30ElectrostaticHistory
Inthelate1800’s,anyloudspeakerwasconsideredexotic.Today,
mostofustakethewondersofsoundreproductionforgranted.
It was 1880 before Thomas Edison had invented the
first phonograph. This was a horn-loaded diaphragm
thatwasexcitedbyaplaybackstylus.In1898,SirOliver
Lodgeinventedaconeloudspeaker,whichhereferredto
asa“bellowingtelephone”,thatwasverysimilartothecon-
ventionalcone loudspeaker drivers that weknow today.
However,Lodgehadnointentionforhisdevicetoreproduce
musicbecausein1898therewasnowaytoamplifyanelec-
tricalsignal!Asaresult,hisspeakerhad
nothingtoofferovertheacousticalgram-
ophonesoftheperiod.Itwasnotuntil
1906thatDr.LeeDeForrestinvented
thetriodevacuumtube.Beforethis,an
electricalsignalcouldnotbeamplified.
Theloudspeaker,asweknowittoday,
shouldhaveensuedthen,butitdidnot.
Amazingly,itwasalmosttwentyyears
beforethiswouldoccur.
In 1921, theelectrically cut phonograph record became
areality.Thismethodofrecordingwasfarsuperiortothe
mechanicallycutrecordandpossessedalmost30dBofdynamic
range.Theacousticalgramophonecouldn’tbegintoreproduce
alloftheinformationonthisnewdisc.Asaresult,further
developmentsinloudspeakerswereneededtocopewiththis
amazingnewrecordingmedium.
By1923,thedecisionwasmadetodevelopacompletemusical
playbacksystemconsistingofanelectronicphonographandaloud-
speakertotake
advantageofthenewrecordingmedium.T
he
projecttotwoyoungengineers,C.W.RiceandE.W.Kellogg.
RiceandKellogghadawellequippedlaboratoryattheirdispos-
al.Thislabpossessedavacuumtubeamplifierwith
anunheard
of200watts,alargeselectionofthenew
electricallycutpho-
nographrecordsandavarietyofloudspeakerprototypesthat
hadbeencollectingover
thepastdecade.Amongthesewere
Lodge’scone,aspeaker
thatusedcompressedair,acoronadis-
charge(plasma)speaker,andanelectrostaticspeaker.
Afterashorttime,RiceandKellogghadnarrowedthefieldof
“contestants”downtotheconeandtheelectrostat.Theout-
comewoulddictatethewaythatfuturegenerationswouldrefer
toloudspeakersasbeingeither“conventional”or“exotic”.
Theirelectrostatwassomethingtobehold.Thisenormousbipo-
larspeakerwasasbigasadoor.Thediaphragm,whichwas
beginningtorot,wasmadeofapigintestinethatwascovered
withfinegoldleaftoconducttheaudiosignal.
WhenRiceandKelloggbeganplayingthenewelectrically
cutrecordsthroughtheelectrostat,theywerestunnedand
impressed.Theelectrostatperformedsplendidly.Theyhad
neverheardinstrumentaltimbresreproducedwithsuchrealism.
Thissystemsoundedlikerealmusicratherthanthehonking,
squawkingrenditionoftheacousticgramophone.Immediately,
theyknewtheywereontosomethingbig.Theacousticgramo-
phonewasdestinedtobecomeobsolete.
DuetoRiceandKellogg’senthusiasm,
theydevotedaconsiderableamountof
timeresearchingtheelectrostaticdesign.
However,theysoonencounteredthesame
difficultiesthatevenpresentdesignersface;
planarspeakersrequireaverylargesurface
areatoreproducethelowerfrequencies
oftheaudiospectrum.Becausetheman-
agementconsideredlargespeakers
unacceptable,Riceand
Kellogg’s
workonelectrostaticswouldneverbeputtousefora
commercialproduct.Reluctantly,theyadvised
managementto
gowiththecone.Forthenext30years,
theelectrostaticdesign
laydormant.
DuringtheGreatDepressionofthe1930’s,consumeraudio
almostdied.Thenewelectricallyamplifiedloudspeakernever
gainedacceptance,asmostpeoplecontinuedtousetheirold
Victrola-styleacousticgramophones.PriortotheendofWorld
WarII,consumeraudiosawlittle,ifany,progress.However,dur-
ingthelate1940’s,audioexperiencedagreatrebirth.Suddenly
therewastremendousinterestinaudioproducts,andwiththat,
agreatdemandforimprovedaudiocomponents.Nosoonerhad
theconebecomeestablishedthanitwaschallengedbyproducts
developedduringthisnewrebirth.
In1947,ArthurJanszen,ayoungNavalengineer,tookpart
ina
researchprojectfortheNavy.TheNavywasinterested
indevel-
opingabetterinstrumentfortestingmicrophonearrays.Thetest
instrumentneededanextremelyaccuratespeaker,butJanszen
foundthattheconespeakersofthe
periodweretoononlinear
inphaseandamplituderesponse
tomeethiscriteria.Janszen
believedthatelectrostatswereinherentlymorelinearthancones,
sohebuilta
model
usingathinplasticdiaphragmtreatedwitha
conductivecoating.ThismodelconfirmedJanszen’sbeliefs,forit
exhibitedremarkablephaseandamplitudelinearity.
Janszenwassoexcitedwith the resultsthathecontinued
researchontheelectrostaticspeakeronhisowntime.Hesoon
eleCtrostatIC hIstory
Rice and Kellogg had
narrowed the field of
“contestants down” to the
cone and the electrostat.
English