Krell Industries Evolution 202 Quick start guide

OWNER’S REFERENCE
EVOLUTION
EVOLUTION 202
STEREO PREAMPLIFIER
THE LEADER IN AUDIO ENGINEERING

Evolution 202 Stereo Preamplifier
Owner’s Reference, v06.0
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 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. The Evolution 202 preamplifier must be placed on a firm, level surface where it is not exposed
to dripping or splashing.
11. The ventilation grids on the top of the Evolution 202 preamplifier and the space underneath the
Evolution 202 preamplifier must be unobstructed at all times during operation. Do not place
flammable material above or beneath the preamplifier.
12. Before making connections to the Evolution 202 preamplifier, ensure that the power is off and
other components arein mute or stand-by mode. Make sureall cable terminations are of the
highest quality, free from frayed ends, short circuits, or cold solder joints.
13. Do not connect an RS-232 cable to the phono power port. Output from the phono power port
can seriously damage your computer.
14. Do not connect the cable from a Krell KPE phono stage to the RS-232 port.
15. THERE ARE NO USER SERVICEABLE PARTS INSIDE AN EVOLUTION 202 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.
©2006 by Krell Industries, Inc. All rights reserved P/N 309158
TEL [phone]
FAX [phone]
E-MAIL [email protected]
WEBSITE http://www.krellonline.com

3
Contents
List of Illustrations, page 4
ALetter from Dan D’Agostino, page 5
SECTION ONE: Evolution 202 Features and Technology, page 6
Features, Revolutionary Krell CAST Technology,
Definition of Terms
SECTION TWO: Unpacking and Placement, page 11
Opening the Evolution 202 Shipping Carton
SECTION THREE: Quick Start, page 13
Connecting the Evolution 202 to Your System,
Operating the Evolution 202
SECTION FOUR: Anatomy of the Evolution 202, page 15
Front Panel Description, Remote Control Description,
Battery Installation, and Back Panel Description
SECTION FIVE: Connecting the Evolution 202 to Your System, page 26
Input and Output Connections, Connection Steps
SECTION SIX: Evolution 202 Operation, page 28
On/Off and Stand-by Operation
SECTION SEVEN: Customizing the Evolution 202, page 29
Navigation Conventions, Menu Functions
SECTION EIGHT: Troubleshooting System Noise, page 43
WARRANTY, page 44
RETURN AUTHORIZATION PROCEDURE, page 46
SPECIFICATIONS, page 47

4
List of Illustrations
Figure 1, page 15
Evolution 202 Preamplifier and Power Supply Front Panels
Inset Preamplifier and Power Supply Stacked View
Figure 2, page 19
Evolution 202 Remote Control
Figure 3, page 22
Evolution 202 Preamplifier and Power Supply Back Panels

5
ALetter from Dan D’Agostino
Dear Audio Enthusiast,
Thank you for your purchase of the Krell Evolution 202 preamplifier.
The preamplifier plays a vital role in audio playback by mediating the line-level out-
put of a wide variety of source components in preparation for the amplifier’s input.
At no other point in the reproduction process is music so vulnerable to change, as
the signal level is small, and susceptible to noise and distortion.
Having always valued the role of the preamplifier in fine audio systems, I take pre-
amplifier design very seriously.Irealize that, no matter how impressive an amplifi-
er’s performance; it can be no better than that of the preamplifier driving it.
My new Evolution 202 preamplifier employs a powerful, separate power supply,
Krell Current Mode gain stages from input to output, and Current Audio Signal
Transmission (CAST) receivers and transmitters. Utilizing these powerful technolo-
gies, the Evolution 202 conveys the complete range of timbre and dynamics that
comprise the foundation musical performance. Typical of my latest preamplifier
designs, the Evolution 202 preamplifier includes a thoughtful suite of menu
options and can be customized for the greatest ease of operation.
Ihope that you enjoy your new Evolution 202 preamplifier.
Sincerely,
Daniel D’Agostino
Chief Executive Officer

6
SECTION ONE
Evolution 202 Features and Technology
This section describes the innovative features and technology of the Evolution 202
preamplifier, and defines CAST and other key terms used in this reference.
The Evolution 202 Stereo Preamplifier, evolving from the flagship Evolution Two,
works to carefully transmit audio signals without damaging the ephemeral staging
and dimensional components of the music. The Evolution 202 is a two chassis
design with a separate power supply that isolates the critical audio stages for the
lowest possible noise floor. A combination of advanced technologies and inspired
design elevate the Evolution 202 preamplifier’s performance to the reference level.
Features
Preamplifier
The Evolution 202 has a 1 MHz open loop bandwidth in a zero feedback, bal-
anced Krell Current Mode design, terminating in Evolution CAST ™. CAST inputs
and outputs drive a newly designed current mode balanced input stage. Class A,
balanced circuitry is used throughout. Cascoded, current mirror input and output
stages utilize an LED voltage reference to achieve an exceptionally linear state of
operation.
There is no feedback employed anywhere in the design. A digitally controlled, ana-
log volume control is accomplished entirely in the current domain. The bandwidth
and transient response through this circuit is virtually unaffected by the volume
setting. A new, Krell-designed digital control circuit monitors and optimizes the
preamplifier’s operating parameters.
Power Supply
The separate power supply makes extensive use of electrical and magnetic
shielding to keep radiated interference out of critical preamplifier circuits. Internal
line conditioning circuitry filters RF noise on the AC power, and compensates for
asymmetric power waveforms and DC on the mains.
Power for the preamplifier’s analog stages comes from a large 170 VA toroidal
transformer, with four 8-amp bridge rectifiers and 39,600 microfarads of filter
capacitance. A dedicated 90 VA toroidal transformer powers the preamplifier’s
digital control circuitry. The preamplifier has as much power supply capability as
many stereo power amplifiers.

7
In stand-by mode, all the analog circuitry continues to operate at the same bias
current; however, the main analog supply voltages decrease by 30 percent. The
result is a corresponding 30 percent reduction in power consumption and heat
without the need to wait for the electronics to “warm up” before listening.
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,
continued

8
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
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 202 components ele-
vate the CAST technology to another level. This advanced use of the technology
increases the linearity, transient speed, and bandwidth of the Evolution compo-
nents 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.
(SECTION ONE: Evolution 202 Features and Technology continued)

9
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 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 are completely 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 perform as if they are all part of a single circuit.
Single-ended
A two-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 stand-by/power LEDs are not illuminated, the preamplifier is off.
Stand-by
A low-power-consumption status that keeps the audio and regulator circuits at
idle. The stand-by/power LEDs are illuminated in red, when the preamplifier is in
stand-by mode. Krell recommends leaving the preamplifier in stand-by mode when
it is not playing music.
Operation
When the standby/power LEDs are illuminated in blue, the preamplifier is in opera-
tional mode and ready to play music.
continued

10
Technology
Krell Current Mode
A proprietary 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.
(SECTION ONE: Definition of Terms continued)