User manual MCINTOSH MC302

[. . . ] McIntosh Laboratory, Inc. 2 Chambers Street Binghamton, New York 13903-2699 Phone: 607-723-3512 www. mcintoshlabs. com MC302 Power Amplifier Owner's Manual 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. If the provided plug does not fit into your outlet, consult an electrician for replacement of the obsolete outlet. Protect the power cord from being walked on or pinched particularly at plugs, convenience receptacles, and the point where they exit from the apparatus. Use only with the cart, stand, tripod, bracket, or table specified by the manufacturer, or sold with the apparatus. [. . . ] Failure to observe this could result in Electric Shock. How to Connect for Bi-Amp The connection instructions below, together with the MC302 Connection Diagram located on the separate folded sheet "Mc1B", is an example of a typical audio system. Your system may vary from this, however the actual components would be connected in a similar manner. For additional information refer to "Connector and Cable Information" on page 4. For Remote Power Control, connect a power control cable from the Audio Preamplifier or A/V Control Center Power Control Output 1 to the MC302 POWER CONTROL IN Amplifier One. Connect a power control cable from the Audio Preamplifier or A/V Control Center Power Control Output 2 to the MC302 POWER CONTROL IN Amplifier Two. Connect XLR cables from the Balanced Output 1 (L&R) of a Audio Preamplifier or A/V Control Center to the MC302 Balanced INput (RIGHT and LEFT) on Amplifier One. Place the INPUT MODE Switch in the BALANCED Position. Note: An optional hookup is to use unbalanced cables and place the INPUT MODE Switch in the UNBALANCED Position. This McIntosh MC302 Power Amplifier is designed for Loudspeakers with an impedance of 2 ohms, 4 ohms or 8 ohms. Connect a single Loudspeaker only to the Right and Left Output Terminals. When connecting Loudspeakers to the MC302 it is very important to use cables of adequate size, so there is little to no power loss in the cables. The smaller the Gauge number, the larger the wire size: Loudspeaker Cable Distance vs Wire Gauge Guide Loudspeaker Impedance 2 Ohms 4 Ohms 8 Ohms 25 feet (7. 62 meters) or less 50 feet (15. 24 meters) or less 100 feet (30. 48 meters) or less 12AWG 14AWG 16AWG 10AWG 12AWG 14AWG 8AWG 10AWG 12AWG Banana Plugs are for use in the United States and Canada only: 6. Attach the previously prepared bare wire cable ends into the banana plugs and secure the connections. Refering to Figure B, connect the Figure A Loudspeaker hookup cables with banana plugs into the hole at the top of the terminal to the MC302 COM (Negative) Output Terminal A and Figure B Figure Positive Output Terminal indentified as 2 (ohms), 4 (ohms) or 8 (ohms) connection to match the impedance of the Loudspeaker, being careful to observe the correct polarities. If the Loudspeaker's impedance is in-between the available connections, use the nearest lower impedance connection. Refer to "General Information" Note 4 on page 3 for additional information. Note: The illustration on separate sheet "Mc1B"is connections for 8 (ohms) Loudspeakers. 5. Prepare the Loudspeaker Hookup Cables for attachment to the MC302 Power Amplifiers: Bare wire cable ends: Carefully remove sufficient insulation from the cable ends, refer to figures 2, 3 & 4. If the cable is stranded, carefully twist the strands together as tightly as possible. 4. Connect XLR cables from the Balanced Output 2 (L&R) of a Audio Preamplifier or A/V Control Center to the MC302 Balanced INput (RIGHT and LEFT) on Amplifier Two. Place the INPUT MODE Switch in the BALANCED Position. Note: An optional hookup is to use unbalanced cables and place the INPUT MODE Switch in the UNBALANCED Position. Figure 2 Figure 3 Figure 4 Notes: 1. If desired, the twisted ends can be tinned with solder to keep the strands together. The prepared bare wire cable ends may be inserted into spade lug connectors for use in outside the United States and Canada only. Connect the MC302 power cord to an active AC outlet. WARNING: Loudspeaker terminals are hazardous live and present a risk of electric shock. For additional instruction on making Loudspeaker Connections contact your McIntosh Dealer or McIntosh Technical Support. 10 How to Connect for Bi-Amp Spade Lug or Wire Connections: 9. [. . . ] Figure 19 The Power Guard circuit is a waveform Without Power Guard comparator, monitoring both the input and output waveforms. Under normal operating conditions, there are no differences between the shape of these waveforms. If an amplifier channel is overdriven, there will be a difference between the two signal waveforms. When the difference Figure 20 exceeds 0. 3%, the Power Guard activates the PG light and a dynamic electronic attenuator at the amplifier input reduces the input volume just enough to prevent any further increase in distortion. [. . . ]