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MC-7100
Owners manual
20 pgs900.78 Kb0
Service manual
16 pgs581.96 Kb0

McIntosh MC-7100 Owners manual

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MC7100
POWER
AMPLIFIER
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MC7100
POWER
AMPLIFIER
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The serial number, purchase date, and Mclntosh Laboratory Service Contract number are
important to you for possible insurance claim or future service. Record this information here.
Serial Number Purchase Date
Service Contract Number
Upon application, Mclntosh Laboratory provides a Service Contract to the original purchaser. Your Mclntosh Authorized Service Agency can expedite repairs when you provide the Ser­vice Contract with the instrument for repair.
SERVICE CONTRACT 4 INTRODUCTION 5 INSTALLATION 5, 6, 7 HOW TO CONNECT INPUTS 8 HOW TO CONNECT OUTPUTS 8, 9 CONNECTING DIAGRAMS 10 SPECIFICATIONS 11 PERFORMANCE CHARTS 12
TECHNICAL DESCRIPTION 13, 14
BLOCK DIAGRAM 15
TABLE OF CONTENTS
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McINTOSH
THREE YEAR
SERVICE
CONTRACT
TAKE ADVANTAGE OF 3 YEARS OF CONTRACT SERVICE. . .
FILL IN THE APPLICATION NOW.
Your MC7100 Power Amplifier will give you many years of satisfactory performance. If you
have any questions, please contact,
Mclntosh Laboratory Inc.
2 Chambers Street
Binghamton, New York 13903-2699 Phone: 607-723-3512
An application for A THREE YEAR SERVICE CONTRACT is included with this manual. The terms of the contract are:
1. If the instrument covered by this contract becomes defective, Mclntosh will provide all parts, materials, and labor needed to return the measured performance of the instrument to the original performance limits free of any charge. The service contract does not cover any shipping costs to and from the authorized service agency or the factory.
2. Any Mclntosh authorized service agency will repair all Mclntosh instruments at normal service rates. To receive the free service under the terms of the service contract, the ser­vice contract certificate must accompany the instrument when taken to the service agency.
3. Always have service done by a Mclntosh authorized service agency. If the instrument is modified or damaged as a result of unauthorized repair the service contract will be cancell­ed. Damage by improper use or mishandling is not covered by the service contract.
4. The service contract is issued to you as the original purchaser. To protect you from misrepresentation this contract cannot be transferred to a second owner.
5. Units in operation outside the United States and Canada are not covered by the Mclntosh Factory Service Contract, irrespective of the place of purchase. Nor are units acquired outside the USA and Canada, the purchasers of which should consult with their dealer
to ascertain what, if any, service contract or warranty may be available locally.
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The electrical and mechanical design of the MC7100 Power Amplifier is the result of the
many years of engineering and manufacturing experience of the design staff at Mclntosh. This "Know How", along with the meticulous attention to design and production details, makes the MC7100 one of the finest amplifiers ever produced by Mclntosh Laboratory.
The use of 4 complimentary connected output transistors per channel, allows not only full power output into normal loads, but extra high current output to drive uneven speaker loads. Some speakers have design characteristics that cause them to dip below their rated im-
pedances at certain frequencies. It is possible for the MC7100 to deliver as much as 18 amperes peak current into these lower impedance loads.
The MC7100 provides this extra current output with complete reliability due to the use of
Mclntosh Sentry Monitor protection circuits. Some power amplifier manufacturers have claimed
that their products do not use protection circuits since they compromise performance. The
real genius of Mclntosh engineering design has recognized these potential problems and com­pletely eliminated them. Properly designed protection circuits assure you an amplifier that will operate under all types of user conditions with maximum reliability and freedom from possible speaker or amplifier damage. The benefits of these designs mean you own an amplifier that will continue to operate safely for many years.
The MC7100 output is so distortion free, it is difficult to measure with conventional in­struments. The performance limit is 0.005% maximum distortion, yet it is typical for an amplifier to measure as low as 0.002% at mid frequencies into 8 ohms.
As in all Mclntosh power amplifiers, the famous patented Mclntosh POWER GUARD cir­cuit is included. You never have to be concerned with possible amplifier overdrive. You will not experience amplifier clipping with its harsh speaker damaging distortion when playing wide dynamic range program sources such as compact discs.
Many other desirable features are included such as gold plated output terminals, DC out­put protection, thermal protection and a turn on delay circuit. A Toroidal wound power transformer permits a low profile design with quiet cool operation.
Refer to the section in this manual titled TECHNICAL DESCRIPTION for detailed informa­tion on all the outstanding circuit and performance features of the MC7100.
INTRODUCTION
LOCATION
The MC7100 may be installed on a shelf or table, in a Mclntosh cabinet, or custom install­ed in furniture of your choice. Always provide adequate ventilation for the amplifier. The trou­ble free life of any electronic instrument is greatly extended by providing sufficient ventila-
tion. This prevents build-up of internal temperatures that can cause deterioration of circuit components. The Mclntosh cabinet design allows for proper ventilation.
Allow enough clearance so cool air can enter at the bottom of the cabinet and be vented
from the top. Provide at least 1 1/2 inches (3.8cm) above the amplifier heat sink area so airflow
is not obstructed. The recommended minimum space for installation is 18 1/2 inches (47cm)
wide, 14 1/2 inches (36.8cm) deep, (including connectors) and 4 1/2 inches (11.5cm) high. Allow 1 inch (2.54cm) in front of the mounting surface for panel clearance.
McINTOSH PANLOC MOUNTING SYSTEM
The PANLOC system of installing equipment is a product of Mclntosh research. Two steel
PANLOC mounting shelves are attached to the front panel at each side of the panel cutout,
using the screws and brackets provided. The amplifier has runners on the bottom of its chassis,
INSTALLATION
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3. SAW THE PANEL CUTOUT First make the two long horizontal cuts. Then make the two short vertical cuts. After the
cutout is finished, use a file to square the corners and smooth any rough edges.
4. INSTALL THE PANLOC MOUNTING STRIPS
The hardware package includes two mounting strips and two black flat head 6/32 x 1 1/4 inch (31.8mm) screws and two 6/32 x 1 1/4 inch (31.8mm) fillister head screws. Place a mounting strip behind each edge of the cutout and secure it to the back side of the panel inserting a black flat head 6/32 screw through the center holes marked B on the template. Make sure the screws are drawn flush or slightly into the wood before attaching the PANLOC shelves.
5. ATTACH THE PANLOC SHELVES Position the PANLOC shelves inside the
cutout with the short flange against the front face of the cabinet panel. Fasten the shelves by inserting two fillister head 6/32 screws through the holes in each of the PANLOC shelf flanges, through the front panel and into the threaded receptacle on
the mounting strips.
INSTALLATION
6. INSTALL THE AMPLIFIER
Guide the amplifier AC power cord through the panel opening to the back of the cabinet. Slide the amplifier into the opening, making sure the rails on the bottom of each side of the amplifier chassis engage the tracks on the PANLOC shelves. Slide the amplifier completely into the cabinet until the back side of its front panel is pressing gently against the front of
the cabinet panel. Turn the PANLOC buttons approximately one-quarter turn clockwise to lock the amplifier in the cabinet. Turn the PANLOC buttons one-quarter turn counterclockwise to
unlock and remove the amplifier.
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PERFORMANCE
CHARTS
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DESIGN PHILOSOPHY
The MC7100 stereo power amplifier is designed to operate loudspeakers with a nominal impedance of 4 to 8 ohms. It features a new circuit design that keeps distortion levels so low it takes special test gear for accurate measurements.
The design philosophy that resulted in the outstanding performance of this amplifier in-
volved several different techniques. Every stage of voltage or current amplification was design­ed to be as linear as possible prior to the use of negative feedback,
1. Each transistor is selected to have nearly constant current gain (Beta) over its entire
operating range.
2. The load impedance presented to each amplification stage is made as uniform as possi­ble for all signal levels.
3. The input impedance of each amplifier stage is increased and made more linear by us­ing emitter degeneration whenever possible.
4. Resistors and capacitors in the signal path are carefully selected to have exceedingly low voltage coefficients (change of resistance or reaction with applied voltage). Precision metal film resistors and low dielectric absorption film capacitors are used in all 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
together with the automatic tracking bias system eliminate crossover distortion.
TECHNICAL
DESCRIPTION
PROTECTION CIRCUITS
Some manufacturers of power amplifiers claim that their products do not need or use pro-
tection circuits and that such circuits compromise performance. Mclntosh feels that protec­tion circuits are desirable and necessary to prevent amplifier or loudspeaker damage due to abnormal circumstances. The genius of Mclntosh engineering has resulted in protection
circuits which have no effect or compromise on the normal performance of a power amplifier.
The SENTRY MONITOR circuit is a good example. The MC7100 incorporates seven specific protection circuits to enhance its performance, increase its reliability and protect loudspeakers.
SENTRY MONITOR CIRCUIT
All power transistors have limits for the maximum amount of power they can handle. The MC7100 output transistors and power supply have been designed to allow very high current
flow into properly matched load impedances. However, if a short circuit or very low load im-
pedance is connected to the MC7100 outputs, destructive current levels could be reached if it was not controlled by the SENTRY MONITOR circuit. This circuit senses the dynamic operating time, voltage and current of the output stage, and controls it to safe operating limits.
The SENTRY MONITOR circuit does not limit the power output available from the amplifier. THERMAL CONTROL
All power transistors have limits to the maximum amount of heat they can safely tolerate. The MC7100 uses a highly efficient amplifying circuit which produces relatively little heat for the output power produced. The amplifier uses large area heat sinks to efficiently dissipate what heat it does generate. Natural convection air flow is sufficient for safe cool operation.
If the cooling air is blocked, or the amplifier operating temperature is forced too high, ther-
mal cutout switches will turn off the speakers. Both POWER GUARD indicators will light con-
tinuously to show that thermal protection is operating. When the problem is corrected and
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TECHNICAL
DESCRIPTION
the amplifier cools down to its normal operating temperature, the speakers will be turned back on.
DIRECT CURRENT FAILURE PROTECTION
A protection circuit is provided that turns off the speakers if for any reason a DC voltage
should appear at the output terminals. This prevents possible speaker damage. POWER GUARD
A unique and patented feature of Mclntosh power amplifiers insures that each channel of the MC7100 will deliver full power, free of clipping distortion. Clipping occurs when an amplifier is overdriven past its output design capabilities. An overdriven amplifier can pro­duce both audible and ultrasonic distortion levels approaching 40%. The audible distortion is certainly unpleasant, but the ultrasonic distortion is also undesirable, since it can damage tweeter loudspeakers.
The POWER GUARD circuit acts as a waveform comparator, monitoring both the input and output waveforms. Under normal operating conditions there are no differences between these waveforms. When an amplifier is overdriven beyond its maximum distortion free out­put, then there will be a difference between the two waveforms. If the difference exceeds
0.3% (equivalent to 0.3% harmonic distortion), the amber POWER GUARD indicator will light.
If the difference continues to increase, the POWER GUARD circuit controls an electronic attenuator at the input to reduce the gain of the amplifier just enough to prevent any further increase in distortion. Distortion will not exceed 2% with as much as 14dB overdrive.
A Mclntosh power amplifier with POWER GUARD will always deliver its maximum distor­tion free output. This power is always well above the rated power due to the Mclntosh philosophy of conservative design. You will never experience the harsh and damaging distor­tion due to clipping when using a Mclntosh POWER GUARD amplifier.
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BLOCK DIAGRAM
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039942
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