Krell Industries EVOLUTION TWO MONAURAL PREAMPLIFIER Quick start guide

OWNER’S REFERENCE
EVOLUTION
EVOLUTION TWO
MONAURAL PREAMPLIFIER

Evolution Two Monaural Preamplifier
Owner’s Reference, v05.0
Krell Industries, Inc.
45 Connair Road
Orange, CT 06477-3650 USA
TEL [phone]
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).
WARNINGS
The Evolution Two preamplifier 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 Evolution Two preamplifier and the space underneath the
Evolution Two preamplifier must be unobstructed at all times during operation. Do not place flam-
mable material above or beneath the preamplifier.
Before making connections to the Evolution Two preamplifier, ensure that the power is off and other
components are in mute or stand-by mode. Make sure all cable terminations are of the highest quali-
ty, free from frayed ends, short circuits, or cold solder joints.
Do not connect an RS-232 cable to the phono power port. Output from the phono power port can
seriously damage your computer. Do not connect the cable from a Krell KPE phono stage to the
RS-232 port.
THERE ARE NO USER SERVICEABLE PARTS INSIDE AN EVOLUTION TWO MONAURAL
PREAMPLIFIER.
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. Evolution Bias™ is a trademark of Krell Industries, Inc. and is a Krell technology
based on U.S. Patent No. 5,331,291. CAN Link™, CAST™, Evolution CAST™, and Krell Current Mode™ are trademarks of Krell Industries,
Inc. All other trademarks are registered to their respective companies.
© 2005 by Krell Industries, Inc. All rights reserved P/N 307773

iii
Contents
List of Illustrations, page iv
A Letter from Dan D’Agostino, page 1
SECTION ONE: About Krell, page 3
The Krell Legacy, Revolutionary Krell CAST Technology,
Ensuring Maximum Performance, Definition of Terms
SECTION TWO: Unpacking and Placement, page 11
Opening the Evolution Two Shipping Carton
SECTION THREE: Quick Start, page 13
Connecting the Evolution to Your System,
Operating the Evolution Two
SECTION FOUR: Anatomy of an Evolution Two, page 15
Front Panel Description, Remote Control Description,
and Back Panel Description
SECTION FIVE: Connecting the Evolution Two to Your System, page 26
Input and Output Connections, Connection Steps,
Connections Using CAN Link
SECTION SIX: Evolution Two Operation, page 29
On/Off and Stand-by Operation, Play and Record,
Operation Using CAN Link
SECTION SEVEN: Customizing the Evolution Two, page 32
Navigation Conventions, Menu Functions
SECTION EIGHT: Questions and Answers, page 49
Troubleshooting System Noise
APPENDIX: CAN Link and Multiple Evolution Two Preamplifiers, page 51
WARRANTY, page 53
RETURN AUTHORIZATION PROCEDURE, page 55
SPECIFICATIONS, page 56

iv
List of Illustrations
Figure 1, page 15
Evolution Two Preamplifier Chassis and
Power Supply Chassis Front Panels
Inset Evolution Two Preamplifier Channel: Front Panel View
Figure 2, page 16
Evolution Two Remote Control
Figure 3, page 22
Evolution Two Preamplifier Chassis and
Power Supply Chassis Back Panels

A Letter from Dan D’Agostino
Dear Audio Enthusiast,
Thank you for your purchase of the Evolution Two preamplifier.
My new Evolution products represent a watershed in my design philosophy and in
my quest for audio components that deliver absolute truth in music reproduction.
The expanse of the Evolution Two monaural design has allowed me to explore
fully the advantages of current mode topologies. The resulting circuit utilizes no
feedback and has a bandwidth of 2 MHz.
I have always been fascinated by the artistry inherent in great musical performanc-
es, and my new Evolution Two preamplifier delivers the these performances in
their entirety, unaltered, to the amplifier. At the same time, the Evolution Two pre-
amplifier provides the flexibility and control necessary for the listener to thoroughly
enjoy a high performance audio system. It is my pleasure to make the Evolution
products available to you.
The preamplifier plays a vital role in audio playback. At no other point in the repro-
duction process is the music so vulnerable to change. The signal level at the pre-
amplifier stage is small, and is particularly susceptible to noise and distortion. In
order to solve this problem, the Evolution Two employs Krell Current Mode gain
stages from input to output, and Current Audio Signal Transmission (CAST)
receivers and transmitters. Unprecedented in Krell design history, these unique
topologies combine in the Evolution Two preamplifier to form a circuit that has no
audible sonic signature.
The Evolution Series represents a new direction for Krell, where breakthrough cir-
cuit topologies also represent the vanguard in convenience and control. Sophisti-
cated communication circuitry allows from two to eight preamplifiers to be linked
to a single master from which all user interface is accomplished. The Evolution
Two Monaural Preamplifier is designed to complement perfectly the Evolution One
Monaural Power Amplifier. Combine the Evolution One and Two with my new
LAT-1000 loudspeakers, and experience the extraordinary capabilities of an
Evolution System.
1continued

I have some exciting news for you. Work on a new source component for the
Evolution Series is ongoing as of this writing. Possessed of the unique Evolution
technologies that power the amplifier and preamplifier, this Evolution source will
expose the real advantages of the latest recording formats while taking compact
disc playback to the next level. I encourage you to audition it as soon as it is
released.
Sincerely,
Daniel D’Agostino
Chief Executive Officer
2
(A Letter from Dan D’Agostino continued)

About Krell
This section describes the Krell Legacy, the innovative features and technology of
the Evolution Two, and defines CAST and other key terms used in this reference.
The Krell Legacy
“I design every Krell component to set the standard
for workmanship, style, and performance.”
Dan D’Agostino
High-end audio is a demanding pursuit—an ongoing quest for excellence in music
reproduction that drives equipment manufacturers to strive for the absolute in
design and performance. With a keen understanding of this passionate drive, Krell
Industries, Inc., was founded in 1980.
Over the past 2-1/2 decades, Krell has earned a distinguished reputation for engi-
neering innovation and product excellence. The company’s history is replete with
product introductions that have deeply impacted the high-end audio industry. The
most discriminating audiophiles and product reviewers have consistently recog-
nized Krell components for standard-setting performance.
From the company’s inception to the present, Krell C.E.O. Dan D’Agostino has
continually “pushed the envelope” of performance in audio. His exploration of new
technologies, driven by his never-ending quest to elevate the standard of excel-
lence, has resulted in breakthrough audio designs. Evolution Two preamplifiers
build on this Krell legacy.
Dan D’Agostino remains committed to the development of new designs and tech-
nologies. And the Krell legacy will continue to evolve with products that deliver
innovative engineering, perfection in build quality, and outstanding audio perform-
ance.
3
SECTION ONE
continued

4
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 circuitry again 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 are eliminat-
ed. Cable impedances and their effects on the transmitted signal are non-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 takes circuitry signal transmission to the next evolutionary level. In essence,
Krell Current Mode maintains the integrity of the signal within the component and
(SECTION ONE: About Krell continued)

5
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
A CAST system uses cables manufactured by Krell and other manufacturers spe-
cially licensed by Krell. Thin and flexible CAST cables are constructed 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 are part of the standard no-compromise specification devel-
oped for every CAST cable made.
Evolution CAST
By employing radical current mirror circuitry, the Evolution components elevate the
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 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
delivery of the best performance of a musical event for you, using the full expres-
sion of technology to date.
continued

6
Ensuring Maximum Performance
“My pursuit of excellence in sound reproduction and
my love of great musical performance fuels the ongoing
Evolution design effort at Krell.”
Dan D’Agostino
The product of breakthrough Krell technology, the Evolution Two Monaural
Preamplifier works in tandem with the Evolution One Monaural Power Amplifier to
provide a sound that is supremely dynamic and musical. Indeed, it is the sound of
the music itself.
Core Technologies
Zero Feedback Balanced Current Mode Design
The signal path is fully complementary and fully balanced from input to output. All
transistors operate in Class A mode. CAST inputs drive a newly designed current-
mode balanced input stage, which uses a unique topology able to reject com-
mon-mode input noise over an unusually wide bandwidth.
Single-ended and balanced inputs drive a dynamically-cascoded JFET buffer,
which has tremendous open-loop linearity and very high input impedance, to elim-
inate loading effects. The voltage signals are then converted into balanced current
signals, the form in which they remain through the remainder of the signal path.
The audio signal remains in the current domain throughout the entire preamplifier.
Only at the single-ended and voltage outputs is it converted back to the voltage
domain.
All signal gain is realized in the current domain using proprietary multiple-output
current mirrors with nearly 500 times the open loop linearity of other designs.
Negative feedback is not used anywhere in the Evolution Two preamplifier, nor is it
necessary. Open-loop distortion is typically less than 0.005% (50 parts per mil-
lion), and the open loop bandwidth extends to two megahertz. The result is an
extraordinarily wide and deep image, with an open, effortless sound.
The signal switching relays are hermetically sealed and use gold-plated bifurcated
contacts for maximum signal integrity. Where needed multiple relays are connect-
ed in a “T” configuration to virtually eliminate crosstalk from unselected inputs.
The volume setting can be adjusted and displayed either numerically, from 0 to
151, or in dB, from –inf to +12.0 dB.
(SECTION ONE: About Krell continued)