Krell Industries Three-Channel Power Amplifier KAV-250a/3 User manual

Leader in Audio Engineering
KAV-250a
Stereo PowerAmplifier
KAV-250a/3
Three-ChannelPowerAmplifier
Instructionsfor Use,v 99.2
Owner’s Reference

KAV-250aStereo PowerAmplifier and
KAV-250a/3Three-Channel PowerAmplifier
Instructionsfor Use,v 99.2
Cover: KAV-250a/3 Three-ChannelPowerAmplifier
Krell Industries,Inc.
45 Connair Road
Orange, CT 06477-3650 USA
TEL [phone]
FAX[phone]
E-MAILkrell @krellonline.com
WEBSITEhttp://www.krellonline.com
This product complieswith the EMCdirective (89/336/EEC)andthe low-voltage directive
(73/23/EEC).
WARNINGS
Theamplifier mustbeplacedona firm, level surfacewhereit is not exposedto dripping or
splashing.
Theventilation grids onthe top of the amplifier andthe spaceunderneaththe amplifier mustbe
unobstructedat all times during operation. Donot place flammablematerial aboveor beneath
theamplifier.
ContactyourauthorizedKrell dealer, distributor, or Krell beforeusinganydevicesdesignedto
alter or stabilize the ACpowerfor the KAV-250aor KAV-250a/3.
Beforeconnectingthe KAV-250aor KAV-250a/3,makesure the amplifier is off andany output
device(suchas a preamplifier) is in muteor stand-bymode.Makesure all cable terminations
areof the highestquality andfree fromfrayedends,short circuits, or coldsolderjoints.
Useonlyoneset of inputsto the amplifier at a time.
After reconfiguring for MAT,do not usemorethan oneinput at the sametime.
After bridging, donot usebothinputs at the sametime.
THEREARE NO USERSERVICEABLEPARTSINSIDE ANY KRELL PRODUCT
PleasecontactyourauthorizedKrell dealer, distributor, or Krell if youhaveanyquestionsnot
addressedin this reference manual.
Thisproductis manufacturedin theUnitedStatesof America.Krell® is aregisteredtrademarkof Krell
Industries,Inc., andis restrictedfor usebyKrellIndustries,Inc., its subsidiaries,andauthorizedagents.
Multi AmpThroughput
TM is a trademarkof Krell Industries,Inc. All othertrademarksandtradenamesare
registeredto their respectivecompanies.
©1999byKrell Industries, Inc. All rights reserved P/N: I960101710688

Contents
INTRODUCTION’
DEFINITION OF TERMS
UNPACKING
PLACEMENT
ACPowerGuidelines
FRONTPANELDESCRIPTION: KAV-250a
BACKPANELDESCRIPTION: KAV-250a
FRONTPANELDESCRIPTION:KAV-250a/3
BACKPANELDESCRIPTION:KAV-250a/3
CONNECTINGTHEKAV-250a or KAV-250aJ3 AMPLIFIER
TO YOURSYSTEM
Input andOutputConnections
OPTIONAL SYSTEMCONFIGURATIONS
Multi AmpThroughput
Bridged Operation
Examplesof ConnectionScenarios
AMPLIFIER OPERATION
On/Off andOperation
AMPLIFIER TROUBLESHOOTING
Howto Troubleshoot SystemNoise
QUESTION AND ANSWER
WARRANTY
RETURNAUTHORIZATION PROCEDURE
SPECIFICATIONS
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KAV-250aand KAV-250a/3Amplifiers iii

Illustrations
FIGURE1
FIGURE2
FIGURE3
FIGURE4
FIGURE5
The KAV-250aFront Panel
The KAV-250aBack Panel
TheKAV-250a/3Front Panel
The KAV-250a/3Back Panel
Reconfiguring the KAV-250afor MAT
or BridgedOperation
FIGURE6 Reconfiguring the KAV-250a/3for MAT
or BridgedOperation
Page
4
6
9
11
16
19
iv KAV-250aand KAV-250a/3Amplifiers

Introduction
Thankyou for your purchaseof the Krell KAV-250aStereoPowerAmplifier or
KAV-250a/3Three-ChannelPowerAmplifier..
TheKAV-250aandKAV-250aJ3amplifiers provide substantial two- andthree-channel
output powerthat delivers realistic musicproductionat anexceptionalvalue. These
amplifiers canbecustomizedwith a variety of optional systemconfigurations: Multi
AmpThroughput(MAT),bridged operation, and high powermonooperation. These
options provide a wider range of poweroutputs andconnectionoptions. Boththe KAV-
250aandKAV-250a/3amplifiers provide balancedandsingle-endedinputs for
completecompatibility with other components.TheKAV-250aand KAV-250a/3
amplifiers canbeoperatedusing the 12VDCtrigger for other components.Either
amplifier integrates seamlesslyhometheater or whole-housesystems.
This referencemanualcontains importantinformation onplacement,installation, and
operation of the KAV-250aandKAV-250a/3amplifiers. Pleaseread this information
carefully. Athoroughunderstandingof thesedetails helpsensuresatisfactory operation
andlong life for your KAV-250aor KAV-250aJ3amplifier andrelated system
components.
Definition of Terms
Multi AmpThroughput
Aninternal connectionoption that sendsthe samemusicsignal to all amplifier channels
using onebalancedor single-endedconnection. MATreducesinstallation complexity
andcabling requirementsin systemscontainingmultiple amplifiers. MATalso allows a
variety of connectionscenarios,including poweringloudspeakersthat havetwosets of
binding postsandindependentlypoweringmultiple pairs of stereo loudspeakersto
extendthe listening environmentthroughoutyour home.
Bridging
Aninternal connectionoption that links twoamplifier channelsto operateasone
combinedamplifier channel,greatly increasing the channel’spoweroutput.
On
Whenthe powerbutton onthe front panel is pressedandthe blue powerLED
illuminates, the amplifier is onandreadyto playmusic.
Off
Whenthe powerbutton on the front panel is pressedandthe blue powerLEDturns off,
theamplifieris off.
KAV-250aand KAV-250a/3Amplifiers 1

Unpacking
Openthe shipping box, whichcontains:
1 amplifier unit (packedin foamend-caps)
2 ribbon connectioncables
KAV-250afuses:
2 AGC-8(~ ’amp)
1 slow-blow(20 ampfor 100/120V or 12 ampfor 220/240V)
or
KAV-250a/3fuses:
3 AGC-.8 ~ amp)
1 slow-blow(20 ampfor 100/120V or 12 ampfor 220/240V)
1 12 VDCoutput (12 Vtrigger) cable
1 IECconnector(ACpower)cord
1 T-15Torx wrench
1 packetcontainingthe owner’sreferencemanualandthe warrantyregistration
card.
Graspthe undersideof the foamend-capsthat encasethe amplifier andlift the
amplifier straight outof theshippingbox.
Placethe amplifier in a safelocation andremovethe protective plastic wrapping.
Notes
If anyof theseitemsare not includedin the shippingbox,pleasecontactyour
authorizedKrell dealer,distributor, or Krell for assistance.
Saveall packingmaterials.If youshipyouramplifier in the future, repackthe unit in its
original packagingto prevent trans# damage.SeeReturnAuthorization Procedure,
onpage29, for moreinformation.
2KAV-250aand KAV-250aJ3Amplifiers

Placement
Before you integrate the KAV-250aor KAV-250a/3into your system, review the
following guidelinesto choosethe location for the component.Thiswill facilitate a
clean,trouble-freeinstallation.
TheKAV-250aandKAV-250aJ3require at least two inches (5 cm)of clearance
eachside andat least twoinches(5 cm)of clearanceabovethe componentto provide
adequateventilation.
Youramplifier doesnot requireanytype of special rackor cabinetfor installation. For
the dimensionsof your amplifier seeSpecifications, on pages30 and31.
Placethe amplifier as close to the loudspeakersas possible andkeepthe speaker
cable length to a minimum.Speakercable addsimpedanceto the load the amplifier
mustdrive, regardlessof the cable’s gauge.Krell amplifiers drive the lowest
impedanceswith ease, but long speakercables reducethe maximumpowerthat is
deliveredto the loudspeakers.
AC POWER GUIDELINES
Krell recommendsoperating eachamplifier from a dedicated15-ampACpowerline.
For maximumpoweroutput, operate the KAV-250aor KAV-250a/3amplifier from a
dedicated 20-ampACpowerline.
KAV-250aand KAV-250a/3Amplifiers 3

FIGURE 1 THE KAV-250a FRONTPANEL
1 2
1 PowerButton
2 PowerLED

Front Panel Description: KAV-250a
SeeFigure 1 on page4
1 Power Button
Usethis button to turn the KAV-250apoweron andoff andalso to switch the 12 VDC
output(12Vtrigger) onandoff.
2 Power LED
Theblue powerLEDilluminates whenthe amplifier is on.
KAV-250aand KAV-250a/3Amplifiers 5

FIGURE 2 THE KAV-250a BA(;K PANEL
5
11 12 10 13
BalancedInputs
3 Right Input
4 Left Input (Bridged)
Single-endedInputs
5 Right Input
6 Left Input (Bridged)
Amplifier ChannelOutputs
7 Right Output(Bridged-)
8 Left Output(Bridged+)
Fuses
9 AGC~ Fuses
10 Line Fuse
RemoteControls
11 12 VDCRemotePowerOut
12 12 VDCRemotePowerIn
Power
13 IEC PowerConnector