Wisdom AUDIO SYSTEM CONTROLLER SC-1 - Introduction to Room Acoustics; Start With The Room; Rigid Walls

20
Introduction to Room Acoustics
WisdomAudiobelievesinequalization.Assumeforamomentthatyouhad
a“perfect”loudspeaker:assoonasyouplaceitinyourroom,itsperfectionis
gone.Infact,evengoodroomsoftenintroducedeviationsof20dBtothere-
sponseofthesystem.
Itseemsstrangetoustoworryabouttenths-of-a-decibeldifferencesbetween
onecomponentandanotherwhenthereare10-20dBproblemsrighttherein
theroomwithyou.
Atthesametime,roomequalizationisnotapanacea.Itdoesnotsolveallprob-
lems.Infact,andsomewhatparadoxically,EQworksbestwhenithastheleast
todo.Itisbestusedasthe“nishingtouch”onanotherwisegoodsystem.Un-
fortunately,mostpeopledonotunderstandthatthemostimportantcomponent
intheirsystemistheirroom.
Thismanualdoesnothavethespaceforafulldescriptionofeverythingthat
goesintocreatingexcellentroomacoustics;doingsowouldrequireatextbook
ofseveralhundredpages.Instead,wewillgiveyousomeideas,andsomerefer-
encestopursueshouldyouwanttolearnmore.
Start With the Room Therearemanymythsoatingaroundpertainingtowhata“goodroom”should
belike.Oneofthemostcommonisthatitshouldhavenon-parallelwalls.
Withoutgoingintothedetails,werecommendstayingwithrectangularrooms
whosedimensionsdonotsharecommondivisors.
Thusaroomwithdimensionsof8'by16'by20'wouldbequitepoor(sincethe
dimensionsarealldivisiblebyalengthof4',and16isalsomultipleof8).By
contrast,aroomwhosedimensionsare9'by16'by29'wouldbemuchbetter,
sincenoneofthedimensionsaremathematicallyrelatedtooneanother.
Thereareinnitevariationsonthisidea.Ifyouhavetheexibilitytochoose(or
modify)yourroomdimensionstoavoidsuchproblems,doso.Eitherway,our
roomcorrectionwillbeabighelp.
Rigid Walls Anothermyththatshouldbedispelledisthenotionthatthewalls(andceiling
andoor)oftheroomshouldbeextremelyrigidinordertoreproducegood
bass.Rigid,inexiblewallsreectenergyextremelywell;thusyouwillkeep
moreofthebassenergyintheroom.Thismuchistrue.However,thoserigid
wallswillonlyincreasetheamplitudeofthestandingwavesthatyourroom
naturallysupports.Insimpleterms,youwillhavemorebass,butitwillalsobe
more irregular,withlargerpeaksandvalleysintheresponse.
Wallsthatexabit(butdonotrattle)aremuchbetter.Coincidentally,tradition-
alAmericanresidentialconstructionstandards(sheetrockonwoodenstuds)are
notabadplacetostart.Youcandobetterstillwithprofessionalhelp,butstuds
andsheetrockarebetterthanpouredconcrete.(Ifyourlisteningroomisinthe
basement,afalsewallcaneasilybebuiltinfrontoftheconcrete.Youprobably
needsomethinglikethisforinsulationandaestheticsanyway.)
Theultimateindedicatedlisteningroomconstructioninvolvesthedesignand
constructionofoatingwalls,ceilingandoor.Thisapproachyieldstheadded