Conrad-johnson Et3 User manual

Conrad-Johnson Owner’s Manual:

ET3 Vacuum-Tube Preamplifier

conrad-johnson It just sounds right.

Conrad-Johnson ET3 Preamplifier Owner’s Manual

Thank you for selecting the Conrad-Johnson ET3 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 more than three decades of research at conrad-

johnson into the reproduction of recorded music, the ET3

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 ET3 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 ET3

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 ET3

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 ET3 Preamplifier Owner’s Manual

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 ET3 Preamplifier Owner’s Manual

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 [email protected]m, 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 ET3 Preamplifier Owner’s Manual

Installation

The ET3 Preamplifier dissipates up to nearly 30 watts of heat, and

must be adequately ventilated. Mount the unit horizontally on aflat,

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 ET3s 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 ET3 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 ET3

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 ET3 Preamplifier Owner’s Manual

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. The load they present to the source

varies with the volume control setting, but in no case will it drop

below 25 kOhms. Connect the corresponding source components

to these inputs.

AUX1/PH: If the optional phono stage is installed (see below), this

input provides 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

connection 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 output 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

conveniently 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 connect 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: 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 ET3 Preamplifier" for an explanation.

Conrad-Johnson ET3 Preamplifier Owner’s Manual

Phono Stage

The conrad-johnson ET3 preamplifier is optionally available with

your choice of high-gain or low gain phono stages. If your ET3 has

a factory installed phono stage, there will be a label on the back

panel saying “High Gain Phono Card Installed” or “Low Gain

Phono Card Installed”. The phono card itself will be labeled either

“High Gain Phono Card” or “Low Gain Phono Card”. It is important

that the appropriate card is selected for your phono cartridge. The

high-gain phono card is suitable for cartridges with rated outputs of

1 mV or below, while the low-gain card is suitable for cartridges

with rated output of greater than 1 mV. Using a high-gain card with

a cartridge with too high an output will result in highly distorted

sound, as the output of the phono stage will overload the input

circuitry of the line-stage.

Units with high-gain phono cards can be sent to the factory to be

converted to low-gain phono cards, and vice versa. There is a

charge for this service, so inquire before sending the unit.

Both phono cards have adjustable resistive loading. To select a

phono input impedance of less than the factory preset 47 kOhms,

unplug the ET3 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 ET3. Each dip array includes four switches labeled 1

through 4. Load impedances are selected 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

xindicates switch in “on” position

oindicates 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 ET3 Preamplifier Owner’s Manual

Controls

<power>: Press the switch labeled power to switch the

preamplifier on. A time delay auto-muting circuit is incorporated

into the ET3 to suppress turn-on/turn-off transients. All outputs are

grounded via relays for approximately 90 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 ET3 will turn on in a default mode (after auto-muting), with the

level set at 20, 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.

<vol up>, <vol down>: Level setting on the ET3 can be adjusted

in approximately 0.7 dB increments. The level setting can be

changed by pressing the vol up and vol down buttons on the front

panel. Each time a button is pressed, the level will move up or

down 0.7 dB. If a button is pressed and held, the level control will

cycle through the steps at an accelerating rate.

<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

selected, 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.

Conrad-Johnson ET3 Preamplifier Owner’s Manual

Remote Control

All operations of the ET3 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 ET3 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

directly access any of these inputs by pressing the associated

button on the remote.

EPLS (EPL1, EPL2): Pressing the EPL buttons inserts the

associated 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: The ET3 does not include balance adjustment. These

buttons on the remote control have no effect on the ET3.

Conrad-Johnson ET3 Preamplifier Owner’s Manual

Vacuum Tube Replacement

The line-stage audio circuit of the ET3 Preamplifier uses one type

6922 miniature twin-triode vacuum tube (V1) –note, (V2) is not

used in this model. 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 ET3

Preamplifier. The tube in your preamplifier has 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 ET3 Preamplifier Owner’s Manual

Getting the Most from Your Conrad-Johnson ET3

In a system of commensurate high quality components, the

conrad-johnson ET3 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 ET3 Preamplifier is phase inverting. If your system has an odd

number of inversions, (for example, if the ET3 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 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.

The Importance of Wires

Interconnect and speaker wires are an important element in your

stereo system. Interconnects are available which will permit a ref-

Conrad-Johnson ET3 Preamplifier Owner’s Manual

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 ET3 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 ET3 Preamplifier do not hesitate to call Customer Service

at (703) 698-8581.

Conrad-Johnson ET3 Preamplifier Owner’s Manual

Specifications

Line Stage

Gain: 25 dB

Maximum Output: 20 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: 100 ohms

Optional Phono Stage

Gain:

High Gain: 54 dB

Low Gain: 40 dB

Hum and Noise: 80 dB below 10 mV input

RIAA Equalization: within +/-.25 dB of RIAA specification

Mechanical

Dimensions: 13.125"D x 19"W x 3.315"H

Net Weight: 13 lb net

Fuses

The ET3 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)

Table of contents

Conrad-Johnson ET3 User manual