Krell Industries Evolution 400 Quick start guide

OWNER’S REFERENCE
EVOLUTION
EVOLUTION AMPLIFIERS
302 AND 402 STEREO
403 THREE-CHANNEL
400, 600, AND 900 MONAURAL

Evolution 302, 402, 403, 400, 600 and 900 Power Amplifiers
Owner’s Reference, v08.0
Krell Industries, Inc.
45 Connair Road
Orange, CT 06477-3650 USA
This product complies with the EMC directive (89/336/EEC) and the low-voltage directive
(73/23/EEC).
IMPORTANT SAFETY INSTRUCTIONS
1. Read Instructions.
2. Keep these Instructions.
3. Heed all Warnings.
4. Follow all Instructions.
5. Do not use this apparatus near water.
6. Clean only with a dry cloth.
7. Do not install near any heat sources such as radiators, heat registers, stoves, or other appa-
ratus (including amplifiers) that produce heat.
8. Unplug this apparatus during lightning storms or when unused for long periods of time.
9. Refer all servicing to qualified service personnel. Servicing is required when the apparatus
has been damaged in any way,such as a power-supply cord or plug is damaged, liquid has
been spilled or objects have fallen into the apparatus, the apparatus has been exposed to
rain or moisture, does not operate normally, or has been dropped.
10. An Evolution amplifier must be placed on a firm, level surface where it is not exposed to drip-
ping or splashing.
11. The ventilation grids on the top of everyEvolution amplifier,the ventilation grids on the back of
the Evolution 302 and 400 amplifiers, and the space underneath every Evolution amplifier must
be unobstructed at all times during operation. Do not place flammable material above or
beneath an Evolution amplifier.
12. Before making connections to an Evolution amplifier, ensure that the power is off and other com-
ponents arein mute or stand-by mode. Make sure all cable terminations are of the highest quali-
ty,free from frayed ends, shortcircuits, or cold solder joints.
13. THERE ARE NO USER SERVICEABLE PARTS INSIDE AN EVOLUTION AMPLIFIER.
Please contact Krell if you have questions not addressed in this guide.
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. CAST™, Evolution CAST™, and Krell Current Mode™are trademarks of Krell
Industries, Inc. All other trademarks are registered to their respective companies.
TEL [phone]
FAX [phone]
E-MAIL [email protected]
WEBSITE http://www.krellonline.com
P/N 309888
©2007 by Krell Industries, Inc. All rights reserved .

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Contents
List of Illustrations, page 4
ALetter from Dan D’Agostino, page 5
SECTION ONE: Evolution Amplifier Features and Technology, page 6
Features, Revolutionary Krell CAST Technology,
Definition of Terms
SECTION TWO: Unpacking and Placement, page 11
Opening the Evolution Amplifier Shipping Carton
SECTION THREE: Anatomy of the Evolution Amplifier, page 13
Front Panel Description, and Back Panel Description
SECTION FOUR: Connecting an Evolution Amplifier to Your System, page 22
CAST Connections, Balanced Connections, Single-ended Connections,
Evolution DC Protection Circuitry/Using Tube Preamplifiers, Connection Steps
SECTION FIVE: Evolution Amplifier Operation, page 24
On/Off and Stand-by Operation
SECTION SIX: Troubleshooting System Noise, page 25
How to Evaluate Amplifier Operation, Error Codes
SECTION SEVEN: Questions and Answers, page 27
WARRANTY,page 28
RETURN AUTHORIZATION PROCEDURE, page 30
SPECIFICATIONS, page 31

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List of Illustrations
Figure 1, page 13
Evolution Amplifier Front Panel
Figure 2, page 15
Evolution 302 Stereo Back Panel
Figure 3, page 16
Evolution 402 Stereo Amplifier Back Panel
Figure4, page 17
Evolution 403 Three-channel Amplifier Back Panel
Figure5, page 18
Evolution 400 Monaural Amplifier Back Panel
Figure5, page 19
Evolution Monaural Amplifier Back Panel

ALetter from Dan D’Agostino
Dear Audio Enthusiast,
Thank you for your purchase of a Krell Evolution Series amplifier.
Evolution Series amplifiers continue my quest for amplifiers that deliver absolute
truth in music reproduction. Active Cascode Topology is a unique circuit technique
that minimizes distortion by applying from 2 to 3 times more active devices to
each gain stage. The attributes of this topology is shared throughout the Evolution
Series amplifiers.
Krell amplifiers arebest known for their ability to drive any loudspeaker to sound
its best, without regardto impedance or efficiency.Ibelieve that linearity,an
amplifier’s ability to output an exact duplicate of the input signal, is the ultimate
measureof that amplifier’s work. At Krell, I drive amplifier designs toward the com-
mon goal of linearity,through the rigorous application of Krell design principles
that focus our efforts on four major performance factors: distortion, bandwidth,
output impedance, and current capability. The Evolution Series amplifiers are a
synthesis of these factors.
The Evolution Series amplifiers use Evolution CAST technology,for superior per-
formance and verylow noise.
Ihope that you enjoy your new Evolution Series amplifier.
Sincerely,
Daniel D’Agostino
Chief Executive Officer
5

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SECTION ONE
Evolution Amplifier Features and Technology
This section describes the innovative features and technology of the Evolution
Series amplifiers, and defines CAST and other key terms used in this reference.
There are six amplifier models in the Evolution Series: the 302 Stereo Power
Amplifier, the 402 Stereo Power Amplifier, the 403 Three-channel Power Amplifier,
the 400 Monaural Power Amplifier, the 600 Monaural Power Amplifier, and the 900
Monaural Power Amplifier.The compact chassis of the 400 Monaural Power
Amplifier contains all of the high power,wide bandwidth, and low noise character-
istics designed into all Evolution Series amplifiers.
Features
Evolution Series amplifiers are designed with a signal path that incorporates Krell
Current Mode and CAST circuitry.
All amplifiers feature massive power supplies. The power supply makes use of
extensive electrical and magnetic shielding to keep radiated interference out of
critical amplifier circuits.
The Evolution 302 design utilizes a 3000 VApower supply.The Evolution 402 and
Evolution 600 areequipped with a 5000 VApower supply, and the Evolution 403
and Evolution 900 house 6000 VApower supplies.
Internal high-current line conditioning circuitry filters RF noise on the AC mains, as
well as compensating for asymmetrical power waveforms and DC on the mains.
Advanced microprocessor control monitors critical operational parameters. Output
current, DC offset, rail voltages, and operating temperature are all continuously
monitored.

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Revolutionary Krell CAST Technology
Current Audio Signal Transmission, termed CAST, is a revolutionary method of
connecting analog audio components for unparalleled sonic performance.
Innovative engineering combines the new Krell CAST circuitry with existing Krell
Current Mode technology to create entire CAST systems that reproduce music
with incredible range, tonality, and precision.
The 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 characteris-
tics that act upon the musical signal independently. Each component is unaware
of the other components in the system. The cables that connect the components
also have their own electrical characteristics, which affect the sonic presentation
of the entire system. CAST transmission unifies individual components and inter-
connects into an electrically-linked whole. The original signal remains unaltered
from source to speaker.
CAST Basics
Here is how a CAST audio system works. Internally, each CAST source transfers,
or amplifies, current using Krell Current Mode circuitry. This current signal is then
output using CAST circuitry. When the signal is received by a CAST input, Krell
Current Mode circuitryagain takes over until the signal reaches the loudspeaker.
By maintaining the musical signal in the current domain from beginning to end, an
entire CAST system behaves as if it is one component. With CAST, circuit board
properties and signal transmission aberrations between components areeliminat-
ed. Cable impedances and their effects on the transmitted signal arenon-existent.
How CAST and Krell Current Mode Interact
While CAST is a new method of transferring the musical signal between compo-
nents, its origin stems from Krell Current Mode, the technology developed to
transfer the musical signal within a component. CAST combined with Krell Current
Mode circuitry takes signal transmission to the next evolutionary level. In essence,
continued

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Krell Current Mode maintains the integrity of the signal within the component and
CAST preserves the transmitted signal between components. Together, CAST and
Krell Current Mode technologies unify separate Krell components into a single
global circuit. Krell Current Mode technology enjoys bandwidth increases up to an
order of magnitude greater than their voltage based counterparts. This dramatic
increase in circuit bandwidth delivers near perfection in the audible band that typi-
cally suffers from phase distortions in voltage circuits.
CAST Cable Construction
ACAST system uses cables manufactured by Krell and other manufacturers spe-
cially licensed by Krell. Thin and flexible CAST cables areconstructed with the
same build quality as other Krell components and are aesthetically matched to the
components that Krell manufactures. An all-metal body and locking connectors
with gold contacts arepart of the standard no-compromise specification devel-
oped for everyCAST cable made.
Evolution CAST
By employing revolutionary current mirror circuitry, the Evolution amplifier compo-
nents raises CAST technology to another level. This advanced use of the technol-
ogy increases the linearity,transient speed, and bandwidth of the Evolution com-
ponents while reducing the distortion by an order of magnitude.
The Best Musical Performance
When you operate a CAST system, you will hear significant improvements in every
performance area: speed, precision, dynamic 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
deliveryof the best performance of a musical event for you, using the full expres-
sion of technology to date.
(SECTION ONE: Evolution Amplifier Features and Technology continued)

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Definition of Terms
The following are definitions of key terms used in this owner’s reference:
Inputs and Outputs
Balanced
Asymmetrical input or output circuit that has equal impedance from both input
terminals to a common ground reference point. The industry standard for profes-
sional and sound recording installations, balanced connections have 6 dB more
gain than single-ended connections and allow the use of long interconnect cables.
Balanced connections arecompletely immune to induced noise from the system
or the environment.
CAST and Evolution CAST
Krell Current Audio Signal Transmission, or CAST, is a proprietary Krell circuit tech-
nology for connecting analog components, transmitting the audio waveform
between components in the current domain rather than in the voltage domain. The
speed and bandwidth provided by Krell CAST and its circuitry update, Evolution
CAST,yield accurate, realistic music reproduction, enabling connected compo-
nents to performas if they areall partof a single circuit. CAST and Evolution CAST
arebalanced connections, and reject induced noise.
Single-ended
Atwo-wire input or output circuit. Single-ended connections are not recommend-
ed for connections requiring long cable runs. Use care when using single-ended
connections, because the ground connection is made last and broken first. Turn
the system off/on prior to making or breaking single-ended connections.
Operation
Off
When the power status indicator is not illuminated, the amplifier is off.
Stand-by
Alow-power-consumption status that keeps the audio and power supply circuits
at idle. The power status indicator is illuminated in red, when the amplifier is in
stand-by mode. Krell recommends leaving the amplifier in stand-by mode when it
is not playing music.
Operation
When the power button is pressed, and the power status indicator is illuminated in
blue, the amplifier is in operational mode and ready to play music.
continued

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Technology
Active Cascode Topology
Aunique circuit technique that minimizes distortion by applying from 2 to 3 times
more active devices to each gain stage thereby reducing the load on individual
devices and improving circuit-wide linearity.
Krell Current Mode
Aproprietary Krell circuit topology in which the audio gain stages of a component
operate in the current domain rather than the voltage domain. This unique technol-
ogy provides the component with exceptional speed, and a wide bandwidth.
(SECTION ONE: Definition of Terms continued)