Conrad-Johnson Classic 2 User manual

Conrad-Johnson Owner’s Manual:
Classic 2 Preamplifier
conrad-johnson It just sounds right.

Conrad-Johnson Classic 2 Preamplifier Owner’s Manual
1
Thank you for selecting the Conrad-Johnson Classic Preamplifier
as the control center for your audio system. Using it, we believe
that you will hear more from your favorite recordings than ever
before. Drawing on nearly three decades of research at conrad-
johnson into the reproduction of recorded music, the Classic
Preamplifier excels at the recreation of the dynamics, textures,
tonalities, and ambience of live musical performances.
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 have been
selected with a view to maintaining optimal performance over the
years. Our reputation for producing among the industry's most reli-
able components is a natural consequence of this engineering
approach.
Although the Classic has been designed to operate in an intuitively
apparent way, you will find useful information on its installation and
operation in this manual. Please take a few minutes to read the
manual to better understand the features and capabilities of your
Conrad-Johnson preamplifier. Note that this unit is phase inverting.
See the section entitled "Getting the Most from Your Classic
Preamplifier" for details on correct hookup in your system.
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 Classic
Preamplifier, and to provide any needed service both during, and
after the warranty period. Our goal is to heighten your enjoyment of
recorded music.

Conrad-Johnson Classic 2 Preamplifier Owner’s Manual
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Limited 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 origi-
nal 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 which have been damaged by misuse, abuse, or acci-
dent.
b) Units which 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 inci-
dental 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 which vary from state to state.

Conrad-Johnson Classic 2 Preamplifier 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 coun-
try in which the product was originally purchased, which may differ
from the terms set out herein. Importing distributors are not obli-
gated 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.
2733 Merrilee Drive
Fairfax, VA 22031
The conrad-johnson service department can also be reached by e-
mail at [e-mail], 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

Conrad-Johnson Classic 2 Preamplifier Owner’s Manual
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Installation
The Classic Preamplifier dissipates up to nearly 30 watts of heat,
and must be adequately ventilated. Mount the unit horizontally on a
flat, hard surface, and take care that the ventilation holes in the
bottom are unobstructed. Allow at least two inches of clearance
above the unit and keep the cabinet or shelf open at the back.
Vertical installation is not recommended.
All Classics 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 Classic Preamplifier 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 Classic
Preamplifier to minimize its susceptibility to radio frequency inter-
ference and other forms of EMI. Choice of materials, physical lay-
out, 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 applica-
tion, 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
center conductors, and a separate external shield connected at
only one end).

Conrad-Johnson Classic 2 Preamplifier Owner’s Manual
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Physical location and cable “dress” can be an important factor in
minimizing hum pickup. The installation should situate the pream-
plifier 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.
Connection
SOURCES (TUNER, CD, VIDEO, TAPE): These high level inputs
are electrically equivalent. These inputs present a 20 kOhm load to
the source. Connect the corresponding source components to
these inputs.
AUX1/PH: If the optional phono stage is installed, this input
provides the extra gain and RIAA equalization required for play-
back of LPs. Otherwise, this serves as an additional line-level
input.
MAIN OUT: Connect 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. Since this preamplifier
inverts phase, it may be necessary to invert the speaker leads to
maintain correct absolute phase. See the section on “Getting the
Most From Your Classic Preamplifier" for an explanation.

Conrad-Johnson Classic 2 Preamplifier Owner’s Manual
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Controls
<power>: Press the switch labeled power to switch the
preamplifier on. A time delay auto-muting circuit is incorporated
into the Classic Preamplifier to suppress turn-on/turn-off transients.
All outputs are grounded via relays for approximately 45 seconds
after the unit is turned on in order to suppress warm-up transient
noises.
volume: The Classic Preamplifier features a high-quality, precision
tracking volume control.
source selector (aux1/phono, tuner, cd, video, tape): Rotate the
knob to select the desired input.
load impedance switch (inside chassis, units with installed
phono board only): To select a phono input impedance of less
than the factory preset 47 kOhms on units with installed optional
phono stage, unplug the Classic Preamplifier from the ac mains
and remove the cover. The input impedance is set by the load
selector switches – the two dual inline pin (dip) switch arrays
located near the input connectors at the back of the preamp. Each
dip array includes four switches labeled 1 through 4. Load
impedances are selected by setting switches as follows:
Impedance switch #
1 2 3 4
47 kOhms o o o o
9.6 kOhms x o o o
1.9 kOhms o x o o
500 Ohms o o x o
200 Ohms o o o x
x indicates switch in “on” position
o indicates switch in “off” position
note: off position is indicated by arrow on the body of the switch
array.
Be sure to set both switches the same. When done, replace cover.
Do not operate unit with cover off.

Conrad-Johnson Classic 2 Preamplifier Owner’s Manual
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Vacuum Tube Replacement
The line stage audio circuit of the Classic Preamplifier uses a
single type 6922 miniature twin-triode vacuum tube (V1). Units with
the optional high-gain phono stage have three additional tubes – all
type 12AX7 (V3, V4 and V5). Units with the optional low-gain
phono stage have two type 12AX7 (V3 and V4) and one type
12AU7 (V5). The brand of tubes we supply has been chosen by
first selecting those brands which are known to be most reliable,
then by extensive auditioning of these acceptable brands with the
final choices being made solely on the basis of sonic performance.
We know of no vacuum tubes available which will improve the
sonic performance of your Classic Preamplifier. The tubes in your
preamplifier have been tempered by a controlled burn-in procedure
that permits them to perform for a greatly extended period without
sonic degradation, then selected for minimum residual noise.
Replacement tubes are prepared and selected in the same way.
Therefore, we highly recommend that you purchase replacement
tube sets from conrad-johnson design. We anticipate tube life to
accommodate two to three years of operation without degradation
in normal use - if the preamplifier is switched off when not in use. If
the preamplifier is left on at all times, tube life can be exhausted in
a matter of a few months.

Conrad-Johnson Classic 2 Preamplifier Owner’s Manual
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Getting the Most from Your Conrad-Johnson Classic
In a system of commensurate high quality components, the
conrad-johnson Classic Preamplifier offers a high 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 pres-
sure. 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 Classic Preamplifier is phase inverting. If your system has an
odd number of inversions, (for example, if the Classic is the only
phase inverting unit in the chain) 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 espe-
cially 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 investiga-
tion of absolute phase.

Conrad-Johnson Classic 2 Preamplifier 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 ref-
erence 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 sys-
tem 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 Classic before listening: sonic performance will
improve 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 Classic Preamplifier do not hesitate to call Customer
Service at [phone].

Conrad-Johnson Classic 2 Preamplifier Owner’s Manual
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Specifications
Line Stage
Gain: 27 dB
Maximum Output: 9.5 Vrms
Bandpass: 2Hz to more than 100kHz
Hum and Noise: 98 dB below 2.5V output
Distortion at 1.0 V output: less than .15% THD or IMD
Phase: inverts phase of all inputs (including phono) at main out
Main Ouput Impedance: 200 ohms
Optional Phono Stage
High-Gain: 54 dB
Low-Gain: 40 dB
Hum and Noise: 78 dB below 10 mV input
RIAA Equalization: within +/- .25 dB of RIAA specification
Mechanical
Dimensions: 13.625"D x 19"W x 3.625"H
Net Weight: line stage - 12 lb. net
with phono stage –13 lb. net
Fuses
The Classic Preamplifier’s power transformer is protected by a fuse
located in the ac mains inlet socket on the back of the unit. A
failure of this fuse is a symptom of a more serious problem, and a
competent service technician should be consulted. In no event
should the fuse be replaced with a value or type different than that
originally supplied. Correct fuse values are:
If configured for 100 or 120V:
F1 5 x 20mm T800 (800 ma slow blow)
If configured for 220 or 240V:
F1 5 x 20mm T400 (400 ma slow blow)