Krell Industries 700cx User manual

Full Power Balanced

X Series Power Amplifiers

700cx, 400cx, 300cx Stereo

750Mcx, 450Mcx, 350Mcx Monaural

with Krell CAST II Technology

THE LEADER IN AUDIO ENGINEERING

Instructions for Use

Owner’s Reference

Krell Industries, Inc.

45 Connair Road

Orange, CT 06477-3650 USA

TEL 203-799-9954

FAX 203-891-2028

E-MAIL [email protected]

WEB SITE http://www.krellonline.com

This product complies with the EMC directive (89/336/EEC) and the low-voltage

directive (73/23/EEC).

The Full Power Balanced amplifier must be placed on a firm, level surface where it

is not exposed to dripping or splashing.

The ventilation grids on the top of the Full Power Balanced amplifier must be unob-

structed at all times during operation. Do not place flammable material on top of or

beneath the component.

Before making connections to the Full Power Balanced amplifier, ensure that it is

off and the preamplifier is in mute or stand-by mode. Make sure all cable termina-

tions are of the highest quality and free from frayed ends, short circuits, or cold

solder joints.

The differential circuitry employed with Full Power Balanced amplifiers requires special

attention when connecting speakers. Do not connect the negative speaker terminals

together. Do not connect the negative speaker terminals to ground or attempt to bridge

the left and right speaker binding posts of Full Power Balanced stereo amplifiers.

Do not connect a Full Power Balanced amplifier to a speaker selector device that

employs a common ground scheme, as it may short-circuit the amplifier output.

THERE ARE NO USER SERVICEABLE PARTS INSIDE ANY KRELL PRODUCT.

Please contact your authorized Krell dealer, distributor, or Krell if you have any ques-

tions not addressed in this reference manual.

Full Power Balanced

X Series Power Amplifiers

700cx, 400cx, 300cx Stereo

750Mcx, 450Mcx, 350Mcx Monaural

with Krell CAST II Technology

Instructions for Use

v 03.0

CONTACT

INFORMATION

WARNINGS

This product is manufactured in the United States of America. Krell®is a registered trademark of Krell

Industries, Inc., and is restricted for use by Krell Industries, Inc., its subsidiaries, and authorized agents.

Sustained Plateau Bias III™ is a trademark of Krell Industries, Inc. and is a Krell technology based on U.S.

Patent No. 5,331,291. CAST™, CAST II™, Krell Current Mode™, Krell Link™, and Krell Playback System™

are trademarks of Krell Industries, Inc. All other trademarks are registered to their respective companies.

Contents

Krell Full Power Balanced X Series Power Amplifiers iii

Page

INTRODUCTION 1

DEFINITION OF TERMS 2

REVOLUTIONARY KRELL CAST and CAST II TECHNOLOGY 4

UNPACKING 6

PLACEMENT 7

AC Power Guidelines 7

FRONT PANEL DESCRIPTION 8

700cx, 400cx, and 300cx Stereo Power Amplifiers 8

750Mcx, 450Mcx, and 350Mcx Monaural Power Amplifiers 8

BACK PANEL DESCRIPTION 10

700cx, 400cx, and 300cx Stereo Power Amplifiers 10

750Mcx, 450Mcx, and 350Mcx Monaural Power Amplifiers 10

CONNECTING THE FULL POWER BALANCED AMPLIFIER

TO YOUR SYSTEM 13

Input and Output Connections 13

Krell Trigger Connections 14

DC Protection Circuitry 14

Using a Tube Preamplifier 15

AMPLIFIER OPERATION 16

On/Off and Stand-by Operation 16

Krell Trigger Operation 17

REMOTE CONTROL OPERATION 18

How to Turn Off the Amplifier LEDs 18

How to Turn On the Amplifier LEDs 18

How to Switch between Krell CAST and XLR Inputs 18

Using a Dedicated Wall Outlet and Switch 18

AMPLIFIER TROUBLESHOOTING 19

How to Troubleshoot System Noise 19

How to Evaluate Amplifier Operation 19

QUESTIONS AND ANSWERS 21

WARRANTY 23

RETURN AUTHORIZATION PROCEDURE 24

SPECIFICATIONS 25

Illustrations

Page

FIGURE 1 The Full Power Balanced Stereo Amplifier 8

Front Panel

FIGURE 2 The Full Power Balanced Monaural Amplifier 8

Front Panel

FIGURE 3 The Full Power Balanced Stereo Amplifier 10

Back Panel

FIGURE 4 The Full Power Balanced Monaural Amplifier 10

Back Panel

iv Krell Full Power Balanced X Series Power Amplifiers

Krell Full Power Balanced X Series Power Amplifiers 1

Introduction

Thank you for your purchase of a Full Power Balanced X Series

Power Amplifier.

The Full Power Balanced X Series consists of three stereo ampli-

fiers, the Full Power Balanced 700cx, 400cx, and 300cx Stereo

Power Amplifiers and three monaural amplifiers, the Full Power

Balanced 750Mcx, 450Mcx, and 350Mcx Monaural Power Amplifiers.

Installation, connection, and operation of all amplifiers in the Full

Power Balanced series are identical; however, a pair of Full Power

Balanced Monaural amplifiers are required for stereo operation.

Full Power Balanced amplifiers can be configured to accommodate

any sophisticated music or home theater system and can be oper-

ated by an optional remote control or through the remote control of

other Krell components.

This owner’s reference manual contains important information on

placement, installation, and operation of the Full Power Balanced

amplifiers. Please read this information carefully. A thorough under-

standing of these details will help ensure satisfactory operation and

long life for your Full Power Balanced amplifier and related system

components.

2Krell Full Power Balanced X Series Power Amplifiers

Definition of Terms

Following are the definitions of key terms used in your owner’s ref-

erence manual.

Krell Trigger

Amethod of synchronizing remote control operation for Krell sys-

tems that include multiple preamplifiers, amplifiers, and associated

components. When Krell Trigger in/out connections are used, the

remote capabilities of the linked components are controlled from

one component, called the control component. The linked compo-

nents respond to stand-by and operational mode commands from

the control component via MIDI cables.

Balanced

Asymmetrical input or output circuit that has equal impedance from

both input terminals to a common ground reference point. The

industry standard for professional and sound recording installations,

balanced connections have 6 dB more gain than single-ended con-

nections and allow the use of long interconnect cables. Balanced

connections are completely immune to induced noise from the sys-

tem or the environment.

Krell Current Audio Signal Transmission (CAST)

Aproprietary Krell circuit technology for connecting analog compo-

nents, in which the audio waveform is transmitted between compo-

nents in the current rather than voltage domain. The speed and

bandwidth provided by Krell CAST and the CAST circuitry update,

Krell CAST II, yield accurate, realistic music reproduction. Krell com-

ponents connected via CAST and CAST II perform as if they are all

part of a single circuit.

Single-ended

Atwo-wire input or output circuit. Use care when using single-

ended connections as the ground connection is made last and bro-

ken first. Turn the system off prior to making or breaking single-

ended connections. Single-ended connections are not recommend-

ed for connections requiring long cable runs.

CONFIGURATIONS

INPUT AND OUTPUT

CONNECTIONS

Krell Full Power Balanced X Series Power Amplifiers 3

Off

When the power switch on the back panel is placed in the down

position and the blue power LEDs turn off, the component is off.

Operational Mode

When the power button on the front panel is pressed and the three

blue power LEDs illuminate, the component is in the operational

mode and ready to play music.

Stand-by Mode

Alow power consumption status that keeps the audio and regulator

circuits at idle. Krell recommends leaving the component in the

stand-by mode when it is not playing music.

Krell Current Mode

Aproprietary Krell circuit topology in which the audio gain stages of

a component operate in the current rather than voltage domain.

This unique technology provides the component with exceptional

speed and a wide bandwidth.

Krell Sustained Plateau Bias III

Apatented microprocessor control system that maintains Class A

bias operation regardless of musical demand. Class A bias is the

most accurate method used to amplify musical signals. The new

Sustained Plateau Bias III software is featured in the Full Power

Balanced X Series amplifiers and was developed from the algo-

rithm utilized in the Master Reference Amplifier. Sustained Plateau

Bias III maximizes an amplifier’s efficiency both in power consump-

tion and heat generation.

Definition of Terms, continued

OPERATION

TECHNOLOGY

4Krell Full Power Balanced X Series Power Amplifiers

Revolutionary Krell CAST

and CAST II Technology

Current Audio Signal Transmission, termed CAST, is a revolutionary

method of connecting analog audio components for unparalleled

sonic performance. CAST circuitry, and the CAST circuitry update,

Krell CAST II, combine innovative engineering with existing Krell

Current Mode technology to create entire CAST systems that

reproduce music with incredible range, tonality, and precision.

Voltage Signal Transmission

and the Traditional Audio System

Traditionally, signal is transmitted in the voltage domain between

two components. In an audio system, each component is a discrete

entity with unique characteristics that act upon the musical signal

independently. Each component is unaware of the other compo-

nents in the system. The cables that connect the components each

have their own electrical characteristics, which affect the sonic

presentation of the entire system.

CAST: A New Approach

CAST circuitry recognizes signal transmitted in the current domain

instead of the voltage domain between each component. CAST

transmission unifies the individual components and their intercon-

nects into an electrically linked whole. The sonic presentation of the

entire system remains intact.

CAST Basics

Here’s how a CAST audio system works. Internally, each CAST

source transfers, or amplifies, current using Krell Current Mode cir-

cuitry. This current signal is then output using CAST circuitry. When

the signal is received by a CAST input, Krell Current Mode circuitry

again takes over until the signal reaches the loudspeaker. By main-

taining the musical signal in the current domain from beginning to

end, an entire CAST II system behaves as if it is one component.

With CAST, anomalies of signal transmission between components

are eliminated. Cable impedances and their effects on the transmit-

ted signal are non-existent.

How CAST and Krell Current Mode Interact

While CAST is a new method of transferring the musical signal

between components, its origin stems from Krell Current Mode, the

technology developed to transfer the musical signal within a com-

ponent. CAST combined with Krell Current Mode takes circuitry

signal transmission to the next evolutionary level. In essence, Krell

Current Mode maintains the integrity of the signal within the compo-

Krell Full Power Balanced X Series Power Amplifiers 5

nent and CAST preserves the transmitted signal between compo-

nents. Together, CAST and Krell Current Mode technologies unify

separate Krell components into a single global circuit.

CAST Cable Construction

ACAST system uses cables manufactured by Krell and other man-

ufacturers specially licensed by Krell. Thin and flexible CAST

cables are constructed with the same build quality as other Krell

products and are aesthetically matched to the components that

Krell manufactures. An all-metal body and locking connectors with

gold contacts are part of the standard no-compromise specification

developed for every CAST cable made.

The Best Musical Performance

When you operate a CAST system, you will hear significant

improvements in every performance area: speed, precision, dynam-

ic range, depth and width of the sound stage, transient impact,

tonal balance, harmonic distortion, and more. The goal for CAST is

the same company goal used for all Krell products. Krell strives for

the delivery of the best performance of a musical event for you,

using the full expression of technology to date.

Revolutionary CAST Technology, continued

6Krell Full Power Balanced X Series Power Amplifiers

Unpacking

Two people are needed to remove the Full Power Balanced amplifi-

er from its shipping box safely and easily.

1. Open the shipping box and remove the top layer of foam. You

see these items:

1Full Power Balanced Amplifier

1Packet containing the Quick Setup Guide and the warranty

registration card

2. Orient the shipping box so that one person stands at the front of

the amplifier and one person stands at the back of the amplifier.

Both people need to grab a pair of the cardboard handle cutouts

(one pair located at the front of the amplifier and one pair located

at the back of the amplifier) and simultaneously lift the amplifier

straight up, out of the carton.

3. Place the amplifier in a safe location and remove the protective

plastic wrapping.

If any of the items mentioned above are not included in the ship-

ping box, please contact your authorized Krell dealer, distributor, or

Krell for assistance.

Save all packing materials. If you ship your Full Power Balanced

amplifier in the future, repack the unit in its original packaging to

prevent transit damage. See Return Authorization Procedure on

page 24, for more information.

Notes

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