Conrad-Johnson MF80 Manuel utilisateur
Congratulations on your purchase of the Conrad-Johnson MF80 ampli-
fier. You have acquired one of the finer pieces of musical reproduction
equipment available today. The MF80 is the result of over a decade of
research by conrad-johnson design into the application of solid-state
devices to the reproduction of recorded music. Both design and materi-
als have been carefully selected to yield years of unvarying excellence.
Each unit has been painstakingly hand-assembled and exhaustively
tested.
Please take a few minutes to read this manual so that you will better
understand the featues and capabilities of your MF80.
MF80 Owner’s Manual 1
LIMITED WARRANTY FOR THE Conrad-Johnson MF80
1. conrad-johnson design, inc.warrants to the original owner that the
MF80 will be free from defects in material and workmanship for a period
of three years from the date of original purchase.
2. During the warranty period, conrad-johnson will repair defective
unitswithoutchargeforlabororpartssubjecttothefollowingconditions:
a)The unit must not have been altered or damaged through
misuse, abuse, negligence, accident or improper operation.
b)The purchaser must provide evidence of purchase at the time
service is requested.
c) All repairs must be undertaken at the factory or other service
center designated by conrad-johnson design, inc. Units submitted
for warranty repairs must be shipped in the factory packing carton
to conrad-johnson design or its designated service center, freight
and insurance prepaid by the owner, and will be returned to the
owner, freight and insurance prepaid by conrad-johnson design.
Replacement cartons are available from the factory for a nominal
charge.
d) Normal wear and maintenance are not covered by this warranty.
3. Where permitted by law, conrad-johnson design’s liability shall be
limited to that set forth in this warranty. No other warranty of any kind,
expressed or implied, is made by conrad- johnson design, inc., and all
implied warranties, including merchantability and fitness for a particular
"purpose", which exceed the obligations and time limits set forth herein
are hereby disclaimed. conrad-johnson design, inc. shall not be liable
for incidental or consequential damages. Some states do not allow the
exclusion or limitations on how long an implied warranty lasts, so the
above limitation or exclusion may not apply to you.
4. This warranty gives you specific legal rights, and you may also have
other rights which vary from state to state. Questions about warranty
service should be addressed to:
Service Department
conrad-johnson design, inc.
2800 R Dorr Avenue
Fairfax, VA 22031
MF80 Owner’s Manual 2
REGISTERING THE WARRANTY
Please return the enclosed card to the factory within 30 days of pur-
chase to register the warranty. Proper registration of the warranty is
important! It will enable us to inform you of any alterations in the design
of a given model and of any new products we offer which are likely to be
of interest to you.
MF80 Owner’s Manual 3
INSTALLATION
Because the MF80 amplifier dissipates considerable heat it is essential
that proper attention be paid to ventilation. The unit should be mounted
horizontally on a flat hard surface so that the heat sinks are unob-
structed. At least four inches of clearance should be provided above the
unit, and at least two inches on the sides. The cabinet or shelf should
be open at both front and back. For more restricted installations, cooling
fans are recommended.
The front panel of the MF80 will fit in a standard 19" equipment rack and
isdesigned to carry the weightoftheunitsothat it may berackmounted.
Again,it is important that adequateclearance be provided above sothat
ventilation is not impeded. About six inches of the front of the rack
should be left open above the unit.
To minimize hum pickup, keep the unit well away from the preamplifier
and turntable and route power cords away from input cables.
THE MF80 IS TO BE OPERATED ONLY ON AC LINE VOLTAGE OF
108 TO 125 VOLTS.
The MF80 is optionally available wired for 100 volt, 120V, 220V or 240
volt, 50/60 Hz current.
CONNECTION
INPUT:Connectthepreamplifierto your MF80 amplifier at the RCA type
connections located on the amplifier heat sinks.
OUTPUT: Five way binding posts are provided for connection of your
loudspeakers, with correct spacing to accept a standard "double ba-
nana" plug. They will also accept spade lugs, bare wire, or pin connec-
tors.
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 should move synchronously - in
and out together. Terminals on the speakers are usually coded - one
MF80 Owner’s Manual 4
designated "C", "earth", "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 red (+) amplifier terminal
marked on each channel to the red or "+" coded terminal on each
speaker.
Correct relative phase connection of the speakers can be readily ascer-
tained by ear. With the preamplifier mode switched into the MONO
position, play a record of a solo vocalist. 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 diffuse, with no
identifiablesource.Relativephase may be reversed by switching the "+"
and "-" leads at one speaker only.
MF80 Owner’s Manual 5
GETTING THE MOST FROM YOUR
Conrad-Johnson MF80
The MF80 is a highly sophisticated music reproduction instrument, but
it cannot transform an inferior stereo system. Only the very best loud-
speaker systems will be capable of fully revealing the capabilities of this
precision instrument. On the other hand, the MF80 is highly revealing of
faults in the signal source.
Proper set-up is important in any high-fidelity system, but with state-of-
the-art components it is essential. Before attempting to evaluate the
MF80, be sure that each component in your system has been set up
carefully according to manufacturer recommendations. Adjustment of
the cartridge vertical tracking angle can be especially critical with mod-
ern stylus configurations.
Given a system of high quality components, there remain a number of
important details which must be attended to.
ABSOLUTE PHASE
Musical notes are heard through the ear’s response to waves of alter-
nating rise and fall of air pressure. Musical transients are 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 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
systemiseitherphasecorrectorphaseinverting(includingthecartridge
and speakers-these are normally phase correct). It is of no conse-
quence if an individual component is phase inverting, as long as the
system as a whole is phase correct. This will be the case as long as the
number of phase inversions is even (or zero).
THE MF80 IS PHASE CORRECT. If your system has an odd number of
inversions,then you must add onephaseinversion.Thisisconveniently
MF80 Owner’s Manual 6
done by reversing the positive and negative connections on either your
cartridge or your speakers (be sure to reverse both channels).
If you are not sure about the phase of every component 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 records are phase correct
(including some "audiophile" recordings), so listen to several before
concluding your investigation of absolute phase.
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
stranglethesytemtothepointwhereit becomesnobetterthanaverage.
To complicate matters, our experience suggests that the choice of
interconnects will be system dependent-those that are ranked first on a
given system may be a poor choice for a different system. Consult your
conrad-johnson dealer for recommendations for your specific system.
QUESTIONS: If you have any questions about the installation or func-
tion of your MF80 do not hesitate to call Customer Service at (703) 698-
8581.
MF80 Owner’s Manual 7
SPECIFICATIONS:
Power: 80 watts per channel RMS both channels driven into 8 ohms
from 20Hz to 20KHz at no more than 1% total harmonic distortion or
intermodulation distortion.
Sensitivity: 1.3V to rated power.
Phase: Phase correct (non-inverting)
Frequency response: 20Hz to 20KHz +0, -.25dB
Hum and noise: 98dB below full power output.
Input impedance: 100K ohms.
Dimensions: 12.25D x 19W x 5.25H inches.
Weight: 38 lbs.
Fuses:There are 5 user replaceable fuses in the MF80. The four fuses
abovetheoutputjacksarepowersupplyfuses,type3AG3ampfast-blo.
The ac line fuse is a type 3AG 5 amp slo-blo (3 amp slow blow for 220V
or 240V amplifiers). NEVER REPLACE A FUSE WITH A VALUE OR
TYPE DIFFERENT FROM THAT ORIGINALLY SUPPLIED BY THE
FACTORY.Intheevent ofafuseblowingrepeatedly,contactyourdealer
or the conrad-johnson service department.
MF80 Owner’s Manual 8
SERVICE
In the event your conrad-johnson MF80 stereo amplifier requires serv-
ice, repack it with the original packing material and ship via United
Parcel Service (UPS) to:
conrad-johnson design, inc.
Service Department
2800R Dorr Avenue
Fairfax, VA 22031
Be sure to enclose a note explaining the problem you are having in as
much detail as possible. If the problem is intermittent, please indicate. If
you do not have the original packing material, replacements are avail-
able from conrad-johnson design at a nominal charge. If the unit is
under warranty, be sure to enclose a copy of your receipt as proof of
purchase.
MF80 Owner’s Manual 9
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