User manual MCINTOSH MC225

[. . . ] STEREO POWER AMPLIFIER TABLE OF CONTENTS GENERAL DESCRIPTION TECHNICAL DESCRIPTION Electrical Specifications Mechanical Specifications PANEL FACILITIES Input Output Line Output Fuse AC Outlet Line Voltage INSTALLATION CONNECTIONS Input--Stereo Input--Twin Amp Input--Mono 1 1 2 3 4 4 4 4 4 4 4 5 5 5 5 6 MC225 6 6 6 7 7 7 7 7 7 8 cover pocket cover pocket cover pocket cover pocket Output--Stereo or Twin Amp Output --Mono Line Output--Stereo or Twin Amp Line Output--Mono AC Power OPERATING THE MC225 ADJUSTMENTS Input Switch-Stereo Input Switch-Mono GUARANTEE FREE 3-YEAR FACTORY SERVICE CONTRACT APPLICATION SCHEMATIC DIAGRAM PARTS LIST RESISTANCE AND VOLTAGE CHART MC225 POWER AMPLIFIER GENERAL Over one million watts of amplifier output power capacity have been manufactured by Mclntosh since 1947. In this 1, 000, 000 watts of audio power there are less than 10 watts of distortion capacity and less than 1/100 watt of noise capacity!The dramatic difference in the quality of music reproduction when you listen through Mclntosh instruments is directly due to low distortion performance. The world's finest amplifier is the creation of persevering, resourceful Mclntosh engineers. [. . . ] The MONO input GAIN control permits connecting signal sources up to 30 volts without overloading the amplifier's input: The input impedance is 250, 000 ohms. OUTPUT The two barrier terminal strips marked OUTPUT provide stereo connections for the normal speaker impedances of 4 ohms, 8 ohms, and 16 ohms. For monophonic operation connections for 2 ohms, 4 ohms, 8 ohms, 4 and 16 ohms are provided. The terminal strips may also be connected for a constant voltage output of 25 volts in either stereo or mono. The barrier strip output connections are fed from the secondary of the output transformer. LINE OUTPUT (See also pages 5, 6, and 7) The octal socket marked LINE OUTPUT has connections for 25 volts, 70. 7 volts, and 600 ohms for stereo operation and 300 ohms for monophonic operation. Pin 1 of the octal socket is the center tap for these windings and is grounded. The connections at the octal socket are fed from taps on the cathode winding in the primary of the output transformer. FUSE The MC225 uses a 2. 0 ampere slo-blo type fuse. The auxiliary AC socket is not fused. AC OUTLET The auxiliary AC outlet can be used to supply power to other equipment in the system. The AC outlet is not fused. LINE VOLTAGE The MC225 operates on line voltages between 105 volts to 130 volts, 50 cycles to 60 cycles. INSTALLATION Adequate ventilation should always be provided in the installation of electronic instruments. The trouble free life of these instruments can be extended by adequate ventilation. It is generally found that each 10° centigrade (18°F) rise in temperature reduces the life of electrical insulation by one half. Adequate ventilation is an inexpensive and effective means of preventing insulation breakdown because of unnecessarily high operating temperatures. The direct benefit of adequate ventilation is longer, trouble free life. The suggested minimum space for mounting the MC225 is 16" long x 10" wide x 10" high. Always supply ventilation holes in the bottom of the amplifier mounting space and a means for the warm air to escape at the top. If the amplifier is to be installed on a vertical surface it is recommended that the transformers be on the down side. The advantage of this position is that the flow of heat from the tubes rises vertically and does not tend to heat the transformers. if the MC225 is to be permanently mounted use the two mounting flanges supplied with the amplifier. The flanges are shipped separately and must be attached to the amplifier bottom at each end. Turn the MC225 over with the transformers down and place it on a piece of cloth or cardboard to prevent scratches. Remove the three self tapping screws at one end of the amplifier that hold the bottom cover to the chrome chassis. [. . . ] To balance a stereo system using the STEREO input position use a monophonic signal from the program source. Turn the volume control on the source equipment to the 12 o'clock position (half rotation). Turn up the GAIN control on the LEFT input until the loudness in the room is not quite as loud as you like to listen. Then turn the GAIN control on the RIGHT input until it is equally as loud as the left channel. [. . . ]