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APIntroduction&THD+N•AnalyzerinputandXLRconnector•APPanel•Audiospecifications•THD+NAPintroduction•Analyzerinputcableconnection-Singleendedoutput(MP3headphone)2–Signal,3–Ground.e.g.,ChannelA:2–Leftoutput,3–GroundChannelB:2–Rightoutput,3–Ground-Differentialoutput(loudspeaker)2–Non-invertingsignal,3–InvertingsignalAPintroduction•XLRConnectorAPintroduction•XLRConnector-Inreferencetoitsoriginalmanufacturer,JamesH.Cannon,founderofCannonElectricinLosAngeles,California(nowpartofITTCorporation),theconnectoriscolloquiallyknownasacannonplugorcannonconnector.-Themostcommonisthe3-pinXLR3,usedalmostuniversallyasabalancedaudioconnectorforhighqualitymicrophonesandconnectionsbetweenequipment.-XLRplugsandsocketsareusedmostlyinprofessionalaudioandvideoelectronicscablingapplications.HomeaudioandvideoelectronicsnormallyuseRCAconnectors.APintroduction•AP1PanelAPintroduction•THD+NvsLevelCurveAPintroduction•AnalyzerPanelAPintroduction•SweepDefinitionsPanelAPintroduction•FrequencyResponse-FrequencyResponsemeasurementsaremadebysteppingorsweepingasinewaveoscillator,atafixedamplitude,acrossthespectrumofinterest.-UsuallystatedintermsofdBvariationfromsomereferencemidbandfrequency(e.g.,1KHz).-Thetestmaybeeasilymodified.Thefrequencyrangeanddirectionofsweepcanbechangedfromthe20KHz~20HzstoredbyenteringnewvaluesforSTARTandSTOPunderSWEEP(F9)DEFINITIONSpanel.APintroduction•SignaltoNoiseRatio-Signaltonoiseratio,asarelativemeasurement,mustbemadewithreferencetoaspecificoutputamplitudefromthedeviceundertest.-Theratedoutputamplitudemustbecalibratedasthe0dBrreferenceoftheanalyzer.Thentheresidualoutputamplitude(noise)ismeasuredandexpressedindBrelativetothereference.APintroduction•Crosstalk-Signalsfromonechannelleakingintoanotherchannel.Normally,thishappensbetweenleftandrightstereochannels.-Ageneratordrivesonechannelandthischannel'soutputvalueisnoted;meanwhiletheotherchannelissetforzerovolts.Themeasuredchannelleftopen.-Whateversignalisinducedintothetestedchannelismeasuredatitsoutputwithanrmsvoltmeterandnoted.Aratioisformedbydividingtheunwantedsignalbytheabove-notedoutputtestvalue,andtheanswerexpressedindB.APintroduction•HarmonicDistortionConcepts-Harmonicdistortionmaybemeasuredandexpressedastotalharmonicdistortion(THD),orastotalharmonicdistortionplusnoise(THD+N).-THDisthedistortionthatoccursonharmonicsoftheoriginalsignal.Noiseisthemorerandom,uncorrelateddistortion.-Inallcases,stimulusfromaverypuresinewavegeneratorisfedtotheinputofdeviceundertest.Thegeneratormusthavesignificantlylowerdistortionsthanthatofdevice.APintroduction•HarmonicDistortionConcepts-THDreferstomeasurementmethodswhichindividuallymeasuretheamplitudeofeachsignificantharmonicinanarrowbandwidth,thencombinestheminroot-mean-squarefashiontoproduceasinglenumber.-THD+N,referstothemeasurementtechniqueinwhichthefundamentalcomponentisremovedbyabandreject(norch)filterandallremainingenergymeasured,includingharmonicsandnoise.APintroduction•HarmonicDistortionConcepts-BandwidthandTHD+NThemeasuredTHD+Nofadevicewillvarywiththemeasurementbandwidth.Youwillalmostalwayswanttorestrictthemeasurementbandwidthusinghigh-passandlow-passfilters,andyoumustincludethebandwidthusedwhenyoustatetheresult.THD+Nistypicallymeasuredandreportedina20Hz20kHzbandwidth.APintroduction•HarmonicDistortionConcepts-LevelandTHD+NThemeasuredTHD+Nofadevicewillalsovarywithlevelandthefrequencyoftheappliedsignal.AudioTHD+Nistypicallymeasuredandreportedatamid-rangefrequency(1kHzorso)attheeitherthedevice'snominaloperatingleveloratitsmaximumoutputlevel(MOL).-ATHD+NversusfrequencysweeporaTHD+NversusamplitudesweepswillshowhowaDUTperformsundervaryingstimulus.THD+N•HeadphoneoutputTHD+N•THD+NvsLevelTHD+N•THD+NvsLevelTHD+N•HeadphoneoutputTHD+N•HeadphoneoutputTHD+N•HeadphoneoutputTHD+N•HeadphoneoutputThankyou!