McIntosh MC2301 - Manual (Page 20)

20
feedback designs.
The fully Balanced Push-Pull design is used from input
to output. The resulting fully balanced configuration can-
cels many forms of audible distortion and greatly improves
the Signal-to-Noise ratio of the amplifier.
While conventional designs only take output from
the plate, the Patented Unity Coupled Power Amplifier
Circuitry takes the Power Output from both the plate and
cathode of the Power Output Tubes. This allows for only
one half of the turns ratio in the Output Transformer used
in conventional designs. The result is much lower distor-
tion, wider bandwidth and increased loudspeaker damping
factor. Refer to figure 13.
The output signals of the two matched Patented Unity
Coupled Circuit Power Amplifiers operate in a push-pull
balanced circuit and are coupled together in the unique
McIntosh MC2301 Dual Core Output Transformer. Refer
to figure 14. It provides low distortion power transfer at
frequencies from below 20Hz to well beyond 20,000Hz
with optimum impedance points of two ohms, four ohms
and eight ohms. The unequaled expertise of McIntosh in
the design
and manu-
facturing
of trans-
formers is
legendary
in the high
fidelity
industry.
Preci-
sion metal
film resis-
tors and
low dielec-
tric absorp-
tion film
capacitors
are used in all critical circuit locations. The circuit design
of the MC2301 contributes to low operating temperatures
using convection cooling. No fans are needed.
Power Output Meter
The McIntosh MC2301 has a large Output Watt Meter
that responds 95% full scale to a single cycle tone burst at
2kHz. Refer to figure 15. The voltage outputs are electroni-
cally measured and fed to a special circuit that accelerates
the pointer
movement in
the upward
direction.
When the
pointer
reaches
its peak it
pauses only
long enough
for the hu-
man eye to
perceive its
position,
then drops.
It is almost 10 times faster than a professional VU meter.
A front panel switch is provided to change the meter to
the Watts Hold Mode of operation. This allows fast upward
movement of the pointer but greatly increases Hold Time
at the peak of its travel. The highest power output of the
source material is thus recorded.
Sentry Monitor Protection Circuit
The MC2301 incorporates the newly designed Sentry
Monitor Tube Protection Circuitry. Refer to figure 16.
This circuit provides protection to the Power Amplifier in
the event of an improper load (mismatched impedance),
shorted loudspeaker cable or if a Power Output Tube
Technical Description, con’t
Figure 16
Figure 13 Figure 15
Figure 14