Krell Industries Amplifier KAV-250a Quick start guide

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KAV-250a
Amplifier CONTENTS
KrelPIndustries,Inc.
45 Connair Road
Orange, CT 06477-3650 USA
TEL [phone]
FAX[phone]
E-MAILkrell @krellonline.com
INTRODUCTION
UNPACKING
PLACEMENT
Cabinetry Considerations
ACPowerGuidelines
CONNECTINGTHE KAV-250a
TO YOURSYSTEM
Input and Output Connections
LinkingMultiple Amplifiers
Configuring the KAV-250a
for BridgedOperation
AMPLIFIER OPERATION
On/Off and Stand-byOperation
SystemNoise Considerations
WARRANTY
RETURNAUTHORIZATION
PROCEDURE
SPECIFICATIONS
Page
3
3
3
4
4
4
4
5
6
7
"7
7
8
9
12
ILLUSTRATIONS
THE KAV-250a BACKPLATEAND
CONNECTIONSFOR BRIDGED
OPERATION
Page
6
©1997byKRELL
®
Industries,Inc. All rightsreserved P/N19608,0230,0000

CEMarking
Thisproductcomplieswith the EMCdirec-
tive (89/336/EEC)andthe low-voltage
directive (73/23/EEC).
Introduction
Thankyoufor yourpurchaseof the Krell
KAV-250a.Toobtain the best performance
fromyourKAV-250aamplifier, paycareful
attentionto its placement,installation, and
operation. A thoroughunderstandingof
thesedetails will helpinsuresatisfactory
operation andlong life for the KAV-250a
andrelated systemcomponents.
THERE ARE NO USER-SERVICEABLE
PARTSINSIDE ANYKRELLPRODUCT.
Pleasecontactyourauthorizeddealer,
distributor, or KrelP, if youhaveany
questionsnot addressedin this refer-
encemanual.
Unpacking
1. Openthe boxandremovethe top layer of
foam.Youwill seetheseitems:
1 KAV-250a
1ACpowercord
1 packetcontainingthe Owner’s
Referenceandthe Warranty
Registration Card.~ ,’~ x ~’ ~x~
NOTE:If anyof theseitemsare n~cld~ed,
pleasecontactyourauthorizedKrefl dealer
ordistributorimmediatelyfor assistance.
2. Carefully removethe unit andacces-
soriesfromthe box.Removethe protec-
tive plasticwrapfromtheunit.
NOTE:Saveall packingmaterials. If you
must ship your ~V-250ain the future,
repackthe unff in its original packagingto
preventtransit damage.
Placement
WARNINGS
Theamplifier mustnot belocatedwhereit
couldbeexposedto dripping or splashing
fluids.
Beforeyouinstall the KAV-250ainto your
system,reviewthe followingguidelinesto
choosethe location for the KAV-250a.This
will facilitateaclean,trouble-freeinstallation.
TheKAV-250adoesnot require anytypeof
specialrackor cabinetfor installation.Forthe
dimensions of the KA V-250a, see
Specificationsonpage12.
Placethe KAV-250aamplifierona firm level
surfaceawayfromdirt or moisture.When
usingcustomracks or cabinetry, keepin
mindtheweightandventilation requirements
for this amplifier.Ideally,theamplifiershould
KRELL
® KAV-250a English Page3 of 12

Placement,continued
beplacedascloseto the speakersaspos-
sible. Runlong balancedinterconnect
cablesto the amplifier andkeepthe speak-
er cable length to a minimum.Speaker
cable adds impedanceto the load the
amplifier mustdrive, regardless of the
cable’sgauge.All Krell amplifierswill drive
the lowestimpedanceswith ease,but when
impedanceis addeddueto long cable
lengths, amplifier poweris wastedin the
cable. Longspeakercables reducethe
maximumpowerthat can be delivered to
the speakers.
CabMetryConsiderations
TheKAV-250aamplifier canbecomequite
warmundernormaloperation. Install the
KAV-250ain a location that providesunob-
structedventilation.If youplacetheamplifi-
erin a closedcabinet,extraventilationsuch
as modified shelf spacingmaybe neces-
sary. In extremeinstances,smallfanshelp
to removingexcessheat from enclosed
spaces.In general,whenthefront andrear
of a cabinetis open,theamplifier hasade-
quateventilation with twoinchesof clear-
anceon each side and eight inches of
clearanceaboveandbelow.
ACPowerGuidelines
For best performance,Krell®recommends
usinga dedicatedACpowerline ratedat a
minimumof fifteen ampswith the KAV-250a
amplifier. For maximumpoweroutput, the
KAV-250ashouldbeoperatedfroma dedi-
cated twenty ampACpower line. The
KAV-250aamplifier shouldonlybeoperated
withthe powercordsupplied.Pleaseconsult
yourdealer,distributor,orKrell® beforeusing
anydevicesdesignedto alter or stabilizethe
ACpowerfor the KAV-250a.
Connectingthe KAV-250a
to YourSystem
WARNING
Whenmakingconnectionsto this compo-
nent or any other, makesure the power
amplifieris Off andthepreamplifieris in the
Muteor Stand-bymode.Makesureall cable
terminationsareof thehighestquality, free
fromfrayedends,shorts,orcoldsolderjoints.
Input andOutputConnections
Topreventthe introductionof humor other
noiseinto the system,organizeall wiring
betweenthe KAV-250pandother system
componentsneatly. SeparateACwiresfrom
audiocables.
1. Connectthe cablesfromyour speakers
to theoutputterminalsof theamplifier.
TheKAV-250aamplifier utilizes five-
waybindingpostspeakerterminalsfor
the left andright channels.Thespeaker
terminalsacceptspadelugs, barewire,
bananaplugs,or pins. Theredterminals
are usedfor positive connectionsand
theblackterminalsareusedfor theneg-
ative connections.
2. Connectthe interconnect cablesfrom
yourpreamplifierto theinputterminalsof
theamplifier.
TheKAV-250aamplifier is equippedwith
balancedandsingle-endedinputs. The
balancedinputs usethree pin XLRcon-
nectorsandthe single-endedinputsuse
RCAconnectors.Krell®recommendsthe
useof balancedinterconnects.Balanced
interconnectsnotonlyhavetheability to
Page4 of 12 English KRELL
® KAV-250a

minimizesonic loss but also haveimmu-
nity to inducednoise,especiallyfor instal-
lations usinglongcablelengths..Balan-
ced connections have 6dB more gain
than single-ended connections. When
level matchingis critical, keepthis speci-
fication in mind.
WARNING
Useonlyoneset of inputsto theamplifierat a
time. TheKAV-250aamplifier is shippedwith
shorting pins in the XLRinputs. Thesepins
should remain in the XLRinputs if the
KAV-250aamplifier is operatingin the single-
endedmode.Whenthe shorting pin is insert-
ed, pins 1 and3 are shorted together. The
shorting pins mustbe removedto connectthe
KAV-250aamplifier for balancedoperation.
TheXLRpin configurationis describedbelow:
Pin1 Ground
Pin 2 Non-inverting(0
°)
Pin 3 Inverting (180
°)
3. Insert the ACpowercordinto the recepta-
cle located on the backof the KAV-250a
amplifier. Insert the otherendinto theAC
wallreceptacle.
4. Theamplifier is now~eadyfor operation.
SeeAmplifier Operation, on page7.
Linking Multiple Amplifiers--
Multi AmpThroughput
TM(MAT Ti)
For systemscontainingmultiple amplifiers,
Multi AmpThroughput
TM
(MAT
~M)simplifies
installations. MAT
~-M
providesa daisy-chain
systemoption that reduces installation
complexity and cabling requirements. To
usethis option, connectthe outputs of the
amplifier (either balancedvia XLRor single-
endedvia RCAconnectors)to the inputs of
anotheramplifier. Theoutput of the first
amplifier sendsthe preamplifier signal to
the nextamplifier in the chain.
12 VDC REMOTEPOWERIN
This input accepts12 volt poweron/off sig-
nals from other Krell components,as well
asfromother devicesthat incorporatea 12
volt poweron/off trigger output. Thisallows
for remoteturn on/off of the KAV-250awith
the poweractivation of anotherKrell com-
ponentas well as with with other compo-
nentsusedin a custominstallation.
12 VDC REMOTEPOWEROUT
This output sends12volt poweron/off sig-
nals to other Krell components,as well as
other devices that incorporate a 12 volt
poweron/off trigger input. This allows for
remoteturn on/off of the KAV-250awith the
poweractivation of another Krell compo~
nent as well as with other componentsused
in acustominstallation,
NOTE:Consult the owner’s manualof any
deviceusedin a custominstallation to take
full advantageof the remotecapability of
the KAV-250a.
KRELL
® KAV-250a English Page5 of 12

Configuring the KAV-250a
for Bridged Operation
TheKAV-250amaybe configured to operate
in a bridgedmode.Whenbridged,the amplifi-
er will deliver 1000wattsto an8 ohmload. To
implementthis configuration:
1. Turnthe KAV-250aoff.
2. Locatethe red switch onthe backof the
amplifier andslide it fromthe NORMAL
position to the BRIDGEDposition. The
numeral2 will appearonthe switch, when
the switchis in the BRIDGEDposition.
Connectthe interconnect cable to the
BRIDGEDinput, either balancedvia the
XLRconnector or single-ended via the
RCAconnector. Donot use both inputs
simultaneously. Connectthe speaker
cablesto the speakerterminals labeled
BRIDGED(-)and BRIDGED(+).The
lifier is nowreadyfor bridgedoperation.
THE KAV-250a BACKPLATEANDCONNECTIONSFOR BRIDGEDOPERATI()N
NOTE:The KAV-250amaybe configured for bridged operation using either
a single-endedinput (1) or a balancedinput (2)
1 Single-endedinput, for connection to a preamplifer
2 Balancedinput, for connection to a preamplifier
35-way binding post speaker terminals
4 Redswitch in bridged position, (with the numeral2 displayed)
5Single-endedoutput, for connection to another amplifier
6 Balancedoutput, for connection to another amplifier
7 12 volt trigger input
812 volt trigger output
1
LINE IN
2
RIGHT LEFT
OUTPUT OUTPUT
C) RIGHT ~ED LEFT ~NPUT)
(BRIDGED (~
0 0
33
KAV-250a
PowerAmplifier KRELL
® Industries, Inc.
45 Connair Road
Orange, CT 06477-3650
USA
Nouser serviceable parts inside
VOLTAGEFUSE
100-120MDA-20
200-240MDA-12 Q 50/60Hz
MADEINUSA
12VDCREMOTE
POWER
Page 6 of 12 English KRELL® KAV-250a

Amplifier Operation
It is easyto understandtheoperationof the
KAV-250aamplifier. However,great care
needsto beexercisedwhenoperatinga sys-
temthat includesthe KAV-250a,becauseof
the amplifier’s enormouspoweroutput.
Switchingbetweenactive sourceswithout
mutingthe preamplifier output, or bump-
ing/miscuinga cartridge, cangeneratelarge
transientsat lowfrequencies.TheKAV-250a
amplifier maygenerateenoughpowerwith
thesetransients to damagemostloudspeak-
ers. All switchingof sourcesshouldbedone
withthepreamplifierleveleithermutedorfully
attenuated.Donotchangeinputsto theampli-
fier whiletheamplifieris On.
NOTE:Care mustbe taken whensetting
high playbacklevels. Becauseof their
tremendousreserveof clean power,Krell
amplifierscansafelydrivespeakersto high-
er soundpressurelevels thanotherampli-
fiers. Alwaysturntheleveldownat thefirst
signof speakerdistress.
On~OffandStandbyOperation
Whenpoweringupanysystem,amplifiers
shouldalwaysbeturnedonlast andturnedoff
first.
1. Pressthepowerbuttononthe front panel
of theamplifier.Youwill hearaclick. The
amplifieris readyfor operation.
2. Withthepreamplifierin theMuteposition,
or ’the volumecontrolfully attenuated,
select a source.Turnthe volumecontrol
upto thedesiredlisteninglevel.
3. Whenturning the systemoff, lowerthe
volumeof the preamplifiercompletelyor
placeit into the Muteor Stand-byposi-
tion. Switchtheamplifierto Stand-byby
pressingthepowerbutton.It is nowsafe
to turnoff therestof thesystem.
SystemNoiseConsiderations
ACgroundingbecomescritical whencon-
nectinghighperformanceaudiocomponents.
Whenmixing andmatchingaudio compo-
nents,eachwiththeir owngroundpotential,a
lowfrequencyhummayoccurin oneor both
speakers.Thisoftenoccurswhenintroducing
¯ a newcomponentinto a system.
If there is a lowfrequencyhumemanating
from the speakers whenthe KAV-250a
amplifier is placedinto the system,follow
thesesimpletrouble-shootingstepsbefore
contactingyourauthorizedKrell dealer,dis-
tributor,orKrell®:
1. Checkall input andoutputconnections,
makingsuretheyareof soundconstruc-
tion. Withthe amplifier Off, removethe
interconnectwiringandturn theamplifier
On.If thehumdisappears,turntheampli-
fier Offandreinsertoneof theintercdn-
nectcables.Thenturntheamplifierback
On.If thehumreappearswithoneor both
interconnectsreinserted,theremaybea
defectivecable. Havethe interconnect
cablingcheckedbeforeproceeding.
2. If the interconnectsproveto besound,
youmaybeexperiencinga groundloop.
Thiscanoftenbeeasily eliminated.Con-
tactyourauthorizedKrelldealer,distribu-
tor,orKrell
®.
EnglishPage7 of 12 KRELL
® KAV-250a

Warranty
Krell®warrantsthis productto befree from
defects in material or workmanshipfor a
periodof five yearsfor circuitry andthree
yearsfor all mechanicalcomponentsfrom
the original dateof purchase.Shouldthis
productfail to performat anytimeduringthe
warranty,Krell
®
will repairit at nocostto the
owner,exceptasset forth in this warranty.
Transferof warrantyto asecondowneroccurs
automatically.PleasecontactKrell®to have
the nameonthe warrantychanged.Transfer
of warrantydoesnot extendthe durationof
theoriginal warrantyperiod.
NOTE:This warranty doesnot apply to
damagecausedbyacts of Godor nature.
Thewarrantyperiodbeginsonthe date of
retail purchaseasnotedontheretail sales
slip providedbyanauthorizedKrell dealer
ordistributor,oronthewarrantyregistration
cardsentto Krell®.In theeventthatanade-
quateproofof purchasedateis unavailable,
the warrantyperiodwill beginonthe date
the productwasoriginally shippedfromthe
factory.Thewarrantydescribedin this para-
graphshall bein lieu of anyotherwarranty,
expressorimplied,including,butnotlimited
to, anyimpliedwarrantyof merchantability
orfitnessfor a particularpurpose.Thereare
noWarrantieswhichexceedbeyondthose
describedin this document.If this product
doesnot performaswarrantedherein, the
owner’ssole remedyshall berepair. In no
eventwill Krell® beliable for incidentalor
consequentialdamagesarising from pur-
chase,use,or inability to usethis product,
evenif Krell® hasbeenadvisedof the pos-
sibility of suchdamages.
Thewarrantyfor this Krell productis valid
onlyin thecountryto whichthe productwas
originally shipped,throughthe authorized
Krell distributorfor thatcountry,andat the
factory. Theremayberestrictions onor
changesto Krell’s warrantybecauseof reg-
ulations within a specific country.Please
checkwith yourdistributor for a complete
understandingof the warrantyin yourcoun-
try.
Freightto thefactoryis yourresponsibility.
Returnfreight within the UnitedStates
(U.S.A.)is includedin thewarranty.If you
havepurchasedyourKrell productoutside
the U.S.A.andwishto haveit servicedat
the factory, all freight andassociated
chargesto thefactoryareyourresponsibili-
ty. Krell
®
will payreturnfreightto theU.S.A.-
basedfreight forwarderof your choice.
Freightandotherchargesto shipthe prod-
uct fromthe freight forwarderto youai’e
alsoyourresponsibility.
Theoperating voltage of this productis
determinedat the factory andcanonly be
changedbyanauthorizedKrell distributor or
at thefactory.Thevoltagefor this productin
the U.S.A.cannotbechangedfor six months
fromtheoriginal purchasedate.
Anyunauthorizedvoltageconversion,dis-
assembly,componentreplacement,perfo-
ration of chassis,updates,or modifica-
tions performedto the productwill void
thewarranty.
KRELL
® KAV-250a English Page8 of 12

ReturnAuthorization
Procedure
IMPORTANT:If youbefievetherois a prob-
lemwithyourunit, pleasecontactyourdeal-
er, distributor, or theKrell factoryimmedi-
ately Donot return anyunit to KrelPfor
repair withoutfirst discussingthe problem
and obtaining a Return Authorization
Number.
Toreturn a product, the owner
is requiredto:
¯ Obtaina ReturnAuthorization Number
(R/A number)and shipping address
fromthe Krell ServiceDepartment.
¯ Insureandacceptall liability for lossor
damageto the productduring shipment
to theKrell factoryandprepayall ship-
ping charges.Theproductmayalso be
handdeliveredif arrangementswith the
ServiceDepartmenthavebeenmadein
advance.Proof of purchasemaybere-
quiredfor warrantyvalidationat thetime
of handdelivery.
¯ Usethe original packagingto insurethe
safetransit of theproductto thefactory,
dealer, or distributor. Theuseof any
packagingmaterialotherthantheoriginal
packagingmaterials is not recommend-
ed.Krell® may,at its discretion,returna
productin newpackagingandbill the
ownerfor suchpackagingif the product
received by Krell ®wasboxedin non-
standardpackagingor if the original
packagingwasso damagedthat it was
unusable.If Krell® determinesthat new
packagingis required,theownerwill be
notified beforethe productis returned.
To purchaseadditional packaging,
pleasecontact your authorizedKrell
dealer,distributor, or the Krell Service
Departmentfor assistance.
Krell®is not responsiblefor anydamage
incurredin transit. Krell® will file claimsfor
damagesas necessaryfor products dam-
agedin transit to the factory. Theowneris
responsiblefor filing claimsfor shippingdam-
agesthat occurduringthereturnshipment.
Replacementparts and/orproductswill be
furnishedon anexchangebasis only; any
partsand/orproductsreturnedto Krell® for
exchangebecomethe propertyof Krell
®.
Noexpressedor implied warrantyis made
for anyKrell productdamagedbyaccident,
abuse,misuse,naturalor personaldisaster,
or unauthorizedmodification.
In theeventthat Krell® receivesa product
for warrantyservice whichhasbeenmodi-
fied in anywaywithoutKrell authorization,
all warrantiesonthat productwill bevoid.
Theproductwill bereturnedto original fac-
tory layout specifications at the owner’s
expensebeforeit is repaired.All repairs
requiredafter the producthasbeenreturned
to original factory specification will be
chargedto the customer,at current parts
andlaborrates.
Tocontactthe Krell ServiceDe~artment
TEL [phone]
Monday-Friday
9:00 AMto 5:00 PMEST
FAX [phone]
E-MAILkrell @krellonline.com
KAV-250a
PRODUCT SERIALNUMBER
Toregister your productfor warrantybenefits,
complete and return the Warranty
Registration Card enclosedin the shipping
boxwithin 15 days of purchase.
Page9 of 12 English KRELL
® KAV-250a

Krell
®
Industries,Inc.
45 Connair Road
Orange,CT06477-3650USA
TEL[phone] FAX[phone]
E-MAILkrell @krellonline.com
Specifications
FREQUENCYRESPONSE
20Hz-20KHz
.4Hz-170KHz
KAV-250a
+0.0,-0.1dB
+0.0,-3.0dB
OUTPUTPOWER,each channel driven
8 ohms 1,000W (bridged)
8 ohms 250 W
SIGNALTONOISERATIO
-118dB"A" weighted
DISTORTION
1KHz 0,06% THD
20KHz 0.25% THD
GAIN 26.4dB
INPUTSENSITIVITY
2.15 Vrms
INPUT IMPENDENCE
100Kohms
OUTPUTVOLTAGE
Peakto peak
RMS 138V
49 V
4 ohms 500 W
POWERCONSUMPTION
Idle 210 W
Max. 1850 W
DIMENSIONS
19wx 6.3hx 15.3din.
48.3wx16hx 38.9d cm
WEIGHT
Shipped
Unit only 57Ibs., 25.9kg 43Ibs., 19.5kg
All operationalfeatures,functions,specifications,and
3oliciesaresubjectto changewithoutnotification.