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Full Power BalancedPower Amplifiers200c, 300c, 600c Stereo
250Mc, 350Mc, 650Mc Monaural
with Krell CAST Technology
Instructions for Use
Owners Reference
Full Power BalancedPower Amplifiers200c, 300c, 600c Stereo
250Mc, 350Mc, 650Mc Monaural
with Krell CAST Technology
v 00.0
Krell Industries, Inc.45 Connair RoadOrange, CT 06477-3650 USA
TEL 203-799-9954FAX 203-891-2028E-MAIL krell @ krellonline.comWEBSITE http://www.krellonline.com
This product complies with the EMC directive (89/336/EEC) and the low-voltage directive (73/23/EEC).
WARNINGSThe Full Power Balanced amplifier must be placed on a firm, level surface where it is not exposed to drip-ping or splashing.
The ventilation grids on the top of the Full Power Balanced amplifier must be unobstructed at all times duringoperation. Do not place flammable material on top of or beneath the component.
Before making connections to the Full Power Balanced amplifier, ensure that ff is off and the preamplifieris in mute or stand-by mode. Make sure all cable terminations are of the highest quality and free fromfrayed ends, short circuits, or cold solder joints.
The differential circuitry employed with Full Power Balanced amplifiers requires special attention when connect-ing speakers. DO not connect the negative speaker terminals together. Do not connect the negative speaker ter-minals to ground or attempt to bridge the left and right speaker binding posts of Full Power Balanced stereo ampli-fiers.
Do not connect a Full Power Balanced amplifier to a speaker selector device that employs a commonground 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 questions not addressed inthis reference manual.
This ;~roduct is manufactured in the United States of America. Krell~ is a registered trademark of Krell Industries. Inc.. and is restricted for use by Krell Indus-tdes. Inc., its subsidiaries, and authorized agents. Sustained Plateau Bias II is a patent of Krell Industries, Inc. Krell CASTTM is a patent pending of KrellIndustries, Inc. Krell Current ModeTM, Krell LinkTM, and Krell Playback SystemTM are trademarks of Krell Industries, Inc. All other trademarks are registeredto their respective companies.
2000 by Krell Industries, Inc. All rights reserved P/N 303969
ContentsINTRODUCTION
DEFINITION OF TERMS
REVOLUTIONARY KRELL CAST TECHNOLOGY
UNPACKING
PLACEMENTAC Power Guidelines
FRONT PANEL DESCRIPTION200c, 300c, and 600c Stereo Power Amplifiers250Mc, 350Mc, and 650Mc Monaural Power Amplifiers
BACK PANEL DESCRIPTION200c, 300c, and 600c Stereo Power Amplifiers250Mc, 350Mc, and 650Mc Monaural Power Amplifiers
CONNECTING THE FULL POWER BALANCED AMPLIFIERTO YOUR SYSTEM
Input and Output ConnectionsKrell Link ConnectionsDC Protection CircuitryUsing a Tube Preamplifier
AMPLIFIER OPERATIONOn/Off and Stand-by OperationKrell Link Operation
REMOTE CONTROL OPERATIONHow to Tum Off the Amplifier LEDsHow to Tum on the Amplifier LEDsHow to Switch between Krell CAST and XLR InputsUsing a Dedicated Wall Outlet and Switch
AMPLIFIER TROUBLESHOOTINGHow to Troubleshoot System NoiseHow to Evaluate Amplifier Operation
QUESTIONS AND ANSWERS
WARRANTY
RETURN AUTHORIZATION PROCEDURE
SPECIFICATIONS
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Krell Full Power Balanced Power Amplifiers iii
IllustrationsFIGURE 1 Full Power Balanced Stereo Amplifier Front Panel
FIGURE 2 Full Power Balanced Monaural Amplifier Front Panel
FIGURE 3 Full Power Balanced Stereo Amplifier Back Panel
FIGURE 4 Full Power Balanced Monaural Amplifier Back Panel
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iv Krell Full Power Balanced Power Amplifiers
Introduction Definition of Terms
The Full Power Balanced series of amplifiersconsists of three stereo amplifiers, the FullPower Balanced 200c, 300c, and 600c, andthree monaural amplifiers, the Full Power Bal-anced 250Mc, 350Mc, and 650Mc. Installation,connection, and operation of all amplifiers in theFull Power Balanced series are identical; how-ever, a pair of Full Power Balanced Monauralamplifiers are required for stereo operation.
Full Power Balanced amplifiers can be config-ured to accommodate any sophisticated musicor home theater system and can be operatedby an optional remote control or through theremote control of other Krell com ponents.
This owners reference manual contains impor-tant information on placement, installation, andoperation of the Full Power Balanced ampli-fiers. Please read this information carefully. Athorough understanding of these details willhelp ensure satisfactory operation and long lifefor your Full Power Balanced amplifier andrelated system components.
Following are the definitions of key terms usedin your owners reference manual.
CONFIGURATIONS
Krell LinkA method of synchronizing remote control oper-ation for Krell systems that include multiple pre-amplifiers, amplifiers, and associated compo-nents. When Krell Link in/out connections areused, the remote capabilities of the linked com-ponents are controlled from one component,called the control component. The linked com-ponents respond to stand-by and operationalmode commands from the control componentvia MIDI cables.
INPUT AND OUTPUT CONNECTIONS
BalancedA symmetrical input or output circuit that hasequal impedance from both input terminals to acommon ground reference point. The industrystandard for professional and sound recordinginstallations, balanced connections have 6 dBmore gain than single-ended connections andallow the use of long interconnect cables. Bal-anced connections are completely immune toinduced noise from the system or the environ-ment.
Krell Current Audio Signal Transmission(CAST)A proprietary Krell circuit technology for con-necting analog components, in which the audiowaveform is transmitted between componentsin the current rather than voltage domain. Thespeed and bandwidth provided by Krell CASTyields accurate, realistic music reproduction.Krell components connected via CAST performas if they are all part of a single circuit.
Krell Full Power Balanced Power Amplifiers 1
Definition of Terms, co,,tinuo,
Single-endedA two-wire input or output circuit. Use carewhen using single-ended connections as theground connection is made last and brokenfirst. Turn the system off prior to making orbreaking single-ended connections. Single-ended connections are not recommended forconnections requiring long cable runs.
OPERATION
OffWhen the power switch on the back panel isplaced in the down position and the blue powerLEDs turn off, the component is off.
Operational ModeWhen the power button on the front panel ispressed and the three blue power LEDs illumi-nate, the component is in the operational modeand ready to play music.
Stand-by ModeA low power consumption status that keeps theaudio and regulator circuits at idle. Krell recom-mends leaving the component in the stand-bymode when it is not playing music.
TECHNOLOGY
Krell Current ModeA proprietary Krell circuit topology in which theaudio gain stages of a component operate inthe current rather than voltage domain. Thisunique technology provides the componentwith exceptional speed and a wide bandwidth.
Krell Sustained Plateau Bias IIA proprietary Krell digital circuit that continuallymonitors the input signal and output impedanceof a Krell amplifier and adjusts the bias accord-ingly to ensure Class A operation. SustainedPlateau Bias II provides the enormous sonicbenefits of continuous Class A operation whileminimizing the heat generation and power con-sumption normally associated with Class Adesigns.
2 Krell Full Powered Balanced Power Amplifiers
Revolutionary Krell CASTTechnologyCurrent Audio Signal Transmission, termedCAST, is a revolutionary method of connectinganalog audio components for unparalleledsonic performance. Innovative engineeringcombines the new Krell CAST circuitry withexisting Krell Current Mode technology to cre-ate entire CAST systems that reproduce musicwith incredible range, tonality, and precision.
Voltage Signal Transmissionand the Traditional Audio SystemTraditionally, signal is transmitted in the voltagedomain between two components. In an audiosystem, each component is a discrete entity withunique characteristics that act upon the musicalsignal independently. Each component isunaware of the other components in the system.The cables that connect the components eachhave their own electrical characteristics, whichaffect the sonic presentation of the entire sys-tem.
CAST: A New ApproachCAST circuitry recognizes signal transmitted inthe current domain instead of the voltagedomain between each component. CAST trans-mission unifies the individual components andtheir interconnects into an electrically linkedwhole. The sonic presentation of the entire sys-tem remains intact.
CAST BasicsHeres how a CAST audio system works. Inter-nally, each CAST source transfers, or amplifies,current using Krell Current Mode circuitry. Thiscurrent signal is then output using CAST cir-cuitry. When the signal is received by a CASTinput, Krell Current Mode circuitry again takesover until the signal reaches the loudspeaker.By maintaining the musical signal in the currentdomain from beginning to end, an entire CASTsystem behaves as if it is one component. WithCAST
