active mains purification - ifi audio · these sources of noise are found in hi-fi systems and come...

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. MUCHbetteratupto-40dBand…ii. Effectiveacrossawidefrequencyrange,comparedtopassivefilterswhichcover

onlyveryhighRFfrequencies.

EveryaudiosystembenefitsfromtheACiPurifier

TheACiPurifierisdesignedforuseinANYmainspoweredaudiosystemandisveryeffectivewhenaddedtomodernaudiosystemsthathaveanabundanceofdigitalandanaloguecomponents.Typicallythesesystemsarepoweredfromaplethoraofmainsplugs.Allofthese‘wallwarts’canaddtheirownunwantednoiseissuesandpollutethelocalmainssupply.However,thedesignoftheACiPurifierissuchthatitisevenmoreeffectiveifseveralareusedto‘contain’thesametypeofnoisysources.

InsertitintotheACmainswalloutletsupplyingtheaudiosystemORinsertintothemainsextensionblockpoweringtheaudiosystem.Trybothlocationstodeterminewhichhasthegreatestimpactonimprovinganynoiseissues.

December2017

ACiPurifierParts1-5

TechNotes

BristlingwithseriousPowerTechnology

ComparedtosimilarACpowerproducts,theACiPurifiercanboastthetechnologicalfeaturesbelow,makingitfarmorecomprehensiveandeffectivethanitsrivals.

1.Purification 1.1ActiveNoiseCancellation(ANC)

Militarytechnology–themostadvancedactivenoise-cancellationavailablecovermuchlowerfrequencynoisethanpassivefilters

1.2PassiveNoiseReduction(PNR)

Apassivecircuitthatsignificantlyreduceshigherfrequencypowerlinenoisewithoutaudibleorvisibleside-effectsandremainseffectivetoseveral100MHz.

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,duetothemainswiringactingasaerial.Mostofthesources,wecandolittleaboutastheyarefoundineverydaylifesuchasradiosormobilephones.

Thenextchartshowsthe‘local’noisesourcesfoundinandaroundanaudiosystem.

December2017

ACiPurifierParts1-5

TechNotes

Localnoisecomesfromhi-ficomponents

Thesesourcesofnoisearefoundinhi-fisystemsandcomefromthreemainsources:

i.ACmainspowersupplies

ii.Switch-ModePowerSupplies

iii.Digitalcircuitry.

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).

TechNotesACiPurifierParts1-5

LPSvsSMPS

Itisworthnotingthat,asmuchasLPSdesignsgetagoodreputationandSMPSdesignsgetabadreputation,therealityissomewhereinbetween.Andthesituationisdynamic.

First,LPSdesignsareonthewhole,goodand,onaverage,arequieterthanpoorlydesignedSMPSpowersupplies(whichtendtobemoreforchargingmobilephonesandarenotoptimisedfornoise).ThisiswhyLPSisoftenperceivedassuperiortoSMPS.

Hybridandelectriccarsusedtobeshunned,yettheyarenowalltherage.WebelievethesameishappeningforSMPS.Thesearenowmoreenvironmentally-friendlyandconsumefarlesspower.WhereasallSMPSusedtobe‘noisy’,weareoneofthefewcompanieswhohavebrokendowntheSMPSintoitsconstituentpartsandfundamentallyre-designeditforaudiophileuseiesuperlow-noise.TheiPOWERisthe‘Model3’ofSMPSpowersupplies.

NeverthelessnoteveryonehasaniPOWERattheirdisposal.ItisthereforeimportanttobeabletoeffectivelydealwithnormalSMPSnoisewhichcanbequitesevere.

ThenextsectionexplainswhichaspectsoftheACiPurifiertargetthedifferentgroupsofnoiseandhowthiscomparestothecommonapproach.

December2017

ACiPurifierParts1-5

TechNotes

Part3:ActivebeatsPassive.Passivefiltrationisthemostcommonapproachseeninaftermarketpowersupplyaccessories.

However,itisnotwithoutitslimitations:

i. ItfiltersonlyintheveryhighfrequenciesinthehighMHzregion.ii. Tobeeffective,thecapacitorsmustbelargeandthismeansbulkyandcostly.

Giventhesedrawbacks,theACiPurifierhadtobedifferent,morethoroughandmorecomprehensive.

ThesolutionfortheACIPurifierisactive+passivesectionsforthemostcompletepurificationoverthefrequencyrange.

1. ActiveNoiseCancellation(ANC) -covershighKHzandlowMHzranges2. PassiveNoiseReduction(PNR) -coversthehighMHzrange3. IntelligentEarth -connectstodeviceswithoutearthtodrainmains

leakagenoisetoearth

Thechartbelowillustratestheimpactuponnoise.

TechNotesACiPurifierParts1-5

Theblacklinerepresentsnormalnoisefoundinasystemwithnoremedyforit.Itrunsacrossthefrequencyrangeat0dBasitisnotreduced.

Theredlinerepresentstypicalmainsaccessoriesthathavepassivecircuitry–thesetypicallystarttoworkataround1MHz.

ThegreenlinerepresentstheACiPurifierimpactbystartingat10kandthenreducingnoisebyupto40dBallthewayupto100Mhz!Bycomparisonpassivefiltrationstartsmuchhigherinthefrequencyrangeat1MHzsomissesoutonfilteringtwo-thirdsofthenoise.

ACiPurifieragainstgenericpassivefilters

Asexplainedearlier,externalsourcesofnoise,fromradiostoTVstomobilephones,arenotconcentratedinjustoneareaastheycontributetonoiseacrossthefrequencyrange.

ThegraphbelowshowshowtheACiPurifiernullifiesexternalnoisesourcesacrossthefrequencyspectrum.

Bycomparison,thegenericpassivefilterdoesnotdealwithcertainradiosandwalkie-talkietypeproducts.

Withlocalsourcesofnoise,theserangefromlinearpowersupplies(yestheymakenoise!)toswitch-modepowersuppliestodigitalcircuitryandalltherelatedharmonics.Itshouldbenosurprisethat,withtheACiPurifieractivelycoveringthefrequencyrange,farmorenoiseisreduced–byanimpressive-45dBorso!Bycomparison,withagenericpassivefilter,noisefromlinearpowersuppliesandswitched-modepowersuppliesremainwithonlysomedigitalcircuitrybeingattendedto.

December2017

ACiPurifierParts1-5

TechNotes

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.

TechNotesACiPurifierParts1-5

Part5:Notjustaprettycase.NotonlydoestheACiPurifiercarryoutexceptionalnoisefiltration,italsohasseveralotherfeaturestogothatextramile:

1) SmartDiagnosticsofPolarity–withbothversions,EUandUSA,itispossibletoconnectintheoppositepolarity.TheACiPurifierdetectsachangeandindicatesthis.

2) SmartDiagnosticsofEarth–detectsiftheaudiomainssystemitisinsertedintohasaGround/Earthornot.

3) IntelligentGround–byattachingtheoptionalgroundcable,itispossibletogiveanysystemanaudioground.GoingdirectlytotheACiPurifierandintothemains,theGround/Earthwillbeofthehighestqualityconnection,makingitthemosteffectiveatdrainingsystemnoise.

4) OvervoltageProtectionSystemmeansthatelectricalshorts,lightningstrikesandsurgesinthemainswillbedetectedandtheACiPurifierwillclampthevoltagetosafelevelstoprotectyourAVcomponentsfromdamage.

Tosummarise:

TheACiPurifierisnoordinarymainsfilter.

Firstly,andmostimportantly,itpurgestheaudiosystemmainsofnoiseusingbothActiveandPassivetechnologiestoworkacrossawidefrequencyspectrum.

Secondly,itprovidesanintelligentGround/Earthtoreducenoiseforcasesofa“missingearth”causingproblemswithnoise.

Thirdly,itchecksanddetectsthelocalmainsforEarthandPolarityanomalies.

Thereissimplynoothermainspowerimprovementaccessorylikeit.