扬声器等效模型.doc

《扬声器等效模型.doc》由会员上传分享，免费在线阅读，更多相关内容在行业资料-天天文库。

1、扬声器等效模型Youcansimulatethebehaviourofaspeakeranditscrossoverbyprofessionalspeakerdesignsoftware.Incaseyoudonothaveaccesstothesesoftware,analternativewouldbetousetheSPICEsimulationsoftwaretodothespeakersimulation.HereIwilldemonstratehowtodothisusingOrCad.ThereisademoversionofOrCad

2、release10whichyoucandownloadfromOrcad'swebsitetotry.Thiele-smalleqivalentcircuitBeforeyoucansimulateyourdriverinOrcad,youneedtocalculatetheeqivalentcircuitforyourdriverunit.ThiscircuitcanbederivedfromtheThiele-smallparameters.Forexample,ifadriverhasthefollowingThiele-SmallParam

3、eters:Thiele-Small Parameters Revc5.8ohmsDCresistanceofvoicecoilLevc0.55mHvoicecoilinductanceBl6.5T.mforcefactorQts0.35totalQQes0.45electricalQQms1.55mechanicalQFs37HzresonantfrequencyMmd0.014kgmassofcone+voicecoil+etcRms2.08resistanceofsuspensionCms1.34mm/Ncomplianceofsuspensi

4、onSd0.0136sq.meffectiveconeareaVas0.0347cu.mequivalentacousticvolumeXmax0.004mlineartravelofvoicecoilFR37-5000kHzfrequencyresponseVd0.0005cu.mdriverunitvolumedisplacementThenthisdrivercanbemodelledwiththefollowingcircuit:Someofthecircuitvaluesabovearealreadyobvious.Vegrepresent

5、stheamplifierandisassumedtohavenooutputresistance.Theremainingvalueswerecalculatedfrom,Cmes=Mmd/(Bl*Bl)=electricalanalogofdrivermechanicalconemassLces=Cms*Bl*Bl=electricalanalogofdrivermechanicalsuspensioncomplianceRes=Bl*Bl/Rms=electricalanalogofdrivermechanicalsuspensionresis

6、tanceCmef=8*po*Ad*Ad*Ad/(3*Bl*Bl)=electricalanalogofairloadonthedriverunit'sconewhere:po=airdensity=1.18kg/cu.mAd=effectiveradiusofthedriverunit'scone=SquareRootof(Sd/3.14)Someoftheseparameterscanbelookupfromthedriver'sspecification.ThismissingonecouldbecalculatedusingtheUnibox

7、excelfile.Uniboxisafreetoolthatcanhelpyoutodesignspeakerenclosure.SpeakerDriverUnitSimulationAfteryoucreatedyourdrivermodels,youcouldstartbytestingifyourdrivermodel'simpedanceresponseissimilartoyourdriver'sactualimpedanceresponse.NowyouneedtofamiliaryourselfwithOrCadifyouhaveno

8、tuseditbefore.HereisagreatOrcadtutorialthatIsuggestyou