Krell Industries 200c User manual

-ri-i I: I~:Ai~I:I:i i1~1 ~lLaI-~ll~l I:I~III~II~IEEI:ilI~IC!
Full PowerBalanced
PowerAmplifiers
200c, 300c, 600c Stereo
250Mc, 350Mc, 650McMonaural
with Krell CASTTechnology
Instructions for Use
Owner’s Reference

Full PowerBalanced
PowerAmplifiers
200c, 300c, 600c Stereo
250Mc, 350Mc, 650Mc Monaural
with Krell CASTTechnology
v 00.0
KrellIndustries,Inc.
45 ConnairRoad
Orange, CT06477-3650 USA
TEL[phone]
FAX[phone]
E-MAILkrell @krellonline.com
WEBSITEhttp://www.krellonline.com
Thisproductcomplieswith the EMCdirective (89/336/EEC)andthe low-voltagedirective (73/23/EEC).
WARNINGS
TheFull PowerBalancedamplifiermustbeplacedona firm, level surfacewhereit is not exposedto drip-
pingor splashing.
Theventilationgridsonthetopof theFull PowerBalancedamplifiermustbeunobstructedat all timesduring
operation.Donotplaceflammablematerialontopof or beneaththecomponent.
Beforemakingconnectionsto the Full PowerBalancedamplifier, ensurethat ff is off andthe preamplifier
is in muteor stand-bymode.Makesureall cableterminationsareof the highestquality andfree from
frayedends,shortcircuits, or coldsolderjoints.
Thedifferential circuitry employedwithFull PowerBalancedamplifiersrequiresspecialattentionwhenconnect-
ingspeakers.DOnotconnectthenegativespeakerterminalstogether.Donotconnectthenegativespeakerter-
minalsto groundor attemptto bridgetheleft andright speakerbindingpostsof Full PowerBalancedstereoampli-
fiers.
Donot connecta Full PowerBalancedamplifier to a speakerselector device that employsa common
groundscheme,asit mayshort-circuit theamplifieroutput.
THEREARENOUSERSERVICEABLEPARTSINSIDE ANYKRELLPRODUCT.
PleasecontactyourauthorizedKrell dealer,distributor, or Krell if youhaveanyquestionsnotaddressedin
this referencemanual.
This;~roductis manufacturedin theUnitedStatesofAmerica.Krell~is aregisteredtrademarkof KrellIndustries.Inc.. andis restrictedfor usebyKrellIndus-
tdes.Inc., its subsidiaries,andauthorizedagents.SustainedPlateauBiasII is apatentof Krell Industries,Inc. Krell CAST
TM
is apatentpendingofKrell
Industries,Inc. Krell CurrentMode
TM,Krell Link TM, andKrell PlaybackSystem TM
aretrademarksof Krell Industries,Inc. All othertrademarksareregistered
to their respectivecompanies.
©2000byKrellIndustries,Inc.All rightsreserved P/N303969

Contents
INTRODUCTION
DEFINITION OF TERMS
REVOLUTIONARYKRELL CAST TECHNOLOGY
UNPACKING
PLACEMENT
ACPowerGuidelines
FRONTPANELDESCRIPTION
200c,300c,and600cStereoPowerAmplifiers
250Mc,350Mc,and 650McMonauralPowerAmplifiers
BACKPANELDESCRIPTION
200c,300c,and600cStereoPowerAmplifiers
250Mc,350Mc,and 650McMonauralPowerAmplifiers
CONNECTINGTHE FULL POWERBALANCEDAMPLIFIER
TO YOURSYSTEM
Input andOutputConnections
Krell Link Connections
DCProtectionCircuitry
Usinga TubePreamplifier
AMPLIFIER OPERATION
On/OffandStand-byOperation
Krell LinkOperation
REMOTECONTROLOPERATION
Howto TumOff the Amplifier LEDs
Howto Tumon the Amplifier LEDs
Howto Switch betweenKrell CASTand XLRInputs
Usinga DedicatedWallOutlet andSwitch
AMPLIFIER TROUBLESHOOTING
Howto TroubleshootSystemNoise
Howto EvaluateAmplifier Operation
QUESTIONSAND ANSWERS
WARRANTY
RETURNAUTHORIZATION PROCEDURE
SPECIFICATIONS
Page
1
1
3
4
4
5
8
8
8
11
11
12
13
,13
13
14
14
15
15
15
16
16
16
16
16
17
17
17
19
20
21
22
Krell FullPowerBalancedPowerAmplifiers iii

Illustrations
FIGURE1 Full PowerBalancedStereo Amplifier Front Panel
FIGURE2 Full PowerBalancedMonauralAmplifier Front Panel
FIGURE3 Full PowerBalancedStereo Amplifier BackPanel
FIGURE4 Full PowerBalancedMonaural Amplifier BackPanel
Page
6
7
9
10
iv Krell FullPowerBalancedPowerAmplifiers

Introduction Definition of Terms
TheFull PowerBalancedseries of amplifiers
consists of three stereo amplifiers, the Full
PowerBalanced 200c, 300c, and 600c, and
three monauralamplifiers, the Full PowerBal-
anced250Mc,350Mc,and650Mc.Installation,
connection,andoperationof all amplifiers in the
Full PowerBalancedseries are identical; how-
ever, a pair of Full PowerBalancedMonaural
amplifiers are requiredfor stereooperation.
Full PowerBalancedamplifiers canbe config-
ured to accommodateany sophisticated music
or hometheater system and can be operated
by an optional remotecontrol or through the
remotecontrol of other Krell components.
This owner’sreference manualcontains impor-
tant informationonplacement,installation, and
operation of the Full PowerBalancedampli-
fiers. Pleasereadthis informationcarefully. A
thorough understandingof these details will
help ensuresatisfactory operationandlonglife
for your Full PowerBalancedamplifier and
related systemcomponents.
Followingare the definitions of keytermsused
in your owner’sreference manual.
CONFIGURATIONS
Krell Link
A methodof synchronizingremotecontrol oper-
ation for Krell systemsthat includemultiple pre-
amplifiers, amplifiers, andassociated compo-
nents. WhenKrell Link in/out connectionsare
used,the remotecapabilities of the linked com-
ponents are controlled from one component,
called the control component.Thelinked com-
ponents respond to stand-by and operational
modecommandsfrom the control component
via MIDIcables.
INPUT ANDOUTPUTCONNECTIONS
Balanced
A symmetricalinput or output circuit that has
equalimpedancefrom both input terminals to a
commongroundreference point. Theindustry
standardfor professional andsoundrecording
installations, balancedconnectionshave6 dB
moregain than single-ended connections and
allow the useof long interconnectcables. Bal-
ancedconnections are completely immuneto
inducednoise from the systemor the environ-
ment.
Krell Current AudioSignal Transmission
(CAST)
A proprietary Krell circuit technologyfor con-
necting analogcomponents,in whichthe audio
waveformis transmitted betweencomponents
in the current rather than voltage domain.The
speedand bandwidth provided by Krell CAST
yields accurate, realistic musicreproduction.
Krell componentsconnectedvia CASTperform
asif theyareall partof asinglecircuit.
KrellFull PowerBalancedPowerAmplifiers 1

DefinitionofTerms,co,,tinuo,
Single-ended
Atwo-wire input or output circuit. Usecare
whenusing single-endedconnectionsas the
groundconnection is madelast and broken
first. Turnthe systemoff prior to makingor
breaking single-endedconnections. Single-
endedconnections are not recommendedfor
connectionsrequiringlongcableruns.
OPERATION
Off
Whenthe powerswitch on the backpanel is
placedin thedownposition andthe bluepower
LEDsturn off, thecomponentis off.
OperationalMode
Whenthe powerbutton on the front panel is
pressedandthe three blue powerLEDsillumi-
nate, the componentis in the operationalmode
andreadyto play music.
Stand-by Mode
A lowpowerconsumptionstatus that keepsthe
audioandregulatorcircuits at idle. Krell recom-
mendsleaving the componentin the stand-by
modewhenit is not playingmusic.
TECHNOLOGY
Krell CurrentMode
AproprietaryKrell circuit topologyin whichthe
audiogain stagesof a componentoperatein
the current rather than voltagedomain.This
unique technology provides the component
with exceptionalspeedanda widebandwidth.
Krell SustainedPlateauBiasII
AproprietaryKrelldigital circuit thatcontinually
monitorstheinput signal andoutputimpedance
of a Krell amplifierandadjuststhebiasaccord-
ingly to ensureClassAoperation.Sustained
PlateauBias II providesthe enormoussonic
benefitsof continuousClassAoperationwhile
minimizingtheheatgenerationandpowercon-
sumptionnormally associated with Class A
designs.
2 Krell Full PoweredBalancedPowerAmplifiers

Revolutionary Krell CAST
Technology
Current Audio Signal Transmission, termed
CAST,is a revolutionary methodof connecting
analog audio componentsfor unparalleled
sonic performance. Innovative engineering
combinesthe newKrell CASTcircuitry with
existing Krell Current Modetechnologyto cre-
ate entire CASTsystemsthat reproducemusic
with incrediblerange,tonality, andprecision.
Voltage Signal Transmission
andthe Traditional AudioSystem
Traditionally, signalis transmittedin thevoltage
domainbetweentwo components.In an audio
system,eachcomponentis a discrete entity with
uniquecharacteristics that act uponthe musical
signal independently. Each component is
unawareof the other componentsin the system.
Thecables that connect the componentseach
havetheir ownelectrical characteristics, which
affect the sonic presentationof the entire sys-
tem.
CAST: A NewApproach
CASTcircuitry recognizessignal transmitted in
the current domaininstead of the voltage
domainbetweeneach component.CASTtrans-
missionunifies the individual componentsand
their interconnectsinto an electrically linked
whole.Thesonicpresentationof the entire sys-
temremainsintact.
CASTBasics
Here’s howa CASTaudio systemworks. Inter-
nally, eachCASTsourcetransfers, or amplifies,
current usingKrell CurrentModecircuitry. This
current signal is then output using CASTcir-
cuitry. Whenthe signal is received by a CAST
input, Krell CurrentModecircuitry againtakes
over until the signal reachesthe loudspeaker.
Bymaintainingthe musicalsignal in the current
domainfrom beginning to end, an entire CAST
systembehavesas if it is onecomponent.With
CAST,anomaliesof signal transmissionbetween
componentsare eliminated. Cable impedances
andtheir effects onthe transmitted signal are
non-existent.
HowCASTand Krell Current ModeInteract
While CASTis a newmethodof transferring the
musical signal betweencomponents,its origin
stemsfrom Krell Current Mode,the technology
developedto transfer the musicalsignal within
a component. CASTcombinedwith Krell Cur-
rent Modetakes circuitry signal transmissionto
the next evolutionary level. In essence,Krell
CurrentModemaintainsthe integrity of the sig-
nal within the componentand CASTpreserves
the transmitted signal betweencomponents.
Together, CASTand Krell Current Modetech-
nologiesunify separateKrell componentsinto a
singleglobalcircuit.
CASTCable Construction
A CASTsystem uses cables manufactured by
Krell and other manufacturers specially
licensed by Krell. Thin andflexible CASTcables
are constructedwith the samebuild quality as
other Krell products and are aesthetically
matchedto the componentsthat Krell manufac-
tures. Anall-metal bodyandlocking connectors
with gold contactsare part of the standardno-
compromisespecification developedfor evenj
CASTcable made.
The Best Musical Performance
Whenyou operate a CASTsystem, you will
hear significant improvementsin every perfor-
mancearea: speed, precision, dynamicrange,
depth andwidth of the soundstage, transient
impact, tonal balance, harmonicdistortion, and
more. Thegoal for CASTis the samecompany
goalusedfor all Krell products.Krell strives for
the delivery of the best performanceof a musi-
cal eventfor you, using the full expressionof
technologyto date.
KrellFull PowerBalancedPowerAmplifiers 3

Unpacking Placement
Twopeople are needed to removethe Full
PowerBalancedamplifier fromits shippingbox
safelyandeasily.
1. Openthe shipping box andremovethe top
layer of foam.Youseetheseitems:
1 Full PowerBalancedAmplifier
1 Packetcontaining the owner’s
reference manualandthe warranty
registration card
2. Orient the shippingboxso that oneperson
standsat the front of the amplifier andone
personstandsat the rear of the amplifier.
Bothpeopleneedto graba pair of the card-
boardhandlecutouts(onepair locatedat the
front of the amplifier andonepair locatedat
the rear of the amplifier) andsimultaneously
lift theamplifierstraightup,outof thecarton.
3. Place the amplifier in a safe location and
removethe protective plastic wrapping.
Notes
ff any of the items mentionedaboveare not
included in the shipping box, please contact
yourauthorizedKrell dealer,distributor, or Krell
for assistance.
Saveall packingmaterials. If youship yourFull
PowerBalancedamplifier in the future, repack
theunff in its original packagingto preventtran-
sit damage.SeeReturn Authorization Proce-
dure, on page21 for moreinformation.
Before you install the Full PowerBalanced
amplifier into your system, please follow the
guidelines in this section to chooseits proper
location.Thiswill facilitate a clean,trouble-free
installation.
TheFull PowerBalancedamplifier requires at
least two inches (5 cm) of clearance on each
side andat least eight inches(20 cm)of clear-
ance above the componentto provide ade-
quateventilation.
Although Sustained Plateau Bias II circuitry
reducesthe high heat dissipation andheat out-
put of traditional ClassA circuitry, Full Power
Balancedamplifiers still canbecomehot under
normaloperation.
Whenthe front andrear of a cabinet are open
the air spacebetweenthe chassis an~l shelf
mustbeunobstructed.If you place the amplifi-
er in a closed cabinet, you mayneedto modify
shelf spacingor usesmall fans to increaseven-
tilation. For the dimensionsof your Full Power
Balancedamplifier, see Specifications, on
pages 22-23.
Placethe amplifier as close to the speakersas
possible. Krell CASTtechnologypermits you to
useinterconnectcablesof anylength, seeFlev-
olutionary CASTTechnology on page 3;
however,try to keepthe cablelength to a mini-
mum.
All Full PowerBalancedamplifiers drive the
lowest impedances with ease. Whenimped-
ance is added due to long speaker cable
lengths, amplifier poweris wastedin the cable.
Long speaker cables reduce the maximum
powerthat is delivered in the speakers.
4 KrellFull PowerBalancedPowerAmplifiers

Placement,continued
AC POWERGUIDELINES
The Full Power Balanced 200c and 250Mc
amplifiers needto be operatedfrom a dedicat-
ed ACpower line rated at a minimumof 15
amps.The Full PowerBalanced300c, 350Mc,
600c, and650Mcamplifiers needto be operat-
ed from a dedicated ACpowerline rated at a
minimumof 20 amps.
PleasecontactyourauthorizedKrell dealer, dis-
tributor, or Krell before using any devices
designedto alter or stabilize the ACpowerfor
Full PowerBalancedamplifiers.
KrellFullPowerBalancedPowerAmplifiers 5

FIGURE 1 FULL P( IWER BALANCED STEREO AMPLIFIER FR()NT PANEL
123 456
1 Power Stand-by LED
2 Bias LED
3 PowerButton
4 Infrared Sensor
5 Krell CASTLED
6 Regulator LED
6Krell Full PoweredBalancedPowerAmplifiers

FIGURE 2 FULL POWERBALANCED MONAURALAMPLIFIER FR( INT PANEL
789 101112
7 PowerStand.by LED
8 Bias LED
9 PowerButton
10 InfraredSensor
11 Krell CASTLED
12 RegulatorLED
Krell FullPoweredBalancedPowerAmplifiers 7

FrontPanelDescription
Thefront panel accesses power on/stand-by
andinfrared sensor(remotecontrol) functions.
Thepowerstand-by, bias, regulator, andKrell
CASTLEDs,arrangedin a triangle on the front
panelabovethe powerbutton, illuminate to indi-
cateamplifierstatus.
FULL POWERBALANCED200c,
300c, AND600c STEREOPOWER
AMPLIFIERS
SeeFigure1 onpage6
1 Power Stand-by LED
Theblue powerstand-by LED(top of LEDtri-
angle) illuminates whenthe back panel power
breaker switch has beenmovedto on, engag-
ing the input circuitry andplacingthe amplifier
in stand-by mode.
2 Bias LED
Thebluebias LED(lowerleft of triangle) illumi-
nates after the front panel powerbutton is
pressed, indicating that the SustainedPlateau
BiasII is engaged.
3 Power Button
Usethe silver powerbutton, to poweron the
amplifier from stand-by mode.
4 Infrared Sensor
Theinfrared sensorreceives the signal from a
remotecontrol.
5 Krell CASTLED
Thered Krell CASTLED(center of triangle) illu-
minates whena Krell CASTinput on the back
panelis connectedto anotherKrell productwith
a Kreil CASToutput.
6 Regulator LED
Theblueregulator LED(lower right of triangle)
illuminates after the front panelpowerbuttonis
usedto poweron from stand-by mode,indicat-
ing that the regulator is providing powerto the
output stage.
Note
Anoptional remotecontrol is available for Full
PowerBalancedamplifiers.
FULL POWERBALANCED250Mc,
350Mc, AND650Mc MONAURAL
POWERAMPLIFIERS
SeeFigure2 onpage7
7 PowerStand-by LED
Theblue powerstand-by LIED(top of LEDtri-
angle) illuminates whenthe back panel power
breaker switch hasbeenmovedto on, engag-
ing the input circuitry andplacingthe amplifier
in stand-bymode.
8 Bias LED
Thebluebias LED(lowerleft of triangle) illumi-
nates after the front panel powerbutton is
pressed,indicating that the SustainedPlateau
BiasII is engaged.
9 PowerButton
Usethe silver powerbutton to poweron the
amplifier fromstand-bymode.
10 Infrared Sensor
Theinfrared sensorreceives the signal froma
remotecontrol.
11 Krell CASTLED
TheredKrell CASTLED(center of triangle) illu-
minates whena Krell CASTinput on the back
panelis connectedto anotherKrell productwith
a Krell CASToutput.
12 Regulator LED
Theblue regulator LED(lower right of triangle)
illuminates after the front panelpowerbuttonis
usedto poweron fromstand-by mode,indicat-
ing that the regulator is providingpowerto the
outputstage.
8 KrellFullPowerBalancedPowerAmplifiers

FIGURE 3 FULL POWER BALANCED STEREO AMPLIFIER BACK PANEL
19 13 14 15 16 17 18 16 14 1319
13 Left andRight SpeakerBindingPosts
14 Krell CASTInputs
15 BackPanelPowerBreakerSwitch
16 Left andRightBalancedInputs
17 Krell LinkOut/In
18 ACMainsPowerCord
19 Handles
KrellFull PoweredBalancedPowerAmplifiers

FIGURE 4 FULL POWER BALANCED MONAURAL AMPLIFIER BACK PANEL
20 21 22 23 24 25 26
20 Handle
21 SpeakerBindingPosts
22 Krell CASTInput
23 BalancedInput
24 ACMainsPowerCord
25 KrellLinkOut/In
26 BackPanel Power
BreakerSwitch
10 KrellFull PoweredBalancedPowerAmplifiers

BackPanelDescription
Theback panel provides connections for all
inputs and outputs, poweron/oft, andremote
control links. Thebackpanel also hashandles
that allow you to safely andeasily movethe
amplifier.
FULL POWERBALANCED200c,
300c, AND600c STEREOPOWER
AMPLIFIERS
SeeFigure3 onpage9
13 Left andRight SpeakerBinding Posts
Full PowerBalanced 200c, 300c, and 600c
stereoamplifiers areequippedwith four pairs of
speakerbinding posts (upperleft, lower left,
u pperright, andlowerright).
Notes
Twopairs of speakerbinding posts are usedfor
eachchannelof amplification. Onthe stereo or
monaural Full Power Balanced amplifiers,
either the upperor the lower pair canbeused
with speakershavingtwopairs of bindingposts.
For biwiring applications, with speakershaving
morethan onepair of binding posts, useboth
upperandlowerpairs of speakerbinding posts.
See the speaker’s instruction manual for
biwiring connections.
Speakerbinding posts for stereo andmonaural
amplifiers accept spadelugs only. Barewire,
bananalugs, or pins will not work. Usethe red
terminal for the positive connection andthe
blueterminal for the negativeconnection.
14 Krell CASTInputs
Full PowerBalanced 200c, 300c, and 600c
stereoamplifiersareequippedwith oneleft Krell
CASTinput andoneright Krell CASTinput via 4-
pin bayonetconnectors. TheKrell CASTinputs
allow the Full PowerBalancedamplifier to be
connectedto the KPS25scKrell PlaybackSys-
tem and other CAST-equippedcomponents.
15 BackPanel PowerBreaker Switch
Full PowerBalancedamplifiers are equipped
with a back panel powerbreaker switch, for
powering on the amplifier. Placing the back
panel powerbreaker switch in the up position
placesthe amplifier in stand-bymode,whereit
remainsuntil the front panelpowerbutton(3)
pressed.
Note
Krell recommendsthat the amplifier remainon,
in stand-by mode,evenwhennot in use, once
it is poweredon from the back panel power
breakerswitch(15).
16 Left andRight BalancedInputs
Full Power Balanced 200c, 300c, and 600c
stereoamplifiers are equippedwith oneleft bal-
ancedinput andone. right balancedin pr~t via
XLRconnectors.
17 Krell Link Out/In
Full PowerBalancedamplifiers are equipped
with Krell Link Remoteout/in connectorsthat
allow the remotecontrol to operate a linked
amplifier configuration. SeeKrell LinkConnec-
tions, onpage13for moreinformation.
Note
Anoptional remotecontrol is available for Full
PowerBalancedamplifiers.
18 AC Mains PowerCord
All Full PowerBalancedamplifiers are equipped
with a permanentlyattached ACpowercord.
19 Handles
All Full PowerBalancedstereo amplifiers are
equippedwith two handles, located beside the
speakerbinding posts, to help you easily and
safelymovethe amplifier.
Krell FullPowerBalancedPowerAmplifiers 11

BackPanelDescription,continued
FULL POWERBALANCED250Mc,
350Mc, AND 650Mc MONAURAL
POWER,AMPLIFIERS
SeeFigure4 onpage10
20 Handle
All Full PowerBalancedmonauralamplifiers are
equipped with a handle, located beside the
speakerbinding posts, to help youeasily and
safelymovethe amplifier.
21 Speaker Binding Posts
Full Power Balanced 250Mc, 350Mc, and
650Mcmonauralamplifiers are equippedwith
two pairs of speakerbinding posts (oneupper
pair andonelowerpair). For stereo operation,
twomonauralamplifiers are required.
22 Krell CASTInput
Full Power Balanced 250Mc, 350Mc, and
650Mcmonauralamplifiers are equippedwith
oneKrell CASTinput via a 4-pin bayonetcon-
nector. TheKrell CASTinput allows the Full
PowerBalancedamplifier to be connectedto
the KPS25sc Krell PlaybackSystemand other
CAST-equippedcomponents.
23 BalancedInput
Full PowerBalanced250Mc,350Mc,and 650Mc
monauralamplifiers are equippedwith onebal-
ancedinput via anXLRconnector.
24 AC Mains Power Cord
All Full PowerBalancedamplifiers are equipped
with a permanentlyattached ACpowercord.
25 Krell Link Out/In
Full PowerBalancedamplifiers are equipped
with Krell Link Remoteout/in connectors that
allow the remotecontrol to operate a linked
amplifier configuration. SeeKrell LinkConnec-
tions, onpage13for moreinformation.
Note
Anoptional remotecontrol is available for Furl
PowerBalancedamplifiers.
26 BackPanel PowerBreaker Switch
Full PowerBalancedamplifiers are equipped
with a back panel powerbreaker switch, for
powenngon the amplifier. Poweringon u§ing
the backpanelpowerbreaker switch places the
amplifier in stand-by mode,whereit remains
until the front panelpowerbuttonis pressed.
Note
Krell recommendsthat, oncethe amplifier is
poweredon from the back pane/powerbreaker
switch, it remainson, in stand-by mode,even
whennot in use.
12 KrellFull PowerBalancedPowerAmplifiers

Connectingthe Full PowerBalanced
Amplifier to YourSystem
INPUT ANDOUTPUT
CONNECTIONS
Krell recommendsusingits proprietary Krell
CASTsystemfor unparalleled sonic perfor-
mancebetween the Full PowerBalanced
amplifiers andother CAST-equippedcompo-
nents andthe KPS25scKrell PlaybackSys-
tem.
Full PowerBalancedamplifiersalsooffer bal-
ancedoperation.Thecircuitry andconnections
associatedwith balancedoperationnot only
canminimizesonicloss but also areimmuneto
inducednoise,especiallyfor installationsusing
longcables.
AonepieceRCA-to-XLRadapteris available
fromKrell Industries,to allowsingle-endedoper-
ationusingthebalancedXLRinputs.
Thefollowing stepsdescribehowto connect
cablesto theFull PowerBalancedAmplifiers.
1. Neatlyarrangeandorganizewiring to and
fromtheamplifier andall components.Sep-
arateACwiresfromaudiocablesto prevent
humor other unwantednoise frombeing
introducedinto thesystem.
2. Connectthe Krell CASTcablesfromyour
CAST-enabledpreamplifier/source compo-
nentto theleft andright Krell CAST4-pin
bayonetinputsontheamplifier backpanel.
Forbalancedoperation,connectthe inter-
connectcablefromyourpreamplifierto the
left andright balancedXLRinput onthe
amplifierbackpanel.
3. Connectthe speakercables to the Full
PowerBalancedamplifier’s speakerbinding
posts,locatedontheamplifier backpanel.
Speakerbindingpostsfor bothstereoand
monauralamplifiersacceptspadelugsonly.
4. Insert the endof the ACmainspowercord
into theACwallreceptacle.
5. Proceedwith Krell Link Connections,if
desired,or turn to AmplifierOperation,on
page15.
KRELL LINK CONNECTIONS
Krell Link Remoteout/in connectorson the
backpanelof the Full PowerBalancedamplifi-
er allow you to synchronizeremotecontrol
operation for systemsthat include multiple
amplifiers andassociatedcomponents.When
the Krell Link Remoteout/in connectorsare
used,theremotecapabilities of the linkedcom-
ponentsare controlled fromoneamplifier or
preamplifier,called the controlcomponent.The
linked componentsrespondto stand-by and
operational modecommandsfrom the control
componentvia MIDIcables.
Note
Kre// Link usesstandardfive pin M/D/commu-
nication cab/es,sometimesreferred to asM/D/
P/us cab/es. M/D/ cab/es can be purchased
fromyourauthorizeddistributor or dea/er, or
fromanaudiosupp/ystore.
Howto Connect Components
throughKrell Link
1. Turnall componentsoff, using the back
panelpowerbreakerswitch. This ensures
that the componentsare synchronizedwhen
theMIDIcableis connected.
2. Selectthecomponentto bethe control com-
ponent.Thecontrol componentmustbe in
plain viewfor properremotecontrol opera-
tion.
3. Connectoneendof the MIDIcable to the
Krell Linkoutconnectoronthebackpanelof
the component.
KrellFullPowerBalancedPowerAmplifiers 13

Connecting,continued
4. Connectthe other endof the MIDIcable to
the Krell Link in connectoronthe next com-
ponent.
Tolink anothercorn ponent,connecta sec-
ondMIDIcable to the Krell Link out con-
nector on the back panel of the second
component.Connectthe remaining end of
the MIDIcableto the Krell Link in connec-
tor onthe backpanelof a third component.
5. Link additional components,if desired, as
describedin Steps3 and4.
Thecomponentsare nowreadyfor operationwith
KrellLink.
DC PROTECTIONCIRCUITRY
Full PowerBalancedamplifiers use unobtrusive
direct current (DC)protection circuitry that
strips DCfrom the signal without corrupting
sound reproduction. Full Power Balanced
amplifiers feature direct coupledcircuitry from
input to output. Thistopologyeliminatesall cou-
pling capacitors from the audio signal path.
Coupling capacitors block damagingDCbut
havesonic characteristics that corrupt sound
reproduction.
Note
For moreinformation aboutDCprotection cir-
cuitry features, seeAmplifier Troubleshooting,
onpage17.
USING A TUBEPREAMPLIFIER
Thehigh DCoutput of tube preamplifiers may
exceed the DCprotection circuitry of Full
Power Balanced amplifiers. Excessive DC
level in a signal candamageamplifiers, speak-
ers, or both. Thecoupling capacitors in Full
PowerBalanced amplifiers must be engaged
whenusing a tube preamplifier. Anauthorized
Krell dealer, distributor, or Krell mustactivate
these capacitors.
Couplingcapacitors mustbe inserted into the
signal pathby yourauthorizedKrell dealer, dis-
tributor, or Krell before youcan useyour Full
PowerBalancedamplifier with a tube preampli-
fier.
IMPORTANT
Please read the Warranty, on page 20, to
understand the warranty limitations of Full
Power Balanced amplifiers when used with
tube preamplifiers.
14 Krell FullPowerBalancedPowerAmplifiers

AmplifierOperation
Full PowerBalancedamplifiers are easy to
install andoperate.However,it is importantto
exercise care during operation, dueto the
amplifiers’ enormouspoweroutput. Switching
betweenactive sources(such as a CDplayer,
tape monitor, or VCR)without mutingthe pre-
amplifier output, or bumpingor miscuing a
sourcecangeneratelarge transients at lowfre-
quencies. Full PowerBalancedamplifiers may
generate enoughpowerwith these transients
to damageloudspeakers.
IMPORTANT
Alwaysmuteor fully attenuatethe preamplifier
level whenswitching sources.
Donot changeinput connectionsto the amplifi-
er whenthe amplifier is on.
Usecare whensetting high playback levels.
Becauseof their tremendousreservesof clean
power,Full PowerBalancedamplifiers cansafe-
ly drive speakersto highersoundpressurelev-
els thanotheramplifiers. Alwayslowerthe vol-
umelevel at thefirst signof speakerdistress.
ON/OFFANDSTAND-BYOPERATION
Whenpoweringon any system, turn on ampli-
fiers last. Turnoff amplifiersfirst.
1. Movethe backpanel powerbreaker switch
to the upposition to engagethe input cir-
cuitry andplacethe amplifierinto thestand-
by mode.Thefront panel bluepowerstand-
by LEDilluminates.
2. Pressthe silver powerbuttononthe amplifi-
er front panel.TheblueregulatorLEDillumi-
nates.Oncethe regulator providespowerto
the outputstage, the blue bias LEDillumi-
nates.TheSustainedPlateauBiasII system
is nowengaged.After the protectioncircuitry
hasconfirmedthat safe operatingconditions
exist, the input relays engage.Youheara
click. Theamplifier is readyfor operation.
If the Krell CASTinput is beingused,the
Krell CASTred LED illuminates and
remainsilluminated at all times during the
stand-by or poweron modes.
3. Withthe preamplifier mutedor volumecon-
trol completelylowered, select a source.
Increasethe volumecontrol to the desired
listeninglevel.
4. Whenturning off the system,muteor com-
pletely lower the preamplifier volume,or
place the Full PowerBalancedamplifier in
the stand-by powermodeby pressing the
powerbutton on the front panel. It is now
safeto turn off the rest of the system.
Note
For best performanceof Full PowerBalanced
amplifiers, leave the backpanelpowerbr~eaker
switchonat all times.
KRELLLINK OPERATION
1. Whenall componentsare linked, place
each componentin the stand-by modeby
moving the back panel power breaker
switchto the upposition. Thisensuresthat
all componentswill be synchronizedwhen
signals fromthe control componentare sent
to the linked componentsin the system.
2. Whenthe componentsare in stand-by,
switch the control componentto the opera-
tional modefrom the control component’s
front panel or by using the component’s
remotecontrol.
Thelinked corn ponentsswitch to the oper-
ational modesimultaneously.
A linked componentcan be switched between
the operational modeandstand-by, individual-
ly, fromits front panel.Switchinga linked com-
ponenttemporarily breaksthe chain of linked
components.Tore-establish linked operation,
return all componentsto stand-by.
KrellFullPowerBalancedPowerAmplifiers 15

RemoteControl
Operation
Full PowerBalancedamplifiers are compatible
with the remotecontrols includedwith Krell pre-
amplifiers, the Krell Audio+ VideoStandard,
the KAV-300rRemoteControl Receiver, the
HomeTheater Standard, and the KPS25sc
Krell PlaybackSystem.
PleasecontactyourauthorizedKrell dealer, dis-
tributor, or Krell to purchasea remotecontrolfor
Full PowerBalancedamplifiers.
Full PowerBalancedamplifiers canbelocated
in a roomor spaceclose to the speakersbut out
of sight, andpoweredon or off remotelyfrom
the listening room,througha control amplifier.
SeeKrell Link Connections, on page13.
HOWTO TURNOFF
THE AMPLIFIERLEDs
The amplifier must be in the stand-by mode
with the rear panel powerbreaker switch on.
Whileholding the silver powerbutton in, press
the powerkeyonthe remotecontrol. After the
amplifier finishes its turn-onsequence,the front
panelblue LEDsturn off. Theblue LEDsremain
off throughoutnormaloperation as long as the
amplifier’s rear panelpowerbreakerswitch is
notturnedoff.
HOWTO TURN ON
THE AMPLIFIERLEDs
With the amplifier in the stand-by mode,turn
the rear panel powerbreaker switch to the off
position. Thenturn the rear panelpowerbreak-
er switch backto the onposition. Thenext time
the amplifier is poweredupfromthe front panel
or the remotecontrol, the blue LEDsilluminates
during the turn-on sequence.
HOWTO SWITCH BETWEEN
KRELLCAST ANDXLR INPUTS
Pressthe meterkeyon a Krell remoteto switch
between CASTinputs and the balanced XLR
inputs.
Full PowerBalancedamplifiers default to CA~ST
operationuponstartup, if the amplifier is tumed
off fromthe rear panel powerbreakerswitch and
a CASTsource and cable are connectedto the
CASTinputs. Theoperational modedoes not
changeif the Full PowerBalancedamplifier is in
stand-by mode.
USING A DEDICATEDWALL
OUTLETAND SWITCH
Full PowerBalancedamplifiers can be powered
on froman ACwall receptacle with a dedicated
switch, rather than from the front panel power
button or optional remotecontrol.
PleasecontactyourauthorizedKrell dealer, dis-
tributor, or Krell for moreinformationbeforeyou
connectyour Full PowerBalancedamplifier to a
dedicatedACwall outlet with a switch.
16 KrelFull PowerBalancec~PowerAmplifiers