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THANK YOU
Judging from the stereo equipment you own, you rank high
among discriminating music listeners. You are probably no
freshman when it comes to stereo. Never-the-less we ask you
to read and carefully follow these instructions to insure a
successful partnership between you and your new stereo
equipment.
You now have "THE BEST." Used properly you are in for
thousands of hours of musical enjoyment.
If you are in a hurry, read page 3 first. This gives you a brief
outline of what each control and indicator does. Reading time
for this manual is 30 minutes. This is time well spent.
MR 71 FM STEREO TUNER
INTRODUCTION
The Mclntosh MR 71 is a precision engi-
neered, highly sensitive FM Multiplex Tuner.
The research staff of Mclntosh Laboratory
has developed five new tuner circuit improve-
ments for the MR 71.
1. Automatic stereo-mono switching that
is "clickless" and completely electronic.
(Patent applied for.)
2. Multipath indicator to eliminate multi-
path reception by showing when your anten-
na is rotated to the correct position for mini-
mum multipath distortion.
3. Double tuned input circuits before the
first R.F. amplifier to reduce spurious re-
sponses.
4. New D'Arsonval movement meters of
increased sensitivity which do not need zero
setting adjustments.
5. A new computer designed filter to re-
duce noise from stations broadcasting sub-
carrier auxiliary music services. No other
tuner uses such a filter.
The MR 71 also uses the exclusive Mc-
lntosh PANLOC method of installation. The
PANLOC system gives you absolute ease of
installation, operation, and maintenance.
PANLOC is the first professional installation
technique to be used on stereo instruments.
In the PANLOC system a metal shelf is
mounted first. The tuner slides into position
on this shelf. Depressing the PANLOC but-
tons on the front panel locks the tuner firmly
into place for normal operation. To unlock
the tuner depress the PANLOC buttons a
second time. The tuner can now slide from
the front panel. The tuner will lock into this
position, preventing accidental release of
the tuner from the installation. Depressing
the holding latches allows the tuner to be
taken out of the PANLOC shelf or to slide
back into position against the mounting panel.
The finest possible reception of FM mono-
phonic and FM multiplex stereophonic broad-
casts is assured by the Mclntosh MR 71
tuner.
Once you have enjoyed the outstanding
performance of the MR 71, you will under-
stand why Mclntosh products have earned
their reputation as "THE BEST." Your Mc-
lntosh MR 71 tuner will give you years of the
finest possible FM reception, and will be a
valued part of your home music system.
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SPECIFICATIONS
Useable Sensitivity
2.5 microvolts at 100% modulation (±75KC
deviation) for less than 3% total noise and
harmonic distortion in accordance with
IHF standards.
Audio Frequency Response
Within ½db from 20 to 20,000 cycles.
Distortion
Lessthan0.5%at 100% modulation ±75KC
deviation
Capture Ratio
1.5db at 100% modulation.
Muting
IF injected ultrasonic muting: at least 60db
noise reduction between stations.
Oscillator Drift
Less than 25KC with AFC disabled; negli-
gible with AFC in operation.
Image Rejection
Better than 80db at 90MC; better than
70db at 105MC.
Hum
Better than 70db below 100% modulation.
Output
Approximately 2.5 volts; low impedance.
Antenna Inputs
300 ohms balanced; 75 ohms unbalanced.
RF Amplifier
Cascode with 6DS4 Nuvistor in first stage.
IF Stages
Five, with 200KC bandwidth, flat top
response.
Limiters
Two.
Radiation
Substantially below FCC requirements.
Multiplex Channel Separation
Better than 30db at 1000 cycles.
Multiplex Filter
Greater than 48db suppression of 19KC
pilot and 38KC carrier.
Multiplex Indicator
Front panel multiplex stereo light activated
by 19KC carrier-only.
Multiplex Type
Peak-detecting, self matrixing detector.
SCA Filter
50db down at 67KC to 74KC 275db per
octave slope.
Automatic Mono-Stereo Switch
An exclusive Mclntosh development; all-
electronic automatic mono-stereo switch-
ing circuit. (Pat. Pend.).
Tube and Semiconductor Complement
1-6DS4 Nuvistor, 1st RF.
1-12AT7, 2nd RF and Mixer.
1-6BN4A, Oscillator.
1-6AU6, 1st IF.
1-6AU6, 2nd IF.
1-6AU6, 3rd IF.
1-6AU6, 4th IF and 1st Limiter.
1-6CS6, 5th IF 2nd Limiter and Muting.
1-6BN8, Muting Amplifier, Muting
Detector, AVC Clamper.
2-6BL8, Left and Right, 1st and 2nd
Audio Amplifiers.
1-6U8,
MPX
Amplifier,
MPX
Indicator
Control.
1-6HU6/EM87 Multipath Indicator.
1-12AU7, MPX Oscillator.
1-ST2-275, Voltage Reference.
1-MA113
(Transistor),
MPX
Indicator
Lamp Switch.
2-1N542
Diodes, Wide Band
Discriminator.
2-1N542 Diodes, Narrow Band
Discriminator.
4-1N542
Diodes, Balanced
MPX
Detector.
2-1N542 Diodes, Balanced Detector for
MPX Indicator.
2-Selenium Rectifiers, High Voltage
Power Supply.
1-No. 1850 Lamp, MPX Indicator.
Power Consumption
70 watts, 105 to 125 volts, 50 to 60 cycles.
Dimensions
Front Panel; 16 inches wide by 57/16 inches
high; chassis (including PANLOC shelf) 15
inches wide by 5 inches high by 13 inches
deep, including connectors; clearance in
front of mounting panel including knobs.
1½ inches.
Weight
Chassis only, 27 pounds.
In shipping carton, 37 pounds.
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2 CHAMBERS STREET, BINGHAMTON, N. Y.
Made in U.S.A.
Phone-Area Code 607-723-5491
038-029
BE022003
Printed in U.S.A.
LABORATORY INC.
