Conrad-johnson design ET2 Vacuum User manual

Conrad-Johnson Owner’s Manual:
ET2 Vacuum-Tube Preamplifier
conrad-johnson It just sounds right.

ET2 Owner’s Manual 1
Thank you for selecting the ET2 vacuum-tube 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 ET2 excels at the rec-
reation of the dynamics, textures, tonalities, and ambience of live
musical performances.
At conrad-johnson, we expect our products to be a source of satis-
faction and of pride to their owners for many years to come. Ac-
cordingly, 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 reliable com-
ponents is a natural consequence of this engineering approach.
Although the ET2 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
ET2. Note that this unit is phase inverting. See the section entitled
"Getting the most from your ET2" 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 ET2, and
to provide any needed service both during, and after the warranty
period. Our goal is to heighten your enjoyment of recorded music.

ET2 Owner’s Manual 2
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 origi-
nal purchaser, or five years from the date of shipment to the au-
thorized conrad-johnson dealer. During the warranty period, con-
rad-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 re-
paired 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 pack-
ing 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 ex-
press warranty. Some states do not allow limitations on the dura-
tion 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.
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ET2 Owner’s Manual 3
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 cus-
tomer 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 [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

ET2 Owner’s Manual 4
nstallation
The ET2 dissipates approximately 20 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 ET2s 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 ET2 will have the correct operating voltage and fre-
quency 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 ET2 to
minimize its susceptibility to radio frequency interference and other
forms of EMI. Choice of materials, physical layout, grounding prac-
tice, and power supply design have all been specified with a view
to reducing the impact of electromagnetic fields on the perform-
ance 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 objec-
tive 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 prob-
lems which could be treated locally as needed, rather than com-
promising the performance of our product in the 99.9% of installa-
tions where EMI is not a problem.
Care in installation can often avoid EMI induced problems. The fol-
lowing 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
center conductors, and a separate external shield connected at
only one end).
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ET2 Owner’s Manual 5
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.

ET2 Owner’s Manual 6
onnection
SOURCES (TUNER, CD, VIDEO, AUX2): These high level inputs
are electrically equivalent. These inputs present a 13.5 kOhm load
to the source. Connect the corresponding source components to
these inputs.
PH/AUX1: If the optional phono stage is installed, this input pro-
vides the extra gain and RIAA equalization required for playback of
LPs. Otherwise, this serves as an additional line-level input.
EPL: This set of line-level inputs and outputs provides for connec-
tion of an external signal processor (e.g. parametric equalizer, tone
controls) or a tape recorder. Connect the EPL OUT to the input of
your signal processor or tape recorder, and the EPL IN to the out-
put of your processor or tape recorder. Alternatively, the EPL IN
connection can be used as an additional line level input.
THEATER: This is an external processor loop designed to conven-
iently accommodate the addition of a surround-sound processor
(SSP) to a high-quality two-channel system without compromising
two-channel performance. Connect the front left and front right
channel outputs from your SSP to THEATER IN. You can also con-
nect the THEATER OUT to an input on your SSP, allowing you to
do signal processing on selected two channel sources. When
THEATER is selected, the level controls are set and locked to unity
gain. Level and balance control are then accomplished via your
surround sound processor.
MAIN OUT: Two pairs of main outputs are provided. 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 the ET2 inverts phase, it may be neces-
sary to invert the speaker leads to maintain correct absolute phase.
See the section on “Getting the most out of your ET2" for an expla-
nation.
TRIGGER OUTPUT: When the ET2 is switched on, these termi-
nals provide a constant dc voltage that can be sensed by the “trig-
ger” circuits used to switch on some power amplifiers. If your am-
plifier employs such a trigger circuit, and you wish to switch it on
and off from the preamplifier, connect this output to the trigger in-
put on your amplifier. Observe the coded polarities center pin is
positive).
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ET2 Owner’s Manual 7
ontrols
<power>: Press the switch labeled power to switch the preampli-
fier on. A time delay auto-muting circuit is incorporated into the
ET2 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. During
auto-muting, the mute indicator led will flash. Level and balance
control functions are disabled during the auto-muting cycle. The
muting relay also grounds the outputs immediately at turn-off or in
the event of any power line interruption.
When first connected to ac mains, or after an interruption of power,
the ET2 will turn on in a default mode (after auto-muting), with the
level set at 40, and the CD input selected. In subsequent sessions,
as long as the ac mains has not suffered a power outage, the unit
will turn on at the last used volume setting and input.
<mute>: Pressing the mute button will silence the preamplifier
main outputs, and set the level display to zero on both channels.
Pressing the mute button again will restore the previously selected
level setting.
<level up>, <level down>: Level setting on the ET2 can be ad-
justed in 0.5 dB increments. The level setting can be changed by
pressing the level up and level down buttons on the front panel.
Each time a button is pressed, the level will move up or down 0.5
dB. If a button is pressed and held, the level control will cycle
through the steps at an accelerating rate. Balance can only be set
using the remote control and is also adjusted in 0.5 dB increments.
<source>: Pressing the button labeled source will cause the unit
to step through the five source inputs (ph/aux, tuner, cd, video,
aux2). The selected input will be indicated by an illuminated led.
<epl/thtr>: Pressing the epl/thtr button will cause the unit to step
from source through epl1 and theater. When source is selected,
the input selected by the source selector will be passed directly to
the volume control. When the EPL1 or THEATER inputs are se-
lected, the selected source will first pass through the external
processor loop before being routed to the volume control. When
THEATER is selected, the level will be set and locked to unity gain.
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ET2 Owner’s Manual 8
Remote Control
All operations of the ET2 can be controlled by the wireless remote
unit.
MUTE: Pressing the mute button will cause the main outputs to
mute and the level display to be zero. Pressing it again will restore
the last level setting. Pressing and holding the mute button for
more than three seconds will switch the ET2 into standby mode (all
tube circuitry switched off). Pressing the mute button when the unit
is in standby mode will switch it back on.
SELECTORS (PH/AUX, TUNER, CD, VIDEO, AUX2): You can di-
rectly access any of these inputs by pressing the associated button
on the remote.
EPLS (EPL1, EPL2): Pressing the EPL buttons inserts the associ-
ated processor in the signal path. Pressing the button again will re-
establish a direct connection to the selected source. Pressing the
EPL2 button selects the THEATER input, setting and locking the
level to unity gain.
LEVEL (+, -): Duplicates the function of the front panel <level up>,
<level down> controls.
BALANCE: Allows attenuation of either channel independently of
the other. Pressing the right balance button will reduce the left
channel level setting by one step. Pressing and holding the right
balance button will cause the left channel to cycle down through its
level settings at an accelerating rate. Pressing the left balance but-
ton will attenuate the right channel in the same manner.

ET2 Owner’s Manual 9
acuum Tube Replacement
The audio circuit of the ET2 uses two type 8080 miniature triode
vacuum tubes. 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 ET2. 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 degra-
dation, 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 preampli-
fier is left on at all times, tube life can be exhausted in a matter of a
few months.
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ET2 Owner’s Manual 10
etting The Most From Your ET2
In a system of commensurate high quality components, the
conrad-johnson ET2 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 al-
ternating 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 tran-
sients 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 re-
spond 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 invert-
ing. 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 inver-
sions is even (or zero).
The ET2 is phase inverting. If your system has an odd number of
inversions, (for example, if the ET2 is the only phase inverting unit
in the chain) then you must add one phase inversion. This is con-
veniently 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 estab-
lish 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 (in-
cluding some “audiophile” recordings), so listen to several before
concluding your investigation of absolute phase.
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ET2 Owner’s Manual 11
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 be-
comes little better than average. To complicate matters, our ex-
perience 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 ET2 before listening: The sonic performance of the
ET2 improves noticeably as the unit warms up. The midrange be-
comes more lucid, the highs smoother, and the soundstage ex-
pands. The warm up period can be expected to last about fifteen
minutes.
Questions: If you have questions about the installation or function
of your ET2 do not hesitate to call Customer Service at (703) 698-
8581.

ET2 Owner’s Manual 12
pecifications
Line Stage
Gain: 28 dB
Maximum Output: 5.5 Vrms
Bandpass:2Hz to more than 100kHz
Hum and Noise:95 dB below 2.5V output
Distortion at 1.0 V output: less than .1% THD or IMD
Phase:inverts phase of all inputs (including phono) at main out
Ouput Impedance:200 ohms
Mechanical
Dimensions: 16.125"D x 19"W x 4.625"H
Net Weight: 18.5 lb net
Fuses
The ET2 has two power transformers each of which is protected by
a fuse. These fuses (F1 and F2) are located on the main pc board
near the transformers. There is also an ac mains fuse (F3) located
in the ac mains inlet socket on the back of the unit. A failure of any
of these fuses is a symptom of a more serious problem, and a
competent service technician should be consulted. In no event
should a fuse be replaced with a value or type different than that
originally supplied. Correct fuse values are:
If configured for 100 or 120V:
F1 3AG type 3/4 amp, slow blow
F2 3AG type 1/2 amp, fast blow
F3 5 x 20mm T800 (800 ma slow blow)
If configured for 220 or 240V:
F1 3AG type 1/2 amp, slow blow
F2 3AG type 1/4 amp, fast blow
F3 5 x 20mm T400 (400 ma slow blow)
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