Halcro DM8 User manual

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TABLE OFCONTENTS
IMPORTANTSAFETY INSTRUCTIONS.............................................................2
INTRODUCTION....................................................................................................3
ELECTRONICDESIGN.....................................................................................4
MICROPROCESSOR CONTROL.....................................................................5
INDUSTRIALDESIGN......................................................................................6
MECHANICAL DESIGN...................................................................................7
INSTALLATION.......................................................................................................8
UNPACKING .........................................................................................................8
POSITIONING ........................................................................................................8
FRONTPANEL CONTROLS.................................................................................9
REMOTE CONTROL............................................................................................10
DISPLAY..................................................................................................................10
DISPLAY..................................................................................................................11
REAR PANEL.........................................................................................................12
CONNECTIONS.....................................................................................................13
CONNECTINGTOAPOWERAMPLIFIER...............................................................13
REMOTE POWER AMPLIFIERCONTROL OUTPUT................................................14
BRIDGING...........................................................................................................14
BREAK-IN PERIOD ..............................................................................................14
PROGRAMMABLE INPUT SELECTIONS................................................................14
OPERATINGINSTRUCTIONS...........................................................................15
CONNECTINGSIGNALSOURCES .........................................................................15
HOME THEATRE PROCESSOR CONTROLLINGVOLUME ......................................15
CONNECTINGTHE MAINS POWER SUPPLY CABLE ............................................15
REMOTE CONTROL BATTERIES..........................................................................15
SWITCHINGTHE UNITON ...................................................................................16
ALLOCATINGSIGNALSOURCES AND THE REMOTE CONTROL............................16
DE-ALLOCATING PROGRAM BUTTONS ..............................................................16
DISPLAYEDINFORMATION.................................................................................17
DISPLAY CONTRAST ..........................................................................................17
BACK LIGHT.......................................................................................................17
VOLUME.............................................................................................................17
VOLUME – BALANCINGFUNCTION....................................................................18
SWITCHINGBETWEENSOURCES.........................................................................18
PHASE CONTROL................................................................................................19
ELECTRONIC PROTECTIONANDRELIABILITY.........................................19
SPECIFICATIONS&FEATURES.......................................................................20
CAREAND MAINTENANCE...............................................................................22
TROUBLESHOOTING..........................................................................................23
SERVICE..................................................................................................................24
WARRANTY...........................................................................................................25

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Important SafetyInstructions
CAUTION
RISK OFELECTRIC SHOCK
DONOTOPEN
Thisproduct shall be connectedtoaMAINS socket outlet witha
protective earthing connection.
OnlysuitableapprovedMAINS cords, as perEuropean
individualcountryrequirements intheCE LowVoltage Directive
Scheme, shall be usedwiththis unit.
Do notuse extensioncords: To avoidsafety hazards, use onlythe
powercord suppliedwithyour unit. We do notrecommendthat
extensioncords be usedwiththis unit.
Weighs 23 kg (50 lbs.)perunit. Shipping weight 36 kg (79 lbs)
Designedfor indoor use only. Thedm8preamplifierisnot
protectedagainst liquids.
Theunitshall notbe exposedtodrippingor splashing. Noobjects
filledwithliquids, suchas vases, shall be placedonthe
apparatus.
Nonakedflamesources, suchas lightedcandles, shouldbe
placedonthe apparatus.
Designedtooperate onanymainssupplyintherange of90Vto
240 V. 50 to60 Hz, without any internalor externalswitches.
Therearenouserserviceablecomponents insidethisunit. Do not
attempttoopenthepreamplifiercompartment: thismay expose
youtodangerous voltages andwill voidthe warranty.
Compartments aresealedat thefactory. Ifthesealsarebroken,
thewarranty will be voidandall service costs will be chargedto
the owner.
Requires F1AL250v fuse for continuedprotectionagainst the
risk offire. Neverbypass or use any othertype offuse. The fuse is
locatedonthe rearpanelinthe mainswitch.
90 -240 V
50 -60 Hz
10A

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Introduction
Congratulations onpurchasing the HALCRO™ dm8 preamplifier.
It has takentwoyearsandthegenerouscontributionsofleadingreviewers,
distributorsanddealersfrom aroundtheworldtodesign,thencreate, the
HALCRO™preamplifiers. We areconfidentthat thiscombinationof
expertise, alongwiththeknow-howofthehigh-endaudioindustry’sleading
ResearchandDevelopmentteamwill ensurethesuccess oftheHALCRO™
preamplifiers.
Thebriefgiventoour R&Dteam,headedby Bruce Candy, was toproduce
twomodels ofpreamplifiertosatisfy the needs ofevery audioconnoisseur:
Ÿ Lowest distortionspecifications ofany preamplifierinthe world.
Ÿ Physicaldimensionstosuitastandard domesticequipmentrack, while
retaining the stunning HALCRO™ industrialdesignsignature.
Ÿ Tractable controls.
Ÿ Superior reliability.
Ÿ Innovationindesign.
TheHALCRO™dm8&dm10 preamplifierswill add nocolorationstothe
music. WhenusedinconjunctionwithHALCRO™poweramplifier(s),all
youwill hearistheoriginalrecordingreproducedtheway theartist intended
ittosound.Notransistor or valve-addedsoundsarepresent, just alevelof
musicalpurity that was thought impossible until now.

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ELECTRONICDESIGN By Bruce Candy
Inkeepingwithmyphilosophyofdesign,mybasicaimwas toproduce a
preamplifierwithwhichI, personally, amquite satisfied. I sincerely hope that
others will share my satisfactionwiththese products.
As I sawit, the major issues were:
Ÿ Zero compromise onTransparency.
Ÿ Flexibility.
Ÿ Ease ofuse.
Ÿ Progressive designconcepts.
Inordertomeet thischallenge, theresultingcircuits have particular
characteristics:
Ÿ First, all circuits inthepreamp have distortionsolowthat itis
immeasurable, whetherTHD, IM etc.
Ÿ Second,all circuits inthepreamp exhibitexceptionallylownoise (see
specifications).
Ÿ Third,thereisnocompromise whateverwiththechoice ofcomponents
(Vishay resistors, FKP1 capacitors etc).
Ÿ Fourth,thecircuits arehighlyimmunetoelectromagneticinterference.
Someinputs andoutputs includebothfirst orderfiltersandcommon
mode chokes.
Ÿ Fifth,thepowersupplyandmicroprocessor circuits aredesignedfor
minimalelectromagnetic emissions (extensive 2nd to6th orderfilters).
Ÿ Sixth,thepowersupplyswitchingfrequency was chosentobe much
higherthanthe audioband(>200kHz).
Ÿ Seventh,thepowersupplyrailsareexceptionallywell regulated,
double regulationinfact (switch-mode andlinearservoloops).
Ÿ Eighth, components anddesignare selectedfor highreliability.
Thevolumecontrolisimplementedsoas toincludetwoidenticalstages in
series. This minimizes output noise.
Thedm8&dm10 preamplifiersfeaturebalanced,unbalanced,currentmode
andbridgedcurrentmodeoutputs. Thelatterconsists ofanon-invertedand
invertedcurrentoutput. Thereisalsoanunbalancedoutputfor tapeand
headphones.

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Audible relay noise
Thedm8&dm10 use mechanicalrelays inall switchingincludingthevolume
controlbecause they exhibit the following idealcharacteristics ;
• zero ON resistance,
• infinite OFF impedance,
• very lowOFF capacitance,
• zero distortion.
Incontrast, thenowuniversallypopularsolidstate relays/switches exhibit
none ofthese idealproperties anddetract from performance.
Hence, sonically, HALCRO™feelsthat itisworththesideeffect of
mechanicalclicking sounds whenparameters are changed.
MICROPROCESSORCONTROL By PaulRainbow
Theexcellentaudioelectronics arecomplementedandcontrolledby a number
ofhighlyintegratedmicro-controllerslocatedclose totheelectronics they
serve. Beingas nearas possibletothecontrolledelectronics allowsshort
controlpathsandvirtuallyeliminates internalconnectors, thereby greatly
increasing systemreliability.
Eachamplifierchannelhas its ownmicro-controller;thefrontpaneldisplay
anduserinterface has another.Afourthmicro-controller,locatedontherear
connector panel,co-ordinates theactivity oftheothers. Thefour micro-
controllers are linkedvia only four interconnections each.
Auniqueprogrammingfeatureofthemicroprocessor has beendeveloped
whichallowstheusertodedicate aparticularpairofinputsockets toa
specificinputdevice. Thisfeatureprovides theuserwithgreat flexibility for
connectinginputdevices tothepreamplifier.Therearpanelhas provisionto
accommodate five inputdevices intosevenphysicalpairsofinputsockets.
Thereisonepairofcurrentinputs, three pairsofbalancedinputs andthree
pairsofunbalancedinputs. Phonoinputs do not require programming as they
are permanently allocatedtothe phonosource (in the dm10).

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INDUSTRIALDESIGN By MaxDickison&Tony Kearney
ProductForm
Theaimwhendesigningthedm8anddm10 was tocreate apreamplifierthat
was unmistakablypartoftheHALCRO™product family, butat thesame
time a component that wouldcompliment any highendaudiosystem.
Thepreamplifierhadtositcomfortablywithinacontemporarydomestic
environment, retainthevisualsignatureoftheHALCRO™familyof
products whichdifferentiates themfrom otherhighendaudioproducts and
have anappearance that reflectedthehighleveloftechnicalinnovation.As
withotherHALCRO™products, softerformsandtextures areused,all
fastenersareconcealedandtheheatsinks areintegratedintotheexternalform
tomaintainsimple, cleanlines.
Whilst theuniquepillarformsofthepoweramplifiershave beencarried
throughtothepreamp,proportionshave beenreworkedtoallowthis
componenttobe eitherfreestandingor housedwithina standard 19” shelving
system.
ControlInterface
Knobsand buttons:
Thevolumeandinputselector knobs use auniquemagneticincremental
indexingmechanismdevelopedtoprovideaverysubtleandreliableindexing
action.Theknobs andbuttonsarefinishedinthesamesofttexturalfinishas
the pillars.
Display:
Ahigh-resolutiondisplay was choseninordertoprovidecleansimple
graphics withouttheroughedges associatedwithdisplays oflesserquality.
Thegraphiclayoutofthedisplay has beenoptimizedtogive prominence to
thefunctionsthat areviewedmost often.These includevolumelevels,
balance andinputselection.Functionsthat areaccessedless oftenare
displayedinsmallertypealongthebottom ofthescreen.These include
stereo/monoandin-phase/out-of-phase. Thevolumelevelsfor eachchannel
aredisplayedside-by-sidesothat whenthelevelsarenotequalizedtheuser
will easily notice it.

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Remote control:
WhendesigningtheHALCRO™Remote Control,weaimedtoreflect the
quality andformsoftheHALCRO™preamplifiers. Machinedfrom asolid
aluminumextrusion,theremote rests comfortablyinthehandwithits
minimalist array ofbuttonsfallingwithinthenaturalsweepofthethumb.
Simpleandlogicaltooperate, everyefforthas beenmadetokeepthisproduct
free ofunnecessary complexity.
MECHANICALDESIGN By Lance Hewitt
TheHALCRO™dm8anddm10 canboast theirspectacularlylownoise and
distortionspecificationswhiletheircases containinherentlynoisy digital
circuitry, includingaswitch-modepowersupply, partlyduetothe
mechanicaldesignoftheircircuitboardsandtheboxes that containthem.
Supports offoldedaluminumserve notonlyas bases towhichtheelectronics
areanchored,butalsotoshielddifferentsectionsofthecircuitryfrom one
another.
Eachoftheaudio,panelanddisplay, andpowersupplysectionsiscontained
withinits owninternalaluminumenclosure. Cables connectingtheseparate
sectionsarefewandshort, minimizingbothradiationandreceptionof
unwantedsignals.
Please enjoy the HALCRO™ audioexperience.
HALCRO™has enjoyedcreatingperfect audioreproductionfor theworld's
music connoisseurs.
Ifyouwishtocontact HALCRO™tosupplyfeedback onyour purchase or for
generalenquiries, please feelfree tocontact us:
Email: [e-mail]
Telephone: [phone]
Facsimile: [phone]

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Installation
Ensureyouhave readtheImportantSafety Instructionssectiononpage 2prior to
installingyour HALCRO™preamplifier.Ifyourequireassistance intheunpackingand
installationofyour HALCRO™ preamplifier, please contact your dealer.
Unpacking
Undo the4fastenersat thebase ofeachbox.Thenremove theupperpartofthecontainer
by liftingdirectlyupwards, beingcarefulnottorubitagainst thepreamplifier.(To have
gainedaccess tothis manualyoumust have completedthe above steps).
Remove thematerialwrappingandfoampieces, thenliftthepreamplifierfrom thebase
ofthecontainer.(It isrecommendedthat theusertake off all jewelrythat may scratchthe
unit andput onthe white cottongloves providedwiththe unit.)
Remove thecenterpiece offoaminbase oftransitcase, tolocate theremote controland
powercable.
Remove the covering from the unit. Please save it for lateruse.
Move the unit toits finallocation(see Positioning).
Important
Do not connect any cables as yet.
Safelystorethepackagingfor futurerelocationoftheunitandshippingif service is
required.
Positioning
TheHALCRO™dm8preamplifiercanbe placedanywhereindoors. Thereisnoneedto
leave room aroundtheunittoallowittobreathe. Thedm8does notgenerate significant
amounts ofheat.
To ensureultimate performance andtoavoidpotentialsafety hazards, place theunitona
firm andlevelsurface. Whenplacingtheunitonashelf,be certainthat theshelf and
mounting hardware cansupport the weight ofthe product.

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Front PanelControls
1. LCD Information
Display
2. Balance ControlLeft
3. Standby/Onbutton
4. Mute button
5. Balance ControlRight
6. Input Select Control
7. Volume Control
8. Phase button
9. Remote Sensor
Window
1. LCDInformationDisplay: This
display deliversmessages andsystem
statustoassist youinoperatingtheunit.
See page 11 for acomplete breakdownon
the display.
2. Balance ControlLeft:Usingthis
buttoninconjunctionwithBalance
ControlRight(Fig1, 5),theusercan
change therelative volumefor theleft
andrightchannels. PressingtheLeft
buttonwill increase thevolumeonthe
lefthandchannelanddecrease the
volume onthe right.
3. Standby/Onbutton: TheHALCRO™
dm8isdesignedtoremaininstandby
modewhennotinuse. Thisbuttonwill
toggletheunitbetweenStandby andOn.
To turntheunitoff completely, use the
rearpanelMasterPowerSwitch(Fig 6, 6).
4. Mutebutton:Depressingthisbutton
will Mute the output tothe speakers.
5. Balance ControlRight:Usingthis
buttoninconjunctionwithBalance
ControlLeft(Fig1, 2),theusercan
change therelative volumefor theleft
andrightchannels. PressingtheRight
buttonwill increase thevolumeonthe
righthandchannelanddecrease the
volume onthe left.
6. InputSelectcontrol:Byturningthis
knob, thepreamplifierwill scroll through
all the programmedinputdevices (CD
player,Tuner,DVD,etc.)attachedtothe
unit.
Figure 1

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7. Volumecontrol:Turnthisknob
clockwise toincrease thevolumeand
counter-clockwise todecrease the
volume. To mute thesystem,whenthe
speakersarebalanced,continuetoturn
theknobcounter-clockwise until the
word MUTE appearsonthedisplay, or
press the Mute button(Fig 1, 4)
8Phase Button:Depressingthisbutton
will toggletheunitbetweenin-phase and
out-of-phase mode.
9Remotesensorwindow:Behindthis
windowisasensor that receives infrared
signalsfrom theremote control.Aimthe
remote at thisarea anddo notblock or
coverthis sensor window.
Remote Control
1. Volume buttons
2. Mute button
3. Standby/Onbutton
4. SignalSource buttons
5. Functionbutton
1. Volume buttons: For
volume controlandalso
usedinconjunctionwith
the functionbuttonfor
various functionselections.
2. Mute button: Press to
Mute the sound, press
againtoreactivate the
sound.
3. Standby/Onbutton:
Press totoggle the system
betweenStandby andOn.
4. Signalsource buttons:
Press toselect any one of5
signalsources onthe dm8.
5. Functionbutton: Press
tochoose the following
functions: speakerbalance,
inandout ofphase andto
toggle the systembetween
stereoandmono. See
relevant operating
instructions for full details.
Figure 2
Note: Remote controltakes 3 xAAA batteries (supplied)