McIntosh MC205 - Manual (Page 17)

17
Power Supply Circuits
To compliment the design of the MC205, there is a high
current power supply for the five power amplifier channels.
Refer to figure 18. The very large Power Transfomer, has
toroidal windings on a toroidal core and can supply over 35
amps of continuous current. Refer to figure 19 (golf ball is
for size comparsion). It is enclosed in the legendary McIn-
tosh Potted
Enclosures
and weighs
over
12.06kg.
The super
size main
filter
capacitors
can store
over 310
Joules of
energy for
the five
amplifier channels, necessary for the wide dynamic range
that “Digital Audio” demands. Refer to figure 23. The
power amplifier 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 MC205 is equipped with a circuit that
provides remote Power Control from a McIntosh A/V Con-
trol Center. When the A/V Control Center is switched On,
a (+5V) signal operates the power relay in the MC205. The
MC205 also has a remote Power Control input for Zone B
operation (two of the five channels).
distortion is unpleasant to hear, but the inaudible ultrasonic
distortion is also undesirable, since it can damage valuable
Loudspeaker System tweet-
ers. You will never experi-
ence the harsh and damaging
distortion due to clipping.
The Power Guard circuit is a
waveform comparator, moni-
toring both the input and out-
put waveforms. Under normal
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 waveforms. When the
difference exceeds 0.3% (equivalent to 0.3% harmonic dis-
tortion), the Power Guard activates the PG light and a dy-
namic electronic attenuator at the amplifier input reduces
the input volume just enough
to prevent any further
increase in distortion. 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 pre-
served. The MC205 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.
Technical Description
Figure 19
Block Diagram
of the
Power Supply
Figure 18
Figure 16
Without Power Guard
Figure 17
With Power Guard