Owner`s manual

19
Technical Description, con’t
is a waveform
comparator,
monitoring both
the input and
output wave-
forms. Under
normal operat-
ing conditions,
there are no
differences be-
tween the shape
of these wave-
forms. If an am-
plier channel
is overdriven,
there will be
a difference
between the two signal waveforms. When the difference
exceeds 0.3% (equivalent to 0.3% harmonic distortion), the
Power Guard activates the PG light and a dynamic elec-
tronic attenuator at the amplier input reduces the input
volume just enough to prevent any further increase in dis-
tortion. The Power Guard circuit acts so fast that there are
absolutely no audible side effects and the sonic purity of
the music reproduction is perfectly preserved. The MC207
Power Amplier 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 design of the MC207, there is a high
current power supply for the seven power amplier chan-
Figure 20
With Power Guard
nels. Refer to gure 21. The very large Power Transfomer,
has toroidal windings on a toroidal core and can supply
over 35 amps of continuous current. Refer to gure 22
(golf ball is for size comparsion). It is enclosed in the
legendary McIntosh Potted Enclosures and weighs over
12.06kg. The super size main lter capacitors can store
over 430 Joules of energy for the seven amplier channels,
necessary for the wide dynamic range that “Digital Audio”
demands. Refer to gure 23 on the next page. The power
amplier draws high current from the AC power line.
Therefore, it is important that they plug directly into the
wall outlet.
Also, most owners desire one power switch for the
whole audio system. The MC207 is equipped with a circuit
that provides remote Power Control from a McIntosh A/V
Control Center. When the A/V Control Center is switched
On a digital “1” (+5V) signal operates the power relay in
Figure 21
Block Diagram
of the
Power Supply
Figure 22