FM DE-EMPHASISSwitch position,
is shown under the appropriate mode of opera-
tion .
'~
De-Emphasis Dolby Switch Position
Mode Switch Listening Record
Input
Position W
ithout Dolby With Dolby
F.M.
75J1.S
"Off" "Off" "Record I"
(Normal)
F.M.
with Dolby
7511s
"Dolby FM" "Record II"
"Dolby FM" If
7511s
Pre-emphasis
the
F.M.
with Dolby
25J1.S
"Dolby FM"
"Record II" "Dolby FM" rect
25J1.S
Pre-emphasis
Non Dolbyized
sources
"Off"
(Phone, Tape, -
"Off " "Record I"
Aux inputs,
"Record I"
A.M.) terial
Dolbyized
sources (de-
rived from
"Play"
"Record II"
"Play"
to
"Tape" or -
"Record II" mode.
"Aux" inputs
etc.)
For initial calibration, utilizing the Dolby standard alignment tape, see detailed instructions
on Pages 14 thru 16 of this manual.
Notes :
-
there is a doubt regard-
ing
the pre-emphasis used on
transmission,
the F.M.
station should be contacted,
where possible, to ensure cor-
position for de-emphasis
switch.
Pre-recorded tape manufac-
turers indicate when
the rna-
has been recorded in a
Dolbyized format. Home reo
corded tapes should also be
clearly marked as
to format,
ensure
correct play back
Table 1. Dolby Mode Chart
16