Ampetronic MLD7 System manual

MLD5
Installation Handbook
www.ampetronic.com

Handbook Contents
• Safety
• Introduction
• Quickstart
• Installation
• Overview
• Troubleshooting
• Accessories
• Technicalspecications
• Warranty
• Declarationofconformity
Box Contents
• 1xMLD5
• 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 MLD5 Installation Handbook Page 1

Ampetronic MLD5 Installation HandbookPage 2
Introduction
TheMLD5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MLD5canprovidecompliancewithIEC60118-4forperimeterloopareasofupto2x
420m2orphasedarraysystemsupto360m2.
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MLD5s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MLD5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 MLD5 Installation Handbook Page 3
CONNECTIONS
Inputs

  
  
 
  
 
 
 
 





Outputs

  
  
 
  
 
 
 
 





BLOCK DIAGRAM
1=TwistedPair,2=QuadCore
Refertotechnicalspecicationsforconnectiondetails

  
  
 
  
 
 
 
 





INPUT 1
PHANTOM
POWER
GAIN BOOST
INPUT 1
GAIN
INPUT 2
PHANTOM
POWER
GAIN BOOST
INPUT 2
GAIN
AUTOMATIC
GAIN
CONTROL
(AGC)
METAL
LOSS
CORREC-
TION
(MLC)
MLC
LEVEL
PHASE
SHIFTER
AGC
DISPLAY
RED L.E.D.
YELLOW L.E.D.
YELLOW L.E.D.
YELLOW L.E.D.
GREEN L.E.D.
GREEN L.E.D.
PHASE
SWITCH
0/90°
CHANNEL
CURRENT
LEVEL
CHANNEL
CURRENT
LEVEL
POWER
AMPLIFIER
POWER
AMPLIFIER
CURRENT A
CURRENT B
TEMP
RED L.E.D. MONITOR
OUTPUT
YELLOW L.E.D.
GREEN L.E.D.
GREEN L.E.D.
GREEN L.E.D.
GREEN L.E.D.
GREEN L.E.D.
YELLOW L.E.D.
GREEN L.E.D.
GREEN L.E.D.
GREEN L.E.D.
GREEN L.E.D.
GREEN L.E.D.
CLIP A RED L.E.D.
LOOP A RED L.E.D.
CLIP B RED L.E.D.
LOOP B RED L.E.D.
OUTPUT

Ampetronic MLD5 Installation HandbookPage 4
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MLD5,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:


  
  
 
  
 
 
 
 






Ampetronic MLD5 Installation Handbook Page 5
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MLD5.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MLD5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 MLD5 Installation HandbookPage 6
OVERVIEW
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
Gain boost Phantom
Gain boost Phantom
MIC LINE MIC LINE
INPUT 2
INPUT1
OUTPUT
PHASE
STATUS
0.1A
+12V
LOOP OUTPUT
CHANNEL A CHANNEL B
Induction Loop Driver
AC POWER INPUT
230V
45 - 65Hz
Power: 85W
Fuse: T 630mA L
Designed and Engineered in the UK
Serial No
DC OUTPUT
MLD5
LOOP O/P CONNECTIONS
1-
2-
1+
2+
01
36
30
24
18
12
6
INPUT 1 INPUT 2 MLC
AGC (dB)
7.0
5.5
3.5
2.5
1.8
1.2
CURRENT (A pk)
CLIP
LOOP
CLIP
LOOP
CH BCH A TEMP
MLD5
01 01 01 01
INDUCTION LOOP DRIVER
www.ampetronic.com
3
4
5
6
7
8
1098
765
4
321
9
10
11
12 13 14 15 16 17
Gain boost Phantom
Gain boost Phantom
MIC LINE MIC LINE
INPUT 2 INPUT1
OUTPUT
PHASE
STATUS
0.1A
+12V
LOOP OUTPUT
CHANNEL A CHANNEL B
Induction Loop Driver
AC POWER INPUT
230V
45 - 65Hz
Power: 85W
Fuse: T 630mA L
Designed and Engineered in the UK
Serial No
DC OUTPUT
MLD5
LOOP O/P CONNECTIONS
1-
2-
1+
2+
01
36
30
24
18
12
6
INPUT 1 INPUT 2 MLC
AGC (dB)
7.0
5.5
3.5
2.5
1.8
1.2
CURRENT (A pk)
CLIP
LOOP
CLIP
LOOP
CH BCH A TEMP
MLD5
01 01 01 01
INDUCTION LOOP DRIVER
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Ampetronic MLD5 Installation Handbook Page 7
Gain boost Phantom
Gain boost Phantom
MIC LINE MIC LINE
INPUT 2 INPUT1
OUTPUT
PHASE
STATUS
0.1A
+12V
LOOP OUTPUT
CHANNEL A CHANNEL B
Induction Loop Driver
AC POWER INPUT
230V
45 - 65Hz
Power: 85W
Fuse: T 630mA L
Designed and Engineered in the UK
Serial No
DC OUTPUT
MLD5
LOOP O/P CONNECTIONS
1-
2-
1+
2+
01
36
30
24
18
12
6
INPUT 1 INPUT 2 MLC
AGC (dB)
7.0
5.5
3.5
2.5
1.8
1.2
CURRENT (A pk)
CLIP
LOOP
CLIP
LOOP
CH BCH A TEMP
MLD5
01 01 01 01
INDUCTION LOOP DRIVER
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11
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.
XLR INPUTS: SocketforbalancedMICorLINEsignals.
INPUT GAIN BOOST SELECTOR SWITCH: Gainselector(ON=+15dB)
INPUT SELECTOR SWITCH:ModeselectbetweenMICandLINEinputsignals.
INPUT PHANTOM POWER SELECTOR SWITCH
AC POWER: Standard3-poleIEC320connectorcontainingprimaryfusefortheunit.
12
13
19
18 20 21
14
15
16
17
18
19
20
21
Gain boost Phantom
Gain boost Phantom
MIC LINE MIC LINE
INPUT 2
INPUT1
OUTPUT
PHASE
STATUS
0.1A
+12V
LOOP OUTPUT
CHANNEL A CHANNEL B
Induction Loop Driver
AC POWER INPUT
230V
45 - 65Hz
Power: 85W
Fuse: T 630mA L
Designed and Engineered in the UK
Serial No
DC OUTPUT
MLD5
LOOP O/P CONNECTIONS
1-
2-
1+
2+
01
36
30
24
18
12
6
INPUT 1 INPUT 2 MLC
AGC (dB)
7.0
5.5
3.5
2.5
1.8
1.2
CURRENT (A pk)
CLIP
LOOP
CLIP
LOOP
CH BCH A TEMP
MLD5
01 01 01 01
INDUCTION LOOP DRIVER
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Ampetronic MLD5 Installation HandbookPage 8
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 MLD5 Installation Handbook Page 9
•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 MLD5 Installation HandbookPage 10
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.com

Ampetronic MLD5 Installation Handbook Page 11
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
MLD5 MLD7 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.MLD7&9haveseparateinde-
pendentsystemsforeachchannel,MLD5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

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1.6mAL
(T3.15AL)
T2.5mA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.com(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: MLD5
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 MLD5 Installation Handbook
Page 12

INSTALLATION NOTES:
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Ampetronic MLD5 Installation Handbook Page 13

Contents Copyright © Ampetronic Ltd 2013. All rights reserved.
UP17601-4