Krell Industries Evolution 600 User manual

~The L~eade~r in A~udio Engineen’ng
Full Power Balanced
PowerAmplifiers
600,300,200Stereo
650M,350M,250MMonaural
Instructions for Use,v 98.2
Owner’sReference

A note fromDanD’Agostino
Thankyoufor yourpd~chaseof a Full PowerBalancedamplifier. This
componenthasbeendesignedto exceedall otheramplifier productsin ultimate
performance,musicality,andoveralldurability. I amsurethat it will giveyou
manyyearsof superiorperformance.Someof the featuresthat r[Lakethis Full
PowerBalancedamplifier uniqueinclude:
Kreil CurrentModeTM:This advancedcircuit topologyis a KRELL
introductionto the audioindustryandyields a far greaterdegreeof speed
andstagepresencethanis possiblethroughconventionaltechnologies’.
Fully Regula-~edOutputStage:Oneof the mostobviouscausesof musicat
corruptionin anamplifieris voltageandcurrentdropin theoutputstage.
Whilethe large capacitivebanksusedbyothermanufacturersare marginally
effective with currentdrop,capacitorscannotcompensatefor voltagedrop.
~, Full PowerBalancedamplifier’s regulatedoutputstageandpowersupplyis
imperviousto theseformsof corruption. Currentandvoltageremainconstant
underall operatingconditions.
BalancedAmplifierDesign:YourFull PowerBalancedamplifier
incorporatescompletelybalancedcircuit topologyfrominput to output,
maintainingthe integrity of the audiosignalandexercisinggreaterspeaker
control bymeansof its balanced,push-pullrelationshipwith the speaker
drivers.
ClassAOperation:ClassAis the only linear operatingstate in electronics.
YourFull PowerBalancedamplifier operatesin ClassAto its full ratedpower
to providethe mostaccurateandrichly detailedmusicalexperiencepossible.
SustainedPlateauBiasIi~: SustainedPlateauBias II TM is a KRELL
patentedprocessthat enablesyouramplifierto playall music(upto full rated
power)in ClassA, yet greatly reducethe heatdissipationandenergy
consumptionassociatedwith conventionalClassA designs.Sustained
3

¯Pla~teauBiasii TM is a true ClassAcircuit, asopposedto sliding or adaptive
biasing schemes.
TheFull PowerBalancedamplifier follows all classic KRELLmar~ufaoturingand
materialsrequirements,andI amsurethat youwill not find its equalanywherein
theworld.
Enjoyyour KRELLFull PowerBalancedamplifier.
Sincerely,
DanD’Agostino
C.E.O
4

Introduction
Toobtainthe bestperformancefromyourFull PowerBalancedamplifier, careful
’attention shouldbepaidto its placement,installation, andoperation.Athorough
understandingof thesedetails will helpinsuresatisfactoryoperationandlong
life for the Full PowerBalancedamplifier andrelatedsystemcomponents.
ThisOwner’sReferenceis dividedinto severalsections,eachdesignedto
performa different function. Asyoureadthroughthe Owner’sReferenceyou
will becomebetter acquaintedwith the featuresandfunctionsthat makethe Full
PowerBalancedamplifiers a superbvalue..A Troubleshootingsection is
includedwith solutionsto potential problems.Shouldyouhaveanyquestions
or suggestions,pleasefeel free to contactyourauthorized~ealeror the KRELL
staff for assistance.
TheFull PowerBalancedseriesof amplifiersconsistsof threestereoamplifiers,
the Full PowerBalanced200,300, and600, andthe three monauralamplifiers,
the Full PowerBalanced250M,350M,and650M.Installation, connection,and
operationof all amplifiersin theseriesis identical; however,pleasenotethat two
Full PowerBalanced250M,350Mor 650Mamplifiers are requiredfor stereo
operation.
In the unlikely eventthat yourFull PowerBalancedamplifier shouldrequire
service, youwi!! bepleasedto knowthat is backedbya comprehensive
CustomerSatisfactionpolicy andoneof the mostadvancedservicefacilities in
the industry. Fordetailedinformationonthe termsandconditionsof service,
pleaserefer to the WarrantyandServicesectionof this Reference,Warranty
RegistrationCard,or anauthorizedKRELLDealeror Distributor.
Unpacking
After openingthe boxandremovingthe top layer of foam,the Full Power
Balancedamplifierandthefollowingitemswill nowbevisible:
IEC32020 ampACpowercord
Owner’sReference
Warrantycard
NOTES:
If anyof theseitemsare not included,pleasecontactyourauthorizedKRELL
dealeror distributor.
Saveall packingmaterials.If youmustshipyourFull PowerBalancedamplifier
in the future, repacktheunit in its original packingto preventshippingdamage.
5

Location
Placethe Full Powe~Balancedamplifier ona firm level surfaceawayfromdirt or
moisture.Whenusingcustomracksor cabinetry, keepin mindthe weightand
ventilationrequirementsfor theseamplifiers.Ideally, theamplifiershouldbe
placedascloseto the speakersaspossible.It is preferableto runlong
balancedinterconnectcablesto the amplifier andkeepthe speakercable
lengthto a minimum.Speakercableaddsimpedanceto the I-6ad the amplifier
mustdrive, regardlessof the cable’sgauge.All KRELLamplifierswill drive the
lowestimpedanceswith ease,but whenimpedanceis addeddueto long cable
lengths,amplifier poweris wastedin the cable.Longspeakercablesreducethe
maximumpowerthat canbe deliveredto the speakers.
RemoteInstallation
Someinstallations donothaveadequate,spaceor flexibility to placetheamplifier
closeto the speakers.TheFull PowerBalancedamplifierscanbesituatedin a
roomor spacecloseto thespeakers,butout of sight, .andturnedOnor Offfrom
the listening room.Intemally,a provisionhasbeenmadeallowingthe amplifier
to bepoweredOnfromanACwall receptacleandnot fromthe front panelpower
switchor optional remotecontrol. Wesuggestmountinga standardwall switch
in the listening roomthat controlsanACpoweroutlet dedicatedto the power
amplifier. Thisarrangementcanbeprovidedbyanelectrician. Pleasecontact
yourdealerfor assistance.
NOTE:OnceACpoweris applied, the front panelpowerswitch andthe remote
P.csntml pnw~r.~vifP.h =r=
CabinetryConsiderations
ClassAoperationoffers tremendoussonicbenefits. Unfortunately,traditional
ClassAamplifiers dissipate a tremendousamountof heat. KRELL’spatented
SustainedPlateauBiascircuitry combatsthis characteristicandreducesthe heat
outputconsiderably.However,the Full PowerBalancedamplifierscanstill
becomequite warmundernormaloperation. TheFull PowerBalancedamplifiers
shouldbeinstalledin a locationthat providesunobstructedventilation.
IMPORTANT:Theventilation gddsonthe top of all Full PowerBalanced
amplifiersneedto beunobstructedat all timesduringoperation.Donotplace
flammablematerialontop of or beneathFull PowerBalancedamplifiers. For
installations insidecabinetry,extraventilation maybenecessary.Makesurethe
Full PowerBalancedamplifiershaveadequateair circulation. Generally,two
inchesof clearanceoneachsideof the amplifier andeight inchesof clearance
abovethe amplifier will provideadequateventilation. In moreextremeinstances,
-, smallfanscanaidin removingexcessheatfrominternal spaces-.Contactyour
dealer,distributor, or Kreil®formoreinformation.
6

ACPowerConsiderations
Forbestperforman¢-e,a dedicatedACpowerline ratedat a minimumof fifteen
ampsis recommendedfor eachamplifier. Formaximumpoweroutput, the Full
PowerBalanced300and600amplifiers Shouldbeoperatedfroma dedicated
twentyampACpowerline. TheFull PowerBalancedamplifiers shouldonly be
operatedwith the powercord supplied. Pleaseconsult KRELL.oryourdealer
beforeusinganydevicesdesignedto alter or stabilize the ACpowerfor the Full
PowerBalancedamplifiers.
Connections
CAUTION:Thedifferential circuitry employedwithin the Full Power
Balancedaml~lifiers requires special attention whenconnectingspeakers.
Becareful not to connectthe negativespeakerterminals together. Donot
connectthe negativespeakerterminals to ground,or attemptto bridge the
left andright channelstogether of the Full PowerBalancedstereo
amplifiers.-PleasecontactKRELL:Industriesfor assistance.
Input andOutputConnections
Caution:Whenmakingconnectionsto this componentor anyother, makesure
the poweramplifier is off andthe preamplifieris in themuteor stand-bymode.
Thewidngto andfromthe amplifier andall componentsin generalshouldbe
arrangedin a neat, organizedmanner.Specifically, ACwiresshouldbe
separatedfromaudiocables. This practice preventshumor other unwanted
noisefrombeingintroducedinto the system.
1. Connectthe speakercablesto the amplifier’s outputterminals.
TheFull PowerBalancedamplifiersutilize twocustomsetsof identical speaker
terminalsfor the eachchannel.This configurationmakescableconnectionsand
biwiring simple.Thespeakerterminalsonly acceptspadelugs. Barewire,
bananalugs, or pinswill not work.Theredterminalsareusedfor positive
connectionsandthe blueterminalsare usedfor the negativeconnections.
Either the upperor lowerset of speakerterminalsmaybeusedwith speakers
havingonepair of bindingposts.Forbiwiring, bothsetsof terminalsshouldbe
used.Consultyourspeaker’sinstruction manualfor biwiring connections.
CAUTION:Makesureall cableterminationsare of the highestquality, free from
frayedends,shorts, or poorsolderconnections.

2, C~nnectthe interconnectcablesfromyourpreamplifier,to the input of the Full
PowerBalancedamplifier.
TheFull PowerBalancedamplifiers are equippedwith balancedandsingle-
endedinputs. Thebalancedinputs usethree pin XLRconnectorsandthe
single-endedinputs use RCAconnectors. Werecommendthe useof balanced
interconnects,.sonicallyandelectrically, becauseof their immur~tyto induced
noiseandminimalsonicloss resulting fromlongcablelengths.
CAUTION:Useonly oneset of inputsto the amplifier at a time. TheFull Power
Balancedamplifiers are shippedwith shorting pins in the XLRinputs, These
pinsshouldremainin the XLRinputsif the Full PowerBalancedamplifier is
operatingin the single-endedmode.Whenthe shorting pin is inserted, pins1
and3 are shortedtogether. Theshorting pins mustbe removedto connectthe
Full PowerBalancedamplifiers for balancedoperation.
Thepin assignmentfor the XLRis:
pin 1 = shield (ground)
pin2=non_-invertinginput(hot)
pin3 =invertingin put
.3~ Insert the ACpowercordinto the receptaclelocatedonthe backof the Full
PowerBalancedamplifier. Insert the otherendin’to the ACwall receptacle.
Theamplifier is nowreadyfor operationasdescribedin the Amplifier
Operationsection below.Shouldyouhaveanyquestionsregardingsystem
set-up,contactyourdealeror KRELLIndustries.
¯ LinkingMultipleAmplifiers- RemoteIn / Outconnections
TheRemoteIn/Outfunction is usedto synchronizeremotecontrol operationin
systemsthat includemultipleamplifiers. Whenthe In/Outportsareutilized, the
connectedamplifier’s remotecapabilities will belinked andcontrolledfromone
amplifier.
Makesureall amplifiersareoff, includingthe powerbreakerslocatedonthe
rear panel,beforeproceeding.Thisinsures-all amplifiers aresynchronized
whenthe communicationcable is connected.
Selecttheamplifierthatwill bethecontrolamplifier,Onlythis amplifierwill
receive remotecommandsandshouldbe in plain viewfor properremote
controloperation.All additionalamplifiersareconsideredslavesandwill
only respondto remotecommandsreceived via the In/Out communication
8

cable. Connectoneendof the linking cableto the connectorlabeledOuton
the backpanel.
3. Connectthe otherendof the linking cableto the In port onthe second
amplifier.
4. Tocouplethreeamplifiers, connecta secondlinking cableto the Out
connectoronthe secondamplifier. Connectthe remainingendto the In port
onthethird amplifier.
5. Connectadditionalamplifiersasdescribedin step4.
6. Point a KRELLremotecontrol at the control amplifier andpressthe Amp.
Powerbutton.Theamplifierswill all powerupat the sametime.
Notes:
Whenconfiguredfor RemoteIn / Outoperation,eachamplifier canbeturned
ON/OFFindividually fromtheir respectivefront panels.All amplifiersmustbe
returnedto the identical powerstate manuallyin orderto maintainremote
synchronization.
Thecommunicationcablesare standardfive pin DIN~;ablesandare commonly
referred to as MIDIcables. Contactyour KRELLdealeror KRELLIndustries to
obtainremotelink cables.
ForUsewith a TubePreamplifer
TheFull PowerBalancedamplifiers featuredirect couptedcircuitryfrom input to
output.Thistopologyeliminatesall couplingcapacitorsfromthe audiosignal
path. Couplingcapacitorsare usedto blockdamagingdirect current (DG)but
havesonic characteristics that impactmusicnegatively. Instead, KRELLuses
non-obtrusiveDCservosthat strip DCfromthe signal withoutcorruptingthe
music.
Tubepreamplifiers,bydesign,arecapacitivelycoupled.Forthis reason,the
benefitsof a direct coupledamplifier cannotberealized whenusedwith a tube
preamplifier.Additionally, manytubepreamplifiersoutputa greatdealof DC.
This DCmayexceedthe servosof a Full PowerBalancedamplifier. Excessive
DClevel in a signal candamageamplifiers, speakers,or both.
Tocombatthis potential problem,the Full PowerBalancedamplifiers include
internal jumpersthat insert couplingcapacitorsinto the signal path.These
capacitorsshouldbeengagedwhenusinga tubepreamplifierwith a Full
9

PowbrBalancedamplifier. If not utilized, KRELLreservestheright to
refuse warrantyservicedueto DCrelated damage.Pleasecontactyour
KRELLdealerfor =assistance.
Amplifier Operation
Understandingthe operationof the Full PowerBalancedamplifiers is veryeasy.
Equallyimportantis anunderstandingof the carethat shouldbeexercisedwhen
operatingthe systemasa whole,in relation to the enormouspoweroutputof the
Full PowerBalancedamplifiers. Simplemistakes,suchas switchingbetween
active sourceswithoutmutingthe preamplifieroutput, or bumping/miscuinga
cartridge, cangeneratelarge transientsat low.frequencies.Withthis typeof
transient the Full PowerBalancedamplifiers cangenerateenoughpowerto
damagemostloudspeakers.All switchingof sourcesshouldbedonewith the
preamplifierlevel eithermutedor fully attenuated.Inputsto the amPlifiershould
notbechange--dwhiletheamplifieris on.
NOTE:Caremustbetakenwhensetting high playbacklevels. Becauseof their
tremendous.reserveof cleanpower,KRELLamplifiers cansafely drive speakers
to highersoundpressurelevels thanotheramplifiers. Alwaysturn the level
d._ownat thefirst signof speakerdistress.
Descriptionof On/OffandStandbyOperati6n
Whenpnw~=ring ,,p=ny
.............. ~ ...... , ....~,,,,,~,~o,,,.,,.,,~, =,~,=y=beturnedonlastand
turnedoff first.
Locatethe powerbreakeronthe rear panelof the amplifier. Movethe switch
to the ONposition. ThepowerLED,labeledP, will illuminate onthe from
panel.Thisengagesthe input circuitry andsets the amplifier to the Standby
position.
Pressthesilver powerbuttononthe front panelof the amplifier. The
regulatorLED,labeledR, will illuminate. Oncethe regulatorsecurescontrol -
of the outputstage,the biasLED,labeledB, will illuminate. TheSustained
PlateauBiasIIsystemis nowengaged.After the protectioncircuits have
confirmedthat safeoperatingconditionsexist, the input relayswill engage.
Youwill heara click. Theamplifier is nowreadyfor operation.
3. Withthepreamplifierin theMuteposition, or volumecontrolfully attenuated,
selecta source.Turnthe volumecontrol upto yourdesiredlistening level.
4. Whenturning the systemoff, lowerthe volumeof the preamplifiercompletely
or placeit into themuteor stand-byposition. Switchthe amplifier to Standby
10

bypressingthesilver powerbutton.It is nowsafeto turn off therest of the
system.
NOTE:Foroptimalperformance,the rear panelpowerbreakershouldbeleft in
the ONpositionat all times.
RemoteControl Operation
Anoptionalremotecontrol is availablefor the Full PowerBalancedamplifiers.
Theamplifiers canbeswitchedbetweenStandbyandOperatevia this remote
control or fromthe remotecontrolsincludedwith KRELLpreamplifiers,the
KRELLAudio+ VideoStandard,andthe KPS25s KRELLPlaybackSystem.
SystemNoiseC0hsiderati0ns
ACgroundingEecomescritical whenconnectinghigh performanceaudio
components.Whenmixingandma.tchingaudiocomponents,eachwith their
owngroundpotential, a lowfrequencyhummayoccurin oneor bothspeakers.
Thisoften occurswhenintroducing a newcomponentinto a system.
If thereis a lowfrequencyhumemanatingfromthe speakerswhenthe Full
PowerBalancedamplifier is placedinto the system,follow thesesimpletrouble-
shootingstepsbeforecont~lctingyourKRELLdealer:"
Checka!! input andoutputconnections,makingsuretheyare of sound
construction.Withthe amplifier off. removethe interconnectwiring andturn
the amplifier backon.if the humdisappears,shutthe amplifier off and
reinsert oneof theinterconnectcablesandturn theamplifier backon. If the
humreappearswith oneor bothinterconnectsreinserted, there maybea
defectivecable. Havethe interconnectcablingcheckedbeforeproceeding.
If the interconnectsproveto besound,youmaybeexperiencinga ground
loop. Thiscanoften beeasily eliminated.Contactyourdealeror KRELLfor
assistance.
ProtectionCircuitry
Therearenooutputfusesin the Full PowerBalancedamplifiers. Theamplifiers
areprotectedbya seriesof non-intrusivecircuitsthatconstantlyevaluatethe
amplifier’s operation.Appropriateprotectionactionexists for input andoutput
DCconditions,shortcircuit, regulatoruniformity, andACpoweranomalies.
Collectively,the protectioncircuitry is designedto avoiddamageto theamplifier
or speakerscausedbyother defectivecomponents,faulty wiring, system
11