Active Mains Purification - ifi-audio.com · PDF fileTech Notes AC iPurifier Parts 1 - 5...
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December 2017 AC iPurifier Parts 1 - 5 Tech Notes Active Mains Purification Part 1: Actively goes where no purifier has gone before Mains is the fuel that powers an audio system. Whether it is clean or not has a material impact upon quality and the user’s enjoyment of playback. iFi’s latest ‘power product’, the AC iPurifier, is no ordinary mains purification commodity. Technologically advanced, it is an ACTIVE not a passive product, so it goes above and beyond and cancels far more noise across the frequency range than passive devices. It is effective against both: i. Common mode noise existing equally on both of the power pins, referenced to the earth pin. ii. Differential noise existing only between the two power pins – the net to earth is zero. They are, in effect, flip sides of the same coin and are the bane of audio systems regardless of the type of power supply.
Transcript of Active Mains Purification - ifi-audio.com · PDF fileTech Notes AC iPurifier Parts 1 - 5...
December2017
ACiPurifierParts1-5
TechNotes
ActiveMainsPurification
Part1:ActivelygoeswherenopurifierhasgonebeforeMainsisthefuelthatpowersanaudiosystem.Whetheritiscleanornothasamaterialimpactuponqualityandtheuser’senjoymentofplayback.iFi’slatest‘powerproduct’,theACiPurifier,isnoordinarymainspurificationcommodity.
Technologicallyadvanced,itisanACTIVEnotapassiveproduct,soitgoesaboveandbeyondandcancelsfarmorenoiseacrossthefrequencyrangethanpassivedevices.Itiseffectiveagainstboth:
i. Commonmodenoiseexistingequallyonbothofthepowerpins,referencedtotheearthpin.
ii. Differentialnoiseexistingonlybetweenthetwopowerpins–thenettoearthiszero.
Theyare,ineffect,flipsidesofthesamecoinandarethebaneofaudiosystemsregardlessofthetypeofpowersupply.
TechNotesACiPurifierParts1-5
Nullifiesnoiseotherscan’treachComparedtoothergenericnoisefilters,theACiPurifierissuperiorbecauseitisACTIVEasopposedtopassive.Thisenablesittoachieveafarmorecomprehensiveterminationofnoiseacrossthefrequencyspectrum.Asnoiseexistsacrossthefrequencyrange,thisclearlymeanstheACiPurifierisunparalleledwhenitcomestoneutralizingnoise.
ThischartcomparestheACiPurifier(greenline)whichisACTIVEtogenericmainsfilters(redline)whicharetypicallypassive.
Theeffectivenoisereductiondifferenceisasdifferentasnightandday.
i. MUCHbetterat-40dBand…ii. Effectiveacrossthefrequencyrange.Whereasthepassivefiltersonlyinthevery
top-endofthefrequencyrange.
EveryaudiosystembenefitsfromtheACiPurifier
TheACiPurifierisdesignedforuseinANYmainspoweredaudiosystemandisveryeffectivewhenaddedtomodernaudiosystemsthathaveanabundanceofdigitalandanaloguecomponents.Typicallythesesystemsarepoweredfromaplethoraofmainsplugs.Allofthese‘wallwarts’canaddtheirownunwantednoiseissuesandpollutethelocalmainssupply.However,thedesignoftheACiPurifierissuchthatitisevenmoreeffectiveifseveralareusedto‘contain’thesametypeofnoisysources.
InsertitintotheACmainswalloutletsupplyingtheaudiosystemORinsertintothemainsextensionblockpoweringtheaudiosystem.Trybothlocationstodeterminewhichhasthegreatestimpactonimprovinganynoiseissues.
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BristlingwithseriousPowerTechnology
ComparedtosimilarACpowerproducts,theACiPurifiercanboastthetechnologicalfeaturesbelow,makingitfarmorecomprehensiveandeffectivethanitsrivals.
1.Purification 1.1ActiveNoiseCancellation(ANC)
Militarytechnology–themostadvancedactivenoise-cancellationavailable.
1.2WirelessNoiseNullification
Acomplexcircuitthatsignificantlyreducespowerlinenoisewithoutaudibleorvisibleside-effectscausedbywirelesssources
1.3AudioEarthconnection AsolidGround/Earthwithground-looppreventioncircuitbuilt-in.
2.Diagnostics 2.1Ground/Earthconnectiondiagnostic
DetectsamissingGround/Earth.
2.2Polarityconnectiondiagnostic
Detectsapolarityfault.
3.SystemProtection 3.1OvervoltageSurgeProtection
Auto-recovery.
TechNotesACiPurifierParts1-5
Part2:Mainsnoise.Arealbane.Powersupplynoiseisthebaneofeveryaudiosystem.Therearealwaysmultiplesourcesofnoiseandtheycomefromtwomainsources–insideandoutside.
Externalnoiseisallaround
Thischartshowsthatnoiseisanywhereandeverywhereandsomeofitinevitablyendsupinthemainsthatsuppliestheaudiosystem.Mostofthesources,wecandolittleaboutastheyarefoundineverydaylifesuchasradiosormobilephones.
Thesesourcesbeingwirelessinnature,meanthatitisverydifficulttodealwiththematthesource.Hence,weneedtoaddressthesymptom.
Thenextchartshowsthe‘local’noisesourcesfoundinandaroundanaudiosystem.
Localnoisecomesfromhi-ficomponents
Thesesourcesofnoisearefoundinhi-fisystemsandcomefromthreemainsources:
i.ACmainspowersupplies
ii.Switch-ModePowerSupplies
iii.Digitalcircuitry.
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Fromlefttoright:Thefirstsetofnoisesources(10k>10MHz)relatetoACsupplyrectifiersandtheirharmonicscausedbyLinearPowerSupplies(LPS).Yes,theymakeanoise!Thesecondsetofnoisesources(67k>200MHz)iscausedbySwitch-ModePowerSupplies(SMPS).Bycomparison,theseharmonicsruninthehigherfrequencies.Thethirdsetofnoisesources(8MHz>500MHz)iscausedbydigitalcircuitry,clocksandtheirharmonics.Andthistypeofnoiseexistsinthemostupperfrequencies.Youcanseefromthechartthattheconcentrationofnoiseisfrom30kHzupwards(thelowerthedB,thelessinfluentialisthenoise).
LPSvsSMPS
Itisworthnotingthat,asmuchasLPSdesignsgetagoodreputationandSMPSdesignsgetabadreputation,therealityissomewhereinbetween.Andthesituationisdynamic.
First,LPSdesignsareonthewhole,goodand,onaverage,arequieterthanpoorlydesignedSMPSpowersupplies(whichtendtobemoreforchargingmobilephonesandarenotoptimisedfornoise).ThisiswhyLPSisoftenperceivedassuperiortoSMPS.
TechNotesACiPurifierParts1-5
Hybridandelectriccarsusedtobeshunned,yettheyarenowalltherage.WebelievethesameishappeningforSMPS.Thesearenowmoreenvironmentally-friendlyandconsumefarlesspower.WhereasallSMPSusedtobe‘noisy’,weareoneofthefewcompanieswhohavebrokendowntheSMPSintoitsconstituentpartsandfundamentallyre-designeditforaudiophileuseiesuperlow-noise.TheiPOWERisthe‘Model3’ofSMPSpowersupplies.
NeverthelessnoteveryonehasaniPOWERattheirdisposal.ItisthereforeimportanttobeabletoeffectivelydealwithnormalSMPSnoisewhichcanbequitesevere.
ThenextsectionexplainswhichaspectsoftheACiPurifiertargetthedifferentgroupsofnoiseandhowthiscomparestothecommonapproach.
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Part3:ActivebeatsPassive.Passivefiltrationisthemostcommonapproachseeninaftermarketpowersupplyaccessories.
However,itisnotwithoutitslimitations:
i. ItfiltersonlyintheveryhighfrequenciesinthehighMHzregion.ii. Tobeeffective,thecapacitorsmustbelargeandthismeansbulkyandcostly.
Giventhesedrawbacks,theACiPurifierhadtobedifferent,morethoroughandmorecomprehensive.
ThesolutionfortheACIPurifierisactive+passivesectionsforthemostcompletepurificationoverthefrequencyrange.
1. WirelessNullificationSystem –coversthehighMHzrange2. ActiveNoiseCancellation -covershighKHzandlowMHzranges3. IntelligentEarth –connectstoSMPSpowersuppliestodrainmainsnoise
Thechartbelowillustratestheimpactuponnoise.
Theblacklinerepresentsnormalnoisefoundinasystemwithnoremedyforit.Itrunsacrossthefrequencyrangeat0dBasitisnotreduced.
Theredlinerepresentstypicalmainsaccessoriesthathavepassivecircuitry–thesetypicallystarttoworkat2MHz.
ThegreenlinerepresentstheACiPurifierimpactbystartingat10kandthenreducingnoiseby-35dBandmoreallthewayupto100Mhz!Bycomparisonpassivefiltrationstartsmuchhigherinthefrequencyrangeat30MHzsomissesoutonfilteringtwo-thirdsofthenoise.
TechNotesACiPurifierParts1-5
ACiPurifieragainstgenericpassivefilters
Asexplainedearlier,externalsourcesofnoise,fromradiostoTVstomobilephones,arenotconcentratedinjustoneareaastheycontributetonoiseacrossthefrequencyrange.
ThegraphbelowshowshowtheACiPurifiernullifiesexternalnoisesourcesacrossthefrequencyspectrum.
Bycomparison,thegenericpassivefilterdoesnotdealwithcertainradiosandwalkie-talkietypeproducts.
Withlocalsourcesofnoise,theserangefromlinearpowersupplies(yestheymakenoise!)toswitch-modepowersuppliestodigitalcircuitryandalltherelatedharmonics.Itshouldbenosurprisethat,withtheACiPurifieractivelycoveringthefrequencyrange,farmorenoiseisreduced–byanimpressive-45dBorso!Bycomparison,withagenericpassivefilter,noisefromlinearpowersuppliesandswitched-modepowersuppliesremainwithonlysomedigitalcircuitrybeingattendedto.
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Part4:Wheretodeploy.TheACiPurifierworksbytakingoutnoiseacrossthefrequencyrange.Intermsofeffectiveness,ittypicallyreducesnoisebyupto100xor40dB(andsometimesmore).
ThefollowingdiagramshowstheplacementofthreeACiPurifiersinonesystem.
ThefirstACiPurifier(1)isbestinsertedintothesharedmainswalloutletthatsuppliesthedownstreamaudiosystem.
AsecondACiPurifier(2)shouldthenbesituatedatthefirstentrypointofthewallmainsintotheextensionblock.
AthirdACiPurifier(3)isthenbestlocatedin-betweenthetwotypesofpowersupplies.ForexamplewerecommendthatalllinearpowersuppliesarelocatedafterthesecondACiPurifierbutbeforethethird.AllSMPSpowersuppliesshouldthenbelocatedafterthethirdACiPurifier.
Byconnectingthisway,alltherespectivenoiseis‘contained’andterminatedinitsimmediatevicinity.Also,thedigitalandanaloguepowersourcesshouldbeintheirrespectivegroupsasshownintheabovediagram.
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Part5:Notjustaprettycase.NotonlydoestheACiPurifiercarryoutexceptionalnoisefiltration,italsohasseveralotherfeaturestogothatextramile:
1) SmartDiagnosticsofPolarity–withbothversions,EUandUSA,itispossibletoconnectintheoppositepolarity.TheACiPurifierdetectsachangeandindicatesthis.
2) SmartDiagnosticsofEarth–detectsiftheaudiomainssystemitisinsertedintohasaGround/Earthornot.
3) IntelligentGround–byattachingtheoptionalgroundcable,itispossibletogiveanysystemanaudioground.GoingdirectlytotheACiPurifierandintothemains,theGround/Earthwillbeofthehighestqualityconnection,makingitthemosteffectiveatdrainingsystemnoise.
4) OvervoltageProtectionSystemmeansthatelectricalshorts,lightningstrikesandsurgesinthemainswillbedetectedandtheACiPurifieritselfwillinstantlyshutdowntoprotectdownstreamcomponentsfromdamage.
Tosummarise:
TheACiPurifierisnoordinarymainsfilter.
Firstly,itchecksanddetectsthelocalmainsforEarthandPolarityanomalies.
Secondly,itprovidesanintelligentGround/Earth.
TechNotesACiPurifierParts1-5
Thirdlyandmostimportantly,itpurgestheaudiosystemmainsofnoiseusingbothActiveandPassivetechnologiestoworkacrossthefrequencyspectrum,wheredifferenttypesofnoiseexist.
Thereissimplynootherpurifierlikeit.
Forfurtherinformation,pleasecontact:[email protected]/+44(0)1704227204
AboutiFiiFiaudioisheadquarteredinSouthport,UK.ItisthesisterbrandofAbbingdonMusicResearch(AMR).Theyrespectivelydesignandmanufactureportableanddesktop‘ultra-fidelity’audioproductsandhigh-endaudio‘home-based’components.Thecombinedin-househardwareandsoftwaredevelopmentteamenablesiFiaudioandAMRtobringtomarketadvancedaudioproductsoftenaheadofthecompetition,withseveral‘worldfirsts’intheirportfolio.
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