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THE MciNTOSH Me 50 SOLID STATE POWER AMPLIFIER

READING TIME 20 MINUTES Price $1.25

Your Me 50 Solid State PowerAmplifier will give you many yearsof pleasant and satisfactory per-formance. If you have any questionsplease contact:

CUSTOMER SERVICEMcintosh Laboratory Inc.2 Chambers StreetBinghamton, New York 13903Phone: 607-723-3512

WARNING: TO PREVENT FIRE OR SHOCKHAZARD, DO NOT EXPOSE THIS UNIT TO RAINOR MOISTURE.

Take Advantage of 3 years.of FREE Factory Service ...Fill in the Application NOW.

CONTENTSSERVICE CONTRACT 1

INSTALLATION 2

HOW TO CONNECT 2,3

ADJUSTMENTS 2

PERFORMANCE LIMITS AND RATINGS 4

TYPICAL PERFORMANCE CHARTS 5

TECHNICAL DESCRIPTION 6

BLOCK DIAGRAM 7

THREE YEAR FACTORY SERVICE CONTRACT

The terms of the contract are:

An application for a FREETHREE YEAR FACTORYSERVICE CONTRACTis included with this manual.

1. Mcintosh will provide all parts, materials andlabor needed to return the measured perform-ance of the instrument to the original per-formance limits free of any charge. TheSERVICE CONTRACTdoes not cover any ship-ping costs to and from the authorized serviceagency or the factory.

2. Any Mcintosh authorized service agency willrepair all Mcintosh instruments at normalservice rates. To receive the free service underthe terms of the SERVICE CONTRACT, theSERVICE CONTRACT CERTIFICATE must ac-company the instrument when taken to theservice agency.

3. Always have service done by a Mcl ntoshauthorized service agency. If the instrumentis modified or damaged, as a result of un-authorized repair the SERVICE CONTRACTwill be cancelled. Damage by improper use

Copyright © 1972 By Mcintosh Laboratory Inc.

or mishandling is not covered by the SERV-ICE CONTRACT.

4. The SERVICE CONTRACT is issued to you asthe original purchaser. To protect you frommisrepresentation this contract cannot betransferred to a second owner.

5. For your protection Mcintosh selects itsdealers carefully. Only one dealer in tenqualifies for a Mcintosh franchise. To receivethe SERVICE CONTRACTyour purchase mustbe made from a Mcintosh franchised dealer.

6. Your completely filled in application for aSERVICE CONTRACT must be postmarkedwithin 30 days of the date of purchase ofthe instrument.

7. To receive the SERVICE CONTRACT all in-formation on the application must be filledin. The SERVICE CONTRACT will be issuedwhen the completely filled in applicationis received at Mcintosh Laboratory Incor-porated in Binghamton, New York.

1

InstallationAdequate ventilation extends the trouble-

free life of electronic instruments. It is gen-erally found that each 10° centigrade (180 F)rise in temperature reduces the life of elec-trical insulation by one half. Adequate ven-tilation is an inexpensive and effective meansof preventing insulation breakdown that re-sults from unnecessarily high operating tem-peratures. The direct benefit of adequateventilation is longer, trouble-free life.

The suggested minimum space for mount-ing the Me 50 is 14 inches long X 8112incheswide X 91,12inches high. Always allow for airflow by either ventilation holes or space nextto the bottom of the amplifier and a meansfor the warm air to escape at the top.

It is recommended that the Me 50 bemounted in a normal or horizontal position.However with adequate ventilation, the ampli-fier can be mounted in any position exceptupside down. If the amplifier is to be installedon a vertical surface it is recommended thatthe autoformer be on the down side. Thisposition permits greater air flow around thetransistors and component parts extendingthe trouble-free life of the amplifier.

How to ConnectINPUT

The input sensitivity of the MC 50 is 0.5 volt for50 watts output. The input impedance is 200,000ohms. There is a GAIN control in the input circuit topermit the use of input voltages up to 30 volts. Theinput jack marked 0.5 VOLT INPUT is located belowthe GAIN control. Plug the shielded lead from theprogram source in the INPUT jack.

OUTPUT

Speakers are connected at the barrier stripsmarked OUTPUT on the sloped panel of the amplifier.Use lamp cord, bell wire, or wire with similar type ofinsulation to connect the speakers to the amplifier.For the normally short distances of under 50 feet be-tween the amplifier and speaker, #18 wire or largercan be used. For distances over 50 feet between theamplifier and speaker use larger wire.

The loudspeaker impedance is usually identified onthe loudspeaker. Connect one of the leads from theloudspeaker to the screw marked COM on the OUT-

PUT barrier strip. Connect the other lead from theloudspeaker to the screw marked with the numbercorresponding to the speaker impedance on theOUTPUT barrier strip.

The only adverse effect on the operation of a Mc-Intosh amplifier when it is improperly matched is areduction in the amount of distortion-free poweravailable to the loudspeaker. Close impedancematching is desirable for maximum distortion-freepower.

SPEAKER CONNECTIONS

Use this table to determine proper speaker con-nection:

If the speaker impedanceis between:

Connect thespeaker leadsbetween COM and:

3.2 to 6.5 ohms 4 ohms6.5 to 13 ohms 8 ohms13to 26 ohms 160hmsFor 25 volt line operation connect one of the leads

to the screw marked COM on the OUTPUT barrierstrip. The other lead is connected to the screwmarked 16 on the OUTPUT barrier strip.

AC POWER

The MC 50 operates on 105 volt to 130 volt, 50to 60 Hz. The amplifier will be turned on and off if itspower cord is plugged in one of the auxiliary ACpower outlets on the program source.

FUSE

The MC 50 is fused with a slo-blo type fuse ratedat 1.5 amperes. For maximum protection always re-place with fuses of the same rating, never larger. TheAC power outlet on the MC 50 is not fused.

AdjUstmentsFor maximum flexibility set the amplifier gain con-

trol as follows: turn the volume control on the pro-gram source equipment (i.e. tape recorder, tuner,preamplifier, etc). to the 12 o'clock position. Turn thegain control on the MC 50 until the loudness of thesound from the speaker is just a little louder than younormally like to listen. The volume control on theprogram source equipment now has the most con-venient amount of loudness change in either direc-tion from the 12 o'clock position:

2

How to Connect

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performance LimitsPERFORMANCE GUARANTEE

Performance Limits are the maximum deviation fromperfection permitted for a Mcintosh instrument. Wepromise you that the Me 50 you buy must be capableof performance at or exceeding these limits or you getyour money back. Mcintosh is the only manufacturerthat makes this guarantee.

PERFORMANCEMcintosh audio power ratings are in accordance withthe Federal Trade Commission Regulation of Novem-ber 4, 1974 concerning power output claims for ampli-fiers used in home entertainment products.

POWER OUTPUT50 watts minimum sine wave continuousaverage power output, operating into 4ohms, 8 ohms, or 16 ohms load impe-dance, whieh is:

14.1 volts RMS across 4 ohms20.0 volts RMS across 8 ohms28.3 volts RMS across 16 ohms

OUTPUT LOAD IMPEDANCE4 ohms, 8 ohms, or 16 ohms; separate ter-minals are provided for each output

RATED POWER BAND20 Hz to 20,000 Hz

TOTAL HARMONIC DISTORTION0.25% maximum harmonic distortion atany power level from 250 milliwatts to 50watts from 20Hz to 20,000 Hz

INTERMODULATION DISTORTION0.25% if instantaneous peak power output is 100 wattsor less for any combination of frequencies 20 Hz to20,000 Hz

FREQUENCY RESPONSE20 Hz to 20,000 Hz +0 -0.25 db10 Hz to 100,000 Hz +0 -3.0 dB at one watt output

NOISE AND HUM90 dB below rated output

RATINGS

OUTPUT VOLTAGES25 volts for distribution lines

DAMPING FACTOR25 at 4 ohms output50 at 8 ohms output17 at 16 ohms output

INPUT IMPEDANCE200,000 ohms

INPUT SENSITIVITY0.5 volt. Level control provided for higher input voltage

GENERAL INFORMATION

POWER REQU'IREMENTS120 volts, 50/60 Hz, 15 watts at zero signal output,120 watts at rate output

SEMICONDUCTOR COMPLEMENT12 silicon transistors12 silicon rectifiers and diodes

MECHANICAL INFORMATION

SIZE5V2 inches high (13.97 cm), 8 inches wide (20.32 cm),12V2 inches deep (31.75 cm)

CHASSISChrome and bl.ack

WE'IGHT20 pounds (9.07 kg) net, 24 pounds (10.89 kg) in ship-ping carton

SPECIAL FEATURES

The amplifier is completely stable when connected toany loudspeaker system or even to any reactive loads.The Me 50 has special circuits to prevent damageby short circuit or open circuit of the output load, orby any amount of output impedance mismatch.

Thermal cutouts are mounted on the output transistorheat sinks to provide protection in the event of ina,de-quate ventilation.

4

10 100POWER OUTPUT IN AVERAGE WATTS

1000

Harmonic Distortion versus Power

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10 20 200 2000 20,000FREQUENCY IN HERTZ

Equivalent Power Output versus Intermodulation Distortion

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Technical DescriPtionA two stage preamplifier with three transistors in-

creases the input voltage 16db.There are 13 transistors in the power amplifier

section. The two stage preamplifier is fed to a pair ofmatched transistors arranged as an emitter coupledamplifier with two inputs and one output. The signalfrom the preamplifier section connects to one ofthese inputs. Both AC and DC negative feedback areapplied to the other input. This large quantity of feed-back is used to reduce noise and distortion. Thesignal is then fed to a voltage amplifier. The voltageamplifier is followed by two driver transistors.

The output section is arranged as a series push-pull amplifier. The power transistors used in the out-put section of your MC 50 are selected for their highpower dissipation capabi lity, wide frequency response,and large "safe operating area." In addition, eachpower transistor is given four separate tests beforeit is put in your MC 50. This additional testing makessure your MC 50 will deliver its rated power from20 Hz to 20,000 Hz with low distortion and completereliability.

The power transistors are mounted on oversizedanodized heat sinks. The heat sinks assure that un-der normal operation the transistors will operate at alow temperature. If temperatures increase due to ashorted speaker, or restricted ventilation, an auto-matic temperature sensing device turns off the powerto the MC 50. The device operates automatically at apreset temperature. The MC 50 will turn on againwhen the temperature has returned to normal limits.This additional feature gives your MC 50 completereliability under the most extreme operating con-ditions.

The output stages are matched to the load by theMcintosh autoformer. The Mcintosh autoformer iscarefully wound using Mcintosh trifilar winding andinterleaving techniques. Trifilar winding and inter-leaving gives the autoformers exceptional band-width. The autoformers properly match the powertransistors to 4, 8 and 16 ohm loads at all audiofrequencies.

The use of the Mcintosh designed trifilar auto-former makes the Mcintosh solid state amplifiers theonly amplifiers that deliver FULL POWER AT ALLSPEAKER IMPEDANCES. You have not been powerpenalized for your choice of loudspeakers whenusing the Mcintosh MC 50.

Another of the advantages of the autoformers isthe 25 volt output for a constant voltage distributionsystem. With the MC 50 several sets of speakers canbe operated independently throughout your home.

To further insure reliability a special power outputSENTRY MONITORING CIRCUIT prevents failure ofthe power output transistors due to excessive mis-match of the output. When your MC 50 operatesnormally the SENTRY MONITORING CIRCUIT has no .effect on signals passing through the power ampli-fier. If the power dissipation should rise above nor-mal operation, the SENTRY MONITORING CIRCUITrestricts the drive to the output transistors. TheSENTRY MONITORING CIRCUIT acts instantaneous-ly for any input signal or load combination. This ar-rangement assures complete circuit reliability. OnlyMcintosh gives you this degree of protection.

There are three separate power supply sections.One positive and one negative high current supply isused for the output stages. The other positive supplyis used for the driving amplifier stages. All suppliesare full wave and use silicon rectifiers. Adequatefiltering is used to assure an absolute minimum ofhum. The power output stage filter capacitors havevery high capacity, which allows full power outputbelow 20 Hz. The power transformer is generous insize and runs cool, even under heavy use.

·BlOCk Diagram

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PROTECTIONFIRST PROTECTION •.••

In these dark days of hurry up-percentage analy-sis-production rush-and limited personal responsi-bility the Mcintosh policy of "Performance Limits" isa bit of bright blue sky. Every Mcintosh instrument-everyone-is tested to be equal to or better than theperformance limits advertised. When a performancelimit of 0.25% harmonic distortion is established foran instrument, Mcintosh means that every, each, allof the instruments manufactured must be capable ofperformance to that limit-or better-or your fullpurchase price is refunded.

One of the reasons Mcintosh can make this prom-ise is: we 100% test every product for maximum per-formance. We are not content knowing that 10% ofour products are tested and meet the performancerequirements established by our engineering group.We must know that everyone meets its requirements.This vigorous pursuit of excellence takes time. AtMcintosh more time means more care, more protec-tion for you. There's no production rush at Mcintosh.

The Mcintosh investment in professional testinginstruments is staggering. On a percentage basisMcintosh probably invests more of its sales dollarsin testing facilities that anyone else in a like busi-ness. For instance, Mcintosh has one professionaldistortion analyzer for every 10 employees. This kindof statistic is repeated for all sorts of test instru-ments. As new testing instruments are produced thatupdate the Mcintosh ability to know, Mcintosh in-vests in them-wave form analyzers-real time ana-lyzers-lowest distortion signal generators-etc.,etc. Even so far as a small FM transmitter so that theentire transmission! reception system can be ana-lyzed.

"What does this mean to me?" you ask. Onlythrough this impressive investment; through con-tinuous testing and research; through product analy-sis; and endless measurement can we promise anddeliver to you reliability, 'Iong life, performance, high-est value, and freedom from service.

SECOND PROTECTION ••••

BECAUSE MciNTOSH MANUFACTURES THE BEST ELECTRONIC MUSICREPHODLJCING INSTRUMENTS, AND BECAUSE MciNTOSH INSTRUMENTSARE DESI(;NED TO HAVE LONG, TROUBLE FHEE LIFE, AND BECAUSEMcfNTOSH WANTS TO ASSURE YOU THAT yOU OWN THE FINEST INSTRU.MENT MADE,

MciNTOSH LABORATORY ISSUES THIS THREE YEAR CONTRACT TO:

State Zip

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Mcintosh Laboratory has great beliefin its engineering, product development,manufacturing and quality control. Tooffer you strong evidence of this confi-dence Mcintosh offers you a FREETHREE YEAR SERVICE CONTRACT.During the first three years you can'tspend one dime for service. Mcintoshquarantees parts and labor. It costs younothing. The extended life of a Mcintosh,the conservative ratings, and the sophisti-cated appearance make a Mcintosh in-strument a greater value when you areready to trade.

(IOIOSMciNTOSH LABORATORY INC.

2 CHAMBERS ST., BINGHAMTON, N. Y. 13903607-723-3512

Design subject to change without notice.

Printed in U.S.A.

038·794

POWER AMPLIFIER

I I ISTARTING WITH SERIAL NO. lOUOl

V'IMciNTOSH LABORATORY INC. 2 CHAMBERS STREET BINGHAMTON, NEW YORK I 0

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MC 50 ELECTRICAL SPECIFICATIONS

PERFORMANCEMcIntosh audio power ratings are in accordance withthe Federal Trade Commission Regulation of Novem-ber 4, 1974 concerning power output claims for ampli-fiers used in home entertainment products.

POWER OUTPUT50 watts minimum sine wave continuousaverage power output, operating into 4ohms, 8 ohms, or 16 ohms load impe-dance, whieh is:

14.1 volts RMS aeross 4 ohms20.0 volts RMS aeross 8 ohms28.3 volts RMS across 16 ohms

OUTPUT LOAD IMPEDANCE4 ohms, 8 ohms, or 16 ohms; separate ter-minals are provided for each output

RATED POWER BAND20 Hz to 20,000 Hz

TOTAL HARMONIC DISTORTION0.25% maximum harmonie distortion atany power level from 250 milliwatts to 50watts from 20Hz to 20,000 Hz

INTERMODULATION DISTORTION0.25% if instantaneous peak power output is 100 wattsor less for any combination of frequencies 20 Hz to20,000 Hz

FREQUENCY RESPONSE20 Hz to 20,000 Hz + 0 -0.25 db10Hz to 100,000 Hz + 0 -3.0 dB at one watt output

NOISE AND HUM90 dB below rated output

RAT'INGSOUTPUT VOLTAGES25 volts for distribution lines

DAMPI.NG FACTOR25 at 4 ohms output50 at 8 ohms output17 at 16 ohms output

INPUT IMPEDANCE200,000 ohms

INPUT SENSITIVITY0.5 volt. Level control provided for higher input voltage

GENERAL INFORMATIONPOWER REQUIREMENTS120 volts, 50/60 Hz, 15 watts at zero signal output,120 watts at rate outputSEMICONDUCTOR COMPLEMENT12 silicon transistors12 silicon rectifiers and diodes

MECHANICAL INFORMATIONSIZE51/2 inches high (13.97 cm), 8 inches wide (20.32 cm),121/2inches deep (31.75 cm)

CHASSISChrome and black

WEIGHT20 pounds (9.07 kg) net, 24 pounds (10.89 kg) in ship-ping carton

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AMPLIFIER SEC

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POWER SUPPLYSECTION

MC 50 154-349

MC 50

SCHEMAHC NOTES

1. Unless otherwise specified: Resistance values are in ohms, 1/2 watt, and 10% tolerance; capacitancevalues smaller than 1 are in microfarads (µF); capacitance values greater than 1 are in picofarads(pF); inductors are in microhenries (µH).

2. Printed circuit board components are outlined on the schematics by dotted lines. The circled numberson the dotted 1 ines correspond to the numbers on the PC board layouts.

3. The heavy 1 ines on the schematics denote the primary signal path.

4. All voltages indicated on the schematics are measured under the following conditions:

a. Use of an 11 megohm impedance VTVM. d. AC input at 117 volts AC, SO/60Hz.

b. All voltages ±10% with respect to e. Front panel controls at:chassis ground.

Gain FULL CCWc. No signal at input terminals.

5. In units with Serial No.'s below 10U51, C14 is not used; R1S and R19 are 5% resistors.

6. In units with Serial No. IS from 13UOO to 1SUSS, C7 is lSOpF.

7. In units with Serial No. IS below 14USO, Qll and Q12 are Mcintosh Part No. 132-536.

S. In units with Serial No.ls below 12U50, R16 is 3.3k; R24 is 160Q; R25 is 220Q; and R21 and R22are used.

9· In units with Serial No1s. below 201J7S R26 is ·120Q.

10. In units with Serial No's. below 2?1J79 R4 and R5 are 3.3k.

Q II TOP

Q 9 BOTTOM

LOCATION OF TRANSISTORS NOT ON PRINTED CIRCUIT BOARDS

Q 12 TOP

Q 10 BOTTOM

MC 50

REPLACEMENT PARTS

Al I parts not I isted are common items obtain-able from radio parts jobbers.

Replacement parts may be obtained when orderedby PART NUMBER from:

Mcintosh Laboratory Inc.Customer Service Department2 Chambers StreetBinghamton, New York 13903(telephone 607-723-3S12)

CAPAC ITORS

Symbol Pa rtNumber Description Number

C I Mylar .47µF 2S0V 064-069

C2,3 E Iec t. 640µF 2SV 066-135

CS E Iec t. 100lJF 15V 066-127

c6 Elect. 10µF 2SV 066-005

c8 E Iec t. 470µF 4v 066-136

C I0 I,102 E Iec t. 4000µF 50V 066-096

CI03 E Iec t . 470µF 40V 066-134

CI04 E Iec t . 80/80/50/ISOµF 066-095200/200/150/150V

DIODES

01 S i. signal diode 070-047

02 S i. I-eference diode 070-046

03,4 S i. signal diode 070-047

05,6 S i. I-ectifiel' 070-031

0101, 102 S i. rectifier 070-031

0103,104 S i. rectifier 070-031

010S,106 S i. l-ectiFier 070-031

FUSES

FIOI Fuse I.S amp, slo-blo 089-003

TRANSISTORS

Q 1,2

Q3,4

QS

Q6

Q7

Q8

Q9

QIO

QII ,12

Si. NPN transistor 132-092

132-0S6

132-0S6

132-S15

132-021

132-032

132-S24

132- 530

132-070

Si. PNP transistor

Si. PNP transistor

Si. NPN transistor

Si. NPN transistor

Si. PNP transistor

Si. NPN transistor

Si. PNP transistor

Si. NPN transistor

POTENTIOMETERS

RI Gain control 134-206

MC 50 SCHEMATIC PART NO. 038-803

RT7

R27

R28

SIOI

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RESISTORS

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SW

SW

139-096

139-048

139-080

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Wi rewound .331l

SW ITCHES

Therma I cut-out 153-007

TRANS FO RM ERS

Audio autoformer 043-607

043-934Power transformer

MISCELLANEOUS ITEMS

Plastic feet 017-144

038-659

090-017

033-100

170-021

178-001

Owners manual

Gain control knob

Shipping carton

AC power cord

Fuseholder

20C1025S7-M4803

SERVICE CONTRACT APPLICATION

1. Mcintosh will provide all parts, materials and labor needed to return themeasured performance of the instrument to the original performancelimits free of any charge. The SERVICE CONTRACT does not cover anyshipping costs to and from the authorized service agency or the factory;

2. Any Mcl ntosh authorized service agency will repair all McI ntosh instru-ments at normal service rates. To receive the free service under the termsoftheSERVICE CONTRACT, the SERVICE CONTRACT CERTIFICATEmust accompany the instrument when taken to the service agency.

3. Always have service done by a Mcintosh authorized service agency. If theinstrument is modified or damaged, as a result of unauthorized repair theSERVICE CONTRACT will be cancelled. Instruments damaged by im-proper use or mishandling are not covered by the SERVICE CONTRACT.

4. The SERVICE CONTRACT is issued to you as the original purchaser. Toprotect you from misrepresentation th is contract cannot be transferred toa second owner.

5. The SERVICE CONTRACT is given to purchasers who live in the 50United States or Canada only.

6. For your protection Mcintosh selects its dealers carefully. Only one dealerin ten qualifies for a Mcintosh franchise. To receive the SERVICE CON-TRACT your purchase must be made from a Mcintosh franchised dealer.

7. Your completely filled in application for a SE RVICE CONTRACT mustbe postmarked within 30 days of the date of purchase of the instrument.

8. To receive the SE RVICE CONTRACT all information on the applicationmust be filled in. The SERVICE CONTRACT will be issued when thecompletely filled in application is received at Mcl ntosh LaboratoryIncorporated in Binghamton, New York. If the application is not receivedat Mcl ntosh Laboratory, only the service offered under the gO-dayguarantee will apply.

Tear Off And Mail Remainder 038·617

PLEASE PRINT ALL INFORMATION

YOUR NAME: __

ADDRESS: _

CITY: _ STATE: _ ZIP: _

MODEL NO: __ SERIAL NO: _

NAME OF DEALER FROM WHOM YOU BOUGHT:

CITY: _

DATE YOU BOUGHT: _

I accept the benefits and the terms of the Factory Service Contract.

Your Signature:Fold Here For Mailing

ould you please take a moment to help others enjoy the best in highfidelity equipment by answering these questions?

1. I learned of Mcintosh from

D ADVERTISEMENT IN

D DEMONSTRATION BY A DEALER

D RECOMMENDATION OF A FRIEND

D OTHER-Please tell us ---------- _

2. What features of Mcintosh attracted you most? _

3. Does your Mcintosh purchase replace any other high fidelity or stereoequipment? If so please describe-

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Mcintosh Laboratory Inc.

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BUSINESS REPLY CARDNO POSTAGE STAMP NECESSARY If MAILED IN THE UNITED STATES

POSTAGE WILL BE PAID BY

mcJotosh LABORATORY INC.

2 Chambers St.

Binghamton, N. Y. 13903

FIRST CLASSPERMIT NO. 676

(Sec. 34.9, P.l.&R.)BINGHAMTON. N. Y.

SERVICE

In the event it is necessary to return your equipment to Mcintosh Laboratory

please fill in the attached postpaid service card. You will help us to give you

the fastest service possible if the information is filled out and the card mailed

to us when you ship the equipment. Be sure to fill out a different tag for each

piece of equipment.

Carefully pack the equipment in the original carton. If the original carton

IS not available please write "Customer Service" at Mcintosh Laboratory for

another. The carton is designed to permit shipment of the equipment with

greatest safety and insure against damage in transportation.

The guarantee service at Mcintosh Laboratory covers all parts and labor

exclusive of tubes, fuses, and transportation to and from our laboratory.

Return the equipment to us with transportation charges paid. It will be returned

with return transportation charges collect.

MODEL No. _SERVICE

SERIAL No. CONTRACT No. _

DATE YOUR PHONE NUMBER _

REASON FOR RETURN __

NAME __

ADDRESS ~

CITY ZIP CODE _

mcIntosh LABORATORY INC. 2 Chambers St., Binghamton, N. Y. 13903

038·038