Conrad-johnson design MOTIF MC8 User manual

OWNER'S MANUAL
MOTIF MC8
STEREO F.E.T. PREAMPLIFIER
conrad-johnson design, inc.
[phone]

Congratulations. In the Motif MC8 you have a precision audio preamplifier of
highest quality. It is the result of nearly a decade of research by William Conrad and
Lewis Johnson into the application of solid state devices to the reproduction of
recorded music. The circuit design has been executed with the highest quality
component parts and each unit has been painstakingly hand assembled by skilled
assembly technicians. The completed instrument has been subjected to a rigorous
quality inspection program entailing more than sixty performance measurements
followed by a 100 hour "burn-in" period and re-inspection.
Every effort has been made to provide you with an audio instrument capable of
achieving a believable illusion of live music when listening to high quality
recordings. This manual contains many important suggestions on how to realize the
full potential of your MC8. Please take a few minutes to read it.

LIMITED WARRANTY FOR THE MOTIF MC8
1. conrad-johnson design, inc. warrants to the original purchaser that the Motif
MC8 will perform to specifications as published in the owner's manual and that it
will be free of defects in materials and workmanship for a period of three years
from the date of original purchase.
2. conrad-johnson will repair defective units without charge for labor or parts
subject to the following conditions:
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. The above warranty may be transferred to subsequent owners provided that the
warranty registration card has been returned to conrad-johnson design, inc.
within 30 days of the original purchase and that the registered owner provides the
factory with a signed notice giving the new owner's name and address and the
model and serial number of the unit.
4. 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 limitation of incidental or
consequential damages, or limitations on how long an implied warranty lasts, so
the above limitation or exclusion may not apply to you.
5. 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.
2733 Merrilee Drive
Fairfax, Virginia 22031
[phone]

INSTALLATION
Because the MC8 dissipates very little heat (less than 10 watts) ventilation is not an
important consideration, allowing great flexibility for custom or built-in installations.
Of course, reasonable judgment must be exercised to see that the MC8 does not
obstruct ventilation required by amplifiers or other equipment in the system. The
MC8 front panel is designed to support the weight of the unit, allowing installation in
standard 19" equipment racks. In custom installations, the unit may be mounted
either horizontally or vertically.
To minimize hum pickup, the MC8 should be mounted well away from amplifier
power transformers. All ac power cords should be dressed away from input cables -
especially phono cables.
The MC8 requires an ac power line providing between 90 and 130 volts at 50 to 60
Hz. Alternatively, the MC8 can be reconnected internally for operation on 220v
power lines. Consult your dealer for details about the conversion.

CONNECTION
Low-gain phono input: This input provides the amplification and equalization
required by moving-magnet and high-output moving-coil cartridges. The input
impedance is the industry standard 47,000 ohms shunted by approximately 100
picofarads capacitance. This is well suited to nearly all moving-magnet and many
high output moving-coil cartridges. If necessary, the input impedance can be lowered
by soldering a resistor across (from center pin to ground) the input jack. To achieve a
desired input resistance of RD, use the following formula to compute the required
additional resistance RA: RA = 47000*RD/(47000-RD)
Some moving magnet cartridges require higher capacitance for optimum
performance. Decreasing the input capacitance may be achieved by soldering a
suitable value capacitor across the phono input jack. Use polystyrene capacitors for
this purpose.
High-gain phono input: This input provides the additional gain and improved signal
to noise ratio required by most moving-coil cartridges. The input impedance is 2000
ohms. Our experience suggests that this value is well suited to many moving-coil
cartridges. Lower resistance can be achieved as suggested above. If a higher value is
required (some people recommend 47000 ohms for example) the MC8 may be fitted
to your specification at the factory. There is no charge for this service. Please take
note that the high gain phono section is phase inverting and read the section that
follows on absolute phase.
Tuner, cd, tape 1, tape 2: These are high level inputs and are electrically equivalent.
They presents a 50k ohm load to the source. The outputs of your tape recorders
should be connected to tape 1 and tape 2.
Record output: The two pairs of record outputs connect the selected signal to your
recorders or external processing loop (eg. equalizer). The output signal is not affected
by the level control. Connect "record out" to the input of your tape recorders.
Main output: Connect this output to the input of your amplifier (or crossover in a bi-
amplified system). We recommend the use of an amplifier with an input impedance
of 20k ohms or higher.

GETTING THE MOST FROM YOUR MC8
The Motif MC8 offers an unparalleled level of sophistication and refinement in
music reproduction, but it cannot transform an inferior stereo system. Only the very
best amplifiers and loudspeaker systems will be capable of fully revealing the
capabilities of this precision instrument. On the other hand, the MC8 is ruthlessly
revealing. For example, it can render unacceptable faults in the phono system which
may be just discernable with a preamplifier of lower resolution.
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 MC8, be sure that your
phono system has been set up carefully according to manufacturer recommendations.
Adjustment of the cartridge vertical tracking angle can be especially critical with
modern 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 alternating 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 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 is either phase correct or phase
inverting (including the cartridge and speakers - these are normally phase correct). It
is of no consequence 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). When used with the low gain phono stage, the
MC8 is phase correct. When used with the high gain stage, it is phase inverting. If
your system has an odd number of inversions, for example if you are using the MC8
high gain phono stage and it is the only inverting piece in your system, then you must
add one phase inversion. This is conveniently 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 piece in your system, you can establish
correct absolute phase by careful listening. When the system is in correct phase,
transients will be noticably 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.
AC LINE POLARITY
Each piece of electronic equipment in your system is subject to minute ac leakage
currents to the chassis. Since the chassis of components in a system are usually
connected via the ground side of the interconnect wires, these leakage currents are
superimposed on the musical signals. It is possible to minimize these current flows
by carefully selecting the way in which each component is plugged into the wall
outlet. Because the power cord on the MC8 is not polarized, it can be plugged in two
ways. It will normally sound better in one orientation than in the other. The same will
be true of each electronic device in your system.
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
that it becomes no better than average. 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 Motif dealer for recommendations for your specific system.

A FEW TIPS
Warm up the MC8 before listening: The sonic performance of the MC8 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
several hours. Consequently, we recommend that the MC8 be left on at all times. The
low power consumption of the unit makes this practical.
Magnetic fields should be controlled: We recommend the use of one VPI "brick"
placed on the top of the MC8 in the right rear corner.
Clean records sound better: The sonic differences achieved by merely cleaning a
record are nothing short of remarkable. Even brand new records benefit from a
thorough cleaning. Economical record cleaning machines are available from Nitty-
Gritty and from VPI. Our own experience is with the VPI HW1 which we have found
to be totally satisfactory.
Questions: If you have questions about the installation or function of your MC8 do
not hesitate to call Customer Service at [phone].

SPECIFICATIONS:
Gain: high gain phono stage: 54 dB
low gain phono stage : 35 dB
high level: 27 dB
Output: maximum 10v rated at .5v
Phase: high gain phono is phase inverting
low gain phono is phase correct
high level stage is phase correct
Phono overload: in excess of 150mv at 1kHz
Response: bandpass 5Hz to more than 100kHz
RIAA equalization to +/- .25 dB (20-20kHz)
Total hum and noise (20-20kHz): Phono inputs: 76 dB
High level: 86 dB
Distortion: THD less than .1%
IM less than .1%
Output impedance: Less than 200 ohms
Dimensions: 19 x 3 ½ x 12 ¼ "

SERVICE
In the event your Motif MC8 stereo preamplifier requires service, repack it with the
original packing material and ship via United Parcel Service (UPS) to:
Service Department
conrad-johnson design, inc.
2733 Merrilee Drive
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 available from conrad-johnson design at a
nominal charge.