User manual MCINTOSH MC275 MK4

[. . . ] Stereo Power Amplifier MC275 Owner's Manual McIntosh Laboratory, Inc. 2 Chambers Street Binghamton, New York 13903-2699 Phone: 607-723-3512 FAX: 607-724-0549 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. The exclamation point within an equilateral triangle is intended to alert the user to the presence of important operating and maintenance (servicing) instructions in the literature accompanying the appliance. WARNING - TO REDUCE RISK OF FIRE OR ELECTRICAL SHOCK, DO NOT EXPOSE THIS EQUIPMENT TO RAIN OR MOISTURE. NO USER-SERVICEABLE PARTS INSIDE. REFER SERVICING TO QUALIFIED PERSONNEL. To prevent the risk of electric shock, do not remove cover or back. No user serviceable parts inside. IMPORTANT SAFETY INSTRUCTIONS! PLEASE READ THEM BEFORE OPERATING THIS EQUIPMENT. 1. [. . . ] The smaller the Gauge number, the larger the wire size. Connection Terminals will accept up to a 8 AWG wire size: If your loudspeaker cables are 50 feet (38. 1m) or less, use at least 14 Gauge. If your loudspeaker cables are 100 feet (76. 2m) or less, use at least 12 Gauge. Introduction Now you can take advantage of traditional McIntosh standards of excellence in the MC275 Stereo Power Amplifier. Two 75 watt output channels will drive any high quality Loudspeaker System to its ultimate performance. The MC275 reproduction is sonically transparent and absolutely accurate. The McIntosh Sound is "The Sound of the Music Itself. " Performance Features · Power Output The MC275 consists of two separate power amplifier channels, each capable of 75 watts into 4, 8 or 16 ohm Loudspeakers in stereo. It may also be operated in mono at 150 watts into 2, 4, or 8 ohm Loudspeakers. Bifilar Wound Transformers and Output Circuit The Power Output Sections utilize the famous McIntosh Patented Unity Coupled Circuit with a Bifilar Wound Output Transformer for low distortion, extended frequency response and cool operating output tubes. Balanced and Unbalanced Inputs Balanced connections guard against induced noise and allow long cable runs without compromising sound quality. Gold Plated Connectors and Tube Socket Contacts Gold Plated Input Jacks and Output Binding Posts provide trouble free connections. Ceramic tube sockets with gold plated contacts provide protection from atmospheric contamination. Output Tube Sockets include Air-Pipe cooling at their bases. Super Mirror Chassis Finish The famous McIntosh Stainless Steel Chassis with Super Mirror Finish ensures the pristine beauty of the MC275 will be retained for many years. · Connector Information XLR Connectors Below is the Pin configuration for the XLR Balanced Input Connectors on the MC275. Refer to the diagram for connection: Pin 2 PIN 1: Shield/Ground PIN 2: + Input Pin 1 PIN 3: - Input Pin 3 · · · 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" 4. 45cm 13-5/8" 34. 61cm Top View of the MC275 12" 30. 48cm Left Side View of the MC275 5-9/16" 14. 13cm Right Side View of the MC275 1-3/4" 4. 45cm 4-3/8" 11. 11cm 1-1/4" 3. 18cm 5 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. To protect the Vacuum Tubes from possible shipping damage, they are packed in four layers of foam and placed into the Tube Cover. It is secured to the MC275 Chassis. Note: Gloves or a soft cloth will prevent "fingerprinting" of the Tubes during their installation. Tinnerman Clip Fasteners Tube Cover Figure 1 Figure 1 1. Orient the MC275 so the Front Panel is facing you. Remove the Tube Cover from the MC275 Chassis by lifting up on both sides. Orient the Tube Cover to the wide opening along one side of its longer dimension. Remove the first layer of foam to expose the Tubes. [. . . ] If the cable is stranded, carefully twist the strands together as tightly as possible. Note: If desired, the twisted ends can be tinned with solder to keep the strands together. of 2S (ohm), 4S (ohm) and 8S (ohm) are provided. If the Loudspeaker's impedance is in-between the available connections, use the nearest lower impedance connection. Place the MC275 POWER Switch to the OFF Position and connect the supplied power cord to an active AC outlet. Mono (Parallel) Hookup Connections Loudspeaker Loudspeaker Negative Impedance (-) Connection 2S (Ohm) 4S (Ohm) 8S (Ohm) Left and Right Output 4S Negative (- ) Connection Left and Right Output 8S Negative (- ) Connection Loudspeaker Positive (+) Connection Left and Right Output 4S Positive (+ ) Connection Left and Right Output 8S Positive (+ ) Connection Left and Right Output 16S Left and Right Output 16S Positive (+) Connection Negative (- ) Connection Spade lug or prepared wire connection: Insert the spade lug connector or prepared section of the cable end under the terminal strip screw and tighten the screw until the cable is firmly clamped into the terminal strip so the wires cannot slip out. Connect the hookup cables to the output terminals that match the connections in the chart below, being careful to observe the correct polarities. [. . . ]