Conrad-Johnson MF2275 User manual

Conrad-Johnson Owner’s Manual:
MF2275 Power Amplifier
conrad-johnson It just sounds right.

MF2275 Owner’s Manual
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Thank you for selecting the MF2275 amplifier to power your audio
system. The MF2275 draws on three decades of research at
conrad-johnson into the reproduction of recorded music. The result
is a power amplifier with a remarkable ability to recreate the
dynamics, textures, tonalities, and ambience of live musical
performances. With the MF2275, we believe that you will
experience the excitement of discovery in hearing more from your
favorite recordings than ever before.
At conrad-johnson, we expect our products to be a source of
satisfaction and of pride to their owners for many years to come.
Accordingly, circuit designs, parts and materials for all conrad-
johnson products are selected with a view to maintaining optimal
performance over the years. Our reputation for producing among
the industry's most reliable components is a natural consequence
of this engineering approach.
Although operation of the MF2275 amplifier is quite
straightforward, please take a few minutes to read this manual for
useful information on its installation and operation.
In closing, we’d like to welcome you to the family of conrad-
johnson owners. We want you to enjoy your conrad-johnson
product to the fullest. To this end, our staff stands ready to answer
any questions you may have about the function and application of
your MF2275, and to provide any needed service both during, and
after the warranty period. Our goal is to heighten your enjoyment of
recorded music.

MF2275 Owner’s Manual
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imited Warranty For Conrad-Johnson Components
Conrad-Johnson Design, Inc. will provide service under warranty to
the original owner on products sold new in the United States for the
lesser period of three years from the date of purchase by the
original purchaser, or five years from the date of shipment to the
authorized conrad-johnson dealer. During the warranty period,
conrad-johnson will repair defective units without charge for labor
or parts (with the exception of vacuum tubes and batteries).
Exclusions. The following are not covered under this warranty:
a) Units that have been damaged by misuse, abuse, or
accident.
b) Units that have been modified, altered, or improperly
repaired by anyone not specifically authorized by conrad-
johnson design, inc.
c) Units not purchased from an authorized conrad-johnson
dealer in the United States for use in the United States.
d) Normal wear
e) Incidental or consequential damages are not covered under
this warranty. Some states do not allow the exclusion of
incidental or consequential damages, so this exclusion may not
apply to you.
Obtaining Warranty Service: To obtain warranty service, the unit
must be shipped, along with evidence of purchase, in factory
packing to conrad-johnson design (or designated service center)
with freight and insurance prepaid by the owner. After repair, the
unit will be returned with freight and insurance prepaid by conrad-
johnson design to any destination in the United States.
All implied warranties, including merchantability and fitness for a
particular purpose are limited in duration to the duration of this
express warranty. Some states do not allow limitations on the
duration of implied warranties so the above limitations may not
apply to you.
This warranty gives you specific legal rights and you may also
have other rights that vary from state to state.
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MF2275 Owner’s Manual
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Conrad-Johnson products purchased outside the United States are
covered by warranty terms of the importing distributor in the
country in which the product was originally purchased, which may
differ from the terms set out herein. Importing distributors are not
obligated to provide warranty service for products originally
purchased outside their country. Conrad-Johnson will provide
warranty service for products outside the United States, but in
these cases, the customer must pay all shipping, handling and
customs costs both to and from our Service Department.
Questions about this warranty should be addressed to:
Service Department
conrad-johnson design, inc.
2800K Dorr Avenue
Fairfax, VA 22031
The conrad-johnson service department can also be reached by e-
mail at [email protected], by phone at 703-698-8581,
or by fax at 703-560-5360.
Service
If your conrad-johnson audio component requires service, repack it
using the original box and packing material and ship to the Service
Department address above. Boxes and packing materials can be
purchased through our service department if you no longer have
yours. Include with the unit a note describing the problem you are
having in as much detail as possible. It is especially important for
our technician to know if the problem is intermittent. If you want an
estimate of cost for out of warranty service, be sure to request it in
this note. Be aware that requesting an estimate will delay service
to your unit, as we will have to contact you for approval before
commencing service.
Registering The Warranty
Please return the enclosed card to the factory within 30 days of
purchase to register the warranty

MF2275 Owner’s Manual
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nstallation
As is the case with most power amplifiers, the MF2275 amplifier
dissipates a significant amount of heat. Provision must be made for
adequate ventilation. Mount the unit on a flat, hard surface, taking
care that the ventilation holes in the bottom are unobstructed.
Maintain at least four inches of clearance above the unit, and at
least three inches on the sides. The cabinet or shelf should be
open at both front and back. For more restricted installations,
cooling fans are essential.
All MF2275 amplifiers sold in the United States are configured for
operation on a 60Hz ac power line producing between 108 and 126
volts. Export versions of the MF2275 will have the correct
operating voltage and frequency clearly marked on the back panel
of the unit, near the ac power cord. In all cases, the actual line
voltage should be within + 5/- 10% of the nominal rated voltage.
Electromagnetic Interference (EMI)
Considerable care has been taken in the design of the MF2275 to
minimize its susceptibility to radio frequency interference and other
forms of EMI. Choice of materials, physical layout, grounding
practice, and power supply design have all been specified with a
view to reducing the impact of electromagnetic fields on the
performance of this unit. At the same time, however, our primary
goal is the accurate reproduction of recorded music in the normal
home environment, and we have elected not to compromise this
objective by the application of heavy-handed RFI filters, or by using
grounding practices that reduce RFI at the expense of degraded
audio performance. We find that the approach we have taken has
worked extremely well, resulting in only rare instances of EMI
problems which could be treated locally as needed, rather than
compromising the performance of our product in the 99.9% of
installations where EMI is not a problem.
Care in installation can often avoid EMI induced problems. The
following practices should generally be observed in any
application, and will be especially important where EMI may be a
problem.
Interconnect cables should be kept as short as possible (3 meters
or less), and shielded cable should be used (cable which has two
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MF2275 Owner’s Manual
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center conductors, and a separate external shield connected at
only one end).
Physical location and cable “dress” can be an important factor in
minimizing hum pickup. The installation should situate the
preamplifier well away from the power amplifier, and power (ac
mains) cords should be dressed to remain at least 4" (100mm)
away from input/output cables.

MF2275 Owner’s Manual
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onnection
INPUT: Connect the preamplifier to your MF2275 amplifier at the
RCA type connectors located on the back of the amplifier.
OUTPUT: Five-way binding posts are provided for connection of
your loudspeakers, with correct spacing to accept a standard
"double banana" plug. They will also accept spade lugs, bare wire,
or pin connectors.
The two channels should be connected in correct "relative phase".
This means that when the same signal is applied to both channels,
the right and left channels speaker diaphragms will move
synchronously - in and out together. Terminals on speakers are
usually coded - one designated "C", "ground", "-" or black, the
other designated "+" or red. "In phase" connection of the speakers
can normally be achieved by taking care to connect the wire from
the "+" amplifier terminal to the red or "+" coded terminal on each
speaker, and connecting the "-" terminal to the black or "-" coded
terminal on each speaker. In phase connection of the speakers can
be readily ascertained by ear. Listen to a recording of a solo
vocalist (use a mono recording if available). With the speakers in
phase the voice should be clearly focused between the two
speakers. With the speakers connected out of phase, the voice will
be diffused, with no identifiable source. Relative phase may be
reversed by switching the "+" and "-" leads at one speaker only.
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MF2275 Owner’s Manual
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etting The Most From Your MF2275 Amplifier
In a system of commensurate high quality components, the
conrad-johnson MF2275 amplifier offers an unparalleled level of
sophistication and refinement in music reproduction. To get the
best performance out of any audio system, there are a number of
important details that must be attended to.
Absolute Phase
Musical notes are heard through the ear’s response to waves of
alternating rise and fall of air pressure. Musical transients are
almost exclusively positive: that is, the initial effect is a rise in
pressure. The ear is capable of distinguishing these positive
transients from the musically unnatural alternative of a negative
transient (an initial fall in air pressure). In terms of your stereo
system, these transients are created by your loudspeakers. If the
speakers respond to musical transients by first moving out, they
are creating a rise in pressure, and the system is said to be phase
correct. If they respond by moving in, they create a fall in pressure
and the system is said to be phase inverting. Each component in
the stereo system either preserves the phase of the incoming
signal, and is said to be phase correct, or inverts the phase and is
said to be phase inverting. It is unimportant whether an individual
component is phase correct or phase inverting, as long as the
system as a whole is phase correct. This will be the case if the
number of phase inversions is even (or zero).
The MF2275 is phase correct (non-inverting). If your system has
an odd number of inversions, (for example, if you have a phase
inverting preamplifier) then you must add one phase inversion.
This is conveniently done by reversing the positive and negative
connections to your speakers (be sure to reverse both channels). If
you are not sure about the phase of every piece in your system,
you can establish correct absolute phase by careful listening.
When the system is in correct phase, transients will be noticeably
cleaner and more sharply defined. The effect is especially apparent
on plucked string sounds. A final warning - not all recordings are
phase correct (including some “audiophile” recordings), so listen to
several before concluding your investigation of absolute phase.
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MF2275 Owner’s Manual
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The Importance Of Wires
Interconnect and speaker wires are an important element in your
stereo system. Interconnects are available which will permit a
reference quality system to blossom and fulfill its promise of
musical reality. Others will strangle the system to the point where it
becomes little better than average. To complicate matters, our
experience suggests that the choice of interconnects will be
system dependent - those that are top ranked on one system may
be a poor choice for a different system. Consult your conrad-
johnson dealer for recommendations for your specific system.
Performance Tip
Warm up the MF2275 before listening: The sonic performance of
the MF2275 improves noticeably as the unit warms up. The
midrange becomes more lucid, the highs smoother, and the
soundstage expands. The warm up period can be expected to last
about fifteen minutes.
Questions: If you have questions about the installation or function
of your MF2275 do not hesitate to call Customer Service at (703)
698-8581.

MF2275 Owner’s Manual
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pecifications
Power: 135 watts per channel RMS both channels driven into 8
ohms from 20Hz to 20KHz at no more than 1.0% total harmonic
distortion or intermodulation distortion.
Sensitivity: 1.35 V rms to rated power
Frequency Response: 20Hz to 20 kHz +0/-.3 dB
Hum and Noise: 100 dB below rated power output
Phase: phase correct
Input Impedance: 100 kOhms
Mechanical
Dimensions: 14.625"D x 19”W x 4.875”H
Net Weight: 33 lb. net
Fuses
There are 5 fuses in the MF2275. One is the ac power line (mains)
fuse. It is located in the IEC power cord receptacle. The other four
fuses are in the DC power supplies for the output stages one for
the positive (B+) and one for the negative (B-) supply to each
channel. These B+/B- fuses are located on the top of the main
printed circuit board. Be sure to disconnect the amplifier from the
ac mains power (wall outlet) before removing the top cover.
Never replace a fuse with a value or type different from that
originally supplied by the factory. Correct values and types are
listed below. In the event of a fuse blowing repeatedly, contact your
dealer or the conrad-johnson service department.
AC Mains Fuse: 5x20mm T-Type:
6.3 amp if configured for 100 or 120V
3.15 amp if configured for 220 or 240V
B+/B- Fuses: 3AG 4 Amp, fast blow
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