Specifications

THE McINTOSH MR 80
DIGITAL FM/FM STEREO TUNER
MANUFACTURER'S PERFORMANCE LIMITS:
Sensitivity: 9.3 dBf (1.6 uV) for 35 dB of quieting;
14.7 dBf (3 uV) for 50 dB of quieting; 13.2 dBf (2.5
uV) for 3% total noise and harmonic distortion (IHF
Usable Sensitivity). Signal-to-Noise Ratio: 75 dB
(mono). Harmonic Distortion: 0.2%, 20 Hz to 15
kHz, mono or stereo; typically 0.08% at 1 kHz. IM
Distortion: 0.1 5% mono or stereo, any combination
of frequencies, from 20 Hz to 15 kHz, with peak
modulation equal to 1 00% or less. Typically 0.1 %.
Frequency Response: Mono and stereo ±1 dB 20 Hz
to 1 5 kHz, with 75, 50 or 25 microsecond de-emph-
asis. Capture Ratio: 1.5 dB. Selectivity: (Alternate
Channel): 90 dB, narrow; 110 dB super-narrow;
(Adjacent): 8 dB narrow; 60 dB super-narrow. Spuri-
ous rejection: 1 1 0 dB. Image Rejection: 90 dB. Max-
imum Signal Input: 8 volts across 75 ohm antenna
input. Audio Hum: 75 dB down from 1 00% modula-
tion. Muting: 70 dB noise reduction between sta-
tions. Muting Threshold: 2 uV to 1000 uV (variable).
SCA Rejection: 60 dB or more. Stereo Separation:
50 dB at 1 kHz. Stereo Filter: 1 0 dB noise reduction.
Audio Output: Variable, 2.5 V into 47k ohm; Fixed,
1V into 47k ohm.
GENERAL SPECIFICATIONS:
Power Requirements: 120 volts, 50/60 Hz, 25
watts. Dimensions: (Front Panel): 1 6" w x 5-7/1 6"
h. (Chassis): 14-3/4" w. x 4-13/16" h. x 13" d.
Weight: 28 Ibs. net.
At your request, we have conducted an impartial
evaluation of your Model MR 80 Stereo FM Tuner in
our laboratory. In addition to extensive measurement
data which we obtained, we have also used the sam-
ple tuner in extended listening tests over a period of
several weeks, employing both a multi-element out-
door directional antenna with a motorized rotor, and
a simple indoor dipole antenna made up of 300-ohm
twin lead.
Our detailed conclusions are summarized at the
end of this test report. In brief, however, we feel that
this tuner is designed for critical listening situations
where other tuners, regardless of their price, would
be unable to provide satisfactory reception in the
face of adjacent channel interference. A description
of the unit, circuit highlights, and test results follow.
In terms of outward appearance there's no mistak-
ing the MR 80 for anything but a Mclntosh Labora-
tory product, with its familiar black front panel and
its back-lighted nomenclature. But there is much that
is new and up-to-date about this product's cosme-
tics, as well as its internal circuitry. Instead of a
printed frequency dial scale, the upper section of the
front panel is dominated by a large digital display
which reads out the frequency of the tuned-to signal
in Megahertz, to the nearest 100 kHz. This tuner
does not employ frequency synthesis, nor does the
manufacturer claim that is does. One could argue
about the use of the word "digital" in connection
with this tuner, since that has come to mean a fre-
quency synthesized tuning system to a great many
audiophiles, but that is largely a semantic argument
these days, since many manufacturers of tuners
who employ digital readout of frequency have begun
to refer to such products as "digital" FM tuners.
To the left of the digital frequency display are four
"touch pad" switches which are used to select one
of four pre-set station frequencies. When one of
these pads is touched, a small rectangle of light ap-
pears above the pad to indicate that the tuning com-
mand has been executed. To the left of these pre-set
selector pads are three indicator lights. The red
stereo light comes on when a stereo transmission is
received. A second amber indicator light, identified
by the word "lock", indicates when the tuner is
locked to an incoming station signal. The third green
light indicates when the stereo multiplex filter is ac-
tive.
To the right of the digital frequency display is a
column of tiny LED's arranged vertically, to indicate
signal strength. No center-of-channel indicator is
necessary since, as we shall see, the unique locking
circuitry of this tuner insures proper tuning. Two
more touch-pads to the right of the signal-strength
column, are labelled "Auto Scan" and are used to
make the tuner tune up and down the FM dial, stop-
ping at received station signals. Finally, to the right
of the auto-scan pads, we find a conventional tuning
knob for manual tuning. There is a fourth method of
tuning the MR 80 which we will discuss when we
examine the rear panel,
The lower section of the front panel of the MR 80
is equipped with six rotary controls and a centrally
located stereo headphone jack which is driven by its
own audio amplifier circuitry and can deliver 2.5
volts of signal into 600 ohm loads; more than
enough to drive low impedance phones, incidentally.
Starting at the left, there is a two position selectivity
switch, with settings identified as "narrow" and
"super narrow". Normally, the "narrow" position is
used and in our tests we found that it provided ex-
cellent alternate channel selectivity and the ability to
34
PRODUCT
ANALYSIS
Electronic Laboratories'
Fig. 1 - Front panel view of Mclntosh MR 80 Tuner