McIntosh C32 Owners Manual
This is the 22 pages manual for McIntosh C32 Owners Manual.
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Extracted text from McIntosh C32 Owners Manual (Ocr-read)
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WARNING: TO PREVENT FIRE OR SHOCK HAZARD, DO NOT EXPOSE THIS UNIT TO RAIN OR MOISTURE. The Mclntosh you have purchased has a serial number located on the rear panel of the chassis. Record that serial number here for future references. The model and serial number are important to you for any future service.
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Your C 32 Stereo Preamplifier will give you many years of pleasant and satisfactory performance. If you have any questions, please contact: CUSTOMER SERVICE Mclntosh Laboratory Inc. 2 Chambers Street Binghamton, New York 13903 Phone: 607-723-3512 Take Advantage of 3 years of FREE Service... Fill in the Application NOW. Contents INTRODUCTION 2 HOW TO INSTALL 2 HOW TO CONNECT 4 USING THE FRONT PANEL CONTROLS 8 USING THE PUSHBUTTONS 11 BALANCING YOUR STEREO 12 LISTENING TO YOUR STEREO 12 PERFORMANCE LIMITS AND RATINGS 13 PERFORMANCE CHARTS 14, 15 TECHNICAL DESCRIPTION 16 BLOCK DIAGRAM 19 THREE YEAR SERVICE CONTRACT An application for a FREE THREE YEAR SERVICE CONTRACT is included with this manual. The terms of the contract are: 1. Mclntosh will provide all parts, materials and labor needed to return the measured perfor- mance of the instrument to the original per- formance limits free of any charge. The SERVICE CONTRACT does not cover any shipping costs to and from the authorized service agency or the factory. 2. Any Mclntosh authorized service agency will repair Mclntosh instruments at normal service rates. To receive the free service under the terms of the SERVICE CONTRACT, the SERVICE CONTRACT CERTIFICATE must accompany the instrument when taken to the service agency. 3- Always have service done by a Mclntosh authorized service agency. If the instrument is modified or damaged, as a result of un- authorized repair the SERVICE CONTRACT will be cancelled. Damage by improper use or mishandling is not covered by the SERVICE CONTRACT. 4. The SERVICE CONTRACT is issued to you as the original purchaser. To protect you from misrepresentation this contract cannot be transferred to a second owner. 5. For your protection Mclntosh selects only dealers who have technical competence to guide purchasers fairly, and provide service when necessary. To receive the SERVICE CONTRACT your purchase must be made from a Mclntosh franchised dealer. 6. Your completely filled in application for a SERVICE CONTRACT must be postmarked within 30 days of the date of purchase of the instrument. 7. To receive the SERVICE CONTRACT all in- formation on the application must be filled in. The SERVICE CONTRACT will be issued when the completely filled in application is received at Mclntosh Laboratory Incorporated in Binghamton, New York. Copyright © 1977 by Mclntosh Laboratory Inc. 1
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gain and differences in input level. The C 32 uses active circuitry, electrically independent of the volume control. Close conformity to Fletcher Munson Equal Loudness Curves is attained regardless of volume control position. Active Filter Circuitry Loudness, equalizer, and band pass filters of the C 32 are all constructed with ion implanted junction field effect operational amplifiers (popularly called "Op Amps"). These new devices amplify with a 6 dB better signal to noise ratio than bipolar input op amps. Program Equalizers To adjust for program limitations and personal prefer- ences the C 32 LISTEN program line has a five band boost/ cut program EQUALIZER based on resonant circuit opera- tional amplifier. The preamplifier is flat when the EQUAL- IZER controls are at the 12 o'clock position. EQUALIZER center frequencies of 30, 150, 500, 1500 and 10,000 Hz were chosen to cover the audio spectrum in approximately equal two octave bandwidths. Maximum boost and cut is 12 dB at band centers. HF and LF Filters The HF and LF filters are selected by pushbutton switches in a manner electrically similar to the program EQUALIZERS and are pushbutton switch selected. The HF filter attenu- ates all frequencies above 5 kHz, reaching a rate of 12 dB per octave, at 7 kHz (at which point attenuation is 3 dB below the 5 kHz level). The LF filter attenuates all fre- quencies below 50 Hz, at a rate of 12 dB per octave. All program EQUALIZERS and HF/LF filters are bypassed when the EQ OUT pushbutton switch is depressed. The EQ OUT switch also removes subsonic and supersonic fil- ters below 20 Hz and above 20,000 Hz, extending total frequency response to 10 Hz to 100,000 Hz. The Expander To overcome the compression imposed in radio broad- casting and recording, and to reduce hum, scratch and hiss, the C 32 has a logarithmic program expander in the LISTEN program line. Controls are provided to adjust the operating point, attack time and expansion ratio. Signal from the equalizer circuit is applied to a voltage controlled amplifier (VCA) which operates as a variable gain block. Control voltages for this VCA are developed from a sample taken from the output of the equalizer. The electronic processing of this sample is detailed. It includes band shaping, logarithmic amplification, full wave rectifi- cation, level setting, expansion ratio regulation, attack timing, level setting and DC amplification. The resulting voltage controls the gain of the VCA to cause logarithmic gain reduction below set level and logarithmic expansion above set level. A switched bypass link provides a program path around the expander, to maintain a constant signal level with the expander in or out of the circuit. The gain of the amplifier block incorporated in the link approximates the gain of the expander circuit. The Record Program Line The C 32 is designed to permit simultaneous recording on up to three tape recorders of any program input selected on the RECORD switch regardless of what is being heard on the LISTEN program line. The RECORD switch selects its input from the same inputs, but entirely independently from the LISTEN switch. As this selection is by means of high impedance FET Analog switches, switching to or over an input in use on the LISTEN program line does not cause any audio interference. Output from the RECORD switch is fed through tape interlock switches to the three pairs of tape recorder output jacks. In the event that one of the tape recorders is chosen as an input signal to the RECORD program line, its asso- ciated tape interlock is opened to prevent feedback through that tape recorder back into the C 32 input. Monitor Amplifier/Headphone Circuits The C 32 contains a stereo power amplifier which pro- vides adequate power to drive electrostatic headphones. The upper HEADPHONE output jack is connected directly to this MONITOR AMPLIFIER output, making the full 12 watts per channel power available to drive those head- phones which require it. The lower HEADPHONE jack is fed through a network designed to match low impedance dynamic headphones. In addition, the MONITOR AMPLIFIER may be switched to either program line, controlled and connected with enough flexibility that several other uses for it are possible. Some of these are: 1. As a preamplifier/power amplifier in a completely separate stereo system. 2. To power rear channel speakers when used in a 4- channel discreet system. 3. To operate speakers in another area. 4. To feed a 600 ohm line. On the rear panel are two green AC power outlets and a slide switch marked AUTO/MANUAL. Plug the AC power cables from the turntable into the green TURNTABLE POWER outlets on the rear panel. When the switch is in the AUTO position, power to the black AC power outlets, can be controlled by the front panel POWER switch or by the current drawn by a turntable plugged into the green TURNTABLE POWER outlets. The current sensing green AC power outlets will control the AC power to the entire system from the AC power on/off switch on the turntable. When the turntable is turned off with its own 17