17
relay in the MC1.25KW. The MC1.25KW also has a
remote Power Control Out Jack. The Power Control
signal from this jack is delayed by a fraction of a sec-
ond 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 break-
ers or blow fuses, a very important feature in a high
power Home Theater System employing three or more
MC1.25KW Power Amplifiers.
Technical Description, con’t
Power Supply Circuits
To compliment the fully balanced design of the
MC1.25KW there are two high voltage power supplies;
one for each of the two amplifier circuits, allowing
each amplifier circuit to be optimized using its own
power supply. Refer to figure 23. High power ampli-
fiers draw high current from the AC power line. The
very large Power Transfomer, has toroidal windings
on a toroidal core and can supply over 35 amps of
continuous current. Refer to figure 24 (golf ball is
for size comparsion). It is enclosed in the legendary
McIntosh Potted Enclosures and weighs over 12.06kg.
The six super size main filter capacitors can store over
450 Joules of energy necessary for the wide dynamic
range that “Digital Audio” demands. Refer to figure
25. 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 MC1.25KW is equipped with
a circuit that provides remote Power Control from
a McIntosh Preamplifier. When the Preamplifier is
switched On, a (5-15VDC) signal operates the power
Figure 24
Figure 23
Block Diagram
of the
Power Supply
INRUSH
CURRENT
LIMITER
AC Power
MAIN RELAYS
BACKUP
POWER SUPPLY
CONTROL
LOGIC
LIGHTING
CONTROL
POWER
CONTROL
FUSE
POWER
SWITCH
LOW VOLTAGE
SUPPLY
POWER
TRANSFORMER
MAIN
SUPPLY
AUTO
OFF
Figure 25
