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15
Technical Description, cont
Figure 17
With Power Guard
Figure 16
Without Power Guard
able, since it can damage
valuable loudspeaker sys-
tem tweeters. You will
never experience the
harsh and damaging dis-
tortion due to clipping.
The Power Guard cir-
cuit is a waveform com-
parator, monitoring both
the input and output
waveforms. Under nor-
mal operating conditions,
there are no differences
between the shape of
these waveforms. If an amplifier channel is overdriven,
there will be a difference between the two signal wave-
forms. When the difference exceeds 0.3% (equivalent to
0.3% harmonic distor-
tion), the Power Guard
activates the PG light and
a dynamic electronic at-
tenuator at the amplifier
input reduces the input
volume just enough to
prevent any further in-
crease in distortion. The
Power Guard circuit acts
so fast that there are ab-
solutely no audible side
effects and the sonic pu-
rity of the music repro-
duction is perfectly pre-
served. The MC602 Power Amplifier with Power Guard is
not limited to just the rated power output, but will actually
produce distortion free output well above its rated power
due to the McIntosh philosophy of conservative design.
Power Supply Circuits
To compliment the fully balanced design of the MC602,
there are two high voltage power supplies; one for each
channel, allowing each channel to be optimized using its
own power supply. Refer to figure 18. High power amplifi-
ers draw high current from the AC power line. Therefore, it
is important that they plug directly into the wall outlet.
Also, most owners desire that there be one power
switch for the whole audio system. The MC602 is equipped
with a circuit that provides remote Power Control from
your McIntosh Preamplifier or Control Center. When you
turn on your preamplifier a digital 1 (+5V) signal oper-
ates the power relay in the MC602. The MC602 also has a
remote Power Control Out Jack. The Power Control signal
from this jack is delayed by a fraction of a second so that
the turn on power surge of the next power amplifier occurs
at a later time. This helps prevent power circuit overload
that could trip circuit breakers or blow fuses, a very impor-
tant feature in a high power Home Theater System employ-
ing three MC602 Power Amplifiers.
The MC602 can provide greater than 150 amperes peak
output current to drive uneven speaker loads. Some poor
speaker designs have input impedance that dip to 1 or 2
ohms at various frequencies and the MC602 has the output
current reserve to drive them. It can deliver over 1,000
Watts Output on tone bursts. The MC602 has huge main
filter capacitors that guarantee an excellent signal to noise
ratio and the energy storage necessary for the wide dy-
namic range that Digital Audio demands.
Figure 18
Block Diagram
of the
Power Supply