5
Numerousversionsof thecabinetwereconstructedandevaluated usingtestinstrumentsand, inparcular,
thehuman ear. Extensivebracingruns thefullinternalheightof eachside panel,acrosstheenretyofthe
crucialtoppanel, andincludes asinglefore-and-a integrangbracemuch likethesparson aship that
resultsinan exceponally quietcabinet.Spacingof thesesparsisbased onFibonacci mulples,ensuring
thatresonancecancellaonisspreadacrossa multudeoffrequencies.The resulngperformancedelivers
exceponallylowbass,repletewithweightandauthority,alongwithtremendoustransientspeed.Theulmate
performanceof Gibraltaris onlyrealizedthroughprecisecabinetformandpreciseassembly techniques.
Divide (Very Rapidly) and Conquer!
Theinput filtertopology (crossover)used inGibraltaris newand,tothe bestofour knowledge,thefastest
analogfiltereverdevisedfora sub-basssystematabout 4millisecondsrise me.Weulizeasecond-order
Besselfuncon forpreservaonofimpulse responsethatcrossesoveraslow as20Hz. Addionally, we
havea secondfilterplacedat approximately250 Hzthatgentlyremovesmidrangeandhigh frequencies
fromthe mix,but allowsformaximumspeed ofthe mainfilterwithinits operangrange.Crossoveris
tunablein 1Hzincrements.
Gainis adjustableforREL ReferenceHigh-Levelconnecon(preferred)or standardlowlevelinput fromthe
mainpreamplifier.Inhigh-levelmode,inputsignalisderivedattheendoftheamplificaonchain,producing
themostnaturalandfullexpressionofthevoiceofthemainsystem.ThisallowstheRELtoblendeffortlessly
withthe mainspeakers.Convenonallow-levelconnecon isalsosupported through rear panelRCAjacks.
Power Corrupts
Orso thesayinggoes.Actually,a lackofpoweris frequentlywhatcorrupts orlimitsthe purepistonic
performanceof asub. RELemploysanexpensive,butin ourexperience,ulmatecircuittopologyfor
Gibraltar. Alinear, ClassABpoweramplifier using6 MOSFETs forthe G-1and fourforthe G-2backedby
stateofthe artpowersupply andapowertransformerwith vastover-specificaon.Expensive?Yes,
unabashedlyso. However,it isboth thefinestand most reliable designapproachweknowof for these
virtuallymilitaryspecificaonamplifiers.Execuonis absolutelyfirstcabin includingsubtletouchessuch
asuse oftelecommunicaonsgradeprintedcircuitboards,highcurrentoutput devicesand ght
voltageregulaon.