Halcro DM38 User manual

Page1
TM
dm38
TableofContents
Important SafetyInstructions....................................................................2
Introduction.....................................................................................................3
Installation.......................................................................................................4
Unpacking.................................................................................................4
Positioning................................................................................................5
Connections.....................................................................................................5
Connecting the MainsSupply Cable...................................................5
Connecting the Loudspeakers..............................................................5
Connecting the ExternalGround.........................................................6
Bridging.....................................................................................................6
Running-inperiod...................................................................................6
dm38InputSelections............................................................................6
Commentsonthedifferentdm38inputs...........................................7
Operating Instructions.................................................................................8
ElectronicProtectionand Reliability........................................................9
Specificationsforthedm38.......................................................................13
CareandMaintenance................................................................................14
Troubleshooting...........................................................................................15
Service.............................................................................................................16
Warranty.........................................................................................................17
Warranty RegistrationForm.....................................................................18

Page2
TM
dm38
ImportantSafety Instructions
120lb
CAUTION
RISKOFELECTRICSHOCK
DO NOT OPEN .
Thisproduct shallbeconnectedtoaMAINS socketoutletwith a
protectiveearthingconnection.
Weighs55kg(120 lbs.)perunit.Shipping weight-85kg (187lbs.).
Neverlifttheamplifierbyyourself.
Alwaysuse twopeople tounpack ormovetheamplifier.Always
bendatthekneeswhenlifting.Donotstrainyour back.
Designedforindooruseonly,thedmrangeof amplifiersarenot
protectedagainstliquids.Theyshouldnotbe exposedtodripping
orsplashingandnoobjectsfilledwith liquids,suchasvases,
shouldbeplacedonthem.
Thedm38isproducedintwomodelsdesignedtooperateon
differentmainpowersupplies.
110Vmodel(Halcroitem411-005):100 -120V,45-65Hz
240Vmodel(Halcroitem411-006):220-240V,45-65Hz
TheAmplifier’sPositiveLoudspeakerTerminal cangenerate
HazardousLiveVoltages.To complywith International Safety
StandardsonlyuseLoudspeakercableswith wellinsulated
terminalssuchasWBT-0660.Alwaysswitchtheamplifiersto
StandByorOFF beforetouchingtheseterminalsoradjusting
loudspeakerconnections.
Neverobstruct the airflowtotheheatsinks.
Containsnouserserviceableparts.Donotattempt toopenanyof
theamplifiercompartments,asthismayexposeyoutodangerous
voltagesandwill voidthe warranty.
Allcompartmentsare sealedatthefactory. Ifthesealsarebroken,
thewarranty will bevoidandallservicecostswill bechargedto
the owner.
RequiresF10AL250Vfuse (if operatingon220–240V)or
F15AL110Vfuse(ifoperatingon100–120V)forcontinued
protectionagainsttheriskoffire. Neverbypassoruseany other
typeof fuse. Thefuseislocatedonthebottomof theamplifier,
nearthe masterON/OFF switch.
Warning do notuse any cableslongerthan3M

Page3
TM
dm38
Introduction
Congratulationsonpurchasingthe HALCRO™dm38 Stereoamplifier.
HALCRO™designsandmanufacturesthe only "SuperFidelity"
amplifiersinthe world.This"Super Fidelity"amplifier reproduceswith
better than 99.9997%purity ofalltonesacrosstheentireaudiorange.
Theconceptbehindtheelectronicdesignwastocreatean amplifier,
whichdidnotcolorthesoundwithitsownelectroniccharacteristics.
i.e.recreatethe originalsoundasitwasatthetimeof recording.
Pleaseenjoy theHALCRO™audioexperience.
HALCRO™hasenjoyedcreatingperfectaudioreproductionforthe
world'smusicconnoisseurs.
IfyoudesiretocontactHALCRO™togiveusfeedbackonyour
purchaseor for generalenquiries;
pleasefeelfreeto:
email [e-mail]
orphone [phone]
orfax+61882380852

Page4
TM
dm38
Installation
Ensureyou have readtheImportantSafetyInstructionssectiononpage2,priorto
installing your HALCRO™amplifier.
Ifyou requireassistanceinthe unpackingandinstallationofyourHALCRO™
amplifier,pleasecontactyour dealer.
PLEASENOTE:
Whenlifting theunit, alwaysusetwo people.
Theunitmustbeliftedbyplacingyourhandsunderthemiddleofthebottom
compartment.Do not lifttheunitunderthetopcompartment.
Unpacking
1.Unscrewthe4knurledknobsatthebaseofeachbox. Thenremovethe upperpart
ofthe containerby lifting directly upwards, tillitclearsthetop oftheamplifier.
2.Withanassistant,removetheplasticwrappingandfoampieces,thenliftthe
amplifierfromthebaseofthe container.Removetheplasticcoveringfromthe unit.
Pleasesaveitfor later use.
3.Movetheunittoitsfinallocation(see Positioning).Whitecottongloveshavebeen
providedtopreventmarkingtheamplifierwhilemoving itintoplace.
Important
• Donotconnectany cablesasyet.
• Safely storethe packagingso itmaybeusedforfuturerelocationofthe unit,and
for shippingif serviceisrequired.

Page5
TM
dm38
Positioning
Wesuggestthatthedm38bepositionedasnear toyourloudspeakersaspractical.This
will reducethelengthofthe loudspeakercablerequired.Thesidesofthe unithouse
theheatsinksthatareusedtodissipateheat.The airflowtotheseshouldnotbe
interrupted. Ensurethereisatleast12 inches(300mm) clearancearoundtheunit.
Connections
ConnectingtheMainsSupply Cable
Plugthemainsplugintotheunit'ssocket,whichispositioned, attherear, onthe base
of the bottomcompartment,whichhousesthepowersupply.Ensurethe cableexitsto
therear of the unit. Do notplug into themainsoutlet.
ConnectingtheLoudspeakers
The dm38has4loudspeakerterminals:
• 2x Positive+(RedBezel).
• 2x Negative-(BlackBezel).
Allofthe pure copperconnectionsarefinishedwiththehighest-gradegoldplating.
• Ensurethepositiveterminalofthe amplifierconnectstothepositiveterminalof
theloudspeaker. Thiswill ensurecorrectphasingoftheaudiosignal.
• The loudspeakerterminalswillacceptspadeorhookterminals.Only fully
insulatedterminal aretobeused.
• Ensuretheloudspeaker terminalsaresecurelytightened.Donotovertightenor
youmaydamagetheterminals.
• Whenconnectingloudspeaker cablesalwaysensurethe conductivesurfacesare
nottouching eachother.DONOTSHORT-CIRCUITTHETERMINALS.
Theremaybehighvoltagespresentattheloudspeakerterminals,whichcanbe
hazardousiftouched.Alwaysensuretheunit isswitchedto OFForSTANDBY
modewhenconnectingordisconnecting loudspeakers.
PRIORTOTURNING ONTHEUNIT,PLEASE CONTINUE TOREADTHE
FOLLOWING PAGES.

Page6
TM
dm38
ConnectingtheExternal Ground
The dm38isequippedwithaseparategroundterminal. Thegroundterminalhasa
greenbezelandislocatedunder thepowersupply. Thisterminalmaybeusedto
reducehumandrippleinsome circumstances.
Bridging
You maybridgetheHALCRO™amplifier,fordetailspleaseemail usat
[e-mail]
Abridging kitisavailablethroughHALCRO™.
Running-in period
The dm38’selectronicrunning-inperiodiscompletedatthefactory. Afurther
running-inperiodisnotrequired.
dm38InputSelections
The dm38hasthree switchselectableinputs,eachhavingaseparateinputsocket.Both
theinputsocketsandswitcharemountedonthetoprear panel.
Input
Styles Requiredoutput source impedance Input socket Inputimpedance
Balancedvoltage
input Lowimpedance.e.g., standardpreamplifier or
CDplayer etc.
XLR10kohms+10kohms
Un-balanced
voltageinput Lowimpedance.e.g., standardpreamplifier or
CDplayer etc.
RCA10kohms
Current-mode
input Very high: “infinite.”RCA60ohms

Page7
TM
dm38
Commentsonthedifferentdm38inputs
The balancedvoltageinputorcurrent-modeinputsaremostdesirableforminimizing
earthloop generatedmainshumandripple,or highfrequency interference.
Sourceswithcurrent-modeoutputsare rare andaremostlikelytohavean RCA
outputsocket.Theadvantagesofthissourcearethat:
• Earthloopgeneratedmainshumandrippleareminimized.
• Cable,plugandsocketgeneratedinterferenceisminimized(from poorconnections
whichmay beaffectedbysoundvibrationforexample).
The unbalancedinputisquitesatisfactoryso longasearthloopgeneratedmainshum
andrippleisnotaproblem.
Allorsome of theinputsocketsmay haveactivesourcessimultaneouslyconnectedto
them.Theselector switchselectsthe inputtobeamplified.

Page8
TM
dm38
OperatingInstructions
• Oncetheexternalcablesare connectedtothe unit,ensurethemasterON/OFF
switchisintheOFFposition. (ThemasterON/OFF switchissituatedonthebase
ofthelowercompartment,nearthemainssocketontheunit.Youwillhaveto
kneelontheflooratthebackoftheunitto accesstheswitch).
• Plug themainsplug intoamainsoutlet.
• Switchthe masterON/OFF switchtoON.The LEDsonthe frontandrear ofthe
amplifierwillglowred.Thisindicatesthattheunitisinstandbymode.Inthis
modeasmallcurrentisdrawnfromthe mainssupply, buttheunitwill notdrive
theloudspeakers.
• Pressthe modeswitchoncetoswitchbetweenStandbyandON modes.(Themode
switchisasmall pressureswitchaccessedwhenstandingat thefrontoftheunit.
It islocatedunderthebottomlipofthetopcompartment.
• Whentheamplifier hasbeenswitchedtoON,theLEDsonthefrontandrearwill
glowgreen.
• The amplifier isnowready todriveyourloudspeakers.
• Itisrecommendedthattheunitbeswitchedtostandby whennotinuse.
Itissafertoturn themainspower offwhennotusingthedm38.Howeverthe
amplifiermaybeleftoninthestandbymodeforprolongedperiods.Ifyouwishto
turnthemainspower off, the amplifierhasaveryminimalwarmup period.

Page9
TM
dm38
Electronic Protectionand Reliability
Electronicprotectioncircuitryandamplifierreliability,alas,isan areasadly neglected
bymanyhigh-endaudioamplifierdesigners.HALCRO™haspaidagreatdealof
attentiontothisarea.
Components
Our componentsareselectedfornotonlyperformancebutreliabilityaswell,for
example:
• AllHalcroelectrolyticcapacitorsareratedataminimumof105degreesCinstead
oftheusual85 degreerating. Theoperationallife ofelectrolyticcapacitorsis
severely shortenedattemperaturesnear the maximumtemperature rating. Thisis
showninthetablebelow.
• AllHalcrointegratedcircuitsareatleast “industrialgrade” ratherthanthe usual
“commercialgrade”.Industrialgradecomponentsareratedatleast from–40
degreesCto+85degreesCwhereascommercialgradecomponentsareonly rated
from0to70degreesC.Inaddition,the electronicspecificationsofindustrialgrade
componentsare superior tocommercialgrade.
Electrolytic
capacitor
temperature
rating
Meanlifetime at
40 degrees
Centigrade
Meanlifetime at
85 degrees
Centigrade
Meanlifetime at
105degrees
Centigrade
85 C (most
commonly used) 50,000Hours2,000Hours(0)
105C (usedin
Halcro
amplifiers)
180,000 Hours8,000Hours2,000Hours
Typicaldatafrom ahighly respectedmanufacturer.
Consideringthatmostamplifiersrunatsignificantly elevatedtemperatures,itcanbe
seenfromthetable,thattheHalcrohightemperatureratedcapacitorsarehighly
advantageouscomparedtothestandard85degreerateddevices.

Page10
TM
dm38
Outputcurrentlimiting
In termsofmaximumavailableoutputcurrent,therearebasically 3amplifiertype
options:
a.Anamplifierwithareasonablelimitplacedonthemaximumavailableoutput
current.
b.Anamplifier withnolimitplacedonthemaximumavailableoutputcurrent,which
will eitherblowafuseorselfdestructifexcessivecurrentisdrawn,forexample
throughadeadshort.
c.Anamplifierwithaveryhighlimitplacedonthemaximumavailableoutput
current,butdesignednottoblowafuseifthisveryhighcurrentisdrawn.
Ifthe maximumcurrentdrawnfroman amplifier withmaximumavailablecurrent
limitingisreachedundervery loudmusicconditions(amplifiertype a.orc.above),
highly obvious“cracking”overloadsoundsmaybeheard.Notethatthisoverload
soundmayalso occurifaloudspeakeroverloadsorif anyamplifiersuffersvoltage
overload.
Thereisan expectationintheaudiophileelectronicindustrythatahighendamplifier
shouldbecapableofdeliveringexactly doublethe outputcurrentfor a halving ofthe
loudspeakerimpedance(downto1ohm)atthemaximumoutputvoltagethatthe
amplifiercan produce.
Thisrequiresan amplifieroftype b.or c. above.Thetablebelowlistsan example ofan
amplifierratedat150 Wattsoutputinto8ohms.
Loudspeaker
load
impedance
Output
power Peakoutput voltage r.m.s. output current Peakoutput current
8ohms 150W49V4.33A6.12A
4ohms 300W49V8.66A12.25A
2ohms 600W49V17.32A24.5A
1ohm 1200W49V34.64A49.A
Ifthe loudspeakercableisinadvertentlyshortedout,thesesortsofcurrentsarequite
capableofcausingsome cablestocatchfire. Weknowofonesuchinstancewithan
amplifierratedaccording tothetable!
Aswedonotwishtosetyourhouseonfire wehavelimitedthepeakoutputcurrent
to15A.