Krell Industries Evolution User Manual

EVOLUTION

EVOLUTION AMPLIFIERS

302 AND 402 STEREO

403 THREE-CHANNEL

600 AND 900 MONAURAL

OWNER’S REFERENCE

Evolution 302, 402, 403, 600 and 900 Power Amplifiers
O

wner’s Reference, v07.0

TEL [phone]
Krell Industries, Inc.
45 Connair Road
Orange, CT 06477-3650 USA

FAX [phone]

E-MAIL [e-mail]

WEBSITE http://www.krellonline.com

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 every Evolution amplifier, the ventilation grids on the back of

the Evolution 302 amplifier, 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 are in mute or stand-by mode. Make sure all cable terminations are of the highest quali-

om frayed ends, shor

ee fr

, fr

ty

13. THERE ARE NO USER SERVICEABLE PARTS INSIDE AN EVOLUTION AMPLIFIER.

Please contact Krell if you have questions not addressed in this guide.

.

t circuits, or cold solder joints.

This pr

oduct is manufactured in the United States of America. Krell
Krell Industries, Inc., its subsidiaries, and authorized agents. CAST
Industries, Inc. All other trademarks are registered to their respective companies.

© 2007 by Kr

ell Industries, Inc. All rights reserved P/N 309888

®

is a r

egistered trademark of Krell Industries, Inc., and is restricted for use by

™, Evolution CAST™, and Krell Current Mode™ are trademarks of Krell

Contents

List of Illustrations, page 4

A Letter from Dan D’Agostino, page 5

SECTION ONE: Evolution Amplifier Features and Technology, page 6

es, Revolutionary Krell CAST Technology,

Featur
Definition of T

erms

SECTION

SECTION THREE: Anatomy of the Evolution Amplifier, page 13

SECTION FOUR: Connecting an Evolution Amplifier to Your System, page 21

SECTION FIVE: Evolution Amplifier Operation, page 23

SECTION SIX: Troubleshooting System Noise, page 24

SECTION SEVEN: Questions and Answers, page 26

ARRANTY

W

RETURN AUTHORIZATION PROCEDURE, page 29

TWO: Unpacking and Placement, page 11

Opening the Evolution Amplifier Shipping Carton

Front Panel Description, and Back Panel Description

CAST Connections, Balanced Connections, Single-ended Connections,
Evolution DC Protection Circuitry/Using Tube Preamplifiers, Connection Steps

On/Off and Stand-by Operation

How to Evaluate Amplifier Operation, Error Codes

, page 27

SPECIFICATIONS, page 30

3

List of Illustrations

Figure 1, page 13

Evolution Amplifier Front Panel

Figure 2, page 15

Evolution 302 Back Panel

Figure 3, page 16

Evolution 402 Back Panel

Figure 4, page 17

Evolution 403 Back Panel

e 5, page 18

Figur

Evolution Monaural Amplifier Back Panel

4

A Letter 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. These four new models utilize Active Cascode
Topology, a unique circuit technique that minimizes distortion by applying from 2
to 3 times more active devices to each gain stage. Evolution Series amplifiers
bring the real-life dynamics and transparency for which Krell is famous, to a whole
new level.

Krell amplifiers are best known for their ability to drive any loudspeaker to sound
its best, without regard to impedance or efficiency. I believe that linearity, an
amplifier
measure of that amplifier’s work. At Krell, I drive amplifier designs toward the com­mon 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
synthesis of these factors.

’s ability to output an exact duplicate of the input signal, is the ultimate

. The Evolution Series amplifiers are a

The Evolution Series amplifiers use Evolution CAST technology

mance and ver

for

I hope that you enjoy your new Evolution Series amplifier.

Sincerely,

Daniel D’Agostino

Chief Executive Officer

y low noise.

5

, for superior per

-

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 five amplifier models in the Evolution Series: the 302 Stereo Power
Amplifier, the 402 Stereo Power Amplifier, the 403 Three-channel Power Amplifier,
the 600 Monaural Power Amplifier, and the 900 Monaural Power Amplifier.

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 VA power supply. The Evolution 402 and
Evolution 600 are equipped with a 5000 VA power supply, and the Evolution 403
and Evolution 900 house 6000 VA power supplies.

nal high-current line conditioning circuitry filters RF noise on the AC mains, as

Inter
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.

6

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 characteris­tics 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 inter­connects into an electrically-linked whole. The original signal remains unaltered
from sour

CAST Basics

ce to speaker.

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

y again takes over until the signal r

ent Mode cir

r

Cur
By maintaining the musical signal in the cur
entire CAST system behaves as if it is one component. With CAST, circuit board

ties and signal transmission aber

oper

pr
ed. Cable impedances and their ef

cuitr

ent domain fr

r

rations between components ar

fects on the transmitted signal ar

eaches the loudspeaker.

om beginning to end, an

e eliminat

e 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 component. CAST combined with Krell Current
Mode circuitry takes signal transmission to the next evolutionary level. In essence,

-

d

7

continue

(SECTION ONE: Evolution Amplifier Features and Technology continued)

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

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 typi­cally suffers from phase distortions in voltage circuits.

CAST Cable Construction

A CAST system uses cables manufactured by Krell and other manufacturers spe­cially licensed by Krell. Thin and flexible CAST cables ar
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 ar

e part of the standard no-compromise specification devel-

oped for every CAST cable made.

Evolution CAST

single

e constructed with the

By employing revolutionary current mirror circuitry, the Evolution amplifier compo­nents raises CAST technology to another level. This advanced use of the technol­ogy increases the linearity, transient speed, and bandwidth of the Evolution com­ponents while reducing the distor

tion by an order of magnitude.

The Best Musical Performance

When you operate a CAST system, you will hear significant impr
per

mance ar

for

ea: speed, pr

stage, transient impact, tonal balance, har

ecision, dynamic range, depth and width of the sound

monic distor

tion, and mor

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

mance of a musical event for you, using the full expr

y of the best per

deliver

for

sion of technology to date.

ovements in every

e. The goal for

es

-

8

Definition of Terms

The following are definitions of key terms used in this owner’s reference:

Inputs and Outputs

Balanced

A symmetrical 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 r
gain than single-ended connections and allow the use of long interconnect cables.
Balanced connections ar
or the environment.

CAST and Evolution CAST

Krell Current Audio Signal Transmission, or CAST, is a proprietary Krell circuit tech­nology for connecting analog components, transmitting the audio waveform
between components in the current domain rather than in the voltage domain. The
speed and bandwidth pr
CAST, yield accurate, realistic music r
nents to perform as if they are all part of a single circuit. CAST and Evolution CAST
are balanced connections, and reject induced noise.

ecording installations, balanced connections have 6 dB more

e completely immune to induced noise from the system

ovided by Krell CAST and its circuitry update, Evolution

eproduction, enabling connected compo-

Single-ended

A two-wire input or output circuit. Single-ended connections are not recommend­ed 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 of

Stand-by

A low-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.

f.

d

9

continue

(SECTION ONE: Definition of Terms continued)

Technology

Active Cascode Topology

A unique 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

A proprietary Krell circuit topology in which the audio gain stages of a component
operate in the current domain rather than the voltage domain. This unique technol­ogy provides the component with exceptional speed, and a wide bandwidth.

10