McIntosh | MAC 4200 | 18 performance charts

VARIOUS REGULATORY AGENCIES
REQUIRE THAT WE BRING THE
FOLLOWING INFORMATION TO YOUR
ATTENTION. PLEASE READ IT CAREFULLY.
WARNING: TO PREVENT FIRE OR SHOCK
HAZARD, DO NOT EXPOSE THIS UNIT TO RAIN
OR MOISTURE.
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.
Copyright 1986 © by Mclntosh Laboratory Inc.
Contents
INTRODUCTION
INSTALLATION
HOW TO CONNECT
FRONT PANEL CONTROLS
PERFORMANCE LIMITS
PERFORMANCE CHARTS
TECHNICAL DESCRIPTION
BLOCK DIAGRAM
SPECTRAL FIDELITY
3
4
5, 6, 7, 8
9, 10, 11,
12, 13, 14, 15
16, 17
18, 19, 20
21, 22
23
24
Your MAC 4200 Receiver will give you
many years of satisfactory performance.
If you have any questions, please contact:
CUSTOMER SERVICE
Mclntosh Laboratory Inc.
2 Chambers Street
Binghamton, New York 13903-9990
Phone: 607-723-3512
Take Advantage of 3 years
of Contract Service...
Fill in the Application NOW.
McINTOSH THREE YEAR SERVICE CONTRACT
An application for A THREE YEAR SERVICE CONTRACT is included with this manual.
The terms of the contract are:
1. Your application for the SERVICE CONTRACT must be
6. Always have service done by a Mclntosh authorized
service agency. If the instrument is modified or damagcompletely filled in and must be postmarked within 30
ed as a result of unauthorized repair, the SERVICE
days of the date of purchase of the instrument.
CONTRACT will be cancelled. Damage by improper
2. To receive the SERVICE CONTRACT, all information on
use or mishandling is not covered by the SERVICE
the application must be filled in. The SERVICE CONCONTRACT.
TRACT will be issued when the application is com7.
Mclntosh will provide all parts, materials and labor
pletely filled in and received by Mclntosh Laboratory
needed
to return the measured performance of the inIncorporated in Binghamton, New York.
strument
to the original performance limits. The SER3. To receive the SERVICE CONTRACT, your purchase
VICE
CONTRACT
does not cover any shipping costs to
must be made from a Mclntosh franchised dealer.
and
from
the
authorized
service agency or the factory.
4. The SERVICE CONTRACT is issued to you as the
8.
Units
in
operation
outside
the United States and
original purchaser. To protect you from misrepresentaCanada
are
not
covered
by
the Mclntosh Service Contion, this contract cannot be transferred to a second
tract,
irrespective
of
the
place
of purchase. Nor are
owner.
units
acquired
outside
the
U.S.A.
and Canada, the pur5. Any Mclntosh authorized service agency will repair
chasers
of
which
should
consult
with
their dealer to
Mclntosh instruments at normal service rates. To
ascertain
what,
if
any,
service
contract
or warranty may
receive service under the terms of the SERVICE CONbe
available
locally.
TRACT, the SERVICE CONTRACT CERTIFICATE must be
presented when the instrument is taken to the service
agency.
2
The Mclntosh MAC 4200 is a high quality, FM/AM Stereo
Receiver whose design has been governed by insistence
on high performance with long life, great flexibility and
sensitivity. The rated power output is a 75 watts per channel into 8 ohms or 100 watts per channel into 4 ohms.
You will derive the greatest enjoyment and most
satisfaction when you understand its operations and its
functions. Your time invested now will return added value
to you because then you will get the best results from
your MAC 4200.
The advanced FM/AM tuner design of the MAC 4200
displays the station frequencies digitally. The display of
frequencies in the MAC 4200 serves a double function. It
shows the input selected as well as the frequency to
which the tuner is adjusted. Stations are selected easlily
either by use of the manual tuning knob, or the scan up
or down feature on either band or by use of the preset
feathertouch-buttons in either FM or AM.
The low noise electronic input switching system uses input leads that are very short, one twentieth of the length
of other systems. This provides for reduced hum and
noise, better source to source isolation (lower crosstalk),
lower distortion and freedom from high power TV and
radar signal interference.
The precision tracking volume control allows completely
noise free performance and accuracy of the channel to
channel balance over the full range. It is a step attenuator
whose channel accuracy is within 1 dB throughout its entire rotation. Such extremely accurate matching is achieved through electronically controlled trimming of the
resistance material deposited on pairs of printed circuits.
Use does not affect performance as in ordinary volume
controls.
The loudness control is continuously variable. It
operates independently of the volume control, and its
contour is accurately modeled after the family of "Equal
Loudness" curves developed by Drs. Fletcher and Munson.
Loudness controls in ordinary equipment are usually simple, passive circuits connected to a portion of the rotation
range of the volume control. As a consequence, loudness
compensation accuracy is dependent on many variables
such as speaker efficiency, amplifier gain and differences
in input level.
A five band program equalizer permits the volume adjustment of five important frequency ranges. Musical
balance can be adjusted to compensate for listener
preferences or recording inaccuracies. At the detent in the
center of the rotation of each control the equalizer circuits are disconnected, completely removed from the
operating circuits.
Front panel tape recorder jacks make playback from, or
copying to, a portable recorder very convenient. The ad-
ditional tape recorder may be connected to the
MAC 4200 without disconnecting your regular system.
The MAC 4200 switching circuits allow the AC power to
the entire stereo system to be controlled from either the
turntable's power switch or the power switch on this exceptional receiver. Connected to a special power outlet is
a current sensing relay that will be energized when the
turntable is turned on or when the red power switch is
pushed on. The relay, in turn, controls the AC power to
the rest of the stereo system.
POWER GUARD dynamically permits the power amplifier circuit in the MAC 4200 to deliver full maximum
power without the music destroying sounds of hard clipping; the music you hear is protected from distortion and
your speakers are protected from damage.
Electronically regulated power supplies maintain stable
operation even during periods of low or changing AC
power line voltage.
INTRODUCTION 3
The MAC 4200 may be used on a shelf or table top in
the enclosure in which it comes or may be installed in a
custom cabinet. In any method of use provide adequate
ventilation.
The trouble-free life of any electronic instrument is
greatly extended by providing sufficient ventilation to prevent the build-up of heat that causes deterioration of
component parts. Allow enough clearance so cool air can
enter at the bottom of the receiver and be vented from
the top and rear. The feet installed on the bottom of the
receiver must be left in place when using a shelf or table
top installation. The feet raise the receiver above the
mounting surface to allow reasonable ventilation. If
temperatures increase due to restricted ventilation or
speaker mismatch, an automatic temperature sensing
device turns off the MAC 4200. The device operates
automatically at a preset temperature. The MAC 4200 will
turn on again when the temperature has returned to normal limits. This additional feature assures complete
reliability under the most extreme operating conditions.
INSTALLING THE MAC 4200
IN A CUSTOM CABINET
The MAC 4200 is installed from the front of a custom
cabinet. The space needed behind the cabinet panel is
15"(38.1cm) deep, 18-1/2" (47cm) wide, and 6" (15.2cm)
high by 17-9/16" (44.6cm) wide. The cabinet panel must
be cut out 5-1/16" (12.9cm) high. Make this cutout carefully. The receiver's front panel has a 1/8" (.32cm) overhang
on both sides and a 3/32" (.24crn) overhang on the top
and bottom, (see Fig. 1)
The weight of the receiver must rest on a shelf in the
custom cabinet with a 15" (38.1cm) x 8" (20.32cm) ventilation hole cut out. (see Fig. 2) In addition, a single 3/8"
to 1/2" (1cm to 1.3cm) diameter hole (see Fig. 2 and Fig.
3) must be drilled in the shelf. A screw inserted through
this hole secures the receiver after installation. The top of
the shelf must be flush with the bottom of the custom
panel cutout.
cover edges of the panel cutout. Lock the unit in place
with a screw and washer inserted through the drilled hole
in the mounting shelf (see Fig. 3). Use a 1-1/4" (3.2crn)
screw for 1/2" (1.3cm) shelf or a 1-1/2" (3.8cm) screw for
3/4" (1.9cm) shelf. Do not use longer screws since they
will contact electrical circuits which can lead to equipment failure and possible injury.
Fig. 1 Custom Cabinet Front Panel Cutout
Fig. 2 Custom Cabinet Shelf Mounting Cutout
Fig. 1 Custom Cabinet Front Panel Cutout
Prepare the MAC 4200 for custom mounting by removing the wood sides and feet:
1. Remove 4 screws; two from each side panel and
remove the panels.
2. On the bottom of the receiver are the 4 plastic feet
held on by screws. Remove these feet. Do not attempt
to remove the 4 plastic button glides as these rest
against the shelf, (see Fig. 2 and 3) At this point the
receiver is ready to be installed.
From the front of the cabinet, thread the power cord
through the opening in the cabinet panel and slide the
MAC 4200 on to the shelf. Adjust the position to evenly
4 INSTALLATION
Fig. 3 MAC 4200 Custom Mounting Profile
Use shielded cables to connect the signal from the
preamplifier or signal source to the power amplifier. To
minimize the possibility of hum the shielded cables
should be of parallel construction or loosely twisted
together, located away from the speaker connecting
cables and AC power cords. Be certain to use good quality shielded cables for all interconnections. Your dealer
can advise you on the kind and length of cable that will
best suit your installation.
The appropriate length and size of the loudspeaker
cable for your installation will help to preserve the high
quality of sound for which the loudspeakers have been
designed. If undersize wire is used, resistance is added to
the amplifier/loudspeakers combination which adversely
affects the performance. Added resistance reduces the
damping factor, modifies the frequency response and
reduces the power output. Your dealer's advice will serve
you best for your installation. The cables to and from the
speaker should be of parallel construction or be loosely
twisted together. The chart shows the recommended
minimum wire size for the length of wire between the
amplifier and the loudspeakers.
SPEAKER CABLE LENGTHS
AMPLIFIER TO SPEAKER
For 4 Ohm Load
For 8 Ohm Load
Wire
Meters
Feet
Meters
Gauge
9.1
18
4.6
30
15.2
25
7.6
50
16
12.2
HO
24.4
14
40
18.3
36.6
12
60
120
60.0
10
100
30.48
200
These speaker cable lengths represent a wire resistance
equal to 5% of a speaker impedance, or 97.5% transfer of
power.
Feet
15
HOW TO CONNECT LOUDSPEAKERS
Rear panel push connectors are provided for three pairs
of stereo speakers. The corresponding front panel
pushbuttons turn the speaker pairs on or off.
Connect the leads from the left main (1) loudspeaker to
the SPEAKERS L 1 and Common push connectors.
Connect the leads from the right main loudspeaker to
the SPEAKERS R 1 and Common push connectors. Connect a second and third pair of speakers to the SPEAKERS
2 and 3 push connectors in a similar manner. To maintain
frequency response, power output and damping
characteristics, each speaker requires a separate cable between the receiver and the loudspeaker.
HOW TO CONNECT A TURNTABLE
Connect the left channel cable of the turntable to the L
PH1 INPUT jack. Connect the right channel cable of the
turntable to the R PH1 INPUT jack. Connect a second
turntable to the PH2 input jacks in the same way. Connect the turntable's ground wire to the GND terminal.
Automatically shorting phono jacks eliminate the potential for hum and crosstalk and the need for shorting plugs.
CONNECTING PROGRAM
SOURCE GROUNDS
A ground (GND) 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
loosely twisted together. Make sure the ground wire does
not make any contact to the shields of the left and right
program cables as they run between the source and the
input of the preamplifier.
HOW TO CONNECT A CD PLAYER
Connect a cable from the left channel output of a compact disc player to the L CD input jack. Connect a cable
from the right channel output to the R CD input jack.
When the MAC 4200 input selector switch is turned to
CD/AU2 (compact disc player or auxilliary source) the station display area will show AU2.
HOW TO CONNECT TV AUDIO
Audio from a TV monitor or any other high level source
is connected to the AUX INPUTS. Connect a cable from
the left channel audio output of a TV monitor or other
high level source, to the L AUX INPUT jack. Connect a
cable from the right channel audio output to the R AUX
INPUT jack.
When the MAC 4200 input selector switch is turned to
the TV AU 1 position (television set or auxilliary source),
the station digital display area will show AU 1.
HOW TO CONNECT TAPE RECORDERS
TO RECORD:
Connect a cable from the MAC 4200 L TAPE 1 OUT jack
to the left high level input of a tape recorder. Connect a
cable from the R TAPE 1 OUT jack to the right high level
input of a tape recorder. Connect a second tape recorder
in the same manner to the TAPE 2 OUT jacks.
TO PLAYBACK OR MONITOR TAPE:
Connect a cable from the left channel output of a tape
recorder to the MAC 4200 L TAPE 1 IN jack. Connect a
cable from the right channel output of a tape recorder to
the R TAPE 1 IN jack. Connect a second tape recorder in
the same manner to the TAPE 2 IN jacks.
FRONT PANEL TAPE 2 RECORDER JACKS
TAPE 2 input and output connections are also available
at the TAPE 2 IN-OUT jacks on the front panel. Metal
shielded 1/4" stereo phone plugs are used. The connec-
HOW TO CONNECT 5
tions are tip: left signal; ring: right signal; sleeve: common
ground.
When a plug is inserted in the front panel TAPE 2
IN jack, the circuits to the rear panel TAPE 2 INPUTS are
disconnected. Inserting a plug in the front panel TAPE 2
OUT jack does not disconnect the rear panel TAPE 2
OUT. It is possible to record from the front panel TAPE 2
OUT jack and the rear panel TAPE 2 OUT jack at the
same time. However, it is not possible to listen (or
monitor) from both the front and rear TAPE 2 IN jacks at
the same time.
THE ELECTRONIC MEMORY BATTERY POWER SUPPLY
A very long life, rechargeable battery power supply provides the energy for the electronic memory when the
receiver is turned off. When first connected, it is wise to
assume that the batteries have not been charged. The
charge rate is dictated by the 'on' time of the receiver. To
bring the batteries to full charge, leave the receiver turned on for twenty-four continuous hours. Programmed instructions will be retained for more than six months with
the receiver turned off if the batteries are fully charged.
After the batteries are fully charged, use for approximately one hour per week, will maintain the batteries in a fully
charged state.
HOW TO CONNECT AC POWER
A polarized AC plug is used on the MAC 4200. Plug it
into a 120 volt 60 Hz wall outlet. The plug blades must
be fully inserted in the outlet to prevent shock from exposed blades.
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.
Three types of AC power outlets are provided on the
back panel of the MAC 4200: 2 black, 2 green and one
red.
The black outlets are switched on or off when the
MAC 4200 is turned on or off. These are intended for CD
players, equalizers or other accessories, whose total
power requirement is 600 watts.
The red outlet is on at all times. For example, a VCR
(video cassette recorder) can be plugged into this outlet
for recording a TV program when the receiver is not turned on. Neither the red outlet nor the black outlets are
fused.
AC power to the green outlets are controlled by the
AUTOMATIC SYSTEM AC ON/OFF.
AUTOMATIC SYSTEM AC TURN ON/OFF
The POWER ON pushbutton shares AC power control,
with the AC power switch on a turntable, through a current detecting switch circuit. On the rear panel, the TURNTABLE AUTO/MANUAL switch selects the mode of operation.
When the switch is in the AUTO position and a turntable plugged into one of the green AC power outlets,
the AC power to the receiver and to the black AC power
outlets can be controlled by the turntable on/off switch.
When AC power to the turntable is turned on, power to
the receiver and the black AC power outlets is turned on.
When in the automatic mode, the system will remain on
until the turntable is turned off. The POWER ON pushbutton controls the AC power when using any source other
than the turntable.
In the MANUAL position only the red POWER ON
pushbutton will turn AC power on or off. Power from the
green AC power outlets can not exceed 100 watts.
Some turntables have electronic circuits that draw current all the time. To use these turntables the
AUTO/MANUAL switch must be in the MANUAL position.
CONNECTING AN FM ANTENNA
Provisions have been made for the use of one of three
antenna systems: (1) an outdoor FM antenna, or (2) a VHFTV antenna, or (3) the indoor dipole supplied.
An outdoor antenna is recommended for optimum performance in all areas. In fringe (outlaying) areas, best
results will be obtained with a highly directional FM
antenna used in conjunction with a rotator. If the antenna
uses a 300 ohm lead, connect it to the ANTENNA 300 ohm
FM push connectors.
If the antenna uses a 75 ohm coaxial cable, connect it to
the rear panel ANTENNA 75ohm type F connector.
An outside antenna system should not be located in the
vicinity of overhead power lines or other electric light or
power circuits, or where it can fall into such power lines
or circuits. When installing an outside antenna system, extreme care should be taken to keep from touching such
power lines or circuits as contact with them might be
fatal.
A VHF-TV antenna can be effective when it is designed
for both FM and TV reception. Connect the two leads
from the VHF-TV antenna to the ANTENNA 300 FM push
connectors.
CONNECTING AN INDOOR
DIPOLE ANTENNA
The flexible folded dipole antenna (300 ohm) is for use
in urban or high strength signal areas. Connect the two
leads from the dipole to the ANTENNA 300 FM push connectors.
The flexibility of the twin flat wire assembly permits it to
be placed under a rug, tacked behind the stereo...or placed in any other convenient location. In some cases, it
6 HOW TO CONNECT
HOW TO CONNECT 7
may be necessary to "position" the antenna for best signal
reception. This should be done before it is permanently
located.
Avoid locating the antenna next to other wires or metal
objects. Any indoor antenna may be ineffective in houses
having metal siding or metal foil insulation.
AM ANTENNA
For local and most moderately distant AM reception the
built-in ferrite loopstick antenna may be used. The
loopstick is mounted on a swivel base and must be adjusted away from the chassis for best reception.
Distance reception can be improved with the use of a
copper antenna wire 50 to 150 feet in length. Suspend
the wire, horizontally, in a straight line as high as possible.
Attach the wire to an anchor at each end with suitable
glass or ceramic insulators. Connect a lead-in wire at a
convenient point on the antenna. Use a lighting arrester
for protection with an outdoor AM antenna. The arrester
should be well grounded to a ground rod or cold water
pipe.
quirements need to be controlled at the remote amplifier
In this configuration, the TAPE 1 connections can not be
used for a tape recorder.
HOW TO CONNECT REMOTE SCAN
The remote scan switch/cable assembly plugs into the
rear panel REMOTE SCAN input jack. The cable assembly
is a Mclntosh accessory (Part No. 045-515} available from
your dealer.
HOW TO CONNECT A MclNTOSH EQUALIZER
POWER AMP IN and PREAMP OUT jacks are provided
on the rear panel for connecting a Mclntosh Environmental Equalizer, or other signal processing equipment. Connect the left and right shielded cables from the signal processor outputs to the Left and Right POWER AMP IN
jacks. Then connect shielded cables between the Left and
Right PREAMP OUT jacks to the equalizer inputs.
The input jacks are automatic switching jacks that
disconnect the preamplifier's output signal from the
power amplifier's input and connects the signal
processor's output with the power amplifier's input.
HOW TO CONNECT
ADDITIONAL POWER AMPLIFIERS
External power amplifiers may be fed from the
MAC 4200 in two ways:
1. Connect a shielded cable from the Left and Right
PREAMP OUT jacks to the Left and Right input of the
power amplifier. The PREAMP OUT jacks are affected by
the VOLUME, EQUALIZER, BALANCE and LOUDNESS controls. Both the MAC 4200 amplifier and the additional
amplifier will be fed from the preamplifier. If the MAC
4200 amplifier is not going to be used, insert a pair of
non-shorting phono plugs in the POWER AMP IN jacks to
disconnect it from the preamplifier output.
2. The TAPE 1 or TAPE 2 OUT jacks may be used to
drive an external amplifier which has its own controls. The
output of these jacks is not affected by the VOLUME,
EQUALIZER, BALANCE and LOUDNESS controls on the
receiver. A suggested use would be to feed an amplifier
in a remote location where volume and tone re-
8 HOW TO CONNECT
INPUT SELECTOR
Use the six position INPUT SELECTOR switch to select
the program source to which you wish to listen. The program selected will also be fed to the TAPE OUT jacks.
TV/AU1: To listen to any high level source such as a TV
monitor or tape recorder. The station display area will
show AU1.
CD/AU2: To listen to a compact disc player or other
high level source. The station display area will show AU2.
AM: To listen to AM radio broadcasts. The station
display area will show the AM station frequency in
kilohertz.
FM: To listen to FM stereo radio broadcasts. The station
display area will show the FM station frequency in
megahertz.
PH1: To listen to a record player connected to PH1 input jacks. The station display area will show PH1.
PH2: To listen to a second record player connected to
the PH2 input jacks. The station display area will show
PH2.
EQUALIZER FREQUENCY CONTROLS
Each of the five EQUALIZER FREQUENCY controls raises
or lowers the volume of a band of frequencies whose
center is the frequency marked above the control. Both
left and right channels are affected by each control. The
center or flat response position of each control has a detent for easy reference. When each control is in the detent position the equalizer is removed from the preamplifier circuits and the response is perfectly flat with
the equalizer circuits removed from the signal path.
Use the EQUALIZER FREQUENCY controls to modify the
sound and balance of program material. Here are some
suggestions with which to start.
ADJUSTMENT TO:
Make deep bass louder
Make all bass louder
Reinforce voices
Brighten violins
and trumpets
Emphasize cymbals
EQUALIZER CORRECTION
Raise 30
Raise 30 and 150
Lower 150 and raise 500
Raise 1500
Raise 10k
FRONT PANEL CONTROLS 9
USING THE PUSHBUTTONS
TAPE PUSHBUTTONS:
The MAC 4200 is designed so it may be used with two
tape recorders. Four TAPE pushbuttons control the signal
inputs and outputs of the tape recorders. Recordings can
be monitored as they are being recorded. Tapes can also
be copied from one recorder to another while listening to
a different program source.
The MONITOR switches are mechanically interlocked to
prevent simultaneous monitoring from two tape
recorders. If one button is at the IN position, it must be
pushed again to release it to the OUT position before the
other button can be pushed.
With either MONITOR pushbutton at the IN position,
the program heard will be that from the tape recorders
only. Signal from any other source will not be heard from
the loudspeakers. To hear any other source, make sure
the MONITOR pushbuttons are OUT.
MONITOR...TAPE 1
Pushbutton OUT: The program source selected by the
INPUT SELECTOR will be heard through the speakers.
Pushbutton IN: Program from a tape recorder plugged
into TAPE 1 IN will be heard through the speakers.
MONITOR...TAPE 2
The functions are the same as MONITOR...TAPE 1. In addition, it controls the signal from a tape recorder plugged
into the front panel TAPE IN jack. A recorder plugged into
the front panel jacks disconnects the rear panel TAPE 2 IN
jacks, automatically. The TAPE 2 OUT jacks on both front
and rear panels are always connected.
TAPE COPY...T1->T2 pushbutton in: connects the output
from tape recorder 1 to the input of tape recorder 2
without affecting the program being heard from the
speakers. In this position, a copy of the program on tape
recorder 1 can be made on tape recorder 2. To monitor
the original, use MONITOR...TAPE 1 pushbutton. To
monitor the copy use MONITOR...TAPE 2 pushbutton.
TAPE COPY...T2->T1 pushbutton in: connects the output
from tape recorder 2 to the input of tape recorder 1
without affecting the program being heard from the
speakers. In this position a copy of the tape program on
recorder 2 can be made on recorder 1. To monitor the
original use MONITOR...TAPE 2 pushbutton. To monitor
the copy use MONITOR...TAPE 1 pushbutton. When both
MONITOR pushbuttons are out, you hear the program
selected by the INPUT SELECTOR.
10 FRONT PANEL CONTROLS
MONO
The MONO pushbutton switches the audio output of
the receiver from stereo mode to MONO. When the INPUT SELECTOR is in the FM position and tuned to a stereo
broadcast the FM MPX light will remain on regardless of
the position of the MONO pushbutton. The program, with
the MONO pushbutton in, will be heard as mono. The
TAPE OUT jacks are not affected by the MONO or MUTE
pushbuttons.
With the MUTE pushbutton in, and when using the
manual tuning knob, between station noise and weak
noisy stations are suppressed. FM muting automatically
eliminates between station noise when using the preset station selector feathertouch-buttons or when SCAN tuning.
SPEAKERS 1, 2, and 3
When each of these pushbuttons are pressed IN, the
output of the receiver is fed to the pair of loudspeakers
connected to the corresponding rear panel SPEAKER push
connectors. SPEAKERS 1, 2, and 3 may be selected singly,
in any combination or all at once.
POWER ON
The red pushbutton turns the AC power on or off.
When the power is on, the display area panel
Illuminates. The turntable can also be used as a power
switch. (See "HOW TO CONNECT" "AUTOMATIC SYSTEM
TURN ON/OFF".)
BALANCE AND LOUDness:
The BALANCE and LOUDNESS controls are concentric.
Adjusting the BALANCE control (large outer knob) adjusts
the volume of the channels relative to each other and
does not change the overall volume of sound in your
listening room.
LOUDness:
After setting the VOLUME control for the desired listening level, adjust the LOUDness control for the preferred
compensation. Adjusting the LOUDness control will not
affect the overall volume of sound in your listening room.
The LOUDness control (small center knob) contours the
frequency response to compensate for the hearing
characteristic of the human ear at lower listening levels.
The contour is accurately modeled after the family of
"equal loudness" curves identified by Fletcher and Munson. At the fully counterclockwise detented position, the
LOUDness compensation is out of the circuit, so the
FRONT PANEL CONTROLS 11
response is electrically flat. As the control is turned
clockwise, both bass and treble frequencies increase in
the correct proportion to each other. The contour is not
affected by different settings of the VOLUME control.
VOLUME
The VOLUME control is a precision step control
manufactured for Mclntosh Laboratory. It has 32 steps
with a 70 dB range. Left and right channel tracking is
within a fraction of a dB. This extreme accuracy is obtained through special electronically controlled resistance element trimming.
HEADPHONE JACKS
Plug headphones into the front panel HEADPHONE jack.
Adjust the front panel VOLUME control for comfortable
headphone listening.
Signal to the headphone jacks is constant and is not affected by the SPEAKER switches.
The circuits feeding the HEADPHONE jacks have been
designed to feed low impedance dynamic headphones.
Electrostatic headphones generally require higher power
than dynamic headphones. Connect electrostatic headphones to the SPEAKER push connectors on the rear
panel.
PRESET STATION SELECTING
FEATHERTOUCH-BUTTONS
A momentary press on one of the feathertouch-buttons
marked 1 through 6, will recall from the electronic
memory the preset AM or FM station assigned to that
feathertouch-button. The corresponding red indicator
above the digital frequency display will then light.
ENTER
The ENTER feathertouch-button and any one of the six
momentary feathertouch-buttons are used to insert into
the electronic memory the tuned FM or AM station. Six
AM and six FM stations can be preset.
To enter a station in the memory, tune to the desired
station with either the manual tuning knob or SCAN tuning. Then, while pressing the ENTER feathertouch-button,
press feathertouch-button 1. Release both feathertouchbuttons and the station tuned will be recorded in the
electronic memory for instantaneous recall when
feathertouch-button 1 is pressed.
The preset memory circuits are maintained by a special
long life battery power supply that is charged when the
AC power is turned "ON". When the receiver is first connected it is wise to assume that the batteries have not
12 FRONT PANEL CONTROLS
been charged. The charge rate is dictated by the time the
receiver is turned 'on' without regard to the mode of
operation. For instance the batteries will charge should
you wish to play records, or tape on FM. To bring the
batteries to full charge, operate for twenty-four continuous hours. When fully charged, and with the receiver
turned off the programmed instructions will be retained
for more than six months. After the batteries are fully
charged, use for approximately one hour per week, will
maintain the batteries in a fully charged state.
MANUAL
A momentary press of the MANUAL feathertouch-button
will activate the manual tuning knob and the red indicator
above the knob will turn on. Rotate the tuning knob until
the frequency of the desired station shows in the station
display area.
A station is correctly tuned when the center vertically
displayed ( ) arrow at the bottom of the SIGNAL/TUNING
display, lights. On each side of the center arrow are
horizontaly displayed (
) arrows. One of these will
light as a station is approaced to indicate tuning above or
below the center frequency of the FM station. FM stations
broadcasting in stereo light the FM MPX bar indicator
above the SIGNAL/TUNING indicator.
An AM station is correctly tuned when the center (vertically displayed) arrow at the bottom of the SIGNAL/TUNING display lights. On AM, the horizontally displayed arrows do not function.
A momentary press on any of the numbered
feathertouch-buttons or SCAN activates that tuning
method selected and deactivates the manual tuning knob.
SCAN
Use the SCAN feathertouch-button to automatically tune
to the next station either up or down the broadcast band
selected. The arrow beside the feathertouch-button indicates the direction of the scan. When a remote scan
cable/switch is inserted in the rear panel receptacle, a
momentary press of the remote button will activate the
tuner scan-up circuit. The remote scan cable/switch
assembly, (Mclntosh Part No. 045-515) can be obtained
from your Mclntosh dealer.
FRONT PANEL CONTROLS 13
SIGNAL/TUNING INDICATOR
The SIGNAL/TUNING indicator is to the right of the station display area. The vertical column of LED indicators
show the relative signal strength of an AM or FM station
being received. The greater the number of dots illuminated, the greater the received station's signal
strength.
AFL
While tuning, the automatic frequency lock (AFL) circuit
is deactivated. When properly center channel tuned, the
center tuning arrow lights and the AFL circuit activates to
lock on to the broadcast stations precise frequency
preventing any detuning or drift from the broadcast station. The locking action of the AFL circuit makes tuning
easy. Mclntosh AFL will give the best FM and AM reception with lowest background noise, lowest distortion and
highest FM stereo channel separation.
Although the tuner can be tuned very slightly off the station's frequency without degrading the program material,
this "near" tuning can cause the station to be 'lost' when
power is turned off and then turned on again. To prevent
this, always rotate the manual tuning knob until the
center tuning arrow only is lighted.
The MANUAL AFL switch is on the back panel, behind
the AM loopstitch antenna. Set this switch to NORMAL for
most listening. To make it easier to tune a weak station
next to a strong station use the manual tuning knob with
the MANUAL AFL switch in the OUT position.
POWER OUTPUT INDICATORS
The amplifier POWER output indicators are to the left of
the station display area. There are two vertical colums of
red Light Emitting Diode (LED) bar indicators; one for each
channel.
The left column represents the output from the left
channel and the right column the right. Each row is independent of the other. As power output increases, more
bar indicators are turned on. The power indicators provide constant and instant information on the amount of
power being fed to your speakers.
When the POWER GUARD* circuit is activated, the top
bar on each side will light and the other POWER indicators turn off.
*U.S. Patent #408573
14 FRONT PANEL CONTROLS
POWER GUARD*
POWER GUARD* assures that the amplifier can not be
overdriven so amplifier output clipping is eliminated.
Clipping is caused when the amplifier is asked to produce
more power output than it can deliver with low distortion. Amplifiers are capable of delivering large quantities
of power when they are driven to clipping and can have
more than 40% harmonic distortion. The extra energy content of the clipped signal will damage most speakers. A
Mclntosh advancement helps to protect your speaker
from this kind of damage. The POWER GUARD* circuit
compares the wave shape of the input signal with the output signal. If the non-linearity between the two signals exceeds 0.5% the POWER GUARD* circuit operates.
BALANCE YOUR STEREO SYSTEM
The performance and enjoyment of a stereo system is
greatly increased when the sound is properly balanced.
The balance of the stereo system is affected by many
things including the phase relationship of the
loudspeakers, room acoustics, furniture placement, room
shape, small differences in loudspeakers etc.
TO ADJUST LOUDSPEAKER PHASE
Press the MONO pushbutton. Play a familar recording.
Turn the BALANCE control to 12 o'clock. Stand about ten
feet in front of and midway between the loudspeakers.
The sound should appear to come directly from in front
of you. If the sound is not directly in front of you, reverse
the leads on one of the loudspeakers only. When the
sound comes from the midpoint between the speakers
they are in phase.
TO BALANCE LOUDNESS
Press the MONO pushbutton. Turn the BALANCE control
to the 12 o'clock position. While the program is playing,
stand between the two loudspeakers. For any difference
in loudness between speakers, turn the BALANCE control
toward the speaker that is not as loud. Adjust until the
sound is equal in loudness from each speaker.
FRONT PANEL CONTROLS 15
PERFORMANCE GUARANTEE
Performance Limits are the maximum deviation from
perfection permitted for a Mclntosh instrument. We promise you that when you purchase a new MAC 4200 from
a Mclntosh franchised dealer, it will be capable of or can
be made capable of performance at or exceeding these
limits or you can return the unit and get your money
back. Mclntosh is the only manufacturer that makes this
statement.
PERFORMANCE
Mclntosh audio power ratings comply with the Federal
Trade Commission Regulation concerning power output
claims for amplifiers used in home entertainment products.
POWER OUTPUT
100 watts minimum sine wave continuous average
power output, per channel, both channels operating into
4 ohms, 20 Hz to 20 kHz, with no more than 0.02% total
harmonic distortion.
75 watts minimum sine wave continuous average power
output, per channel, both channels operating into 8 ohms
20 Hz to 20 kHz, with no more than 0.02% total harmonic
distortion.
OUTPUT LOAD IMPEDANCE
4 ohms, and 8 ohms
RATED POWER BAND
20 Hz to 20,000 Hz
TOTAL HARMONIC DISTORTION
0.02% maximum harmonic distortion at any power level
from 250 milliwatts to rated power per channel from 20
Hz to 20,000 Hz, both channels operating.
INTERMODULATION DISTORTION
0.02% maximum harmonic distortion at any power level
from 250 milliwatts to rated power per channel both
channels operating for any combination of frequencies 20
Hz to 20 kHz.
FREQUENCY RESPONSE
20 Hz to 20 kHz +0 -0.5 dB at rated power.
TAPE OUTPUT
Tuner: 1.0 V at 100% modulation (FM)
Tape: 250 mV with rated input
Phono: 250 mV with rated input
PROGRAM EQUALIZER
±12 dB at 30, 150, 500, 1500, and 10,000 Hz
FM SECTION
SENSITIVITY
20 µV across 300 ohms 1.0µV across 750 ohms (11.25
dBF)
SIGNAL TO NOISE RATIO
STEREO: 70 dB minimum
MONO: 75 dB minimum
HARMONIC DISTORTION:
MONO: 0.08% at 100 Hz
0.08% at 1000 Hz
0.12% at 10,000 Hz
STEREO: 0.12% at 100 Hz
0.12% at 1000 Hz
0.50% at 10,000 Hz
FREQUENCY RESPONSE
20 Hz to 15 kHz +0, -1 dB
CAPTURE RATIO
1.5 dB
ALTERNATE CHANNEL SELECTION
65 dB
SPURIOUS REJECTION
100 dB
IMAGE REJECTION
80 dB
STEREO SEPARATION
45 dB at 100 Hz
55 dB at 1000 Hz
35 dB at 10,000 Hz
SCA REJECTION
65 dB minimum
NOISE AND HUM
Power Amp: 100 dB below rated output (85 dB IHFA).
Tape and AUX Input: 95 dB below rated output (80 dB
IHFA).
Phono Input: 90 dB below 10 mV input (80 dB IHFA).
DAMPING FACTOR
Greater than 40
INPUT SENSITIVITY AND IMPEDANCE
Power Amp: 2.5V (280mV IHF); 22,000 ohrns
Tape and AUX: 250 mV (28mW IHF), 35,000 ohms
Phono: 2mV (22µV IHF), 47,000 ohms 47 pF
16 PERFORMANCE LIMITS
AM SECTION
SENSITIVITY
75µV IMF (External antenna)
SIGNAL TO NOISE RATIO
50 dB at 30% modulation, 60 dB at 100% modulation
HARMONIC DISTORTION
1% maximum at 30% modulation (0.3% typical)
FREQUENCY RESPONSE
-6 dB, at 3500 Hz
ADJACENT CHANNEL SELECTIVITY
30 dB minimum IHF
IMAGE REJECTION
60 dB minimum, 540 kHz 1600 kHz
GENERAL INFORMATION
SEMICONDUCTOR COMPLEMENT
142 Silicon Diodes
18 Tuning Devices
1 Silicon Controlled Rectifier (SCR)
42 Light Emitting Diodes
4 Seven Segment LED Displays
67 Bipolar Transistors
21 Field Effect Transistors
37 Integrated Circuits
AC POWER OUTLETS
2 Green, turntable current-sensing, 100 watts
2 Black, switched, 1 Red, unswitched, 1200 watts, total
POWER REQUIREMENTS
120 volts, 50/60 Hz, 60 to 480 watts
MECHANICAL INFORMATION
SIZE
Width: 18-9/16 inches (47.1 cm); with walnut wood sides
removed: 17-9/16 inches (44.6 cm). Height: 6-1/16 inches
(15.4 cm); with the feet removed 5-1/4 inches (13.3 cm).
Depth: 14 inches (35.6 cm) from the mounting surface to
the rear panel, including connectors. Knob and handle
clearance required is 1-1/16 inches (2,7 cm) in front of the
mounting surface.
FINISH
Front panel is brushed black anodized with gold anodized
trim. Side panels are machined solid walnut with satin lacquer finish.
WEIGHT
40 pounds (18.1 kg) net, 54 pounds (24.5 kg) in shipping
carton.
PERFORMANCE LIMITS 17
HARMONIC DISTORTION IN PERCENT
FM HARMONIC DISTORTION, 100% MODULATION
0.2
0.15
0.1
0.05
0
20
1k
100
10k
20k
INTERMODULATION DISTORTION
IN PERCENT
FREQUENCY IN HERTZ
INTERMODULATION DISTORTION
VS. POWER OUTPUT
8 OHM OUTPUT
INPUT FREQUENCIES 60 Hz AND 7 kH7
INPUT RATIO: 4.1
0.2
0.1
0
0.1
1
10
100
POWER OUTPUT IN EQUIVALENT AVERAGE WATTS
0.02% THD POWER BANDWIDTH
BOTH CHANNELS OPERATING
140
130
0.10
120
0.09
110
0.08
100
0.07
90
0.06
80
POWER OUTPUT
IN WATTS RMS
HARMONIC DISTORTION
IN PERCENT
HARMONIC DISTORTION VS POWER OUTPUT
RL = 8 OHMS, BOTH CHANNELS OPERATING
0.05
0.04
0.03
70
60
50
0.02
40
0.01
30
0
20
0.1
1
10
100
POWER OUTPUT IN WATTS RMS
1k
10
0
10
1k
100
FREQUENCY IN Hz
18 PERFORMANCE CHARTS
10k
100k
FREQUENCY RESPONSE OF
EQUALIZER FREQUENCY CONTROLS
SET AT MAXIMUM AND MINIMUM
20
RESPONSE IN dB
10
0
-10
-20
20
10k
1k
100
20k
FREQUENCY IN HERTZ
OUTPUT SIGNAL AMPLITUDE
OUTPUT SIGNAL WAVEFORM SHOWING ACTION
OF POWER GUARD TO ELIMINATE OUTPUT SIGNAL
CLIPPING. POWER AMPLIFIER INPUT IS OVERDRIVEN BY
20 dB FOR BOTH OSCILLOGRAM TRACES.
FM PERFORMANCE, 98 MHz 1kHz MODULATION
OUTPUT LEVEL IN dB
-20
-30
-40
-50
-60
Time
-70
0
10
20
30
40
50
60
70
8O
90
100
INPUT LEVEL IN dBF
FM FREQUENCY RESPONSE
AND STEREO SEPARATION
+ 10
0
LEVEL IN dB
-10
-20
-30
-40
-50
-60
-70
2(1
100
1k
10k
20k
FREQUENCY IN HERTZ
PERFORMANCE CHARTS 19
AM FREQUENCY RESPONSE
+ 10
RELATIVE OUTPUT IN dB
0
-10
-20
-30
-40
10k
1k
100
20
20k
FREQUENCY IN HERTZ
FM SELECTIVITY
AM SELECTIVITY
+ 10
-20
RELATIVE OUTPUT IN dB
RELATIVE OUTPUT IN dB
0
-30
-40
-50
-10
-20
-30
-40
-60
-70
-80
-600
-400
-200
0
200
400
600
FREQUENCY IN kHz
20 PERFORMANCE CHARTS
ELECTRONIC INPUT SWITCHING
EQUALIZER
Input switching is done electronically using J-FET field effect analog switches. The front panel switch controls small
amounts of DC voltage which turn the J-FET analog
switches on or off. The critical audio signals are switched
silently with instantaneous muting between switch positions. No transient switching noises or pops are present
with this superior design.
The equalizer amplifier uses high technology integrated
circuit operational amplifiers with the output stage optimized for the best transient performance with minimum
distortion. Five other operational amplifiers are arranged
in a circuit configuration equivalent to a series tuned circuit, one at each of the five center frequencies. Each circuit is activated by the control potentiometer in either the
input circuit or feedback circuit of the operational
amplifier providing a boost and cut capability of 12 dB for
each band of frequencies. When the potentiometer is in
the center or detent position, the operational amplifier is
out of the circuit completely.
PHONO AMPLIFIER
The phono amplifier uses a high technology integrated
circuit operational amplifier. Its differential input stage has
been optimized for low noise and low distortion performance. The integrated circuit's open loop gain is 100,000.
With high open loop gain a large amount of negative
feedback can be used around the phono amplifier to further reduce noise and distortion. The feedback network,
provides in addition, RIAA frequency compensation. Components in the network are 1% metal film resistors and 5%
poly film capacitors. To achieve low noise performance it
is essential that the feedback network be very low impedance. The actual power output capability of this
preamplifier stage is more than 100 milliwatts.
The phono amplifier has a very wide dynamic range. Input sensitivity of the phono amplifier is 2 millivolts with a
gain of 40 dB at 1000Hz. At 1000Hz the phono input circuit will accept 100 millivolts without overload. This is a
voltage far greater than the output of any currently used
magnetic phono cartridge, assuring protection from
overload. 10 millivolts at the phono input at 1000Hz will
produce 1 volt at the tape output. The tape output
source impedance is 200 ohms, designed to operate into
a load impedance of 10,000 ohms or greater.
HIGH LEVEL 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.
Typical loudness controls have used simple passive circuits connected to a tap on the volume control. As a consequence, compensation accuracy was dependent on
many variables such as volume control position and differences in the input level. The MAC 4200 loudness control uses active circuits composed of an integrated circuit
operational amplifier with two feedback loops. One has
flat frequency response. The other has response conforming to the Fletcher-Munson equal loudness contours. A
potentiometer is placed between these two feedback
loops making it possible to select any combination of the
two, from a flat response to full loudness compensation.
The overall gain of the stage is 15 dB at mid-frequencies.
Listening volume is not affected by the position of the
loudness control.
AMPLIFIER
POWER AMPLIFIER SECTION
The MAC 4200 power amplifier requires 1.4 volts RMS
to drive it to rated output. The input impedance is 22,000
ohms. The input stage of the amplifier uses two transistors
connected as a differential amplifier output. The differential amplifier permits the best use of negative feedback for
low noise and low distortion performance. The outputs of
the differential amplifier are combined in a current mirror
to form a single output. This combined signal feeds a
linear voltage amplifier which drives two medium power
driver transistors. The driver transistors feed the output
stage.
The output stage is arranged as a fully complementary,
direct coupled, push/pull amplifier. The power transistors
used are selected for their high power dissipation capability, wide frequency response, and large safe operating
area. All power transistors have limits for the maximum
amount of heat they can tolerate. The MAC 4200 uses a
highly efficient amplifying circuit which produces relatively
little heat for the output power produced. The receiver
has 4 oversized heat sinks to dissipate transistor generated
heat. Under normal conditions, the output transistors
operate well below their safe temperature limits. If ventilation is restricted by improper mounting or if amplifier
efficiency is destroyed by operating it into a short circuit
or a very low impedance, extra heat will be produced.
All power transistors have limits for the maximum
amount of electrical current they can handle, the
MAC 4200 output circuit and the power supply has been
designed to allow very high current flow into properly
matched load impedances yet continue to operate well
within the design limits. Should a short circuit or very low
value of load impedance be applied to the output of the
MAC 4200, destructive currents could be reached if they
were not controlled by the SENTRY MONITOR (US Patent
#4048573) circuit. The circuit senses the dynamic
operating conditions of the amplifier output stages and
controls the current flow, confining it to safe limits. The
TECHNICAL DESCRIPTION 21
SENTRY MONITOR circuit does not limit the power output
available from the amplifier nor does it have any effect on
signals passing through the amplifier when operating conditions are normal.
A power amplifier which does not use output
transformers to bypass DC (direct current), can destroy
loudspeakers should there be a failure within the
amplifier. Safety circuits are necessary to protect
loudspeakers. The MAC 4200 has a DC detecting circuit
connected to the output of each channel. When DC is
present, this circuit reacts in milliseconds to open the
speaker relay. The speakers remain disconnected until the
cause has been corrected. Under normal operating conditions the DC protective circuit has no effect on the operation of the output circuit.
POWER GUARD
POWER GUARD (US Patent #4048573), a unique feature
of Mclntosh amplifiers, assures that each channel of the
MAC 4200 will deliver full power free of clipping distortion. Clipping is caused when an amplifier is asked to produce more power output with low distortion than its
design characteristics permit. Amplifiers when driven to
clipping can deliver large quantities of power that will
have more than 40% harmonic distortion which causes the
sound to be grossly distorted. The extra energy content of
the clipped signal will damage most loudspeakers, particularly high frequency speakers. The Mclntosh POWER
GUARD circuit protects your ears and your speakers from
this kind of damage.
The Mclntosh patented POWER GUARD circuit
eliminates amplifier clipping due to overdrive. It also illuminates the red Power Guard indicators at the top of
the POWER indicator when the amplifier is driven beyond
its maximum output capacity.
The POWER GUARD circuit compares the wave shape
of the amplifier input and output signals. Normally there is
no disparity between these signals and the comparison
produces no output. When the amplifier is driven beyond
its maximum power capacity a difference will develop. If
the disparity exceeds 0.5% (equivalent to 0.5% total harmonic distortion) the difference will cause the Power
Guard bar indicators to light. If there is a further increase
in the disparity the difference output controls a fast acting
(microseconds) electronic attenuator at the amplifier input
to reduce the amplifier gain, thus holding the amplifier
output to its maximum undistorted value regardless of the
degree of overdrive to the amplifier. The amplifier must
be overdriven by 20 dB before the output distortion exceeds 2%.
The comparison is achieved in an especially compensated operational amplifier integrated circuit. Its output is
detected by a full wave bridge that feeds signals to the
control circuitry for the Power Guard indicators and to the
electronic attenuator at the amplifier input. The attenuator
is a light emitting diode/light dependent resistor network
selected for its low distorion and time constant
characteristics.
TURN ON DELAY
The MAC 4200 has transient-free turn on/turn off
characteristics, time-controlled by a transistor switch that
operates a heavy duty relay which connects the outputs
to the speakers. The control to the transistor switch is
derived from a long time constant capacitor charging network which energizes the relay approximately one second
after the AC power switch is turned on. The same circuit
has a short turn-off time constant which causes the relay
to drop out before the receiver's main power supply has
a chance to discharge.
POWER SUPPLY
Two high current power supplies, a positive 48 volt and
a negative 48 volt DC are used to drive the output power
amplifier. Four large filter capacitors, 6800 microfarads
each, are used to store the large amount of energy
necessary for good filtering and precise voltage regulation. A stable well regulated power supply is required for
proper low frequency response and negligible low frequency distortion.
22 TECHNICAL DESCRIPTION
BLOCK DIAGRAM 23
MAC 4200 RECEIVER
"... Mclntosh is
one of a kind
in the world of
quality audio..."
Mclntosh owner
M. C. Memphis, TN
Compact Discs have been proclaimed to have a large increase in "dynamic range". Dynamic range is the ratio,
usually given in decibels, between the softest, quietest
sound on the disc and the loudest. Most Compact Discs
claim a dynamic range in excess of 90 decibels. In
numerical ratio this is greater than 1000 times the ratio of
practical commercial analog records.
For equipment to be "digital ready" it must be able to
handle overdrive without "breaking up" or grossly distorting the sound. With one exception all power amplifiers
today are incapable of accepting 10 decibels of overdrive
without gross distortion. Some amplifiers totally collapse
under this punishment. Mclntosh has devised a new test
which shows the spectral fidelity of amplifiers under stress.
SPECTRAL FIDELITY is one of the most meaningful
characteristics of an amplifier. The harmonic distortion
and the two tone intermodulation measurements are important criteria in predicting the sonic performance.
However, to obtain better correlation with human hearing
response, we need to know not only the energy in the
distortion spectrum, but also the number of discords and
their frequency spacing from the desired tones. This is
what the Spectral Fidelity testing can do, enlarge the
scope of the data and showing its meaning more fully.
In these oscillograms, you can see the difference in
Spectral Fidelity when a Mclntosh is stressed, and when
other amplifiers are stressed.
1. The Mclntosh stressed 10 dB above rated power.
2. A foreign amplifier stressed 10 dB above rated power.
3. An American manufactured amplifier which had to be
tested "under-stressed" since it could not take 10 dB
of overload.
The Mclntosh shows only 3 distortion components, which
are more than 44 and 50 dB down, roughly equivalent to
0.3% distortion. The other amplifier shows 17 discords,
some of which are only 10 dB down, or 30% distortion,
with many less than 30 dB down, or 3% distortion.
Note in the third oscillogram the complete failure of
one of the popular American manufactured amplifiers.
When 14 and 15 kHz are amplified at the same time, this
amplifier shuts down by "motor boating".
It is no accident that Mclntosh amplifiers sound better.
It is no accident that a Mclntosh is a better investment.
• It sounds better
• It is more reliable
• It last longer
• Its resale value is the highest
If good enough will do, there are at least 100 answers
for you. But if the best is what you need then there is
only one real answer....
....the amplifier that in 40 years has outlived 60 others
who have simply faded away.
24 SPECTRAL FIDELITY
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