Conrad-Johnson ET7 Manuel utilisateur

Conrad-Johnson Owner’s Manual:

ET7 Vacuum-Tube Line-Stage reamplifier

conrad-johnson It just sounds right.

Conrad-Johnson ET7 Owner’s Manual

Thank you for selecting the conrad-johnson ET7 preamplifier as

the control center for your audio system. Embodying more than

four decades of research at conrad-johnson into the reproduction

of recorded music, the ET7 preamplifier excels at the recreation of

the dynamics, textures, tonalities, and ambience of live musical

performances. We believe that you will experience the excitement

of discovery in hearing more from your favorite recordings than

ever before.

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 for all conrad-

johnson products are selected with a view to maintaining optimal

performance over the years. Our reputation for producing among

the industry’s most reliable components is a natural consequence

of this engineering approach.

Although the ET7 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

ET7. Note that this unit is phase inverting. See the section entitled

“Getting The Most From Your ET7" 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 ET7, 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 ET7 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 ET7 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.

2800K Dorr Avenue

Fairfax, VA 22031

The conrad-johnson service department can also be reached by e-

mail at service@conradjohnson.com, 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 ET7 Owner’s Manual

Installation

Set Up

To maintain proper ventilation, mount the ET7 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.

All ET7s 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 ET7 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 ET7 to

minimize its susceptibility to radio frequency interference and other

forms of EMI. Choice of materials, physical layout, 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

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).

Conrad-Johnson ET7 Owner’s Manual

Physical location and cable “dress” can be an important factor in

minimizing hum pickup. The installation should situate the

preamplifier 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.

Conrad-Johnson ET7 Owner’s Manual

Connection

SOURCES (PH/AUX, TUNER, CD, VIDEO, AUX2): These high

level inputs are electronically equivalent. The load they present to

the source varies with the volume control setting, but in no case

will it drop below 12 kOhms. Connect the corresponding source

components to these inputs.

EPL1: A set of line-level inputs and outputs provided for

connection of external signal processors (e.g. parametric equalizer,

tone controls). These can also be used for the connection of a tape

recorder. In this case, connect the EPL OUT to the recording input

of your tape recorder, and the EPL IN to the output of your tape

recorder. The EPL IN connection can also 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 the EPL2 input. You

can also connect the THEATER OUT to an input on your SSP,

allowing you to do matrix processing on selected two channel

sources. When THEATER is selected, the level controls are set to

unity gain. Level and balance control is 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 ET7 inverts phase, it may be

necessary to invert the speaker leads to maintain correct absolute

phase. See the section on “Getting the most out of your ET7" for

an explanation.

Conrad-Johnson ET7 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 ET7 to eliminate transients generated by the warm-up, and

cool down cycles of the vacuum-tubes. All outputs are grounded

via relays for approximately 60 seconds after the unit is turned on

in order to suppress warm-up transient noises. During this auto-

muting period, the mute indicator led will flash. All 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 the ET7 is turned off (by pressing the

power switch again), the standby led will be illuminated.

When first connected to ac mains, or after an interruption of power,

the ET7 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 supply 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’s

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 dn>: Level setting on the ET7 is achieved by using

a programmed microprocessor to select combinations from among

an array of high-quality precision resistors. This arrangement

allows 100 steps of approximately .7 dB per step. The steps are

numbered 0 through 99, with 0 being silence, and 99 being

maximum volume.

The level setting can be changed by pressing the vol up and vol dn

buttons on the front panel. Each time a button is pressed, the level

will move up or down one step. If a button is pressed and held, the

level control will cycle through the steps at an accelerating rate.

With each step, a slight “click” will be heard from the opening and

closing relays inside the ET7. Balance can only be set using the

remote control.

<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

Conrad-Johnson ET7 Owner’s Manual

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.

Remote Control

All operations of the ET7 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 ET7 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 the

level to unity gain.

LEVEL (+, -): Duplicates the function of the front panel <vol up>,

<vol dn> 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

button will attenuate the right channel in the same manner.

Conrad-Johnson ET7 Owner’s Manual

Vacuum Tube Replacement

The ET7 circuit employs one vacuum tube, a 6922. The 6922

offers low noise, low microphonics, and gain well suited to use in a

zero-feedback line-stage. The brands of tubes we supply have

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 ET7. The tubes that we

supply have been tempered by a controlled burn-in procedure that

permits them to perform for a greatly extended period without sonic

degradation, and 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.

Ce manuel convient aux modèles suivants

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