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The Mclntosh "Always In Style"
TIMELESS LOOKS
PEAK PERFORMANCE
OPTIMUM DEPENDABILITY
CLASSIC DESIGN
The classic appearance of a Mclntosh amplifier
complements any home decorative scheme. Each
component is selected for durability, as well as
aesthetics.
Consider the construction and materials used in
the front panel and knobs. Reverse silk-screened
with thermal setting epoxy screen inks, the glass
panels are meticulously hand inspected and are
free from bubbles, flow marks and other faults.
Anodizing, an electro-chemical process that leaves
a color dyed and hardened surface impervious to
attack from common household cleaning fluids,
oils and acids from the skin, is used on the panel
frame and aluminum knobs to maximize their
resistance to wear.
This handsome combination of glass, anodized
aluminum, and thermal setting epoxy inks requires
very little maintenance to keep the MC7300 look-
ing brand new. Its subtle yet sophisticated styling
will
remain
in
good
taste
throughout
the
years.
Rear view
Mclntosh Quality Begins With Careful
Design For Cool Operation
An
amplifier's
life
can be cut
short
without
the
pro-
per ventilation for cool operation. In fact, as little
as one degree centigrade rise in temperature can
reduce the life of an amplifier by 10%. Mclntosh
has designed its amplifiers to maximize trouble-
free cool operation.
Output stages are mounted on super-sized heat
sinks that have maximum surface areas of cooling
capability. The sinks are placed in an air tunnel
chassis that occupies the amplifier space from top
to bottom. Cooling air, which flows through the air
tunnel, dissipates life-limiting heat. This heat
dissipation capability is coupled with a chassis
construction that encourages ventilation. A Mcln-
tosh designed and manufactured autotransformer
matches the transistor output circuit to the
loudspeakers.
The Mclntosh output circuit uses 20 metal cased
bipolar epitaxial power transistors and 4 metal cas-
ed driver transistors. The output transistors feature
high fT (gain - frequency product) and large SOA
(safe operating area). The power transistor
characteristics, the power supply voltage used, and
the output autoformer ratio have been matched for
high efficiency, maximum power output with low
distortion, and reliable long life operation.
Versatile Mclntosh Power Amplifiers
Deliver Full Power - Always
The Mclntosh output circuit, superior in its perfor-
mance, demands a superior method of coupling
the amplifier output to the loudspeaker load. A
Mclntosh designed and manufactured
autotransformer ensures peak performance and
protection, as well as outstanding compatibility
between amplifier and speaker.
The Mclntosh autotransformer offers these benefits:
- Transistors, used in amplifier output circuits, are
designed to work into an optimum low im-
pedance load. Variations in frequency, or the use
of multiple speakers (which modify the im-
pedance as seen by the output of the amplifier),
often compromise an amplifier's performance.
The Mclntosh autotransformer prevents these
variables from causing restricted performance,
output transistor heating, and/or circuit failure.
- In the event of an output circuit failure, the
Mclntosh autotransformer conducts the speaker-
damaging DC (direct current) directly to ground,
thus protecting expensive loudspeakers from
potential damage.
- The Mclntosh autotransformer contributes a flex-
ibility in loudspeaker connecting capability not
otherwise possible. Here's how:
Ordinary amplifier output circuits are usually
restricted to operating in 4 or 8 ohms. In stereo,
the Mclntosh autotransformer perfectly matches
the output circuit to 2. 4, or 8 ohms. In mono
the MC7300 autotransformers provide matching
into 1, 2, 4, 8 or 16 ohms. In addition, the
autotransformer can provide either a 25 volt or a
70.7 volt output that can feed multiple
loudspeakers for background music applications.
Heat sinks
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The Mclntosh autotransformer is, quite simply, an
engineering advance that enhances amplifier
performance while maintaining technical and per-
formance integrity.
Mclntosh's Exclusive Power Guard-„˘
Music Protection Circuit
Improved recording techniques have imposed
higher power demands on today's amplifiers. Other
amplifier designs, of which there are many, can
present music listeners with unpleasant distortion
due to amplifier overload (hard clipping).
Clipping, which looks and acts like non-musical
square waves (music produces rounded waves), is
caused when the amplifier is required to produce
more power output (with low distortion) than it is
designed to deliver. Amplifiers, when driven to clip-
ping, can deliver up to 40% harmonic distortion-
distortion that significantly decreases listening en-
joyment, and increases listening fatigue. A clipped
Top interior view
signal also produces extra distortion energy, which
can damage speakers.
Mclntosh precision engineering has developed the
Power Guard circuit* to prevent amplifiers from be-
ing overdriven into hard clipping; ensure that the
amplifier produces its maximum output without in-
creased distortion; and protect the speaker from
excessive heating.
(*Power
Guard
is a
patented
Mclntosh
design,
U.S.
patent
#4048573)
Compact discs have a higher 'dynamic range' over
records and audio cassettes. Most compact discs
claim a dynamic range in excess of 90 decibels. In
numerical ratio this is greater than 1000 times the
ratio of popular commercial analog records.
For equipment to be digital ready it must handle
overdrive without breaking up or grossly distorting
the sound. Virtually all power amplifiers today are
incapable of accepting 10 decibels of overdrive
without gross distortion. Some amplifiers totally
collapse under this punishment. Mclntosh has
devised a test which shows an amplifier's spectral
fidelity
under
stress
-- one of the
most
important
characteristics of an amplifier.
Every detail of the complicated panel is inspected
and re-inspected.
The harmonic distortion and two-tone intermodula-
tion measurements are important criteria in predic-
ting the sonic performance. However, to obtain
better correlation with human hearing response,
we need to know not only the energy in the distor-
tion spectrum, but also the number of discords
and their frequency spacing from the desired
tones. Spectral fidelity testing enlarges the scope
of
data
and
more
fully
clarifies
its
meaning.
It is no accident, then that a Mclntosh amplifier is
a
smart
investment,
one
that
will
fill
your
home
with years of audio excitement:
- It is more reliable than other amplifiers
- It has a longer, trouble-free life than other
amplifiers
- It sounds better than other amplifiers
- Its resale value is the highest of all amplifiers
Mclntosh Patented Power Meters
In the past, ordinary power meters have been in-
capable of indicating the short interval information
in a soundwave, which can have a duration of one-
half of one thousandth of a second. And even if a
meter were capable of such high velocity move-
ment, the human eye would be unable to perceive
the information.
Mclntosh engineering solved the dilemma by
developing an electronic circuit that power meters
can respond to with an accuracy of 98%. These cir-
cuits are time-stretched, which allows the meter
pointer position to register in such a way that the
human eye can register its high-speed motion.
The patented peak-reading, peak-locking meter cir-
cuit included in the MC7500 is yet another
Mclntosh electronic design feature that maximizes
your audio pleasure. . .and makes the MC73OO a
sound investment.
If
good
enough
will
do,
there are dozens of brands
to choose from.
But if the best is what you need
there is only one to consider:
The Mclntosh MC73OO.
