Krell Industries Stealth Stereo Preamplifie Quick start guide

A. INTRODUCTION
Thankyou for your.purchase of the Krell STEALTH
AdvancedOne-Bit Digital to AnalogConverter and
welcometo the Krell family of audio compo.n.ents.You
havejoined a select groupof discriminating listeners who
enjoythe finest in musicreproduction.
Krell,D, igital is dedicatedto the d~evelopmentof techno~-
1.o.gicady advancedcomponentstor the reproductio.n ot
digitally recordedmusic.Thesedesigns continue the
Krell tradition of uncompromisingperformancethrough
leading-edge technology.
To obtain the best performance from your STEALTH
processor,careful attention shouldbe paid to its place-
ment,installation andoperation. Athoro~ughunderstand-
ing of these details willhelpinsure satistac.tory operation
ani:l long life for the STEALTHand related systemcom-
ponents.
This Owner’sReferenceis divided into several sections,
eachdesignedto performa different function. Asyou
.read throughthis. O.w,ner’s referenceyouwill become
19et.ter acquaintedwitla the featuresandfunctionstna.t
makethe STEALTHa superb value. AQuestion and
Answersection is also included whereanswersto com-
monquestions are provided. Shouldyou have any ques-
tions or suggestionsplease feel free to contact yourau-
thorized dealer or the KRELLstaff for assistance.
In the unlikely event that your .STEALTHshould require
service, youwill be pleasedto knowtlaat it is backedby_a
comprehensiveCustomerbatisfaction policy and one of
the mostadvancedservic, e facilities in the industry. For
cletailed informationon tlae termsandconditionsof ser-
vice please consult yourwarrantyregistration card or
your authorized KRELLDistributor.
1

B. TABLE OF CONTENTS
3
4
5
7
9
11
12
14
UNPACKING INSTRUCTIONS
BASIC INSTALLATION AND OPERATION
INPUT AND ~UTPUT CONNECTIONS
PROCESSOR OPERATION AND DIGITAL
TAPE LOOP
QUESTIONS AND ANSWERS
FRONT AND REAR PANEL DESCRIPTIONS
SPECIFICATIONS
WARRANTYAND SERVICE INFORMATION
2

C, UNPACKINGINSTRUCTIONS
1. Openthe box and removethe top layer of foam.The
followingitems will nowbe visible:
STEALTHD/A Converter
ACpower cord
PacKetcontaining the OwnersReference and
warranty card
NOTE:If any of these items are not included please
contact yourauthorized dealer immediatelyf6r assis-
tance.
2. Carefully removethe unit andaccessories fromthe
boxand removethe protective plastic wrapfromthe unit.
NOTE:Saveall packingmater.ial.s. If youmustship y.our
STEALTHin the future, re_packtlae unit in its original
packagingto prevent transit damage.
3. Removethe voltage identification sticker onthe back
of the unit.

D. BASIC INSTALLATION
AND OPERATION
Before you install the STEALTHinto your sy.stem we
recommendthat youfollowthese g.uidelines in choosing’
the location. Thiswill facilitate a clean, trouble-free
installation.
CAUTION:Whenmaking connections to this component
or any other, makesure tlie poweramplifier is OFFand
the preamplifier is in the MUTEor STANDBYmode.
1. Althoughwell shielded, the processorshould not be
p.laced in close proximityto hum-sensitivecomponents
~i.e. preamps,turntables, tuners, etc.)
2. Aswith anyhigh quality, component,ensurethat the
vent openingsin the chassis are ]~ree fromobstruction,
allowingthe processorto dissipate heat created byits
highly regulated powersupply and high bias Class A
outputstage.
3. Place the unit on a clean, level surface awayfrom
excessiveheat or moisture.
4. Connectthe ACpowercord to the backof the unit.
Oncethe powercord is secured, plug the other end into
an ACoutlet. The.O. degree, Sourceand Coax1 LEDs
will illuminate, indicatingthe digital signal processoris
powered.
S.houldy~ouru.nit not performas describedabove,unplug
tlae unit tromthe ACoutlet andcontact yourlocal Krell
dealer or the Krell factory.
NOTE:While the STEALTHhas superb regulatio 9 and
doesnot require a dedicatedACcircuit, westrongly
advise, against any connectionsthroughextensioncords
or multiple ACadaptors. Highquality 15 ampgrounded
ACstrips are acceptable.
CAUTION:Donot removeor bypass the ground pin on
the end of the ACcord. This maycause RFI(radio fre-
quencyinterference) to be inducedinto your playback
system.
4

E. INPUT AND OUTPUT
CONNECTIONS
1. Connectthe Stealth analogoutputto the line level
input of yourpreamplifier.
The STEALTHis equipped with two output configura-
tions: Single-ended via RCAconnectors and Balanced
via XLRconnectors. If yourpr.eamplifier has high lev~
balanced inputs werecommenclthe balanced outputs ot
t~.e processorb.e us.ed. Thereare considerablesonic ben-
efits associateclwitt~the useof this typeof interconnec-
tion..H.igh quality tri-axial cableshouldbe usedfor bal-
anceclinterconnects. Thistype of cable is considerably
.different fromcable normallyusedfor single-ended
~nterconnects.
NOTE:Thetwo outputs can be used to simultaneously
feed twodifferent systems.
NOTE:If youdecide to use the single-ended analog
outputs, the type of interconnect cable shouldbe ctiosen
carefully. Highquality shield.ed cable is suggested.
Thered bandedconnectorinoicates the rigtit channeland
the whiteindicates the left channel.
Careshouldbe taken to insure that the channelorienta-
tion betweenthe processor and the high level inputs of
your preamplifier are maintained.
2. Connect.the digital ou.tput of yourCDtransport and
other digital sources to t~ae inputs of the STEALTH;Coax
1, Coax2, Fibre Optic or XLR.If youare using multiple
digital sources, take note of whereeachinput andcorre-
spondingswitchsetting is located.
The STEALTHis equipped with two coaxial digital
inputs, a stan~dardfibre optic digital input anda-balanced
digital input tor use with CompactDiscplayers, Laser
Discplayers, DATsor satellite receivers. AnAT&Twide
bandwidthfibre.optic input is also .available as a special
option. All of tlae inputs can accep~:.asignal fromany
digital source. When.apowereddigital sou.rce .is intro-
duced,to aninputanti tlaat inputis selecteclwitla the Input
switcla, the signal LEDwill ~uminate.

NOTE:If the digital source is ONand the signal LED
doesnot illuminate, checkto makesure the digital inter-
connectcable is secureat bothendsor is not.in needof
repair.
NOTE:Care should be taken in selecting the type of
cable usedto link the digital sourceto yourprocessor.If
coaxialcableis to be..~used,it shouldbe non-capacitive
and have a bandwid~Snexcess of 10MHZto prevent
drop-outerrors.
NOT.E:If an optical cable is selected westrongly re,com-
menclthat it be a highquality Quartzfibre cabbieor the
optional AT&Tfibre optic cable. Abenefit ot using an
optics interconnectis that it reducesthe groundloop
problemsoften associated with quality audio systems.
3. Connectthe digital output of the STEALTHto the
i,n.put 9f a digita~l.recordingdevice.Thenconnecttlae.
oi~ital outputot tlae recorclerto the TAPEinputontlae
STEALTH.
Adigital TapeRecordOutputis provided via an. RCA_
co.n.nector.Thisoutputis usedto feedthe digital input ot
a Oig.ital recordingdevice.TheTapeinputis provi.d.edfor
any_cligital sourceandcan be usedasan additional input.
It shouldbe usedfor the outputof a digital recording
deviceto avoidthe possibility of creating a feedbacl~
loop.
4. Onceyou have completedthe necessary input and
outputconnections,seIect the input of yourchoice. For
eachinput selected, the correspondingLEDwill illumi-
nate wfienthe digital input source(musthaveits power
ON)and the processor have linked.

F. PROCESSOR OPERATION AND
DIGITAL TAPE LOOP
1. Select an input with.the Input switch. Noticethe Signal
LEDwill illuminate whenthe digital source is turned on
and has linked withthe processor. Oncethis link is com-
plete the processoris readyto passa signal.
2. Besure that yourpreamplifier’s volumecontrol is
completelyturned to the OFF(lowest volume)position.
3. Turn ONyour components,rememberingthat the last
componentto be energized should be your amplifier. The
amplifier should only-beturned ONafter all other com-
ponentsin the systemhavebeenon for at least twomin-
utes. Thiswill ~nsurethat there will not be anylarge
pulse created whenthe amplifier is turned on.
4. Switchthe selector sourceof yourpreamp.tothee pgsi
-
tion correlating to yourchoseninput connectiontor the
STEALTH.
5. Youmaynowstart playing yourdigital source, DAT,
CDor satellite.
6. Slowlyturn the volumecontrol up to the lowestlevel
youcan hear. Checkto see that both channels are work-
lng correctly before advancingthe volume.
NOTE:While your STEALTHwill perform beautifully
fromthe momentyou turn it on, it requires a minimum
warmup periodof 8 hoursbeforeit will reachits full.
son!c potential. Discre.te componentsare utilized in the
analog output stage and the warmup period allows them
to reach thermalequilibrium.
fYuO~Uh
r installation is nowcomplete.Sho.uldyouhaveany
er questions whichare not coveredin the remainder
of this manual,contact your authorized Krell dealer. We
wishyoumanyhours of listening fulfillment.
7

STEALTH FEATURES
DIGITAL TAPE LOOP
TheTapeoutputis usedas a direct digital outputfor a
digital recordingsystem.Thedigital sourceyouwa.ntto
re.cord is selectedby:theInputswitch.Tolisten to the
clig~ital sourceselect S:ourceonthe Source/Monitor.
switch. Tolisten.to th6 Tapeoutputduringor after the.
recordingselect Monitoron the Source/Monitorswitcla.
NOTE:TheTapeinput can also be used as an additional
sourceinput.
CAUTION:TheTapeoutput is a dig!tal signal and can
not be usedas an analogoutput to clrlve front endcompo-
nents suchas a preampfifier.
PHASE SWITCH
ThePhase Switchcan reverse output phase. In some
studio recordings the mastertape wasrecordedout of
phase, creating unusually poorsoundingrecordings..The
STEALTHcan reverse the normal0 degree.output.plaase
180degreesto correct for this anomaly.Utilizing tlae
PhaseSwitchcan, in someinstances, restore lif6 to a
previously dull soundingrecording.
EMPHASIS LED
Youwill notice that somediscs, or tracks withina disc,
activate the EmphasisLED.Thissignifies that the re-
cordedmaterial hademphasisfiltration usedduringthe
recor.ding process. Emphasisis a recordingindustry
equalization network, similar to phonoRIAAequaliza-
tion, intendedfor noise reduction.
8

G. QUESTIONS AND ANSWERS
Q. MyCDplayer has both fibre optic and coaxial
outputs. Whichone should I use?
A. Givena choice, weprefer the AT&Toptical link due
to its ability to completelyisolat,e the groundsbetween
the digital sourcecomponentanti the Processor. This
minimizesthe possibifity of groundloops in the digital
components.Theoptional AT&Tformat also has the
addedbenefit of substantially higher bandwidththan
coaxor the standardfibre optic interface..
Q. Will I damagemySTEALTHif I leave the power
"ON"all the time?
A. No.TheClass"A"discrete analog circuits perform
moreconsistently once they reach thermal equilibrium.
Thisprocessorhas beendesignedto be left on at all , ,
times. TheSTEALTHdraws less than 25 watts out ot tlae
ACmains socket.
NOTE:For the protection of your processor werecom-
menddisconnecting the ACcord fromthe wall outlet
before anyelectrical stormsor if youplan on being away
fromhomefor prolongedperiods of time.
Q. DoI have to switch the SamplingFrequencywhenI
go between myCDand DAT?
A. No. YourSTEALTHautomatically senses the input
frequencyand doesall necessary switching.
Q. I amnot ~etting an~vsoundthroughthe processor.
Whatcould oe wrong:
A.Mostlikely there has beena simplemistakein instal-
lation. Checkall connections IN and OUTfromthe
~erOCessor.Checkall powerconnections. Haveyouse-
cted the correc,t source on your preamp?Checkthe
front panelLEDs forpowersupply, stability. If youstill
haveno sound, turn off the power~ndcontact your
dealer.
9

Q. I have somevery fine audiophile interconnect cable
whichhas superior sonic characteristics. CanI usethis
for mycoaxial digital input? ¯
A. Youmayexperimentwith any high quality cable. Do
note, that mostaudiointerconnectcable is not designed"
to carry the ultra highfrequencyinformationof the digi-
tal bit stream.
NOTE:For the STEALTH,we recommendnon-capaci-
tive coaxial cable whichhas a bandwidthin excess of
10MHZand excellent shielding properties.
Q. Whilelistening to mySTEALTHI experience occa-
sional periods of silence throughmyspeakers. Is my
processor malfunctioning?
A. Dropouts are causedby twoprimaryreasons. First,
dropouts can be causedby Datacorruption. Corrup.tion
in the data maybe due to a poorinput connection, dam-
agedor dirty source material, or interconnects whichd.o
not have a wideenoughbandwidth.Theseconditem tlaat
causesthe processorto reset is the presenceof a transient
spike on the incomingACpowerline. Theprocessor is
resettingall of its digital processingcircuits so tlaat it can
be assuredthat all its circuits are properlysynchronized.
Try changingyour source material and checkyour con-
nections. If these are not the cause, speakwithyour
dealer aboutobtainingdifferent cabling. If youare using
fiber optics, andsourcematerial andconnectionsare not
the problem,speakwith your authorized dealer.
Q. SinceI installed the processorin mysystemI havea
lowlevel humthat increases as I turn upthe volume.
Therewasno humin mysystemuntil I addedthe proces-
sor. Is the processormalfunctioning?
A.Thefact that there wasno humin yoursyste~nuntil
youaddedthe processor indicates that youhave a
ground-loopproblem.Often changingthe interconnect to
a fibre optic cable will eliminate this problem.Theway
the digital processoranddigital sourceare connectedto
the ACmainsoften can be t-he cause of groundingprob-
lems. Lif~tingthe groundon a specific component~y
meansot a three prong to two prongACadaptor(Cheater
plug) will often solve the probIem.Checkfor loose inter-
connectcables and or badelectrical connections. Consult
yourdealer or Krell for individual systemsuggestionsif
this humpersists.
10

H. FRONT AND REAR PANEL
DESCRIPTIONS
1. FRONTPANEL
a. InputSelection:
Coax 1
Coax 2
Optics
XLR
Coaxial input
Coaxial input
Standardfibre optic input
Balanceddigital-input or
(Optional)AT&T.fibre optic input; shares
XLRinput switch setting
b. Sourceand Monitorselection:
Source
Monitor Plays the selected input Plays the source connectedto the Digital
TapeInput
c. AnalogBalancedOutputPhaseselection:
0 degree In phase
180 degree Out of phase
2. REARPANEL
b. Digital Inputs:
CoaxialInput 1
CoaxialInput 2
Fibre Optic Input
Balanced Input .
AT&Tfibre optic (optional)
Digital TapeInput
c. Digital Tapeoutput
d. Processor AnalogOutputs:
Single-ended RCAoutputs
Balanced XLRoutputs
e. BalancedXLRoutput pin configuration
p!n1 Ground(shield)
p.an2 0 degrees(non-inverting)
pan3 180degrees(inverting)
To Coax1 Input
To Coax2 Input
ToOptics Input
To XLR Input
To XLR Input
To Monitor Input
Outputof selected Input
InpUt or Monitor

I. SPECIFICATIONS
FREQUENCY RESPONSE
20Hz-20KHz +/- ldB
SAMPLING FREQUENCY
8 Times over sampling
DIGITAL TO ANALOG CONVERTER
18 Bit
ANALOG OUTPUT VOLTAGE
2.1 volts R.M.S.
DIMENSIONS
19" Wide
12" Deep
2.375" High
WEIGHT
13 pounds, unit only
20 pounds, shipping weight
12

¯ 1. WARRANTYANDSERVICE
INFORMATION
Thereare no user-serviceable parts inside the STEALTH:
TheSTEALTHhas a limited warranty of fiveyears parts
andlabor on electronic parts includingreturn freight. The
warranty,per!od, beginson~thedate of-purchaseandis
activatecl witla tlae retUrnot the enclosedWarrantyCard
anda copyof the Sales receipt. Please return the com-
pleted warrantycard immediatelyafter successful instal-
lation and operation are completed.
Thewarrantyfor Krell productsis valid only in th.e coun-
try to whichthey wereoriginally shipped.ard at tlae
fa.-ctory. If youthinkthereare problemsw.itla },ourunit
pleasecontactyourdealer, distributor or tlae tactory
Immediately.
Please do not return any unit to KRELLfor repair with-
out first calling to discuss the problemandto obtain a
ReturnAuthorizationnumber.~Freightto the factory or
distributor is yourresponsibility. Returnfreight to you
will be paidbythe factoryor distributor.
Anyunauthorized updates or modifications performedto
the unit will voidthe warranty.
14

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DIGITALINC.
/KRELL DIGITAL INC.
35 HIGGINS DRIVEMILFORDCT 06460
SALES203-874-3139 FAX[phone]
COPYRIGHT1991 KRELLDIGITAL INC.
(STEALTH9112)