McIntosh C-28 Brochure

D Use 3 tape machines

2 with their own electronics and 1 tape playback deck with complete
easy front panel switching

D Built-in headphone amplifier

listen to your favorite music - - - privately

D Main and remote loudspeaker switching

turn the main speakers on or off without affecting the remote speakers
and vice versa (operates with accessory relay)

D New low noise phono input

listen to your records with a new quietness

D Individual channel phono level controls

match levels from different phono cartridges without degrading signal
to noise ratio

D Individual channel output level controls

perfect balance from your stereo always

D Individual channel tone control switches

complete, repeatable flexibility

D New compensation control

one position for loudness compensation, one position is flat and a third
position that adds presence compensation!

NEW LOW NOISE PHONO CIRCUITS

New records and tapes with greatly increased dynamic range demanded
new low noise circuits. McIntosh scientists developed a new DIFFERENTIAL
INPUT CIRCUIT that reduced phono input noise levels from approximately 2.4
microvolts in an excellent preamplifier to a new level of only 1.2 microvolts!

The differential input circuit has only been used in very sensitive professional
test equipment and in medico-electronics. The preamplifier will not overload
or change distortion for any phono input signal from 2 millivolts up to 500

millivolts. This represents a dynamic range of approximately 3000 to 1 on a

voltage basis. This fantastic improvement necessitated extreme care in lay-
out and manufacturing. The signal circuits need careful shielding and wiring
with coaxial cable to prevent noise and crosstalk in the preamplifier from de-
stroying the low noise advantages of the input circuit.

NEW TAPE FLEXIBILITY

With the C28 you can copy from one tape recorder to another while lis-

tening to a completely different program! In addition, you can monitor the re-
cording by simply pushing a button. In addition, an input circuit has been

provided to accept the signal from a tape playback deck.

NEW HEAD PHONE AMPLIFIER

Use your headphones for private listening. Ample power has been pro-

vided to power todays high quality headphones. All this plus a separate

power switch in the preamplifier to turn the power amplifiers on or off. It is

not necessary to operate the power amplifiers while listening to headphones.

PERFORMANCE GUARANTEE
Performance Limits are the maximum deviation from perfection
permitted for a Mcintosh instrument. We promise you that the C28
you buy must be capable of performance at or exceeding these

'limits or you get your money back, Mcintosh is the only manufac-

turer that makes this guarantee.

FREQUENCY RESPONSE:

+0 -0.5 dB 20 Hz to 20,000 Hz

DISTORTION

Will not exceed 0.1% at rated output level, 20 Hz to 20,000 Hz.

INPUT SENSITIVITY AND IMPEDANCE:

Auxiliary, Tuner, Tape 1, Tape 2, 0.25 volts; 250,000 ohms.
Phono 1 and Phono 2, 2 millivolts; 47,000 ohms (1,000 Hz).
Microphone, 2.5 millivolts; 500,000 ohms.
Tape Head, 2 millivolts; 500,000 ohms (500 Hz).

HUM AND NOISE:

Auxiliary, Tuner, Tape 1, Tape 2: 90 dB below rated output.
Phono 1, Phono 2 and Tape Head: 78 dB below 10 milivolts input,
equivalent to less than 1.2 microvolts at the input terminals.
Microphone: 1.5 microvolts at the input terminals.

OUTPUT LEVEL AND IMPEDANCE:

Main Output: 2.5 volts with rated input, 100 ohms source im-
pedance, to operate into 47,000 ohms or more. Tape Output: 0.25
volts, 150 ohms source impedance, from low level inputs, to op-
erate into 47,000 ohms or more. Headphone/Line Output: 0.75
volts into 8 ohm load or 2.5 volts into 600 ohm line, 0.2 ohm
source impedance, level controls provided. Center Channel Out-
put: 1.25 volts with rated input to both channels, to operate into
47,000 ohms or greater, level control provided.

AMPLIFICATION IN DECIBELS:

Auxiliary, Tuner, Tape 1 and 2 to Main Output: 20 dB. Auxiliary,
Tuner, Tape 1 and 2 to Tape Output: 0 dB. Auxiliary, Tuner, Tape

1 and 2 to Headphone/ Line Output: 17.5 dB.
Phono 1 and Phono 2 at 1,000 Hz to Main Output: 62 dB. Phono
1 and Phono 2 at 1,000 Hz to Tape Output: 42 dB. Phono 1 and
Phono 2 at 1,000 Hz to Headphone/Line Output: 59.5 dB.
Microphone:

to Main Output 60 dB.
to Tape Output 40 dB.
to Headphone/Line Output: 57.5 dB.
Tape Head at 500 Hz.
to Main Output: 64 dB.
to Tape Output: 44 dB.

to Headphone/Line Output: 61.5 dB.

POWER REQUIREMENT:

120 volts, 50/60 Hz, 45 watts.

FACILITIES AND FEATURES

BASS CONTROLS:

Separate 11 position rotary switches for each channel, +20 dB
to -20 dB at 20 Hz.

TREBLE CONTROLS:

Separate 11 position rotary switches for each channel, +18 dB
to -18 dB at 20,000 Hz.

COMPENSATION SWITCH:

Three position switch for Flat, Loudness, or Presence. Loudness
position boosts low frequencies for low level listening. Presence
position boosts mid frequencies 4 dB to increase "presence"
effect. This control operates as a function of volume control posi-
tion so full compensation is obtained at lower volume levels and
flat response is obtained at full volume.

BALANCE CONTROL:

, Natural balance at center position, attenuation of left or right

channel by rOtating control.

VOLUME CONTROL:

Precision "tracked" at all listening levels (0 to -65 dB). Does not
change stereo balance as loudness is changed. The power ON/
OFF switch is coupled with this control.

INPUT SELECTOR:

Six positions: Auxiliary, Tuner, Phono 1, Phono 2, Microphone,
and Tape Head.

MODE SELECTOR:

Seven positions: Left channel only to both speakers, Right chan-
nel only to both speakers. Stereo Reverse, Stereo, Mono, L+R
to left speaker only, and L+R to right speaker only.

TAPE MONITOR SWITCHES:

Two push button switches. Either of two tape recorders can be
monitored by selecting the TAPE 1 push button or TAPE 2 push
button. They are mechanically interlocked to accept only one
push button at the IN position at one time.

TAPE COpy SWITCH:

Two push button switches. Either of two tape recorders can be
connected to copy from tape machine 1 to tape machine 2 or vice
versa. They are mechanically interlocked to accept only one push
button at the IN position at one time.

LF FILTER SWITCH (Rumble Filter):

Flat or roll-off at 12 dB per octave below 50 Hz, down to 18 dB

at20Hz.

!iF FILTER SWITCH (Scratch Filter):

Flat or roll-off at 12 dB per octave above, 7,000 Hz, down to 18

dB at 20,000 Hz.

FRONT PANEL TApE JACKS:

Allows connection to input and output of a tape recorder from
the front panel of the C28. Inserting plugs into their jacks discon-
nects the TAPE 2 circuits from the rear panel of the C28 and
uses the TAPE 2 facilities for the front panel jacks.

HEADPHONE JACK:

For listening with either low or high impedance stereo head-
phones. Power to this jack is supplied by an amplifier provided
in the C28. Headphone listening can be accomplished Without

the use of an external power amplifier.

LOW FREQUENCY TRIM CONTROLS:

Increases the output below 100 Hz up to 6 dB. Use to compensate
for unequal speaker response or the unequal influence of room
accoustics.

PHONO 1 AND PHONO 2 LEVEL CONTROLS:

Adjust for variations in the phono cartridge output up to 10 dB.
Provides for optimum signal to noise ratio and proper balance of
the channels of the phono cartridge.

HEADPHONE LEVEL CONTROLS~

Adjusts the level and balance of the headphone/ line output.

TRANSISTOR COMPLEMENT:

26 silicon-planar transistors, 4 silicon diodes, 2 silicon bridge
rectifiers.

MECHANICAL INFORMATION

SIZE:

Front panel measures 16 Inches wide (40.64 em) by 5-7/16 Inches
high (13.81 em). Chassis measures 15 Inches wide (38.1 em) by
5 Inches high (12.7 cm) by 13 Inches deep (33.02 em) Including

PANLOC mounting brackets and back panel connectors. Knob

clearance required is 1V2inches (3.81 em) In front of the mount-
Ing panel.

FINISH:

Front panel is anodized gold and black with special gold/teal
nomenclature ililumination. Chassis is black.

MOUNTING:

Exclusive Mcintosh developed professional PANLOC.

WEIGHT:

25 pounds (11.34 kg) net, 37 pounds (16.78 kg) In shipping
carton.

mcIntosh

2 Chambers St., Binghamton, N. Y. 13903
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