Williams AV AMPETRONIC MLD9 System manual

MLD9
Installation Handbook
www.williamsav.com
www.ampetronic.co

Handbook Contents
• Safety
• Introduction
• Quickstart
• Installation
• Overview
• Troubleshooting
• Accessories
• Technicalspecications
• Warranty
• Declarationofconformity
Box Contents
• 1xMLD9
• 2xLoopconnector
• 1xStatusconnector
• 1xDCconnector
• 1xInstallationhandbook
• 2x2mmsteel1Urackmountbrackets
• 1xPowercable(regionsspecic)
• 1xInductionLoopSign
This symbol is used to alert the user to important
operating or maintenance instructions.
The Lightning bolt triangle is used to alert the user
to the risk of electric shock.
SAFETY
1. Itisimportanttoreadtheseinstructions,andtofollowthem.
2. Keepthisinstructionmanualinanaccessibleplace.
3. Cleanonlywithadrycloth.Cleaninguidsmayeffecttheequipment.
4. Donotblockanyventilationopenings.Installinaccordancewiththemanufacturer’s
instructions.
5. Donotinstallthisequipmentnearanyheatsourcessuchasradiators,heatingventsorother
apparatusthatproducesheat.
6. WARNING–THISAPPARATUSMUSTBEEARTHED/GROUNDED.
7. Onlypowercordswiththecorrectpowerconnectormaybeusedtomaintainsafety.Cables
incorporatingtheUK13Afusedplug,SchukowithearthingcontactsandULapproved
“groundingtype”areacceptable.Thesemustbepluggedintopoweroutletswhichprovidea
protectiveearth.
8. Referallservicingtoqualiedpersonnel.Servicingisrequiredwhentheapparatushasbeen
damagedinanyway,suchasapowersupplycordorplugisdamaged,liquidhasbeenspilled
orobjectshavefallenintotheapparatus,theapparatushasbeenexposedtoanyrainor
moisture,doesnotoperatenormallyorhasbeendropped.
9. WARNING–Toreducetheriskofreorelectricshock,donotexposethisapparatusto
rainormoisture.Theapparatusshallnotbeexposedtodrippingorsplashingandno
objectslledwithliquids,suchasvases,shallbeplacedontheapparatus.
TO PREVENT ELECTRIC SHOCK DO NOT REMOVE THE
COVER. THERE ARE NO USER SERVICEABLE PARTS
INSIDE. REFER SERVICING TO QUALIFIED PERSONNEL
Ampetronic MLD9 Installation Handbook Page 1

Introduction
TheMLD9Inductionloopdriverhasbeendesignedasahighqualitydualchannelamplierforuse
withmultiplelooporPhasedArrayloopdesigns.
AnArraySystemprovidesasolutionwhereasimplelooparoundtheroomperimeterwillnotwork.
Arraysarethestandardsolutionforbuildingswithmetalstructureorreinforcements,orforcovering
largeareas.Arrayscanalsodramaticallydecreasethe‘spill’ofthemagneticsignaloutsideofthe
room,allowinginductionloopstobeinstalledinadjacentrooms,andprovidinganimprovedlevel
ofcondentiality.Arrayscanalsobeusedtochangethewaytwoloopsinterferewitheachother,
providingwaysofsolvingeventhemostcomplexinstallationproblems.
Dependingonanumberoffactorsregardingtheinstallationoftheloopandtheset-upofthe
ampliertheMLD9canprovidecompliancewithIEC60118-4forperimeterloopareasofupto2x
1,300m2orphasedarraysystemsupto3,300m2.
Easeofinstallationandusehavebeenmajorfactorsinthedesign,combinedwithoptimised
performance,andthefreedomfromR.F.I.generation.
TheMLD9stwooutputchannelscanbeconguredwithorwithout90°ofphaseshiftbetween
thetwo,allowingtheuseofarraysystemsortwoseparateloopswiththesamesignaltherefore
doublingtheareacoverage.
TheMLD9hastwobalancedinputs.Thesecanbeconguredformicrophoneorlineinputswith
individuallyselectablephantomandgainboost.
Formorecomplexinstallations,youmayneedancillaryequipmentsuchasmicrophonepre-
amplier(s),adaptor(s)forusewith100Vline,orsignalprocessingunits.SeeAccessoriesor
contactAmpetronicforadvice.
QUICK START
Forthosewhohaveagoodappreciationofloopsystems,thefollowingisaveryquickguideto
settinguptheamplier:Allyouneedisanacpowersource,asignalsourceandaPhasedArray
looppair.See‘DesigningInductionLoops’handbook(supplied)orcontactAmpetronicforadvice.
Installation
a.Turnallcontrolsfullyanti-clockwise.
b.Connectloopcables.
c.Connectsignalinput(s).
d.Connectpower.Seepoints6and7inSAFETYsection.
e.Ifrackmountedremoveallrubberfeetfromunits.DONOTre-tthefeetxingscrewsasthis
maycausedamageandinvalidatethewarranty
Operation
1. SwitchON–check‘earsymbol’ashesduringselftestandilluminatescontinuouslywhen
checksarecomplete.
2. ApplyinputsignalandincreasetheinputcontroluntiltwogreenCOMPRESSIONLEDsare
illuminatedonthepeaksofthesignal.
3. Selectphaseshiftrequired0or90°.
4. AdjusttheCURRENTcontrolsuntiltheCURRENTLEDsilluminatetoachievethedesired
peakcurrents.
5. Repeatstep2foranyotherinputsused.
6. Listentothemagneticeldproducedinsidetheloopareausingareceivingdevice(e.g.
AmpetronicILR3),orexaminetheperformanceinmoredetailwithaeldstrengthmeter.
7. AdjustMLCcontroltoachieveaatfrequencyresponse.
Ampetronic MLD9 Installation HandbookPage 2

CONNECTIONS
Inputs
Screen
- (Signal cold)
+ (Signal hot)
Connection of balanced
male XLR
1- 1+
2+ 2-
1- 1+
2+ 2-
LOOP
1-
2-
1+
2+
Outputs
Screen
- (Signal cold)
+ (Signal hot)
Connection of balanced
male XLR
1- 1+
2+ 2-
1- 1+
2+ 2-
LOOP
1-
2-
1+
2+
Screen
- (Signal cold)
+ (Signal hot)
Connection of balanced
male XLR
1- 1+
2+ 2-
1- 1+
2+ 2-
LOOP
1-
2-
1+
2+
1=TwistedPair,2=QuadCore
Refertotechnicalspecicationsforconnectiondetails
BLOCK DIAGRAM
Ampetronic MLD9 Installation Handbook Page 3

INSTALLATION
Location
Theunitmaybefreestandingor19”rackmountableusingtherack‘ears’supplied.Fittingofthe
‘ears’isachievedbyremovingthethreeforwardmostscrewsonbothsides.Thesamescrews
arethenre-usedtosecurethe‘ears’inplace.(APH2screwdriverwillberequired).For19”rack
mountingthefourrubberfeetmustberemoved.
Thelocationmustprovideadequateventilationfortheunit.
Internalfansprovideforcedventilationusingairventsatthefront(intake)andrear(exhaust)ofthe
unit.Theseventsmustbeunobstructedforsatisfactorycooling.Iftheunitisinstalledinanenclosed
environment,sufcientairowintotheenclosuremustbeprovidedthroughvents,fansorother
means,suchthattheunitsexhaustairisnotrecycledtotheinlet-causingareductioninoutput
currentorOVERHEATLEDtobeilluminated.
ContactAmpetronicforadviceoncoolingrequirementsforyourinstallation.
Tools and Equipment
Smallhandtoolsincludingawirestripperandasmallatbladescrewdriverwillberequired.
AnILR3loopreceiveroramagneticeldstrengthmeterisvitaltocheckthattheloopsystemis
providingthedesiredlevelofperformance.
Apairofstereoheadphoneswitha3.5mmjackplugconnectionisalsousefultomonitortheloop
signal.
System Requirements
Theinductionloopcablesshouldbealreadyinstalledaccordingtothe‘DesigningInductionLoops’
handbook,orasperspecicdesigninstructionsprovidedbyAmpetronic.Asaresult,atarget
currentshouldbeknown,basedonachievingacceptableeldstrengthacrosstheareatobe
covered.
Inordertoachievecorrectoperationitisrecommendedtheloopandfeedresistanceshouldbe
between0.5and3Ω(atDC).ValuesoutsidethismaycausetheLOOPERRORLEDtoilluminate
andtheampliersoutputtobedisabled.Loopandfeedimpedance(at1.6KHz)shouldbelessthan
thevoltagecapabilityofthedriverdividedbythetargetcurrentrequiredtoachieveeldstrength.
ValuesabovethisguremaycausetheCLIPLEDtoilluminate.Seetroubleshootingsectionfor
adviceonhowtocorrectthisandgetyoursystemworking.
The‘DesigningInductionLoops’handbookcontainsmoredetailsonloopandfeedcables.The
correctdesignandpositioningoftheactualloopisvitalforsatisfactorysystemperformance.Ifin
doubtconsultAmpetronicforadvice.
CONNECTION & SET-UP
ItisadvisedthattheloopsystemisinitiallysetupusingalocalaudiosourcesuchasaCDplayer,
whichisnotconnectedintoanyothersystem.Thisavoidsthecomplicationofgroundloopsand
feedbacketc,whilsttheunitissetup.
Thefollowingproceduredescribestheinstallationofastand-aloneMLD9,anddoesnotincorporate
connectionofotherancillaryunitssuchasmicrophonepre-amps,mixingdesks,orsignal
processingunits.
1. Turnallcontrolsfullyanti-clockwise.
2. ConnectthefeedcablesfromtheloopsintotheNL4loop
connectorssuppliedasshown:

Screen
- (Signal cold)
+ (Signal hot)
Connection of balanced
male XLR
1- 1+
2+ 2-
1- 1+
2+ 2-
LOOP
1-
2-
1+
2+
Ampetronic MLD9 Installation HandbookPage 4

Note: To avoid unwanted stray magnetic elds the feed cable should be tightly twisted or star-
quad connected.
3. Connectthesignalinputsappropriately:
Microphones:Suitabledynamicorcondensermicrophonewithbalancedcablefeed.Select
phantompowerasrequired.ConnecttoINPUT1andINPUT2(withselectorswitchesinthe
appropriateposition)usinga3-poleXLRplugwiredasperConnectionsdrawing.
Linelevelsignals:FromotheraudioequipmentsuchasPAsystem,mixingdeskorCDplayer.
ConnecttoINPUT1andINPUT2(withselectorswitchesintheappropriateposition)usinga
3-poleXLRplugwiredasperConnectionsdrawing.Youmayuseeitherorbothinputs.
Donotruninputandoutputcablesclosetogether
4. ConnectACpowertotheMLD9.Seepoints6and7inSafetysection.
5. SwitchON.The‘ear’symbolwillashforafewsecondswhilstaninternalself-testisperformed
andtheloopresistanceistested.Ifbothtestsaresuccessful,the‘ear’symbolwillilluminate
continuouslyandtheunitwillbeinanoperationalmode.Ifthe‘ear’symbolcontinuestoash,or
oneorbothLOOPLEDsilluminate,consulttheTroubleshootingsection.
6. Selectoneinputandapplyasuitableaudiosignal(ideallyaCDplayerwithmusicorcontinuous
speechappliedtooneinput,withnoconnectiontotheother).Turntheassociatedinputcontrol
clockwiseuntiltwoCOMPRESSIONLEDsareilluminatedonthepeaksofthesignal.
7. TurnCHACURRENTcontrolclockwiseuntilthetargetcurrentisachieved–asindicatedby
theCHACURRENTLEDs.NotethatconsecutiveLEDsilluminateat3dBintervals.TurnCH
BCURRENTcontrolclockwiseuntilthetargetcurrentisachieved–asindicatedbytheCHB
CURRENTLEDs.HeadphonescanbeusedwiththeMONITORsockettolistendirectlytothe
loopcurrent.NOTE:channelAoutputappearsintheleftheadphoneandchannelBintheright.
Ifhighfrequencyoscillationorlowfrequencyhumisexperienced,consulttheTroubleshooting
section.
8. Theloopsystemshouldnowbeprovidingamagneticeldinsidetheareaoftheloop–usethe
ILR3oreldstrengthmetertoexamineitsperformancewithrespectto:
 a) Magneticeldstrength.Thismayvaryacrossthecoverageduetolayout,metallossand
   loopcurrent.
 b) Frequencyresponse.Metallossestendtoincreasewithfrequency,andmayrequirethe
   adjustmentoftheMLCcontrol.
  Asaresultofthisanalysis,adjusttheCURRENTandsettheMLCtoachievethebestsound
  quality.Thisshouldresultinadequatemagneticeldstrengthandalevelfrequency
  responseinordertosatisfyIEC60118-4.Note:DoNOTadjusttheMLCcontrolwhilst
  listeningtotheMONITORsocketasthiswillnotgiveatrueindicationoftheresponseofthe
  actualloop.
  OncetheCURRENTandMLCcontrolshavebeenadjustedtothecorrectleveltheyshould
  NOTneedre-adjusting.
9. Ifnotalreadydoneso,stepscannowbetakentointegratetheMLD9intoaPA/mixer
arrangementfollowingstandardaudiotechniques.Ifanyunusualeffectsareexperiencedreferto
theTroubleshootingsection.
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.
Repeattheaboveprocedureforeachinputused.Whenadjustingeachinput,makesurethe
signalsareremovedfromtheotherinputs.Thisensuresthatallsignalsaresettoequivalent
loudnessanddrivethecompressorproperly.
Ampetronic MLD9 Installation Handbook Page 5

OVERVIEW
01
36
30
24
18
12
6
INPUT 1 INPUT 2 MLC
AGC (dB)
13.0
9.2
6.5
4.6
3.3
2.3
CURRENT (A pk)
CLIP
LOOP
CLIP
LOOP
CH BCH A TEMP
MLD9
01 01 01 01
INDUCTION LOOP DRIVER
Gain boost Phantom
Gain boost Phantom
MIC LINE MIC LINE
INPUT 2 INPUT1
OUTPUT
PHASE
Induction Loop Driver
~ 230V 45 - 65Hz
Power: 85W Fuse: T 630mA L
Designed and Engineered in the UK
Serial No
MLD9
LOOP O/P CONNECTIONS
1- 2-
1+ 2+
www.ampetronic.com
CHANNEL B
LOOP OUTPUT
CHANNEL A
LOOP OUTPUT STATUS
0.1A
+12V
DC OUTPUT
IN
SLAVE
OUT
1 2 3 45 6 7 8 9 10
01
36
30
24
18
12
6
INPUT 1 INPUT 2 MLC
AGC (dB)
13.0
9.2
6.5
4.6
3.3
2.3
CURRENT (A pk)
CLIP
LOOP
CLIP
LOOP
CH BCH A TEMP
MLD9
01 01 01 01
INDUCTION LOOP DRIVER
Gain boost Phantom
Gain boost Phantom
MIC LINE MIC LINE
INPUT 2 INPUT1
OUTPUT
PHASE
Induction Loop Driver
~ 230V 45 - 65Hz
Power: 85W Fuse: T 630mA L
Designed and Engineered in the UK
Serial No
MLD9
LOOP O/P CONNECTIONS
1- 2-
1+ 2+
www.ampetronic.com
CHANNEL B
LOOP OUTPUT
CHANNEL A
LOOP OUTPUT STATUS
0.1A
+12V
DC OUTPUT
IN
SLAVE
OUT
12 13 14
I/O:PowerSwitch.
INPUT 1 & 2:Screwdriveradjustablecontrolswhichsettheleveloftheinputsignals.
AUTOMTIC GAIN CONTROL (AGC) COMPRESSION:Showstheamountofgain
reductionindecibels(dB)thatisappliedtotheinputsignal(s).
METAL LOSS CORRECTOR (MLC):Screwdriveradjustablecontrolwhichcompensates
forthefrequencydependanteffectsofmetalintheloopedenvironment.
OUTPUT CHANNEL WARNING LEDs:‘CLIP’LEDsigniesoutputvoltageisclipping,
‘LOOP’LEDsigniesacablespecicationerrorordamage.Seetroubleshootingfordetails.
OUTPUT CHANNEL CURRENT ADJUSTMENT:Screwdriveradjustablecontrolwhichsets
thelevelofoutputcurrentdeliveredtotheloop.
OUTPUT CHANNEL CURRENT LEDs:Indicatesthepeakcurrentdeliveredtotheloop.
TEMPERATURE WARNING LED: Indicatesthattheinternalheatsinkistoohot.Loop
currentisnotdeliveredtoeitherchannel.Seetoubleshootingfordetails.
MONITOR: 3.5mmjacksocketforusewithstereoheadphonestolistentothesignalbeing
deliveredtotheloop.
POWER INDICATOR LIGHT:Flashescontinuouslywhenamplierhasfailedselftestand
isinsafemode.Seetroubleshootingfordetails.
FRONT VENT:Fanassistedventilationinletwithlter.DONOTcover.
1
2
3
4
5
6
7
8
9
10
11
Ampetronic MLD9 Installation HandbookPage 6

01
36
30
24
18
12
6
INPUT 1 INPUT 2 MLC
AGC (dB)
13.0
9.2
6.5
4.6
3.3
2.3
CURRENT (A pk)
CLIP
LOOP
CLIP
LOOP
CH BCH A TEMP
MLD9
01 01 01 01
INDUCTION LOOP DRIVER
Gain boost Phantom
Gain boost Phantom
MIC LINE MIC LINE
INPUT 2 INPUT1
OUTPUT
PHASE
Induction Loop Driver
~ 230V 45 - 65Hz
Power: 85W Fuse: T 630mA L
Designed and Engineered in the UK
Serial No
MLD9
LOOP O/P CONNECTIONS
1- 2-
1+ 2+
www.ampetronic.com
CHANNEL B
LOOP OUTPUT
CHANNEL A
LOOP OUTPUT STATUS
0.1A
+12V
DC OUTPUT
IN
SLAVE
OUT
01
36
30
24
18
12
6
INPUT 1 INPUT 2 MLC
AGC (dB)
13.0
9.2
6.5
4.6
3.3
2.3
CURRENT (A pk)
CLIP
LOOP
CLIP
LOOP
CH BCH A TEMP
MLD9
01 01 01 01
INDUCTION LOOP DRIVER
Gain boost Phantom
Gain boost Phantom
MIC LINE MIC LINE
INPUT 2 INPUT1
OUTPUT
PHASE
Induction Loop Driver
~ 230V 45 - 65Hz
Power: 85W Fuse: T 630mA L
Designed and Engineered in the UK
Serial No
MLD9
LOOP O/P CONNECTIONS
1- 2-
1+ 2+
www.ampetronic.com
CHANNEL B
LOOP OUTPUT
CHANNEL A
LOOP OUTPUT STATUS
0.1A
+12V
DC OUTPUT
IN
SLAVE
OUT
11
15 16 17 18 19 20 21 22
12
13
14
15
16
17
18
19
20
21
22
REAR VENT:Fanassistedventilationoutlet.DONOTcover.
LOOP OUTPUT(S):Neutrik‘Speakon’highcurrentconnectionstoloopcable(s).
STATUS:Connectiontorelaycontactsprovidingremotefaultindication.
DC OUTPUT:2-pinconnectionforancillaryunits.
PHASE SHIFT SELECTOR:Selectable90°phaseshiftbetweenoutputs.
SLAVE I/O: 3pole6.4mmjackinsertpointforusewithancillaries
XLR INPUTS: SocketforbalancedMICorLINEsignals.
INPUT SELECTOR SWITCH:ModeselectbetweenMICandLINEinputsignals.
INPUT GAIN BOOST SELECTOR SWITCH: Gainselector(ON=+15dB)
INPUT PHANTOM POWER SELECTOR SWITCH
AC POWER: Standard3-poleIEC320connectorcontainingprimaryfusefortheunit.
Ampetronic MLD9 Installation Handbook Page 7

TROUBLESHOOTING
Ear symbol not illuminated
•CheckthatthepowerswitchistoggledtotheON(I)position.
•Checkfusecontinuity.A20mmfuseisincorporatedintotheACPOWERinlet.Itisnecessary
toremovethepowercordbeforeextractingthefuseholder.Testthecontinuityofthefuse
usingamultimeter.Asparefuseisprovidedinthefuseholder.

AnyreplacementfuseMUSTbeofthesameratingandtypeasprintedontherearof
theunit.
Ear symbol flashing continuously
Amplierhasfailedselftestandisinsafemode.Signalwillnotbefedintooneorbothloops.
Switchtheunitoff,removeallconnectionsexcepttheloopandpowerconnections,turnallfront
panelcontrolstominimumandswitchbackon.Iftheproblempersists,contactAmpetronicfor
advice.
COMPRESSION LEDs not illuminating
Checkinputconnections.
Ensurethattheappropriatefrontpanelcontrol(INPUT1orINPUT2)isturnedup.Checkthereis
sufcientsignallevelfortherequiredinput.
CURRENT LEDs not illuminating
Therearemanypossiblecausesforthis:
•ChecktheCOMPRESSIONLEDsareilluminating.
•CheckthattheCURRENTcontrolsareturnedupsufciently.
•ChecktheLOOP,orTEMPLEDsarenotilluminated.
•EnsuretheEarsymbolisilluminatedandnotashing.
•Checkthattheloopcablesareconnected,terminatedcorrectlyandinsertedintotheLOOP
OUTPUTsockets.
•Checktheloopsarenotopencircuit,shortcircuit,orconnectedtoearth(seeinstabilityorhigh
frequencynoisesectionofTroubleshooting)
•Switchtheunitoffandturnbackon.
Note: You can listen to the actual loop signal by using a pair of headphones plugged into the
monitor socket. Channel A = left, channel B = right.
CLIP LED(s)illuminated
Indicatesthattheoutputvoltageisclipping.Occasionallightingofthisindicatorisnormalonpeaks
ofsignal.
•TurndowntheCURRENTcontrolonthechannel(s)inquestiontoavoidcausingtheoutput
voltagetoclip.
•Checktheloopisnotopencircuit,shortcircuit,orconnectedtoearth(seeinstabilityorhigh
frequencynoisesectionofTroubleshooting)
•Checktheloopiswithinspeciedlimits.
TEMP LED illuminated
Indicatesthattheinternalheatsinkistoohot.Loopcurrentisnotdeliveredtoeitherchannel.
•Ensurethattheunitisinstalledinalocationwithsufcientventilation
Ampetronic MLD9 Installation HandbookPage 8

•Checkthatnothingisblockingthefreeowofairthroughtheventsatthefrontandbackofthe
unit.
•Checktheloopsarenotopencircuit,shortcircuit,orconnectedtoearth(seeinstabilityorhigh
frequencynoisesectionofTroubleshooting)
LOOP LED(s)illuminated
Indicatestheloopcablesconnectedtotheunitareoutsidetheloopresistancetestlimits(see
technicalspecications).IfthesevaluesareexceededtheLOOPLED(s)willilluminateandthe
amplieroutput(s)willbedisabled.
Important: Once the cause of any loop error has been established the unit will need to be restarted.
Turn the power OFF - wait 5 seconds, and switch ON.
•Checkthattheloopcablesareconnected,terminatedcorrectlyandinsertedintotheLOOP
OUTPUTsockets.Restarttheamplierasabove.
•EnsuretheDCresistanceisbetweentheupperandlowerloopresistancetestlimits(see
technicalspecications).
Note: Meter leads can easily measure 0.2Ω, and should be factored out.
•Ifeitherloopisopencircuit-itmayhavebeencutsomewhereandwillrequireinvestigation
andpotentiallyre-laying.
•Ifeitherloopishighresistance>5Ω-checkallconnectionsandre-tighten,theremaybe
somethingloose.
•Checkforshortcircuitsintheloopconnectors.
•Ifeitherloophasverylowresistance,useanappropriatelengthofcabletoensuretheloop
resistanceisgreaterthanthelowerloopresistancetestlimit(seetechnicalspecications).
Note: High or low resistance loops can be encountered in a venue with a pre-installed loop, which
was designed for use with an old loop driver which might be being replaced. Before using this loop
ensure that the existing loop will allow the system to perform to an acceptable level by checking it’s
layout details in the ‘Designing Induction loops’ handbook.
Low magnetic field strength
DuetoinsufcientCURRENTorexcessivemetalloss.
Mayrequireaspecialloopdesigntoachieveacceptableperformance,contactAmpetronicfor
advice.
Instabilityorhighfrequencynoise
1. Itispossiblefortheloopcablestobegroundedunderfaultconditions,resultingininstability
whichmaysoundlikehighfrequencynoise,buzzorwhistling.Theresultsofthistypeoffault
areunpredictableandmayappearasanycombinationofthefrontpanelindicationerrors
2. Thisfaultiseasytodetermine.Simplyunplugtheloopcablesfromtheamplierandtest
witharesistancemeterbetweeneitheroftheloopwiresandagoodearthpointsuchasa
metalradiator.Thereshouldbeaninnitelyhighreadingi.e.noconnectionatall.Anyreading
indicatesafailureoftheloopcableinsulationandyouwillneedtoeitherrepairorreplacethe
loopcable.
3. Instabilitycanbecausedbyusingpoorqualitysignalcables,longunbalanced(2-wire)
signalrunstotheinputs,orbyrunninginputcablesincloseproximitywiththeloopwireover
anappreciabledistance.Loopampliersarecapableofdeliveringhighcurrentsataudio
frequencies.Iftheloopcablesarerunclosetosensitivesignalcablesitmaybepossibleto
induceasignalbackintotheinputoftheampliercausingfeedback.Cablerunsandloop
Ampetronic MLD9 Installation Handbook Page 9

wiresshouldbekeptwellapartfromeachother.Toavoidinterferencemaintainaseparation
ofatleast300mm.
4. InstabilitycancausetheampliertorunhotandmayresultintheTEMPLEDilluminating.
Interference
1. Backgroundmagneticeldsignalsorinterferencemaybepresentinanylocationandmaynot
beanythingtodowiththeloopsystem.Monitorthiswithaloopreceiver(suchasanILR3).If
theinterferenceisstillpresentwiththeloopsystemswitchedoff,thenyouneedtolocateand
eliminatethesourceoftheinterferencebeforeswitchingtheloopsystembackon
2. Magneticeldscaninducecurrentsintoanylowimpedanceelectricalpathorloop.Audioor
videosystemswithmultipleearthsmayexperiencepickupoftheloopsignal.Checkentire
soundsystemforevidenceofloopsignal,andtracesourceofpickup.
3. Undercertaincircumstances,theloopsignalmayappearasjaggedlinesorhumbarsona
CCTVpicture.ThiscouldbeduetorunningCCTV(lowimpedanceunbalanced2-wirecircuit)
cablesincloseproximitytotheloopcable.Separatetheloopcablestoreducetheeffect.
4. Remote(andapparentlyunconnected)PAsystemscansometimespickuploopsignals.This
isusuallybecausetheloopcablebecomesdamaged(seepoint1ofInstability)orinduces
signalsintotheremotesystemthroughlongunbalancedcables.Alwaysrunlongaudiosignal
cablesas3-wirebalancedcircuitsandkeepawayfromloopcables.
5. Seealsopoint1ofInstability
Failed AC power fuse in rear of unit
UnplugtheloopandACpowersupplyfromamplier,andreplacethefailedfusewiththesparefuse
inACpowerinputfusetray.
ReconnecttheACpowersupplyandswitchon.Ifthefusefailsagain,returntheunittoAmpetronic
forevaluation-itmaywellbecoveredunderwarranty,whichwillbeinvalidatedbyremovingthe
cover.Ifthefusedoesnotfaila'looperror'maybeindicated,butshowsthattheunitisworking
correctly.Re-connecttheloopandswitchthepoweroffthenonagaintoresetlooperror.
Ifthefusefailswhentheloopisre-connectedtotheunit,thentheloopcouldbeshortedto
electricalmains(andbuilding)earth.Thiscanhappenevenifnoaudiosignalispresent,asthe
shorttoearthislikelytocauseaninstability/oscillation/feedbackconditiontodevelop.Aloop
cableshorttoearthmostcommonlyoccurswhereatcoppertapeisinstalledonametal-clad
raisedaccessooringsystem.Iftheinsulationontheatcoppertapeisabraded(forexamplebya
pieceofmetalswarftrappedbelowthecoppertape),theconductorcouldshorttotheearthedtiles.
Wheninstallingonraisedaccessoors,itisadvisabletoinsulatebeneaththeatcoppertape
installationusingAmpetronicPWTorsimilartape.
Theloopshorttoearthmayonlybecompletedwhenapersonstepsonthetapeintheaffected
location,whichcancreatesignicantdifcultieswhendiagnosingthecauseoffusefailure.Contact
Ampetronicforfurtheradviceifaunitissufferingrecurringbutuntraceablefailureoftherearpanel
fuse.
ACCESSORIES
DetailsofallproductsandservicesprovidedbyAmpetroniccanbefoundatwww.ampetronic.co
Ampetronic MLD9 Installation HandbookPage 10

Technical Specifications
INPUTS AND PROCESSING MIC Line UNITS
Inputguresquotedatmaximumfrontpanelgaincontrolsetting. Low gain High gain Low gain High gain
INPUTS;XLRconnector.Balanced,Suitableforupto600Ωmicrophonesorlinelevel.
Inputimpedance
Sensitivity
Overload
Phantom(via680Ωsource)
8700
-62
-24
12
8700
-77
-39
12
8700
-37
+1
-
8700
-52
-14
-
Ω
dBu
dBu
Vdc
AGC;CompressionofsignalindBshownonsixfrontpanelLEDs
Inputrange
Outputrange
Min.inputlevelforAGC
Attacktime
Decaytime
>36
±1
Dependsoninputmodeused(seesensitivity)
8
2
dB
dB
ms
s
METAL LOSS CORRECTION; Speciallydesignedadjustableltertocompensatefor
theeffectsofmetalloss.Gain@1kHzremainsconstant
Min.slope
Max.slope
0
+3
dB/oct.
dB/oct.
PHASE SHIFT; Theloopoutputscanbeconguredforphasedarraysystemsby
selectingtheappropriaterearpanelswitchoption.Phaseshiftbetweenoutputs:
Phaseshiftoff
Phaseshifton
0
90
°
°
SLAVE IN; 6.35mmjack.Inputforlinkingmorethanoneamplier.Insertingplug
disablesotherinputs.
Inputimpedance/channel
Inputlevel/channel
MLD9 MLD9 MLD9 UNITS
N/A
N/A
N/A
N/A
Ω
Vpk
100k
1.5
OUTPUTS MLD5 MLD7 MLD9 UNITS
SLAVE OUT; Processedaudiosignaloutput.PostAGC,MLCandPhaseshift.For
linkingtoanotheramplier.
Sourceimpedance/channel
Outputlevel/channel
N/A
N/A
N/A
N/A
220
1.5
Ω
Vpk
LOOP OUTPUT;(perchannel);NL4speakon.1perchannel.
Voltagepeak/RMS
Currentpeak/RMSintosingleturnloop.
Absolutemaximumshorttermpeakcurrent.
THD+N(@1kHzfulloutput)
Outputimpedance
Frequencyresponse(±1.5dBnoAGC)
OutputcurrentindicatedviasixfrontpanelLEDs(perchannel)at3dBintervals.
BipolarPPMstylecircuit
Attack
decay
14.5/10
7/5
>10
<0.2
22
100to5000
4.7
1
24/17
9/6.4
>13
<0.2
22
100to5000
4.7
1
45/32
13/9.2
>19
<0.2
24
100to5000
4.7
1
V
A
A
%
Ω
Hz
ms
s
STATUS SOCKET;2pin5mmpitch90°header.Thestatussocketconsistsofapair
ofisolatedcontacts.
Amplierorloadfault
AmplierandloadOK
Contactrating
Dielectricstrength(coil–contact)
Open
Closed
DC2A,28V,60W
AC0.5A,125V,60VA
1000Vac50/60Hz
DC POWER SOCKET; 2pin5mmpitch90°header.TheDCPOWERsocketisused
topoweravarietyofAmpetronicaccessories.
Outputvoltage
Outputcurrent(max.)
12
0.1
12
0.1
12
0.1
V
A
PROTECTION FEATURES MLD5 MLD7 MLD9 UNITS
CLIPPING;ClippingofeitheroutputisshownonthefrontpanelCLIPLEDs.Ifclipping
persistsamplierwillshutdownandrestart.
Clipthreshold(%ofpeakoutputvoltage) 93 93 93 %
OUTPUT DC OFFSET;IfDCoffsetisdetectedamplierwillshutdownandrestart
Threshold ±0.7 ±0.7 ±0.7 Vdc
TEMPERATURE; Internalheatsinksaremonitored.Iftemperaturereachessetlimits
theoutputcurrentisreducedandeventuallymuted.MLD9&9haveseparateinde-
pendentsystemsforeachchannel,MLD9hasasinglecontrolforbothchannels.
Outputcurrentreduction(3dBmax)
Outputmute(illuminatesTEMPLED)
Any of the above faults also cause the status relay contacts to open.
Commences88,max@92
92(outputreturnsatapprox.60)
°C
°C
LOOP RESISTANCE TESTING;Checkstheresistanceoftheloadonstartup(The
POWERLEDashesduringthisperiod)andonlyallowsoperationifwithinlimits.The
LOOPLEDsareilluminatedifloadsareoutsidelimits
Startuptime
Lowerlimit
Upperlimit
Upperlimit(linkremoved)
8approx.
0.3
5
Nolimit
8approx.
0.3
5
Nolimit
8approx.
0.5
5
Nolimit
s
Ω
Ω
OUTPUTS
SLAVE IN; 6.35mmjack.Inputforlinkingmorethanoneamplier.Insertingplug
disablesotherinputs.
Inputimpedance/channel
Inputlevel/channel
MLD5 MLD7 MLD9 UNITS
N/A
N/A
N/A
N/A
100
1.5
kΩ
Vpk
Ampetronic MLD9 Installation Handbook Page 11

PROTECTION FEATURES CONTINUED MLD5 MLD7 MLD9 UNITS
CURRENT LIMIT; 15 22 22 Apk
COOLING;internalvariablespeedfan(s).Intakeonfront,exhaustonrearpanel
No.offans
Fannoise(@1mnoload)
Fannoise(@1mEN600625testsignalmax
ratedcurrent)
1
33
<47
2
33
<47
2
33
<47
dBA
dBA
POWER REQUIREMENTS & PHYSICAL MLD5 MLD7 MLD9 UNITS
Standard IEC inlet
Mainssupplyvoltage
Frequency
230(115)
45-65
230(115)
45-65
230(115)
45-65
Vac
Hz
Power (EN60065testsignalmaxratedcurrent) 80 160 220 W
Fuse T630mAL
(T1.25AL)
T1.6AL
(T3.15AL)
T2.5AL
(T5AL) A
Inrush Current 16 27 40 Apk
Weight 3.75 4.77 6.35 Kg
Dimensions;
Width
Height
Depth
430
44
220
430
44
250
430
44
330
mm
mm
mm
ENVIRONMENTAL;
IngressProtection
Operatingtemperaturerange
Relativehumidity
IP20
0-35
20-90
IP20
0-35
20-90
IP20
0-35
20-90
°C
%
WARRANTY
ThisproductcarriesaveyearpartsandlabourwarrantyfromdateofshipmentfromAmpetronic.
Toqualifyfortheveyearwarranty,theproductmustberegisteredatwww.ampetronic.co(products/
warranty),withoutwhichthewarrantywillbevalidfortwoyearsonly.
Thewarrantycouldbeinvalidatediftheinstructionsinthishandbookarenotfollowedcorrectly,orif
theunitismisusedinanyway.
DECLARATION OF CONFORMITY
Manufacturer: AmpetronicLtd.
   Unit2,TrentsideBusinessVillage,FarndonRoad,Newark,Nottinghamshire,
   NG244XB,UnitedKingdom.
Declaresthattheproduct:
Description: InductionLoopDriver
Typename: MLD9
ConformstothefollowingDirective(s)andNorm(s):
 Directive 2004/108/EC
 EMC:  EN55103-1:2009Emission
   EN55103-2:2009Immunity
 Directive 2006/95/EC
 Safety: EN60065:2002+A12:2011
 Directive 2011/65/EU RoHS
Date:  May2013
J.R.Pieters
ManagingDirector,
AmpetronicLtd.
Ampetronic MLD9 Installation Handbook
Page 12

INSTALLATION NOTES:
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Ampetronic MLD9 Installation Handbook Page 13

Contents Copyright © Ampetronic Ltd 2013. All rights reserved.
UP17801-9