User manual MCINTOSH MA6900

[. . . ] Integrated Amplifier MA6900 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. [. . . ] If the amplifier is not going to be used for an extended time, turn off all AC Power with the Power Switch. You may also turn On the MA6900 by simply pressing the desired Source Selection Push-button on the Front Panel or Remote Control. For an explanation of the Remote Control Pushbutton functions, refer to pages 16 and 17. PH/AUX Inputs When using a phono player with a moving magnet cartridge connected to the PH/AUX inputs, set the PH AUX switch to the PH position. When using an auxiliary program source component connected to the PH/AUX inputs, set the PH AUX switch to the AUX position. Refer to figure 4. Figure 4 Balance Control Adjust the BALANCE control as needed to achieve approximately equal listening volume levels in each loudspeaker. Turn the BALANCE to the left to emphasize the Left Channel by reducing the level of the Right Channel. Turn the BALANCE to the right to emphasize the Right Channel by reducing the level of the Left Channel. Equalizer Controls Each of the five Equalizer Frequency Controls will raise or lower by approximately12dB, the amplitude of the band of frequencies centered at the frequency marked above the controls. Both Left and Right Channels are affected. At the center detent or flat position of the controls, all equalizer circuit components are removed from the signal path. Source Selection Select the desired source with the appropriate pushbutton switch on the Front Panel or Remote Control. Refer to figures 2 and 3 and page 16 for additional information. Volume Control Adjust the VOLUME control for the desired listening level. Figure 2 Figure 5 Loud Switch Press the LOUD push-button to add loudness bass compensation to the volume control for improved low level listening. Mono Press the MONO push-button to combine left and right stereo signals to mono at the SPEAKERS 1 and 2 and HEADPHONES output. Mute Press the MUTE push-button to mute audio in all outputs except the HEADPHONES and TAPE OUTPUT. The MUTE LED above the push-button will flash on and off to indicate that Mute is active. To unmute audio, press MUTE, press the Remote Control Volume push-button(s) or press an Input push-button. 13 Figure 3 How to Operate, con't Outputs 1 and 2 Press OUTPUTS Push-button 1 to switch the Speakers On or Off. The push-buttons also switch the Preamplifier OUTPUTS 1 Figure 6 and 2 On or Off for connection to external Power Amplifier(s). Press either push-button individually, or both together. Headphones Jack Connect a pair of dynamic headphones to the Headphones Jack for private listening. Press Mute to mute all other outputs including the amplifier connected to the loudspeakers. Reset of Microprocessors In the event that the controls of the MA6900 stop functioning, push the POWER switch OFF and wait about two minutes. Then push the POWER switch ON followed by pushing the STANDBY/ON push-button. This will reset the MA6900 microprocessors and the Integrated Amplifier should be functioning normally. Note: The above condition is usually caused by either interruptions in AC power and/or major changes that may occur in AC power line voltage. How To Make A Tape Recording 1. [. . . ] A power amplifier connected to a load that is lower than optimum, causes more output current to flow, which results in extra heat being generated in the power output stage. This increase in temperature will result in a reduced life expectancy Figure 12 for the amplifier. 20 With Power Guard PG light and a dynamic electronic attenuator at the amplifier input reduces the input volume just enough to prevent any further increase in distortion. The Power Guard circuit acts so fast that there are absolutely no audible side effects and the sonic purity of the music reproduction is perfectly preserved. The MA6900 Amplifier with Power Figure 16 Guard is not limited to just the rated power output, but will actually produce distortion free output well above its rated power due to the McIntosh philosophy of conservative design. Power Supply Circuits To compliment the design of the MA6900, there is a high voltage power supply for both channels. [. . . ]