Specifications

METER MODE
The METER MODE switch has two positions:
WATTS and HOLD.
WATTS
In the WATTS position, the meter needle
indicates the variations in program loudness.
Although the primary output calibration of the meters
is from 3.0 milliwatts up to 300 watts, the rated
power output of the MC7300; the additional
indications to the right of the 300 watts mark, are
600 and 1200 watts. While the MC7300 cannot
reach this power level continuously it is possible for
short interval peaks to considerably exceed the 300
watts continuous rating.
HOLD
In the HOLD position, the meter needle locks to
the highest power peak in a sequence of peaks. The,
meter is driven to maximum power, electronically held
there until a higher peak passes through the amplifier,
which moves the meter needle to a new indication.
If no further peaks are reached the meter needle will
very slowly return to its rest position (decay rate: 6dB
per minute).
POWER
The POWER switch turns the MC7300 ON or
OFF. The switch does not control the power outlet
on the back panel. If you wish to control the AC
power from a preamplifier control center, leave the
switch in the ON position. Be sure the AC cord of
the MC7300 is plugged into the switched outlets on
the rear of the preamplifier control center.
POWER GUARD
OPERATION - McIntosh Exclusive Digital
Dynamic Protection Circuit
Improved recordings and recording techniques
have imposed higher power demands on today's
amplifiers. Poorly designed amplifiers can present
music listeners with a form of harsh unpleasant
distortion due to amplifier overload (hard clipping).
Clipping, which looks and acts like non musical
square waves, is caused when the amplifier is asked
to produce more power output with low distortion
than it is capable of or designed to deliver.
Amplifiers, when driven to clipping, can deliver up to
40% harmonic and intermodulation distortion that
decreases the pleasure and enjoyment you get from
listening. This form of distortion (clipping signal) also
produces extra heat energy which will damage most
speakers. Mclntosh leadership in engineering has
developed the Power Guard circuit which - (1)
dynamically prevents power amplifiers from being
overdriven into hard clipping - (2) assures that the
amplifier will produce its maximum output without
increased distortion - (3) protects your speaker from
excessive heating. Power Guard is a patented
Mclntosh design (U.S. patent #4048573).
The MC7300 has a circuit that compares the
wave shape of the output signal to the input signal.
If the disparity between the two signals, due to
overdrive, exceeds an average of 0.3% (equivalent to
0.3% total harmonic distortion) an amber POWER
GUARD indicator illuminates. With any further
increase in distortion the POWER GUARD circuit
operates to limit the amplifier input dynamically so
that the amplifier cannot be overdriven. POWER
GUARD eliminates amplifier output clipping. POWER
GUARD only operates when the amplifier is asked to
deliver more power than that for which it was
designed. While the power output remains within
these limits the POWER GUARD indicators do not
illuminate.
REAR PANEL INFORMATION
MODE SWITCH
The MC7300 will operate in three modes,
Stereo, Mono Bridge, and Mono Parallel.
INPUT LEVEL
The input sensitivity of the MC7300 is 1.4
volts or 2.5V depending on the position of the INPUT
sensitivity switch. For the best signal to noise ratio
when using Mclntosh source equipment, place the
INPUT sensitivity switch in the 2.5V position and the
front panel LEFT GAIN and RIGHT/MONO GAIN
controls in the fully clockwise position. If more gain
is desired, the 1.4V position may be used. All
Mclntosh preamplifiers have been designed to deliver
2.5 volts output with rated input. For source
equipment other than Mclntosh, set the switch in the
position nearest to stated output rating of the source
equipment.
MC7300 Product Preview/Page 4
MClNTOSH LABORATORY INC., 2 CHAMBERS STREET, BlNGHAMTON, NEW YORK 13903