Specifications

in the right channel to the desired listening level. Turn
the control clockwise to increase the output.
The input sensitivity of the MC7100 is 1.4V with
the gain controls full CW If one desires to match the
2.5 V rating for Mclntosh preamps simply turn each gain
control CCW to the detent position on the control.
The right gain control also controls the gain in the
MONO mode of operation.
LEFT AND RIGHT OUTPUT
For STEREO operation, output connections for
impedances of 4 to 8 ohms are provided on secure,
screw type, gold plated terminals. Connections for
mono output are marked below the terminals.
INPUT
In the STEREO mode of operation both input jacks
accept signal. For MONO operation use only the Right
input jack and place the MODE switch in MONO.
AC POWER
The MC7100 is rated for 120 volts, 50/60 hertz.
It uses 0 5 amperes when there is no signal output and
up to 5 amperes with both channels delivering rated
power A 5 ampere fuse protects the MC7100 electri-
cally. The AC power outlet provided for auxiliary
equipment is neither fused nor switched.
Technical Description
The MC7100 is a stereo power amplifier designed
to operate with loudspeakers having a nominal im-
pedance of 4 or 8 ohms
It features a new circuit design that holds harmonic
distortion far below the amplifiers remarkably low noise
floor Only by using special spectrum analysis
measuring techniques is the distortion measurable at
all
DESIGN PHILOSOPHY
The secret to this performance will sound very
simple, but it is more difficult to carry out than it may
seem The principle used in the design of the MC7100
was to arrange every stage of voltage or current
amplification to be as linear as possible
This linear operation is accomplished by using
several different techniques.
1 Each transistor is selected to have nearly constant
current gain (Beta) over the entire range of currents
at which the transistor must operate
2. The load impedance presented to each
amplification stage is made to be as uniform as
possible for all signal levels.
3. The input impedance of stages is increased and
linearized where possible by using emitter degen-
eration.
4. Resistors and capacitors in the signal path are
carefully selected to have exceedingly low
voltage coefficients (low change of resistance
or reactance with applied voltage). Precision
metal film resistors and low dielectric absorption
film capacitors are used in ail critical circuit
locations.
5 Output transistors have matched uniform current
gain, high current gain-bandwidth product, low
output capacitance, and large active-region safe
operating area. These characteristics and the
automatic tracking bias system eliminates cross-
over distortion. The distortion graphs show
clearly that distortion does not increase at low
power output levels.
OVER 50 JOULES OF ENERGY STORAGE
Huge main filter capacitors are used to guarantee
an excellent signal to noise ratio and the energy storage
necessary for the wide dynamic range that "Digital
Audio" demands.
PROTECTION CIRCUITS
Some manufacturers of power amplifiers
advertised that their products do not require or use
protection circuits and that such circuits compromise
performance Mclntosh Laboratory agrees that diligent
measures are required to allow unrestricted performance,
but we also insist that protection circuits are desirable
and necessary to prevent amplifier or loudspeaker
damage due to abnormal circumstance and that they
actually enhance performance The MC7100
incorporates seven protection circuits to enhance its
performance, assure its reliability and to protect
loudspeakers
POWER GUARD
Power Guard, a unique feature of Mclntosh
amplifiers, assures that each channel of the MC7100
will deliver full power free of clipping distortion Clipping
is caused when an amplifier is asked to produce more
power output than its design is capable of delivering
with low distortion. Amplifiers that are overdriven may
MC7100 Product Preview/Page 4
MClNTOSH LABORATORY INC., 2 CHAMBERS STREET, BlNGHAMTON, NEW YORK 13903