Stereo Power Amplifier MC275 Owner’s Manual McIntosh Laboratory, Inc.
The lightning flash with arrowhead, within an equilateral triangle, is intended to alert the user to the presence of uninsulated “dangerous voltage” within the product’s enclosure that may be of sufficient magnitude to constitute a risk of electric shock to persons. WARNING - TO REDUCE RISK OF FIRE OR ELECTRICAL SHOCK, DO NOT EXPOSE THIS EQUIPMENT TO RAIN OR MOISTURE. IMPORTANT SAFETY INSTRUCTIONS! PLEASE READ THEM BEFORE OPERATING THIS EQUIPMENT. 1. Read these instructions. 2. Keep these instructions. 3.
Thank You Table of Contents Your decision to own this McIntosh MC275 Stereo Power Amplifier ranks you at the very top among discriminating music listeners. You now have “The Best.” The McIntosh dedication to “Quality,” is assurance that you will receive many years of musical enjoyment from this unit. Please take a short time to read the information in this manual. We want you to be as familiar as possible with all the features and functions of your new McIntosh. Safety Instructions ......................
Introduction and Performance Features Important Information Introduction 1. Caution: To prevent electrical shock make sure that the AC POWER CORD IS NOT CONNECTED TO THE MC275 when inserting or removing Vacuum Tubes, as there are hazardous voltages present at the pins of the Tube Sockets. 2. When Vacuum Tubes are installed or removed make sure to reattach the Tube Cover to the MC275 Chassis. 3. If the MC275 has been On, please allow the Hot Vacuum Tubes to cool first before removing them. 4.
MC275 Dimensions MC275 Dimensions The following dimensions can assist in determining the best location for your MC275. There is additional information on page 7 pertaining to installing the MC275 into cabinets. 16-1/2" 41.91cm 7-7/8" 20.00cm 8-1/4" 20.96cm Front View of the MC275 1-3/4" 13-5/8" 4.45cm 34.61cm Top View of the MC275 12" 30.48cm Left Side View of the MC275 5-9/16" 14.13cm 1-3/4" 4.45cm Right Side View of the MC275 4-3/8" 11.11cm 1-1/4" 3.
Installation of Tubes and Tube Cover Caution: To prevent electrical shock make sure that the AC POWER CORD IS NOT CONNECTED TO THE MC275 when inserting or removing Tubes, as there are hazardous voltages present at the pins of the Tube Sockets. Your MC275 has gone through an extensive series of performance tests during the manufacturing process. The MC275 is supplied with the actual Tubes that were used to test and confirm the performance of this amplifier.
Installation of Tubes, Tube Cover, Location and Ventilation Small Signal Tubes: 1. Locate a 12AX7A Tube. 2. On the top left side of the amplifier, locate the Tube Socket that has the nomenclature V1 12AX7A next to it on the chassis. Refer to figure 4 and 5. 3. Orient the Tube so the area where no pins are located on the base of the Tube is aligned with the corresponding area on the Tube Socket. 4. Carefully insert the Tube into the socket until the base of the Tube is fully seated in the Tube Socket. 5.
Left Side Panel Connections LEFT OUTPUT Connections for loudspeakers BALANCED INPUTS for audio cables from a preamplifier or control center audio outputs RIGHT OUTPUT Connections for loudspeakers UNBALANCED INPUTS for audio cables from a preamplifier or control center audio outputs 8
Right Side Panel Connection and Fuse Holder Connect the MC275 power cord to a live AC outlet.
How to Connect for Stereo How to Connect for Stereo 1. Connect cables from the Balanced Outputs of a McIntosh Preamplifier or Control Center to the MC275 Left and Right Balanced Inputs. Note: An optional hookup is to use unbalanced cables. 2. Prepare the Loudspeaker Hookup Cables that attach to the MC275 by choosing one of the methods below: Bare wire cable ends: Carefully remove sufficient insulation from the cable ends, refer to figures 1, 2 & 3.
How to Connect for Mono Parallel How to Connect for Mono Parallel 1. Connect cables from the Balanced Output of a McIntosh Preamplifier or Control Center to the MC275 Right Balanced Input. Note: An optional hookup is to use unbalanced cables. 2. Prepare the Loudspeaker Hookup Cable and Jumper Wires for connection to the Power Amplifier Output Terminals; two 4-1/2 inch (11.43 cm) Jumper Wires, and one Loudspeaker Hookup Cable cut to the desired length.
Left Side Panel Controls and Switches UNBALANCED LEVEL Controls for each channel when using the Unbalanced Inputs Power Switch turns all AC power On or Off MODE switch selects MONO (Parallel) or STEREO Modes of operation INPUTS switch selects between the BALanced or UNBALanced Inputs 12
How to Operate the MC275 How to Operate the MC275 Power On and Off Press the POWER switch to the ON position and sound will be heard from the Loudspeakers when the tubes have reached their operating temperature. The amount of time it takes is dependent upon the temperature of the Tubes. Press the POWER Switch to the Off position to stop amplifying the audio signal. Refer to figure 7.
Specifications Specifications Power Output Stereo Minimum sine wave continuous average power output per channel, both channels operating is: 75 watts into 4, 8 or 16 ohm load Power Output Mono (Parallel) Minimum sine wave continuous average power output is: 150 watts into 2 ohm, 4 ohm or 8 ohm load Output Load Impedance 4, 8, or 16 ohm (Stereo Mode) 2, 4, or 8 ohm (Mono Mode) Rated Power Band 20Hz to 20,000Hz Total Harmonic Distortion Maximum Total Harmonic Distortion at any power level from 250 milliwatts
Packing Instructions Packing Instructions In the event it is necessary to repack the equipment for shipment, the equipment must be packed exactly as described and shown below. The MC275 Vacuum Tubes must be removed from the Amplifier Tube Sockets and placed into the inside openings of the four layer foam packing material. The foam with the tubes located inside are placed into the Amplifier Tube Cover and secured to the Chassis.
McIntosh Laboratory, Inc. 2 Chambers Street Binghamton, NY 13903 The continuous improvement of its products is the policy of McIntosh Laboratory Incorporated who reserve the right to improve design without notice. Printed in the U.S.A. McIntosh Part No.
