Specifications

HOLD time at the peak of its travel. The highest power
output of the source material is thus recorded.
OUTPUT AUTOFORMER
The unequaled expertise of Mclntosh in the design
and manufacture of output transformers is legendary
in the Hi Fi industry. In the MC1000 it provides proper
matching for 2, 4 and 8 ohm loads. It protects your
speaker from damage in the event of an output
transistor failure, provides low distortion power transfer
at frequencies well beyond human hearing and delivers
peak output currents in excess of 160 amperes.
PROTECTION CIRCUITS
Some manufacturers of power amplifiers advertised
that their products do not require or use protection
circuits and that such circuits compromise performance.
Mclntosh Laboratory agrees that diligent measures are
required to allow unrestricted performance, but we also
insist that protection circuits are desirable and necessary
to prevent amplifier or loudspeaker damage due to
abnormal circumstance and that they actually enhance
performance. The MC1000 incorporates seven
protection circuits to enhance its performance, assure
its reliability and to protect loudspeakers.
POWER GUARD
Power Guard, a unique feature of Mclntosh
amplifiers, assures that the MC1000 will deliver full
power free of clipping distortion. Clipping is caused
when an amplifier is asked to produce more power
output than its design is capable of delivering with low
distortion. Amplifiers that are overdriven may deliver
large quantities of power when they are clipping but
they have more than 40% harmonic distortion. In this
mode, the sound is grossly distorted and the extra
energy content of the clipped signal will damage most
loudspeakers. The Mclntosh Power Guard circuit
protects your ears and your speakers from this kind of
damage.
The Power Guard circuit consists of a waveform
comparator which monitors the wave shape of the
amplifier input and output signals. Normally there is no
disparity between these signals and the comparator
produces no output. When the amplifier is' driven
beyond its maximum power capacity a difference will
develop. If the disparity exceeds 0.3% (equivalent to
0.3% total harmonic distortion) the comparator output
causes the amber power guard indicator to light. If
there is a further increase in the disparity the comparator
output controls an electronic attenuator at the amplifier
input to reduce the amplifier gain, thus holding the
amplifier output to a low distortion value. Overdrive
by 14dB is possible before the output distortion exceeds
2%.
SENTRY MONITOR
All power transistors have limits for the maximum
amount of power they can handle. The MC1000 output
transistors and power supply have been designed to
allow very high current flow into properly matched load
impedances. If, however, a short circuit or very low
value of load impedance is applied to the output of the
MC1000, destructive current levels could be reached
if it was not controlled by the Sentry Monitor circuit.
This circuit senses the dynamic operating time, voltage,
and current of the amplifier output stage and controls
the current flow confining it to nondestructive limits.
Sentry Monitor does not limit the power output available
from the amplifier.
THERMAL CONTROL
All power transistors have limits for the maximum
amount of heat they can tolerate. The MC1000 uses
a highly efficient amplifying circuit which produces
relatively little heat for the output power produced. The
amplifier has 8 oversized heatsinks to dissipate transistor
generated heat. Natural convection air flow is sufficient
for cool operation. Should the cooling air be blocked
or should the amplifier operating temperature become
too high, thermal cutouts within the amplifier will turn
off the power to the amplifier. When the amplifier has
cooled, it will automatically turn on again.
TURN-ON DELAY
The MC1000 has a turn-on delay circuit that
delays amplifier operation for about 2 seconds after
power turn on. This prevents pops or thumps generated
in other equipment from causing annoying noises or
damaging your loudspeakers.
DIRECT CURRENT FAILURE PROTECTION
The auto transformer protects speakers from
damage in the event of amplifier failure. Should a direct
current component appear in the output it is shunted
by the auto transformer and DC cannot damage the
speaker.
POWER LINE INRUSH PROTECTION
Turn on inrush current is cushioned by
thermistors in the power transformer primary circuit.
A soft start is achieved that eliminates component stress
during turn-on.
CIRCUIT OPERATION
The power output amplifier uses two balanced
stages of voltage amplification followed by three stages
MC1000 Product Preview/Page 6
MClNTOSH LABORATORY INC., 2 CHAMBERS STREET, BlNGHAMTON, NEW YORK 13903