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Krell Industries, Inc.
45 Connair Road
Orange, CT 06477-3650 USA
TEL 203-799-9954
FAX 203-891-2028
E-MAIL krell@krellonline.com
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.
©2003 by Krell Industries, Inc. All rights reservedP/N 305976
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.
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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
