
Note: To avoid unwanted stray magnetic elds the feed cable should be tightly twisted or star-
quad connected.
3. Connectthesignalinputsappropriately:
Microphones:Suitabledynamicorcondensermicrophonewithbalancedcablefeed.Select
phantompowerasrequired.ConnecttoINPUT1andINPUT2(withselectorswitchesinthe
appropriateposition)usinga3-poleXLRplugwiredasperConnectionsdrawing.
Linelevelsignals:FromotheraudioequipmentsuchasPAsystem,mixingdeskorCDplayer.
ConnecttoINPUT1andINPUT2(withselectorswitchesintheappropriateposition)usinga
3-poleXLRplugwiredasperConnectionsdrawing.Youmayuseeitherorbothinputs.
Donotruninputandoutputcablesclosetogether
4. ConnectACpowertotheMLD9.Seepoints6and7inSafetysection.
5. SwitchON.The‘ear’symbolwillashforafewsecondswhilstaninternalself-testisperformed
andtheloopresistanceistested.Ifbothtestsaresuccessful,the‘ear’symbolwillilluminate
continuouslyandtheunitwillbeinanoperationalmode.Ifthe‘ear’symbolcontinuestoash,or
oneorbothLOOPLEDsilluminate,consulttheTroubleshootingsection.
6. Selectoneinputandapplyasuitableaudiosignal(ideallyaCDplayerwithmusicorcontinuous
speechappliedtooneinput,withnoconnectiontotheother).Turntheassociatedinputcontrol
clockwiseuntiltwoCOMPRESSIONLEDsareilluminatedonthepeaksofthesignal.
7. TurnCHACURRENTcontrolclockwiseuntilthetargetcurrentisachieved–asindicatedby
theCHACURRENTLEDs.NotethatconsecutiveLEDsilluminateat3dBintervals.TurnCH
BCURRENTcontrolclockwiseuntilthetargetcurrentisachieved–asindicatedbytheCHB
CURRENTLEDs.HeadphonescanbeusedwiththeMONITORsockettolistendirectlytothe
loopcurrent.NOTE:channelAoutputappearsintheleftheadphoneandchannelBintheright.
Ifhighfrequencyoscillationorlowfrequencyhumisexperienced,consulttheTroubleshooting
section.
8. Theloopsystemshouldnowbeprovidingamagneticeldinsidetheareaoftheloop–usethe
ILR3oreldstrengthmetertoexamineitsperformancewithrespectto:
a) Magneticeldstrength.Thismayvaryacrossthecoverageduetolayout,metallossand
loopcurrent.
b) Frequencyresponse.Metallossestendtoincreasewithfrequency,andmayrequirethe
adjustmentoftheMLCcontrol.
Asaresultofthisanalysis,adjusttheCURRENTandsettheMLCtoachievethebestsound
quality.Thisshouldresultinadequatemagneticeldstrengthandalevelfrequency
responseinordertosatisfyIEC60118-4.Note:DoNOTadjusttheMLCcontrolwhilst
listeningtotheMONITORsocketasthiswillnotgiveatrueindicationoftheresponseofthe
actualloop.
OncetheCURRENTandMLCcontrolshavebeenadjustedtothecorrectleveltheyshould
NOTneedre-adjusting.
9. Ifnotalreadydoneso,stepscannowbetakentointegratetheMLD9intoaPA/mixer
arrangementfollowingstandardaudiotechniques.Ifanyunusualeffectsareexperiencedreferto
theTroubleshootingsection.
Note: Ideally, each input signal level should be set up to achieve 6dB (one LED) of
COMPRESSION with the quietest level of input likely to be used. This will maximize the dynamic
range of the system and ensure satisfactory performance.
10.
Repeattheaboveprocedureforeachinputused.Whenadjustingeachinput,makesurethe
signalsareremovedfromtheotherinputs.Thisensuresthatallsignalsaresettoequivalent
loudnessanddrivethecompressorproperly.
Ampetronic MLD9 Installation Handbook Page 5