Subjective Method—If testinstrumentationisnotavailable,
properresultscanbeobtainedbasedonprogrammaterial
asfollows:
1.
Adjustvolumelevelforcomfortablelisteningandset
approximatesystembalanceusingpinknoiseorthenoise
heardbetweenstationsofanFMtuner.
2.
Listentoa recordingofa malevoicelongenoughto
becomeaccustomedtotheperformanceofthe
loud-
speakersystem.
3.Reversepolarityofthehighfrequencyloudspeaker,which
willproducea changeinvoicecharacter.
Whenthetransducersareproperlyphased,a recorded
malevoiceshouldsoundnaturalandexhibitpresence(oran
"upfront"quality),ascontrastedtoanundesirable"hollow"
soundthatcanbeheardwhentransducersareoutofphase.
Note:
Ifthecrossoverfrequencyliesabove2000Hz,
"eversingpolarityofthehighfrequencycomponentwill
„reateverylittle,ifany,perceptibledifferenceinsystem
performance.The"correct"polaritywillbethatwhich
yieldsthemostnaturalqualitywitha varietyofprogram
material.
Onceproperphaseamongthetransducersofa
loud-
speakersystemhasbeendetermined,otherloudspeaker
systemsintheinstallation(assumingtheyarethesame)may
bephasedaccordingly.Ifdifferentloudspeakersystemsare
used,
establishcommonphaseamongthelowfrequency
driversandfollowtheaboveproceduresforeachsystem.
LevelControlAdjustment
Inmostinstances,manufacturersofmulti-amplified
loud-
speakersystemsprovideinstructionsforbalancinglevelsof
theindividualdriversofthesystem.Intheabsenceofformal
instructions,orinthecaseofcustomloudspeakersystems,
balancecanbeestablishedbyadjustinglevelstoachieve
ittestresponseona realtimeanalyzer,asdescribedinthe
transducerphasinginstructionsbeginningonthepreviouspage,
oronthebasisofsubjectiveevaluationoffamiliarprogram
material(or,moreaccurately,byusingpinknoiseorthenoise
betweenFMstations)asdescribedinthefollowingparagraphs.
Eachprogramchannelshouldbeadjustedindividually;
subjectiveevaluationshouldbemadewhileseatedinthe
normallisteninglocation.Ifsubjectiveanalysisistobeused,
andthepoweramplifiersareequippedwithlevelcontrols,
initiallyadjustthecontrolstoone-halfoftheirfullrotationand
thenregulateasnecessary.
Subjective Adjustment Of Bi-Ampiified Systems—The
fol-
lowingappliestoa 5231ortoeachchannelofa 5232usedin
dualchannelbi-amplification.
1.
WiththeHighFrequencyLevelcontrolat"0,"adjust
programsourcelevelforcomfortablelistening.
2.
Rotatethenetworkcontrolclockwiseuntila satisfactory
highfrequencybalancehasbeenobtainedintheprogram
material.
Ifnecessary,trimsourceoramplifierlevels.
Subjective Adjustment Of Tri-Amplified Systems—When
bothchannelsofa 5232areusedfora tri-amplified
loud-
speakersystem,itisgenerallyinstalledsothattheChannel1
levelcontrolsimultaneouslyregulatesoutputofbothmid-
rangeandhighfrequencydriversandtheChannel2 level
controlgovernsonlythehighfrequencydriver.
1.
WithbothHighFrequencyLevelcontrolsat"0,"adjustthe
sourcelevelforcomfortablelistening.
2.
RotatetheChannel1 levelcontrolclockwiseuntila satis-
factorymidrangelevelhasbeenobtainedintheprogram
material.
Ifnecessary,adjustsourceoramplifierlevels
asappropriate.
3.IncreasetheChannel2 leveluntila satisfactoryhigh
frequencybalancehasbeenobtained.Itmaybenecessary
toreadjustmidrange,sourceoramplifierlevelstoachieve
themostdesirableoverallbalanceoftheloudspeaker
system.
Oncehighfrequencyandamplifieroutputlevelshavebeen
established,readjustmentisnotgenerallyneeded.Some
methodofmarkingorlockingthepoweramplifierlevel
controlsisrecommended.
Appendix
BlankCrossoverCardAssembly
Inadditiontothestandardcrossovercards,circuitsforcross-
overfrequenciesof900Hz,1100Hz,1200Hz,1500Hz,
2000Hz,2500Hz,5000Hz,6000Hz,7000Hzand9500Hz
maybeassembledona blankcrossovercard(JBLModel
52-5120)usingstandardcomponents.Filterslopes
(12dB/octave)areidenticaltothoseofthestandardcross-
overcards.Thecircuitsaredesignedtousefiveidentical
resistorsandfiveidenticalcapacitors.Thecrossover
frequencycanbewrittenonthecardbracketandwillappear
throughthefrontpanelwindowofthenetwork.
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