Halcro DM10 User manual

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TABLE OF CONTENTS
IMPORTANTSAFETYINSTRUCTIONS................................................................2
INTRODUCTION..........................................................................................................3
ELECTRONICDESIGN ........................................................................................................3
MICROPROCESSOR CONTROL............................................................................................6
INDUSTRIAL DESIGN .........................................................................................................7
MECHANICAL DESIGN.......................................................................................................8
INSTALLATION............................................................................................................9
UNPACKING......................................................................................................................9
POSITIONING ....................................................................................................................9
FRONTPANELCONTROLS....................................................................................10
REMOTE CONTROL..................................................................................................11
DISPLAY........................................................................................................................12
REARPANEL................................................................................................................13
CONNECTIONS..........................................................................................................15
CONNECTINGTO APOWER AMPLIFIER ...........................................................................15
REMOTE POWER AMPLIFIER CONTROL OUTPUT ............................................................16
BRIDGING.......................................................................................................................16
BREAK-INPERIOD ..........................................................................................................16
PROGRAMMABLE INPUT SELECTIONS ............................................................................16
OPERATING INSTRUCTIONS................................................................................17
CONNECTINGSIGNAL SOURCES......................................................................................17
HOME THEATRE PROCESSOR CONTROLLING VOLUME ...................................................17
PHONO STAGE................................................................................................................17
CONNECTINGTHE MAINS POWER SUPPLY CABLE.........................................................18
REMOTE CONTROL BATTERIES......................................................................................18
SWITCHING THE UNITON................................................................................................18
ALLOCATING SIGNAL SOURCES AND THE REMOTE CONTROL.........................................18
DE-ALLOCATING PROGRAMBUTTONS ...........................................................................19
SETTING THE LOAD RESISTANCE/CAPACITANCE FOR MOVING MAGNETIC
CARTRIDGE PHONO PLAYERS..........................................................................................19
DISPLAYED INFORMATION .............................................................................................19
DISPLAY CONTRAST.......................................................................................................19
BACK LIGHT...................................................................................................................19
VOLUME.........................................................................................................................20
STORED VOLUMES .........................................................................................................20
VOLUME– BALANCING FUNCTION................................................................................21
MONO/STEREOFUNCTION..............................................................................................21
PHASE CONTROL............................................................................................................21
SWITCHING BETWEEN SOURCES.....................................................................................22
ELECTRONICPROTECTION AND RELIABILITY.............................................22
SPECIFICATIONS&FEATURESOFTHEHALCRODM10.............................23
CAREAND MAINTENANCE...................................................................................25
TROUBLESHOOTING...............................................................................................26
SERVICE........................................................................................................................27
WARRANTY.................................................................................................................28

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Important SafetyInstructions
CAUTION
RISK OFELECTRIC SHOCK
DONOTOPEN
Thisunitshall be connectedtoaMAINS socket outlet witha
protective earthing connection.
OnlysuitableapprovedMAINS cords, as perEuropeanindividual
countryrequirements 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. Thedm10 preamplifieris not protected
against liquids.
Theunitshall notbe exposedtodrippingor splashing. Noobjects
filledwithliquids, suchas vases, shall be placedonthe apparatus.
Nonakedflamesources, suchas lightedcandles, shouldbe placedon
the unit.
Designedtooperate onanymainssupplyintherange of90Vto240
V, 50 to60 Hz, without any internalor externalswitches.
Do notattempttoopentheunitas this will voidthewarranty and
will expose youtodangerous voltages.
Compartments aresealedat thefactory. Ifthesealsarebroken,the
warranty will be voidandall service costs will be chargedtothe
owner.
Requires F1AL250v fuse for continuedprotectionagainst therisk of
fire. Neverbypass or use anyothertypeoffuse. Thefuse islocated
onthe rearpanelinthe mainswitch.
90 -240 V
50 -60 Hz

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Introduction
Congratulations onpurchasing the HALCRO™ dm10 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™poweramplifiers, all you
will hearistheoriginalrecordingreproducedtheway theartist intendeditto
sound.Notransistor or valve-addedsounds are present, just a levelofmusical
purity that was thought impossible until now.
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.

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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.
Thefigurebelowshowsafunctionalblock diagramofthepreamplifier
(Diagram1).Ascanbe seen,thephonostage has 4stages. Firstly, thereisan
ultralownoise inputstage withagainofx20 for movingcoil cartridges. This
canbe switchedout ofthe circuit train.
Diagram1

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Thefirst stage isfollowedby ahighinputimpedance (FETinput)lownoise
amplifierwithagainselectabletox4or x8. Theoutputofthisstage isfedto
aninvertingamplifierwithagainselectedtobe x-2if thehighinput
impedance amplifierstage gainisselectedtobe x4, or x-1if thehighinput
impedance amplifierstage isselectedtobe x8. (The“minus” indicates
inverting.)Theoutputoftheinvertingamplifierisconnectedback tothe high
inputimpedance amplifierstage inputviaacontinuouslyvariable
potentiometer.Acontinuouslyvariablecapacitor isalsoconnectedtothis
inputandtoground.Thevariableresistor andcapacitor set theload
impedance ofthehighinputimpedance amplifierstage andact toload
moving magnet cartridges.
Thisconfigurationformsanactive load.Thevariablecapacitance sets theload
capacitance andtheloadresistance is1/8th ofthevalueofthepotentiometer
resistance. Thisconfigurationlowersthenoise floor at highfrequency, andits
attributes are describedbelow.
Theoutputofthehighinputimpedance amplifierstage is, as well,fedtoa
15Hz3
rd orderhigh-pass Besselfilter.Thisacts as a“rumble-filter.”
FollowingthisistheRIAA equalizationstage. TheRIAA equalizationadheres
tothe RIAA specificationwithin0.25dB at all frequencies.
TheoutputofthisRIAA stage isfedtoalownoise inputselector stage which
has againof2. Intruth,if aphonoinputisselected,thisgaincanbe set to
either1or 2, dependinguponthegainoftheselectedphonoinput. Some
inputs arebalancedinputs andoneinputisacurrentinputwithaload
impedance of51 ohms, for optimalinter-connect loadmatching. The
equivalentinputnoise ofthevoltage inputs isapproximately3.5nV/sqrt(Hz),
andthat ofthe current input is 13pA/sqrt(Hz).
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:
Ÿ zero ON resistance,
Ÿ infinite OFF impedance,
Ÿ very lowOFF capacitance,
Ÿ zero distortion.
Incontrast, thenowuniversallypopularsolidstate relays/switches exhibit
noneofthese idealproperties anddetract from performance. Hence,
sonically, HALCRO™feelsthat itisworththesideeffect ofmechanical
clicking 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 sixinput devices intonine physicalpairs ofinputsockets. There
are twopairs ofdedicatedphonoinputs, one pairofcurrentinputs, three pairs
ofbalancedinputs andthree pairsofunbalancedinputs. Phonoinputs do not
require programming as they are permanently allocatedtothe phonosource.

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INDUSTRIALDESIGN By MaxDickison&Tony Kearney
ProductForm
Theaimwhendesigningthedm8&dm10 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/monoandinor out-of-phase. Thevolumelevelsfor eachchannelare
displayedside-by-sidesothat whenthelevelsarenotequalizedtheuserwill
easily notice it.

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Remote control:
WhendesigningtheHALCRO™Remote Control,weaimedtoreflect the
quality andformsoftheHALCRO™preamplifiers. Machinedfrom asolid
aluminumextrusion,theremote rests comfortablyintherighthandwithits
minimalist array ofbuttonsfallingwithinthenaturalsweepofthethumb.
Simpleandlogicaltooperate, everyefforthas beenmadetokeepthisproduct
free ofunnecessary complexity.
MECHANICALDESIGN By Lance Hewitt
TheHALCRO™dm8&dm10 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].

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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™dm10 preamplifiercanbe placedanywhereindoors. Thereisnoneedto
leave room aroundtheunittoallowittobreathe. Thedm10 does 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
Figure 1
1. Headphone Jack
2. Remote Sensor
Window
3. LCD Information
Display
4. Balance ControlLeft
5. Standby/Onbutton
6. Mute button
7. Balance ControlRight
8. Input Select Control
9. Volume Control
10. Phase button
11. Mono/Stereobutton
1. HeadphoneJack: Thisjack may be
usedtolistentothedm10’soutput
throughapairofheadphones. Ensure
that theheadphones have astandard ¼”
stereoplug.
2. RemoteSensorWindow:Behindthis
windowisasensor that receives infrared
signalsfrom theremote control.Aimthe
remote at thisarea anddo notblock or
coverthe sensor window.
3. LCDinformationdisplay: This
display deliversmessages andsystem
statustoassist youinoperatingtheunit.
See page 12 for acomplete breakdownon
the display.
4. Balance ControlLeft:Usingthis
buttoninconjunctionwithBalance
ControlRight(Fig1, 7),theusercan
change therelative volumefor theleft
andrightchannels. PressingtheLeft
buttonwill increase thevolumeonthe
lefthandchannelanddecrease the
volume onthe right.
5. Standby/Onbutton: TheHalcro dm10
isdesignedtoremaininstandby mode
whennotinuse. Thisbuttonwill toggle
the unit betweenStandby andOn.
To turntheunitoff completely, use the
MainPowerSwitchonthe rearpanel.
6. Mutebutton:Depressingthisbutton
will Mute theoutputtothespeakersbut
not the headphones.