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THE MclNTOSH MC 2200 SOLID STATE STEREO POWER AMPLIFIE

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Your MC 2200 Stereo Power Amplifierwill give you many years of pleasantand satisfactory performance. If youhave any questions, please contact:

C U S T O M E R S E R V I C EMclntosh Laboratory Inc.2 Chambers StreetBinghamton, New York 13903Phone: 607-723-3512

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

T a k e A d v a n t a g e o f 3 y e a r s

of FREE Serv ice . . .

F i l l i n t h e A p p l i c a t i o n N O W .

C o n t e n t sSERVICE

INSTALLATION

HOW TO CONNECT

FRONT PANEL INFORMATION

REAR PANEL INFORMATION

PERFORMANCE LIMITS AND RATINGS

PERFORMANCE CHARTS

TECHNICAL DESCRIPTION

BLOCK DIAGRAM

1

2

4

8

10

11

12

14

16

T H R E E Y E A R S E R V I C E C O N T R A C T

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 andlabor needed to return the measured perform-

ance of the instrument to the original per-

formance limits free of any charge. The

SERVICE CONTRACT does not cover any ship-

ping costs to and from the authorized service

agency or the factory.

2. Any Mclntosh authorized service agency will

repair all Mclntosh instruments at normal

service rates. To receive the free service under

the terms of the SERVICE CONTRACT, the

SERVICE CONTRACT CERTIFICATE must ac-

company 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 SERV-

ICE 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 1976 by Mclntosh Laboratory Inc.1

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The MC 2200 can be housed in the Mclntosh L22 cabinet,

installed in a custom cabinet or, with the addition of RACK

MOUNTING ADAPTERS (RMA 7), mounted in a standard 19

inch rack panel. The MC 2200 weighs 85 pounds (38.6 kg).

In any installation it is necessary to provide proper support

for the weight. The mounting methods described and theamplifier have been designed to accommodate the weight

so be sure that the panel and its mounting can also handle

the weight.

INSTALLATION IN MclNTOSH CABINET

Remove the instrument and hardware package from the

carton. Remove the MC 2200 from its plastic bag and place

it upside down on the shipping pallet; unscrew the four

plastic feet from the bottom of the chassis. Use the screws

from the plastic feet to secure the instrument to the cabi-

net. Do not substitute longer screws. Longer screws may

penetrate the electronic components in the chassis which

would cause severe damage. Do not overtighten the screws.

INSTALLATION IN A CUSTOM CABINET

The trouble-free life of an electronic instrument is

greatly extended by providing sufficient ventilation to pre-

vent the buildup of high internal temperatures that cause

deterioration. Allow enough clearance so that cool air can

enter at the bottom of the cabinet and be vented from the

top. With adequate ventilation the instrument can be

mounted in any position. The recommended minimum

space for installation is 15 inches (38.1 cm) deep, 17 inches

(43.2 cm) wide, and 8 inches (30.3 cm) high.

Vertical mounting the MC 2200 requires careful con-

sideration. The total weight is transmitted to the panel and

shelf on which the amplifier is to be mounted. Thought

should be given to providing a means for raising the MC

2200 out of the panel. More consideration should be given

to providing adequate ventilation at the panel in vertical

mounting. The heat sinks are at the rear of the chassis

permitting the heat to pass over the entire chassis. It is then

trapped behind the panel causing the overall temperature

to rise. In any case, air flow for cooling can be improved by

the use of a properly installed low noise fan. Adequatecooling will extend the life of the components.

Fig. 1. Top view of the panel cutout and mounting shelf.

2

1 / 4 " D I A . ( 2 H O L E S )

C U T O U T

F R O N T P A N E L

M T G . S U R F A C E

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Fig. 2. Views showing mounting shelf in position.

INSTALLATION PROCEDURE

1. Mark for Position

Mark cabinet panel where the instrument is to be

installed. The solid lines in Fig. 2 represent the outline of

the rectangular cutout and also represent the outside

dimensions of the chassis. Make sure these lines clear

shelves, partitions, or any equipment. The broken line

represents the outside dimension of the panel.

2. Drill Holes

Using a drill bit slightly wider than the tip of your saw

blade, drill one hole at each of two diagonally opposite

corners. The holes should barely touch the inside edge of

the outline.

3. Saw Panel Cutout

Sawing carefully on the inside of the lines, first make

the two long cuts and then the two short. After the

rectangular opening has been cut out, use a file tosquare the corners and smooth any irregularities in the

cut edges.

4. Shelf Installation

Install the shelf on which the MC 2200 will sit. It

must be capable of supporting the total weight of the

instrument. Drill the two " holes shown in Fig. 1.

5. Install Instrument

Guide the AC power cord through the panel opening

to the back of the cabinet; then, slide the instrument into

the opening until its front panel is flush with the cabinet

panel. Secure the MC 2200 to the shelf with #10 wood

screws of the proper length." thick shelfuse 1" screws5/8

" thick shelfuse 11/8" screws

" thick shelfuse 1" screws

Do not use screws longer than this recommended

length. They may penetrate electronic components

inside the chassis and cause severe damage. In any

event, the screw length must not exceed the shelf

thickness by more than ".

Insert two proper length screws through the mount-

ing shelf and into the holes in the bottom of the ampli-

fier. Do not overtighten the screws.

INSTALLATION IN A 19 INCH RACK

The RACK MOUNTING ADAPTERS install on each end of

the front panel. On each side of the amplifier, three screws

secure the front panel bracket to the chassis. These three

screws are removed, the RACK MOUNTING ADAPTER

placed over the screw holes and the screws replaced. The

entire weight is transmitted through the RACK MOUNTING

ADAPTERS to the rack. No weight is carried by the front

panel. Additional support for the weight can be provided

at the rear of the chassis as desired.

Fig. 3. Rack Mounting Adapters installed.

3

6 9/16"

D E P T H R E Q U I R E D15" .

T O P O F S H E L F & B O T T O MO F C U T O U T S H O U L D C O I N C I D E .

S H E L F

M O U N T I N G S C R E W S

D I F F E R E N C E B E T W E E N S C R E W

L E N G T H & T O T A L S H E L F T H I C K N E S S

M U S T N O T E X C E E D 1 / 2 "

3"

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INPUTSTEREO OR TWIN AMPLIFIER OPERATION

Use shielded cables to connect the signal from the pre-ampl i f ier or s ignal source to the power ampl i f ier input. Tominimize the possibi l i ty of hum the shielded cables shouldbe run parallel to each other or loosely twisted together.Locate the cables away from speaker leads and AC powercords. All connections are made on the back panel of theMC 2200 .

For stereo operation, the left output of the preampl i f iershould be plugged into the Left input jack of the powerampl i f ier. The r ight output of the preampl i f ier should be

plugged into the Right (MONO) input jack of the poweramplifier.

Fo r twin amplifier operation a separate signal source canbe connected to each input. In stereo or twin ampl i f ieroperation the MODE SWITCH must be in the STEREO posi-t ion.

MONOPHONIC OR SINGLE CHANNEL OPERATION

A shielded cable from the signal source is plugged intothe Right (MONO) input jack of the MC 2200 only. TheMODE SWITCH on the back panel of the amplifier must beplaced in the MONO position. In the MONO position theright channel input jack connects to both left and r ight

power ampl i f iers. Mono output is obtained by strappingboth outputs in parallel. The Left INPUT is disconnected.Only the signal fed into the Right (MONO) input wil l beampli f ied.

Should the MODE SWITCH be left in the STEREO positionand the output transformers remain strapped for a mono-phonic load, one channel wi l l attempt to drive the otherwhich causes high ci rculating currents and overheating. B ec e r t a i n t h a t t h e M C 2 2 0 0 i s n e v e r o p e r a t e d i n t h e s t e r e om o d e w i t h t h e o u t p u t s c o n n e c t e d f o r m o n o p h o n i c o p e r a -t i o n .

OUTPUTB e c e r t a i n t h e l o u d s p e a k e r s c o n n e c t e d t o t h e M C 2 2 0 0

a r e c a p a b l e o f h a n d l i n g t h e p o w e r o u t p u t o f t h e a m p l i -f i e r .

For multiple speaker operation, run separate leads fromeach speaker to the amplifier. Because of the high power

avai lable from the MC 2200, large diameter speaker leadsmust be used. Use lamp cord, bel l wi re, or wire wi th simi lartype of insulation to connect the speakers to the ampl i f ier.In al l cases, the leads to and from the speaker should betwin conductor or twisted together. When using 8 ohmspeakers and for the normally short distances of under 30feet between the ampl i f ier and speaker, #18 wire orlarger can be used. For distances over 30 feet between theamplifier and speaker use larger diameter wire. Select thecorrect s ize wire for the wire distance from the chart. I t isrecommended that the DC resistance of the speaker leadsbe less than 5% of the speaker impedance. Up to 10% canbe tolerated. Resistance of the leads should be comp uted for

the length of wire both to and from the speaker or speakers.

W i r e

Gauge

2220

181614

12

10

M A X I M U M W I R E

F o r 4 O h m L o a d

F e e t

61015

2540

60

100

M e t e r s

1.833.054.57

7.62

12.19

18.29

30.48

LENGTHS

For 8

F e e t

122030

50

80120

200

O h m L o a d

M e t e r s

3.66

6.109.14

15.24

24.38

36.58

60.96

Wire lengths above represent the wire resistance equal to5% of the speakers impedance. Use of smaller wire sizeswil l produce more resistance which causes more powerloss and less loudspeaker damping.

STEREO OR TWIN AMPLIFIER OPERATIONCheck the impedance of the speaker which is usually

identified on the speaker i tself or in the speaker owner'smanual . Connect a lead from the common terminal of theleft speaker to the amplifier LEFT OUTPUT terminal stripCOMmon screw. Connect another lead from the other term i-

nal of the left speaker to the screw with the number cor-responding to the speaker impedance on the LEFT OUTPUTterminal str ip. The r ight channel speaker is connected inthe same manner on the RIGHT OUTPUT terminal strip. Forstereo or twin channel operation it is not necessary to usethe same impedance loudspeaker on each output. Connect

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each channel for the impedance desired. Full power will

be delivered to each properly connected speaker.

When multiple speakers are to be connected to either or

both outputs, the combined load impedance must be calcu-

lated. The load must be connected to the appropriate im-

pedance tap. Use this table to aid in selecting the correct

impedance match:

Load

impedancein ohms

0.8 to 1.6

1.6 to 3.2

Connect for

1 ohm output

2 ohm output

Load

impedancein ohms

3.2 to 6.4

6.4 and up

Connect for

4 ohm output

8 ohm output

If a load impedance is used that is lower than the output

impedance tap, then reduced power and possible distortion

will result. If a load impedance is used that is higher than

the output impedance tap, then neither the signal nor the

amplifier will be harmed but the power available is limited.

FOR STEREO OR TWIN AMPLIFIER CONSTANT VOLTAGE

OPERATION:

For outputvoltage of Connect for

25 volts 4 ohms

MONOPHONIC OR SINGLE CHANNEL OPERATION

When the MC 2200 is used as a monophonic or single

channel power amplifier the two channels are combined to

produce output up to 400 watts. The outputs must be tied

together at the appropriate load impedance tap. In connect-

ing a load to the MC 2200 for single channel operation

connect the common side of the load to the LEFT CHANNEL

OUTPUT terminal marked COM., the other lead is con-

nected:

FOR MONOPHONIC CONSTANT VOLTAGE LINE

OPERATION

For output

voltage of Connected for

25 volts 2 ohm output (mono)

For multiple speaker operation, run separate leads from

each speaker to the amplifier.

Should the MODE SWITCH be left in the STEREO position

and the output transformers be strapped for a monophonic

load, one channel will attempt to drive the other and cause

circulating currents and overheating. Be certain that the

MC 2200 is never operated in the stereo mode with the

outputs connected for monophonic operations.

A C P O W E RThe MC 2200 operates on 120 volts 50/60 Hz. The aux-

iliary AC OUTLET on the MC 2200 is not fused or switched.

If the speaker

or load

impedance is

0.5 ohm

1 ohm

2 ohms

4 ohms

The hot side

of the line is

connected to

Left 1

Left 2

Left 4

Left 8

Connect a jumper

wire between

Left 1 and

Left 2 and

Left 4 and

Left 8 and

Right 1

Right 2

Right 4

Right 8

Do not connect unequal impedance taps together

If the load impedance is between any of the above fig-

ures, select the best impedance match from:

Load

impedance

in ohms

0.4 to 0.8

0.8 to 1.6

Connect for

0.5 ohm output

1 ohm output

Load

impedance

in ohms

1.6 to 3.2

3.2 and up

Connect for

2 ohm output

4 ohm output

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F r o n t P a n e lI n f o r m a t i o n

LEFT GAIN

Use the LEFT GAIN control to adjust the volume in the

left channel to the desired listening level. Turn the control

clockwise to increase the volume.

RIGHT/MONO GAIN

Use the RIGHT/MONO GAIN control to adjust the volume

in the right channel to the desired listening level. Turn the

control clockwise to increase the volume.

MONO

With the output of MC 2200 connected for monophonic

operation and the rear panel MODE SWITCH in MONO the

volume is controlled by the RIGHT/MONO GAIN control

only.

LIMIT/NORMAL

The NORMAL (green) and LIMIT (red) indicators are a

new Mclntosh development. As long as the amplifier

operates without overload the NORMAL indicator illu-

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minates. A waveform comparator in the MC 2200 con-

stantly compares the amplifier input and output waveform.

Waveform difference of the output wave is converted to

a voltage which is used as a control signal to "turn off" the

NORMAL indicator and to "turn on" the LIMIT indicator.

The LIMIT indicator turns on whenever the waveform dif-

ference exceeds 0.5%. Generally, these waveform differ-ences are the result of applying voltages at the input in

excess of its rating. Because the limit indicator circuit can

show an overload condition as short as one cycle of a

20,000 Hz signal a holding circuit keeps the red indi-

cator on long enough for the eye to see.

HEADPHONES

The output of the front panel HEADPHONE jack has been

designed to feed low impedance dynamic stereo head-

phones. Electrostatic headphones generally require higher

power than dynamic headphones. Connect them to the

LEFT and RIGHT OUTPUT contacts on the back of the

MC 2200. Plug dynamic headphones into the front panel

HEADPHONE jack. Adjust the front panel LEFT GAIN and

RIGHT/MONO GAIN control for comfortable headphone

listening.

POWER

The power switch turns the MC 2200 ON or OFF. Theswitch does not control the power outlet on the back panel.

If you wish to control the AC power from a preamplifier

control center leave the switch in the ON position. Be sure

the AC cord of the MC 2200 is plugged into the controlled

outlets on the rear of the preamplifier control center.

OFF: In the OFF position the AC power to the amplifier

is turned off.

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R e a r P a n e l I n f o r m a t i o nLEFT and RIGHT OUTPUT

For stereo operation, output impedances of 1, 2, 4 and

8 ohms have been provided on a secure, screw type barrier

strip. For monophonic operation proper interconnection

provides 0.5,1, 2 and 4 ohms from the same barrier strips.

POWER GUARD

Amplifiers are capable of delivering large quantities of

power when they are driven to clipping. Clipping is

caused when the amplifier is asked to produce more power

output than it can deliver with low distortion. A clipped

amplifier can have more than 40% harmonic distortion.

The extra energy content of the clipped signal will dam-

age most speakers. A new Mclntosh advancement helps

to protect your speaker from this kind of damage. The

MC 2200 has a built in "waveform comparator" that com-

pares the wave shape of the input signal with the output

signal. If the non-linearity between the two signals exceeds

0.5% a front panel signal illuminates in red (LIMIT}. With

the POWER GUARD switch in the NORMAL position, 1.0%

distortion will cause the POWER GUARD circuit to operate.

The POWER GUARD circuit limits the input dynamically so

that the amplifier cannot be overdriven. This eliminates

amplifier output clipping. Recommended operation is with

the POWER GUARD switch in the NORMAL position at all

times.

MODE SWITCH

The MC 2200 can be used in these different manners:

stereo (or as a twin amplifier) and mono. Because of the

excellent channel separation of the MC 2200, it can fulfill

all of these functions. When the instrument is properly con-

nected the MODE switch is used to select the method of

operation desired.

INPUTIn the stereo or twin amplifier mode of operation both

input jacks accept signal. In the mono mode of operation

the Left channel input jack is disconnected and only the

Right (MONO) channel input jack accepts signal.

INPUT LEVEL

The input sensitivity of the MC 2200 is 0.75 volts or

2.5 V depending on the position of the INPUT LEVEL switch.

With indicated voltage applied and the GAIN control clock-

wise, the amplifier will deliver its rated power. All Mclntosh

preamplifiers have been designed to deliver 2.5 volts out-

put with rated input. For the best signal to noise ratio when

using Mclntosh source equipment, always have the INPUTLEVEL switch in the 2.5 V position and the front panel LEFT

and RIGHT/MONO GAIN controls in the fully clockwise

position. If more gain is desired the 0.75 V position may be

used. For source equipment other than Mclntosh set the

switch in the position nearest to the stated output rating of

the source equipment.

AC POWER

The MC 2200 is rated for 120 volts, 50/60 hertz. A

10 ampere fuse protects the MC 2200 electrically. An

auxiliary AC power outlet has been provided. The auxiliary

outlet is neither fused nor switched.

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P e r f o r m a n c e L im i t s a n d R a t in g s

P E R F O R M A N C E G U A R A N T E E

P e r f o r m a n c e L i m i t s a r e t h e m a x i m u m d e v i a t i o n f r o m p e r -f e c t i o n p e r m i t t e d f o r a M c l n t o s h i n s t r u m e n t W e p r o m i s ey o u t h a t t h e M C 2 2 0 0 y o u b u y m u s t b e c a p a b l e o f p e r -f o r m a n c e a t o r e x c e e d i n g t h e s e l i m i t s o r y o u g e t y o u rm o n e y b a c k , Mc l n t o s h i s t h e o n l y m a n u f a c t u r e r t h a t m a k e st h i s g u a r a n t e e .

P E R F O R M A N C EMc l n t o s h a u d i o p o w e r r a t i n g s a r e i n a c c o r d a n c e w i t h t h eF e d e r a l T r a d e C o m m i s s i o n R e g u l a t i o n o f N o v e m b e r 4 , 1 9 7 4c o n c e r n i n g p o w e r o u t p u t c l a i m s f o r a m p l i f i e r s u s e d i n h o m ee n t e r t a i n m e n t p r o d u c t s .

P O W E R O U T P U T

STEREO2 0 0 w a t t s m i n i m u m s i n e w a v e c o n t i n u o u sav e rage power ou t pu t , pe r c hanne l , bo t hc h a n n e l s o p e r a t i n g i n t o 1 o h m , 2 o h m s , 4o h m s , o r 8 o h m s l o a d i m p e d a n c e , w h i c h i s :

1 4 . 1 v o l t s R M S ac ros s 1 ohm2 0 . 0 v o l t s R M S ac ros s 2 ohms2 8 . 3 v o l t s R M S ac ros s 4 ohms4 0 . 0 v o l t s R M S ac ros s 8 ohms

MO N O

4 0 0 w a t t s m i n i m u m s i n e w a v e c o n t i n u o u sav e rage power ou t pu t i n t o 0 . 5 ohm, 1o h m , 2 o h m s , o r 4 o h m s l o a d i m p e d a n c e ,wh i c h i s :

1 4 . 1 v o l t s R M S ac ros s 0 . 5 ohm20.0 vo l t s RMS ac ross 1 ohm2 8 . 3 v o l t s R M S ac ros s 2 ohms4 0 . 0 v o l t s R M S ac ros s 4 ohms

O U T P U T L O A D I M P E D A N C ESTEREO

1 o h m , 2 o h m s , 4 o h m s , a n d 8 o h m s ; se p a -ra t e t e rm ina l s a re p rov i ded f o r eac h ou t pu tMO N O

0 . 5 o h m , 1 o h m , 2 o h m s , a n d 4 o h m s ; o b -t a i n e d b y c o n n e c t i n g t o g e t h e r t h e a p p r o -p r i a t e t e rm ina l s o f bo t h c hanne l sR A T E D P O W ER B A N D

2 0 H z t o 2 0 , 0 0 0 H zT O T A L H A R M O N I C D I S T O R T I O NSTEREO

0 . 1 % m a x i m u m h a r m o n i c d i s t o r t i o n a t a n ypower l ev e l f r om 2 50 m i l l iwa t t s t o 2 00

w a t t s p e r c h a n n e l f r o m 2 0 H z t o 2 0 , 0 0 0

H z , bo t h c hanne l s ope ra t i ngM O N O

0 . 1 % m a x i m u m h a r m o n i c d i s t o r t i o n a t a n ypower l ev e l f r om 2 50 m i l l iwa t t s t o 4 00w a t t s f r o m 2 0 H z t o 2 0 , 0 0 0 H zI N T E R M O D U L A T I O N D I S T O R T I O NSTEREO0 . 1 % m a x i m u m i f i n s t a n t a n e o u s p e a k p o w e r o u t p u t i s 4 0 0w a t t s o r l e s s p e r c h a n n e l w i t h b o t h c h a n n e l s o p e r a t i n g f o ra n y c o m b i n a t i o n o f f r e q u e n c i e s , 2 0 H z t o 2 0 , 0 0 0 H zMO N O0 . 1 % m a x i m u m i f i n s t a n t a n e o u s p e a k p o w e r o u t p u t i s 8 0 0

w a t t s o r l e s s f o r a n y c o m b i n a t i o n o f f r e q u e n c i e s , 2 0 H z t o2 0 , 0 0 0 H zF R E Q U E N C Y R E S P O N S E ( a t o n e w a t t o u t p u t )2 0 H z t o 2 0 , 0 0 0 H z , + 0 - 0 . 2 5 d B1 0 H z t o 1 0 0 , 0 0 0 H z + 0 - 3 . 0 d BN O I S E A N D H U M9 5 d B b e l o w r a t e d o u t p u t

R A T I N G SO U T P U T V O L TA G E S2 5 v o l t s f o r d i s t r i b u t i o n l i n e sD A M P I N G F A C T O RSTEREO1 6 a t 1 o h m o u t p u t , 5 0 a t 2 o h m s o u t p u t , 3 0 a t 4 o h m s o u t-p u t , 1 6 a t 8 o h m s o u t p u tMO N O1 6 a t 0 . 5 o h m s , 5 0 a t 1 o h m , 3 0 a t 2 o h m s , a n d 1 6 a t 4o h m s o u t p u tI N P U T I M P E D A N C E1 0 0 , 0 0 0 o h m sI N P U T S E N S I T I V I T YS w i t c h a b l e : 0 . 7 5 v o l t o r 2 . 5 v o l t s L e v e l c o n t r o l p r o v i d e df o r h i g h e r i n p u t v o l t a g e s

G E N E R A L I N F O R M A T I O NP OW E R R E Q U I R E M E N T S1 2 0 v o l t s 5 0 / 6 0 H z , 7 0 t o 5 5 0 w a t t sS E M IC O N D U C T O R C O M P L E M E N T4 3 s i l i c o n t r a n s i s t o r s2 4 s i l i c o n r e c t i f i e r s a n d d i o d e s

2 i n t e g r a t e d c i r c u i t sM E C H A N I C A L I N F O R M A T I O N

S I Z EF r o n t p a n e l m e a s u r e s 1 6 i n c h e s w i d e ( 4 0 . 7 c m ) b y 6 3 1 / 3 2i n c h e s h i g h ( 1 7 . 7 c m ) . C h a s s is m e a s u r e s 1 4 5 / 8 i n c h e sw i d e ( 3 7 . 2 c m ) b y 6 9 / 1 6 i n c h e s h i g h ( 1 6 . 7 c m ) b y 1 4 1 / 2i n c h e s d e e p { 3 6 . 8 c m ) , i n c l u d i n g c o n n e c t o r s . K n o b c l e a r -a n c e r e q u i r e d i s 1 1 / 2 i n c h e s ( 3 . 8 c m ) i n fr o n t o f m o u n t i n gp a n e lF I N I S HF r o n t p a n e l i s a n o d i z e d g o l d . C h a s s i s i s c h r o m e a n d b l a c kW e i g h t7 3 p o u n d s ( 3 8 . 6 k g ) n e t , 8 7 p o u n d s ( 4 4 . 0 k g ) i n s h i p p i n gc a r t o n

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TechnicalDescriptionINPUT AMPLIFIER

Separate input amplifiers are used for the right and

left channels. Each input amplifier is a two transistor feed-

back amplifier which has unity gain. They are used to pro-

vide high input impedance and low output impedance for

driving the power amplifier sections. In addition, impe-

dance matching is provided for the POWER GUARD system

input attenuator.

When the MODE selector is switched to MONO, only the

right channel input, GAIN control, POWER GUARD attenua-

tor, and input amplifier is used to drive both power am-

plifiers.

POWER AMPLIFIER

There are two identical power amplifier sections. At the

input to each power amplifier is a monolithic differential

transistor selected for low noise. The monolithic design

yields closely matched transistors for low distortion. The

input and the feedback signals are applied to this differen-

tial amplifier. The second stage is a class A voltage ampli-

fier using a single transistor with feedback.

The predriver, driver, and output sections follow and are

fully complimentary with high efficiency and negligible dis-

tortion. The predriver is a complimentary transistor pair

biased to nearly class A operation for low crossover dis-tortion. Bias is supplied by a transistor which serves as

a temperature tracking circuit so the predriver is properly

biased regardless of temperature. The predriver has a

generous amount of emitter degeneration for low distortion.

Another complimentary pair of power transistors biased

for class AB operation make up the output driver stages.

Their bias is developed across a termistor which holds the

bias current stable regardless of temperature.

The output stage consists of 6 rugged complimentary

power transistors connected in single ended push-pull

parallel. This stage is connected as a balanced emitter fol-

lower which allows great stability and low distortion. Dueto a unique arrangement of the output bias network, the

output transistors are operated class B free of crossover

distortion. Heat is not produced by these transistors when

there is no output. The bias network for the output stage

is temperature compensated assuring class B operation

at any temperature or power level.

The output transistors and drivers are mounted on gener-

ous sized black anodized aluminum heat sinks. The free

flow of room temperature air that passes through the over-

sized heat sinks provides the cooling necessary for the long

life of components.

The MC 2200 has transient free turn on and turn offcharacteristics. This is because the output of the amplifier is

switched by a heavy duty relay to the output auto trans-

former. The relay is driven by a transistor switch. The con-

trol to this transistor is derived from a long time constant

capacitor charging network. The switch turns on the relay

approximately two seconds after the MC 2200 is turned on.

The same circuit has a short turn-off time constant which

turns off the relay before the amplifier's main power supply

has had a chance to drop. The output signal is fed through a

matching network to the front panel HEADPHONE jack. The

HEADPHONE output is designed to feed low impedance

dynamic stereo headphones.

The amplifier output signal is fed to the output terminals

through the autotransformer. The Mclntosh designed inter-

leaved multifilar wound autotransformer is used to properly

match the amplifier to any output impedance tap. The MC

2200 will deliver full power over the entire audio frequency

range at any of these impedances. The MC 2200 will not

overheat when driving low impedance loads {1 ohm, 2

ohms or 4 ohms). The autotransformer also protects speak-

ers from damage in the event of amplifier failure. Should a

direct current component appear in the output it is shunted

by the autotransformer and cannot damage the speaker.

The Mclntosh patented Sentry Monitoring circuit con-stantly monitors the output signal and instantly reacts to

prevent overload of the output transistors. At signal levels

up to rated output this circuit has high impedance and has

no effect upon the output. If the power output exceeds

design maximum, the Sentry monitoring circuit oper-

ates to limit the signal to the output transistors. In the

event of a short circuit across the amplifier output or

severe impedance mismatch the Sentry Monitoring

circuit will protect the output transistors from failure.

The positive and negative halves of the output signal are

monitored independently.

LIMIT INDICATOR AND POWER GUARDThe front panel NORMAL (green) and LIMIT (red) indica-

tors are activated by a newly designed Mclntosh circuit. The

MC 2200 has a built in "waveform comparator." The wave-

form comparator electrically compares the amplifier's out-

put waveform with the input waveform. Should the wave-

form differences reach 0.5%, the red LIMIT indicator on the

front panel is turned on and the NORMAL indicator is

turned off. If the differences increase to 1% the POWER

GUARD circuit is activated. POWER GUARD provides an

unusual margin of safety for loudspeakers by the preven-

tion of amplifier clipping yet permits the amplifier to de-

liver designed maximum power.

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The input waveform and the output waveform are

compared in an integrated circuit differential amplifier.

Any differences, due to distortion of the output waveform,

are converted to a control voltage. This control voltage is

applied differentially to a high gain operational amplifier

where it is amplified about 100 times. The amplified

control voltage is detected by a full wave bridge rectifier

then enters a Schmidt trigger which is programmed to

sequence the front panel indicators from NORMAL (green)

to LIMIT (red} at a preset distortion level. Also built into

the trigger circuit is a timing capacitor which holds theLIMIT indicator on long enough to be visible even when the

duration of the overload is much shorter. The LIMIT indica-

tor will be illuminated for an overload condition as short

as one cycle of a signal at 20,000 Hz.

The same control voltage used to activate the LIMIT

indicator also actuates the POWER GUARD system. If the

control voltage is greater than is needed to illuminate

the LIMIT indication then the POWER GUARD begins op-

erating. The control voltage is used to operate a light

emitting diode/light dependent resistor (LOR) network.

The LDR is part of an attenuator between the volume con-

trol and the input amplifier. The input to the power am-plifier can be attenuated to as little as one tenth, if neces-

sary, in order to maintain low distortion in the event of

excessive input signal.

The POWER GUARD circuit is activated when the rear

panel switch is in the NORMAL position. POWER GUARD

protection is disabled in the OUT position. The LIMIT indi-

cator operates regardless of the position of the POWER

GUARD switch.

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MclNTOSH LABORATORY INC.

2 CHAMBERS ST., BINGHAMTON, N. Y. 13903

607-723-3512

Design subject to change without notice.

Printed in U.S.A.

038-910BE022004