A CONSUMER'S GUIDE
Preparation supervised by
Robert Long. Harold A Rodgers.
and Edward J. Foster
Laboratory data (unless otherwise rioted)
supplied by CBS Technology Center
Mclntosh's New Receiver: Breeding Tells
Mac 4100 stereo FM/AM receiver, in case with simulated
wood-grain finish, Dimensions: 185/8 by 53/4 inches (front), 14
inches deep plus clearance for controls and connections. AC
convenience outlets: 2 switched plus 1 unswitched (600 wafts
total), 2 for auto on turntable switching (100 watts total).
Price: $1,499; optional RMA-5 rack-mounting adapter. $29.
Warranty: three-year service contract, free with purchase of
the receiver, has provisions comparable to typical "limited"
warranties but covers normal wear and tear. Manufacturer:
Mclntosh Laboratory, Inc.. 2 Chambers St., Binghamton. N.Y.
13903.
Mclntosh has for some years kept a very low profile vis-a-vis
the press. This hiatus in communications has fostered a polarization of opinion about Mclntosh: Is the company still de
serving of its reputation for superb engineering, or is it trading on past glories? One review can't provide a definitive
answer, of course, but the Mac 4100 receiver can be taken as
a positive sign of health in Binghamton.
The personality of this receiver is like that of an accom-
plished servant used to coping with pampered aristocrats who
FEBRUARY 1979
demand the finest but are not always technically knowledgeable or manually dexterous. Accordingly, it takes responsibility in a manner that, paradoxically enough, is unassuming
yet quite intolerant of intervention by its master. But once it
has taken over, it performs virtually impeccably and can even
ward off the consequences of ineptitude without noticeable
fuss.
REPORT POLICY Equipment reports are based on laboratory measure
merits and controlled listening tests Unless otherwise noted, test data and
measurements are obtained by CBS Technology Center, Stamford. Connecticut,
a division of Columbia Broadcasting System. Inc . one of the nation's leading
research organizations. The choice of equipment to be tested rests with the
editors of HIGH FIDELITY Samples normally are supplied on loan from the manutacturer Manufacturers are not permitted to read reports in advance of pubhcation, and no report, or portion thereof, may be reproduced for any purpose
or in any form without written permission of the publisher. All reports should
be construed as applying to the specific samples tested, neither HIGH FIDELITY
nor CBS Technology Center assumes responsibility for product performance or
quality
33
Very tittle of the receiver's special quality is immediately
apparent from the outside, though in hooking it up you get a
clue from the convenience outlets. In addition to the conventional switched (black) and unswitched (red) ones, there are
two green ones marked TURNTABLE, plus an AUTO/MANUAL
switch. If you use the AUTO setting and a turntable plugged
into one of the green sockets is turned on, the receiver and
any outboarded equipment run off the switched outlets will
come on automatically, even when the receiver's power switch
is off, and all will turn off again when the turntable shuts
down. Thus an automatic model can be made to turn off the
whole system unattended. Since the feature works by sensing
current drain through the turntable outlets, the switch serves
to override it should the turntable be one of those that draw
some current even when they are off.
The receiver's switching is handled by DC control voltages,
actuated by the front-panel controls and fed to FETs that actually do the signal switching. There are two fundamental advantages to this approach: Switching transients are eliminated, and the short, direct signal paths made possible
minimize noise pickup, RFI, and crosstalk. In all of these re-
Mclntosh Mac 4100 Receiver
Tuner Section
Capture ratio
Alternate channel selectivity
THD
+ N
80 Hz
1 kHz
10 kHz
IM distortion
19-kHz pilot
38-kHz subcarrier
S/N ratio (at 65 dBf)
stereo
mono
L ch
0.25%
0.17%
1.8%
2 dB
76 dB
R ch
0.25%
0.22%
1.7%
0 06%
-63½ dB
-66½ dB
67 dB
71 dB
mono
0.16%
0.15%
0.21%
spects the 4100 is above reproach. We seldom have RFI problems in our area, but we do often find that, for example, some
audio from an FM tuner section will "'leak" into the tape-monitor signals; none was detectable in the Mac.
The FM section is unusual in that—in addition to conventional
automatic stereo/mono switching—it has an automatic-blend
feature that progressively reduces stereo separation (and
hence out-of-phase noise) as signal strength drops. Since the
full audio band is blended, the resulting stereo image may be
a bit stabler than in the more usual high-blend solution, but
the hiss seems a little more intrusive for a given degree of separation loss. On weak signals it does work, however—and, like
so many features of the Mac, without drawing undue attention to itself. Similarly, the Automatic Frequency Lock gently
holds onto an FM station that has been tuned correctly; were
it not for the front panel AFL LED, which lights when lock occurs, you would be unaware of its action. This LED acts as a
tuning aid; when the muting is on, the LED announces arrival
at a receivable station before the unmuting action (which is
gentle and slightly delayed) allows any audio to pass. The
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Amplifier Section
Manufacturers rated power
Power output at clipping (channels driven simultaneously)
Lch
R ch
Dynamic headroom (at 1 kHz) 1 ½i dB
Frequency response
RIAA equalization
Input characteristics (re 0 dBW (1 watt); noise A-weighted)
phono 1, 2
aux 1, 2
tape 1, 2
Phono overload (clipping point) 88 mV at 1 kHz
Damping factor at 50 Hz
17¾ dBW (75 watts)/ch.
20 dBW (98 watts)
20 dBW (98 watts)
+ V,, -V, dB, 20 Hz to 20 kHz
+
V»,
-3 dB, 13 Hz to 35 kHz
±1 dB, 20 Hz to 20 kHz
Sensitivity
0.27 mV
30.0 mV
30.0 mV
100
S/N ratio
76½ dB
80 dB
80 dB
HIGH FIDELITY MAGAZINE
range of the signal-strength meter is well chosen as an aid in
antenna orientation for best reception of problem stations.
The amplifier section, too, exemplifies the extra care that
sets the receiver apart. Whether the option that enables
switching in three speaker pairs simultaneously requires
them or not, it has three distinct protection systems. The
most conventional is triggered by a heat sensor and shuts
down the output until the heat sink has cooled to within safe
operating limits. The Sentry Monitor circuit reacts to abnormal current conditions by restricting the drive to the output
transistors. And the Power Guard circuit responds to over-
drive that normally would create hard clipping by shaving off
the potentially dangerous harmonics—"softening" the clip
ping, so to speak. None impinges on normal operation; all
minimize the effects—aural, thermal, or electrical—of abnormal operation.
The Power Guard, for example, limits peaks so smoothly
that you are unlikely ever to hear this receiver overload, as
such. The top LEDs in the front-panel power display—the one
possible concession to fashion in the design—are Power
Guard pilots; below that, the display is calibrated from 100
watts down to 0.1 watt in 5 dB steps. As we've said before,
we're not convinced of the utility of such indicators, but the
calibration points do seem relatively well chosen.
Two unusual features of the front panel are the equalizer/
tone controls and the "loudness" knob. The latter might better be marked "contour" since it does not adjust midband
level like most loudness controls, but simply adds boost in the
deep bass plus some in the upper treble to compensate for
low listening levels. Like other separate-knob schemes, this
frees the loudness compensation from the volume control
and makes it adjustable to the actual listening levels through
the system; unlike some, the appropriate setting must be determined by ear alone—which is arguably the most reasonable
approach.
The equalizer's five bands have maximum ranges of ap-
proximately ± 13 dB and are marked for center frequencies
of 30, 150, 500, 1,500, and 10,000 Hz—making them, re-
spectively, controls for subbass, bass, midrange, treble, and
sparkle. The 30-Hz control is most effective as a rumble-fil-
ter/boom-boost control; the top one might be used as a hiss
filter, though its maximum cut setting dulls the upper treble a
good deal. As an ensemble, they offer genuinely useful flex-
ibility; all have detented center "flat" positions.
While the lab measurements give little clue to the "extras"
from which the receiver's special qualities derive, they docu-
ment its very solid performance. Mclntosh appears to be
thinking in terms of listening quality rather than specsmanship (an attitude we applaud), so distortion, for example, is
only vanishingly low—not infinitesimally low. The frequency
response has been intentionally cut off beyond the audio
band to help maintain clean sound by inhibiting intermodulation with infrasonic and ultrasonic "garbage" (a design criterion that applies to the tuner section as well as the
amplifier); though this, similarly, may dismay those who judge
an amplifier by its square waves, the results with music seem
all the better for it. Tuner data are likewise very good—even
superb—with no offsetting cause for complaint of any kind.
It is obvious, too, that Mclntosh has a clearly formed idea of
the sort of user it is designing for: someone who, while he is
uninterested in playing the "pro," cares very much about
quality and craftsmanship. The cosmetics, the "feel," and the
sound quality of the Mac 4100 are all superb; the controls are
minimal for the degree of useful flexibility they provide, with
little if any concession to users who simply like to putter. This
truly is a receiver for music lovers.
CIRCLE 136 ON PAGE 89
FEBRUARY 1979
In making comparisons between current reports and those published in
the past, readers are cautioned to pay particular attention to the reference
levels and similar test criteria cited S/N ratios tor electronics, in particular, are measured very differently now that we have adopted salient
features of the new IHF amplifier-measurement standard While we believe that the new technique (which also implies a saner approach to
loading of all inputs and outputs) will result in measurements that more
perfectly reflect audible, in use effects. they cannot be compared directly
to the numbers resulting from the former, more conventional lab measurements
NEW MEASUREMENT STANDARDS
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