McIntosh MC-50 User's Manual
Contents
1. WeIntosh so MC 50 CONTENTS GENERAL DESCRIPTION 2 TECHNICAL DESCRIPTION 2 3 BLOCK DIAGRAM SPECIFICATIONS 5 CONTROL PANEL INFORMATION 7 INSTALLATION iest T TYPICAL HOOKUP 8 CONNECTING 00022222 9 Me Store 17 the PERFORMANCE CHARTS 10 OPERATING Standard of Excellence because GUARANTEE The Mcintosh will to perfection requires that we probe constantly into the unknown to bring the performance of our electronic equipment closer to perfection than ever before This requires a constant and relentless search for low noise broad band conservative design with an ever lower distortion factor This is not required of ordinary equipment of average designs It is for us a costly but worthwhile scientific and engineering effort Our continuing research benefits our cus tomers with the almost complete lack of obsolescence and the most reliable equipment ever made It also means the lowest long range cost to you Nearly all of the Mcintosh equipment ever made is still useable or in use though it may have been made twenty years ago 14 4 0 gt lt 14 3 1 5 0 Thank Gu for purchasing the McIntosh MC 50 To insure your enjoyment please read this manual carefully and follow instructions We know you will enjoy countless hours of musical pleasure from this instrument SOLID STATE GENERAL DESCRIPTION T2. 50 RMS watts continuous into 4 8 or 16 ohms HARMONIC DISTORTION Less than 0 25 at 50 watts power output from 20 Hz to 20 kHz Typical performance is less than 0 1 at rated power Distortion de creases as output power is reduced INTERMODULATION DISTORTION Less than 0 25 if instantaneous peak power output is 100 watts or less for any combina tion of frequencies 20 Hz and 20 kHz FREQUENCY RESPONSE 20 Hz to 20 kHz 0 0 1 dB at 50 watts 10 Hz to 50 kHz 0 0 5 dB at 50 watts 7 Hz to 100 kHz 0 3 0 dB at 25 watts NOISE AND HUM 90 dB or more below rated output OUTPUT IMPEDANCE 4 8 and 16 ohms OUTPUT VOLTAGES 25 volts DAMPING FACTOR 25 at 4 ohms output 50 at 8 ohms output 17 at 16 ohms output INPUT IMPEDANCE 200 000 ohms INPUT SENSITIVITY 0 5 volts Level control provided for higher input voltage POWER REQUIREMENTS 117 volts AC 50 60 Hz 15 watts at zero sig nal output 120 watts at 50 watts output SEMICONDUCTOR COMPLEMENT 12 Silicon Transistors 12 Silicon Rectifiers and Diodes MECHANICAL SPECIFICATIONS SIZE 5 inches high 8 inches wide 12 inches deep CHASSIS Chrome and black WEIGHT 20 pounds net 24 pounds in shipping carton SPECIAL FEATURES The amplifier is completely stable when con nected to any loudspeaker system or to any re active load The MC 50 has special circuits to prevent damage by short circuit or open circuit of the output loads or
3. EE FACTORY 12 SERVICE BY FILLING IN THE APPLICATION NOW Welntosh McINTOSH LABORATORY INC 2 CHAMBERS ST BINGHAMTON N Y 13903 607 723 3512 Design subject to change without notice Printed in U S A
4. ITORING CIRCUIT restricts the drive to the output transistors The SENTRY MONITORING CIRCUIT acts instantane Ously for any input signal or load combination This arrangement assures complete circuit reliability Only McIntosh gives you this degree of protection POWER SUPPLY SECTION There are three separate power supply sections One positive and one negative high current supply is used for the output stages The other positive supply is used for the driving amplifier stages All supplies are full wave and use silicon rectifiers Adequate filter ing is used to assure an absolute minimum of hum The power out put stage filter capacitors have very high capacity which allows full power output below 20 Hz The power transformer is generous in size and runs cool even under heavy use o oe e o PERFORMANCE CHARTS PERCENT HARMONIC DISTORTION HARMONIC DISTORTION vs POWER 10 POWER OUTPUT IN WATTS RMS 221144 H uu al s FREQU u To 11101141 33 Y FEE 1 1 1 11 11 a er 25 HARMONIC DIST ORTIQN 0 1 HARMONIC DISTORTIO EQUIVALENT POWER OUTPUT vs HM 1 10 20 40 50 60 70 80 90 100 POWER OUTPUT EQUIVALENT WATTS RMS POWER OUTPUT WATTS RMS gt PERCENT INTERMODULATION DISTORTION SPECIFICATIONS 50 ELECTRICAL SPECIFICATIONS POWER OUTPUT
5. MC 50 The device operates automatically at a preset temperature The MC 50 will turn on again when the temperature has returned to normal limits This additional feature gives your MC 50 complete reliabil ity under the most extreme operating conditions The output stages are matched to the load by the Mcintosh auto former The Mcintosh autoformer is carefully wound using tosh trifilar winding and interleaving techniques Trifilar winding and interleaving gives the transformers exceptional bandwidth The autoformers properly matched the power transistors to 4 8 and 16 ohm loads at all audio frequencies The use of the McIntosh designed trifilar autoformer makes the Mcintosh solid state amplifiers the only amplifiers that deliver FULL POWER AT ALL SPEAKER IMPEDANCES You have not been power penalized for your choice of loudspeakers when using the Mcintosh MC 50 Another of the advantages of the autoformer is the 25 volt output for a constant voltage distribution system With the MC 50 sev eral sets of speakers can be operated independently throughout your home To further insure reliability a Special power output SENTRY MONI TORING CIRCUIT prevents failure of the power output transistors due to excessive mismatch of the output When your MC 50 operates normally the SENTRY MONITORING CIRCUIT has no effect on signals passing through the power amplifier If the power dissipation should rise above normal operation the SEN TRY MON
6. R AMPLIFIER aurora curro SPAMS wore 4 q rem Me 110001 Y DU C O Gy O r SOLID prate in TAPE AC LINE e 2 INPUT OUTPUT CONNECTING THE MC50 OUTPUT 1 5 SLO BLO The shielded cable from the program source is plugged into the INPUT jack Speakers are connected at the output barrier strip on the sloped panel of the amplifier Use lamp cord bell wire or wire with similar type of insula tion to connect the speakers to the amplifier For the normally short distances of under 50 feet be tween the amplifier and speaker 418 wire or larger can be used For distances over 50 feet between the amplifier and speaker use larger wire The loudspeaker impedance is usually identified on the loudspeaker itself Connect one lead from the loudspeaker to the screw marked COM on the OUTPUT barrier strip Connect the other lead from the loudspeaker to the screw marked with the number corresponding to the speaker impedance on the OUTPUT barrier strip The only adverse effect on the operation of a Mc Intosh amplifier when it is improperly matched is a reduction in the amount of distortion free power available to the loudspeaker Close impedance matching is desirable for maximum distortion free power Use this table to determine proper speaker connection the speaker impedance is betwe
7. by any amount of output impedance mismatch Thermal cutouts are mounted on the output transistor heat sinks to provide protection in the event of inadequate ventilation Ee em ia ope eater ar renee emma AN OUTPUT 8 1 5 SLO BLO 117 Y 50 60 Hz 15 110 WATTS The input jack is located below the GAIN control The input sensitivity of the MC 50 is 0 5 volt for 50 watts output The in put impedance is 200 000 ohms There is a GAIN control in the input circuit to permit the use of input voltages up to 30 volts Output connections are provided on the output barrier strip for the normal speaker impedances of 4 ohms 8 ohms and 16 ohms Connection at the terminal strips may be made for a constant voltage output of 25 volts The MC 50 uses a 1 5 ampere slo blo type fuse The auxiliary AC outlet is not fused The auxiliary AC outlet can be used to supply power to other equipment in the system The outlet will provide a maximum of 400 watts of power The AC outlet is not fused The MC 50 operates on any line voltages between 117 volts and 130 volts 50 to 60 Hz The MC 50 operates on 117 to 130 volt 50 60 Hz The amplifier will be turned on and off if its power cord is plugged in one of the auxiliary AC outlets on the program source INSTALLATION Adequate ventilation extends the trouble free life of electronic instruments It is generally found that each 10 centigrade 18 F rise in temperature reduces the lif
8. e of electrical insulation by one half Adequate ventilation is an inexpensive and effective means of preventing insulation breakdown that results from un necessarily high operating temperatures The direct benefit of adequate ventilation is longer trouble free life The suggested minimum space for mounting the MC 50 is 20 inches long x 9 inches wide x 11 inches high Always allow for air flow by either ventilation holes or space next to the bottom of the amplifier and a means for the warm air to escape at the top It is recommended that the 50 be mounted in a normal horizontal position However with adequate ventilation the ampli fier can be mounted in any position except upside down If the amplifier is to be installed on a vertical surface it is recommended that the autoformers be on the down side This position permits greater air flow around the transistors and component parts thereby extending the trouble free life of the amplifier e gt x MINIMUM lt gt er lt gt 9 inches 11 inches e 20 inches TYPICAL HOOK UP REMOTE MONOPHONIC LEFT MAIN CENTER CHANNEL RIGHT MAIN LEFT REMOTE RIGHT REMOTE SPEAKER SPEAKER SPEAKER SPEAKER SPEAKER SPEAKER p 2 4 5414 1 4 0060982031 BBI 1 neces Leonora arrr 2 44 ae a N e a al res PREAMPLIFIER MC 50 MC 50 MC 50 CENTER CHANNEL LEFT CHANNEL RIGHT CHANNEL AMPLIFIER AMPLIFIE
9. en 3 2 to 6 5 ohms 6 5 to 13 ohms 13 to 26 ohms Connect the speaker leads between COM and 4 ohms 8 ohms 16 ohms BLOCK DIAGRAM MC 50 CLASS B OUTPUT STAGE POWER GAIN PRE AMP INPUT AMP AMP INPUT O POWER CONTROLLER CLASS OUTPUT STAGE FEEDBACK NETWORK FEEDBACK NETWORK POWER TRANSFORMER POWER SUPPLY AND FILTER LINE 10 OUTPUT AUTOFORMER 16 SPEAKER OUTPUT OPERATING THE 50 STEREO AMPLIFIER SETTING THE GAIN CONTROL Turn the volume control on the source equipment to the 12 o clock position half rotation Turn up the GAIN con trol on the MC 50 until the loudness in the room is about as loud as you like to listen This setting allows the volume control on the source equipment the greatest range of operation and loud ness change 11 Your 50 power amplifier will give you many years of pleasant and satis factory performance If you have any questions concerning operation or maintenance please contact the dealer from whom you purchased this instrument or CUSTOMER SERVICE HR RR aie ntosh Labo rato ry n E 5 a e 2 Chambers Street i ENS 7 YZ O n g h amto n 1 3903 GR RES RES ee a 7 me Our telephone numbe
10. he dramatic difference in the quality of music reproduced through a Mcintosh instrument is due to low distortion The distortion of your MC 50 is guaranteed to be less than 0 25 at any frequency from 20 Hz to 20 kHz at 50 watts or less Distortion is measured at full rated power output At less than rated power distortion becomes so small it can be measured only by the most sophisticated labora tory instruments Only Mcintosh gives you this kind of performance Your MC 50 passed more than 75 tests before it was ready for you Each connection wire resistor capacitor is checked and re checked All specifications are checked Mcintosh testing takes time The extra investment in thorough testing assures you of greater musical enjoyment The performance of your Mcintosh MC 50 is backed by a money back guarantee Only Mcintosh gives you a money back guarantee of performance Your MC 50 must be capable of meeting its pub lished specifications or you get a refund of your purchase price Mcintosh promises performance We either meet our promise or you get your money back Your MC 50 can be protected by a free three year factory service contract Take advantage of this service Fill in the application card found in the owner s packet The free three year factory service contract covers parts and labor If anything goes wrong just bring your MC 50 to a factory service station or return your MC 50 to Mcintosh All parts and labor necessary to repai
11. r is 50 GUARANTEE McIntosh Laboratory Incorporated guarantees this equipment to be GR capable of performance as advertised We also guarantee the me chanical and electrical workmanship and components of this equip ment to be free of defects for a period of 90 days from date of purchase This guarantee does not extend to components damaged by improper use nor does it extend to transportation to and from the factory 3 YEAR FACTORY SERVICE CONTRACT An application for a FREE 3 YEAR FACTORY SERVICE CONTRACT is included in the pack with this manual The FREE 3 YEAR FAC TORY SERVICE CONTRACT will be issued by McIntosh Laboratory upon receipt of the completely filled out application form The terms of the contract are Transportation charges are excluded This agreement is given to the original purchaser only and is not transferable The application for the contract must be filled out completely If the instrument has been modified or damaged by unauthor ized repair the contract will be cancelled To receive free service the contract must be presented to the factory authorized service agency when the equipment is pre sented for repair If the application is not received at Mcintosh Laboratory only the A lt service offered under the standard 90 day guarantee will apply on AN as this equipment Fe t TAT SoG NG NG NA NAN GA NA Sag SG ee MIC 5C O 5 H A 7 TAKE ADVANTAGE OF 3 YEARS OF FR
12. r your MC 50 will be supplied free of charge Fill in the service contract application found in the owner s packet now 9 A two stage preamplifier with three transistors increases the input voltage 16 dB The two stage preamplifier is fed to a pair of matched transistors arranged as an emmiter coupled amplifier with two inputs and one output The signal from the preamplifier section connects to one of these inputs Both AC and DC negative feedback are applied to the other input This large quantity of feedback is used to reduce noise and distortion The signal is then fed to a voltage amplifier The voltage amplifier is followed by two driver transistors The output section is arranged as a series push pull amplifier The power transistors used in the output section of your MC 50 are selected for their high power dissipation capability wide frequency response and large safe operating area In addition each power transistor is given four separate tests before it is put in your MC 50 This additional testing makes sure your MC 50 will deliver its rated power from 20 to 20 kHz with low distortion and complete reliability The power transistors are mounted on an oversized anodized heat sink The extra large heat sink assures that under normal opera tion the transistors will operate at a low temperature If tempera tures increase due to a shorted speaker or restricted ventilation an automatic temperature sensing device turns off the
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