Mcintosh mac4100 schematic
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
34
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
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