User manual MCINTOSH C30

[. . . ] 039493 C 30 STEREO PREAMPLIFIER VARIOUS REGULATORY AGENCIES REQUIRE THAT WE BRING THE FOLLOWING INFORMATION TO YOUR ATTENTION. PLEASE READ IT CAREFULLY. CAUTION: TO PREVENT ELECTRIC SHOCK DO NOT USE THE (POLARIZED) PLUG ON THIS UNIT WITH AN EXTENSION CORD, RECEPTACLE OR OTHER OUTLET UNLESS THE BLADES CAN BE FULLY INSERTED TO PREVENT BLADE EXPOSURE. The serial number, purchase date, and Mclntosh Laboratory Service Contract number are important to you for possible insurance claim or future service. Record this information here. Serial Number Purchase date Service Contract Number Upon application, Mclntosh Laboratory provides a Service Contract to the original purchaser. Your Mclntosh Authorized Service Agency can expedite repairs when you provide the Service Contract with the instrument for repair. 039493 1 C 30 STEREO PREAMPLIFIER WARNING: TO PREVENT FIRE OR SHOCK HAZARD, DO NOT EXPOSE THIS UNIT TO RAIN OR MOISTURE. Your C 30 Stereo Preamplifier will give you many years of pleasant and satisfactory performance. [. . . ] The AUTO/MANUAL switch also at the rear must be in the AUTO position. When you switch on the power to the turntable, a special sensor circuit will detect the current drain of the turntable and will turn on the C 30 the same way the red POWER pushbutton does. The red pushbutton must be in the OFF or out position to do this. Read the section on AUTO-ON SENSITIVITY on page (14) before using this feature. HOW TO CONNECT PROGRAM GROUNDS: A GROUND post is provided to connect the grounds from record changers, tape decks, etc. To prevent hum pick-up, the left and right program cables and the ground wire from that source should be wound or twisted together. Make sure the ground wire does not make any connection to the shields of the left and right program cables as they run between the source and the input of the preamplifier. FUSE: A 1. 0 AMP fuse protects the C 30 turntable current sensing circuits and the green AC turntable outlet. The fuse does not protect equipment connected to the black AC outlets. This fuse must be replaced with the same type and rating. A 1. 0 AMP fast acting or SLO BLO fuse may be used. 9 MAIN SPEAKERS POWER AMPLIFIER CUSTOM ENVIRONMENTAL EQUALIZER (FOR MAIN SPEAKERS) NOISE REDUCTION PROCESSORS MAIN TAPE POWER AMPLIFIERS CONNECTIONS FOR POWER AMPLIFIERS AND LOUDSPEAKERS USING MAIN SPEAKERS AND ENVIRONMENTAL EQUALIZER. ALSO SHOWN FOR REMOTE SPEAKERS USING SEPARATE POWER AMPLIFIERS AND CONNECTIONS FOR EXTERNAL NOISE REDUCTION SIGNAL PROCESSORS. REMOTE AREA 1 (CONTROLLED BY SPEAKER 1 PUSHBUTTON) REMOTE AREA 2 (CONTROLLED BY SPEAKER 2 PUSHBUTTON) 10 TO AC LINE REMOTE SPEAKERS (CONTROLLED BY SPEAKER 2 PUSHBUTTON) POWER AMPLIFIER MAIN SPEAKERS (CONTROLLED BY SPEAKER 1 PUSHBUTTON) CONNECTIONS FOR POWER AMPLIFIERS AND LOUDSPEAKERS USING SPEAKER CONTROL RELAY (SCR) 11 The Front Panel Controls and How to Use Them INPUT SELECTOR: EQUALIZER FREQUENCY CONTROLS: The INPUT selector switch is located at the upper left on the front panel. This switch selects the input desired for normal listening. The input program selected will also appear at the TAPE OUTPUT jacks. MODE SELECTOR: The MODE SELECTOR allows you to identify each stereo channel, create monophonic program material, and direct program material to one channel or the other. This switch controls the main outputs only, and not the tape outputs. The switch controls the program in seven ways. L TO L&R: Connects the left input to both left and right output circuits. R TO L&R: Connects the right input to both left and right output circuits. STEREO REV: Connects the left input to the right output circuit and the right input to the left output circuit. STEREO: Connects the left input to the left output circuit and the right input to the right output circuit. Use this STEREO position for normal listening. MONO (L+R): Adds the left and right inputs together to produce a monophonic program and connects to both output circuits. L + R TO L: Connects the left plus right program to the left output circuit only. L + R TO R: Connects the left plus right program to the right output circuit only. 12 Each of five EQUALIZER FREQUENCY controls raises or lowers the amplitude of a band of frequencies centered on the frequency marked above the control. [. . . ] Each channel of the filter amplifier uses the same type operational amplifier as in the phono stage and high level amplifier. The resistive and capacitive elements form a 12dB per octave active RC filter. High frequencies roll off above 7000Hz, and low frequencies below 50Hz. The non linear distortion of the active filter elements in the C 30 is very low, even at the cutoff frequencies. HEADPHONE AMPLIFIER: At the input to the high level or loudness amplifier the signal passes through the mode switch matrix, then through the volume control, and into the amplifier. [. . . ]