Grimm Audio MP1 Assembly instructions

Please read this manual before operating the unit!

TPInLB

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Table of Contents
Introduction 4
ImportantSafetyInstructions 5
1.Operation 7
2.Modifyingfactorysettings 8
3.Specifications 12
4.Appendix1,Microphonevoltageslist 13
5.GrimmAudioLimitedWaranty 15

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Introduction
ThankyouforchoosingtheGrimmAudioMP1powersupplyfortubecondensor
microphones.TheMP1iseminentlyfittobeusedwithmoderntubemicrophones,
butithasbeenespeciallydesignedtoreplacethetraditional(usuallypassive)power
suppliesthatorginallycamewiththenowuniqueandverycostlytubemicrophones
fromthefiftiesandsixties.Contrarytowhatmanybelieve,theseoldpowersupplies
canbeimprovedupon,bothwithregardtostability,noiselevelandlastbutnot
leastsoundquality.Andthisisnotjustbecausetheelectrolyticsintheoldsup-
pliestendtodryout,andcarboncompositeresistorshaveshotupinvalueorgone
noisy:evenifthesehavebeenreplacedwithmoderngoodqualitycomponents,the
classicalsupplyisstillnomatchfortheMP1.

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Important Safety Instructions
Grimm Audio gaat er van uit dat u deze Engelstalige tekst volledig begrijpt. Als u hier moeite
mee heeft dient u contact op te nemen met Grimm Audio. Op verzoek sturen wij u een vertaling
toe.
Grimm Audio nimmt an, dass Sie diesen Englischen Text völlig verstehen. Wenn notwendig,
nehmen Sie bitte Kontakt auf mit Grimm Audio. Auf Wünsch wird Ihnen eine Übersetzung zu-
geschickt.
Grimm Audio suppose que le lecteur comprend parfaitement le texte en Anglais ci-dessous. En
cas de doute s.v.p. contacter Grimm Audio. Si necessaire, on pourra vous envoyer une traduc-
tion.
Grimm Audio da por supuesto que el texto en versión Inglesa no ofrece ninguna duda de in-
terpretación y se entiende integramente. Si este no fuese su caso rogamos contacte con Grimm
Audio quien, a petición, se encargaría de enviarle la correspondiente traducción.
Please follow these precautions when using this product:
1.Readtheseinstructions.
2.Keeptheseinstructions.
3.Heedallwarnings.
4.Followallinstructions.
5.Dangerousvoltageisinsidethisapparatus.Openingisonlyallowedbyqualified
servicepersonnel.
6.Verifylinevoltagebeforeuse.
7.Donotdefeatthesafetypurposeofthepolarizedorgrounding-typeplug.A
polarizedplughastwobladeswithonewiderthantheother.Agrounding-typeplug
hastwobladesandathirdgroundingprong.Thewidebladeorthethirdprongare
providedforyoursafety.Whentheprovidedplugdoesnotfitintoyouroutlet,con-
sultanelectricianforreplacementoftheobsoleteoutlet.
8.Protectthepowercordfrombeingwalkedonorpinched,particularlyatplugs,
conveniencereceptables,andthepointwheretheyexitfromtheapparatus.
9.Unplugthisapparatusduringlightningstormsorwhenunusedforlongperiods
oftime.

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10.Donotusethisapparatusnearwater.
11.Donotusethisapparatusoutside.
12.Donotexposetheapparatustodrippingorsplashing.Donotplaceobjects
filledwithliquids(flowervases,drinkcans,coffeecups,etc)ontheapparatus.
13.Cleanonlywithadry,soft,non-fluffycloth.Donotsprayanyliquidcleaneronto
thecabinet,asthismayleadtodangerousshocks.Donotsprayanyliquidcleaner
ontothefaceplate,asthismaydamagethefrontpanel.
14.Installinaccordancewiththemanufacturer’sinstructions.
15.Donotinstallnearanyheatsourcessuchasradiators,heatregisters,stoves,or
otherapparatus(includingamplifiers)thatproduceheat.Avoidexposuretodirect
sunlight.
16.Useonlyattachmentsoraccessoriesspecifiedbythemanufacturer.
17.Useonlywithacart,stand,bracket,ortabledesignedforusewithprofessional
audioormusicequipment.Inanyinstallation,makesurethatinjuryordamagewill
notresultfromcablespullingontheapparatusanditsmounting.Ifacartisused,
useprecautionwhenmovingthecart/apparatuscombinationtoavoidinjuryfrom
tip-over.
18.Thisunitrunsslightlywarmwhenoperatednormally.Operateinanormalventi-
latedarea.Ifthisproductwillbeinstalledinarack,makecertainthereissufficient
airmovementwithintherack.
19.Referallservicingtoqualifiedservicepersonnel.Servicingisrequiredwhenthe
apparatushasbeendamagedinanyway,suchaswhenthepower-supplycordor
plugisdamaged,liquidhasbeenspilledorobjectshavefallenintotheapparatus,
theapparatushasbeenexposedtorainormoisture,doesnotoperatenormally,or
hasbeendropped.
20.WARNING: Toreducetheriskoffireorelectricshock,donotexposethisappa-
ratustorainormoisture.

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1. Operation
Upondelivery,anMP1isfactorysettothetypicalsupplyvoltagesofyourmicro-
phonemodel.ThismicrophonetypeisindicatedatthebackoftheMP1.Ifthe
microphonefeaturesremotecontrolofitspolarpattern,thiscanbecontrolledwith
theoptionalknobonthefrontpaneloftheMP1.Thereisamulti-pinXLRcablecon-
nectorsuppliedwiththeMP1.Youwillneedtoattachthisconnectortoyourown
microphonecable(orletyourdealerdothat).Forwiringdata,refertothe‘specifica-
tions’chapterofthismanual.Pleasemakesureyoudoublecheckifyousoldered
therightwiretotherightXLRpin,yourmicrophonecangetdamagedifyoufailto
doso!
Ingeneral,weadvisetofirstconnectallcablesandthenturnontheMP1.Bydoing
sooneavoidspotentialdamagetotheconnectors’plating.Itisgoodtoknowthat
duetocharacteristicsofour‘shuntregulator’circuitrythepeakcurrentislimited,
whichwilllengthenyourmicrophones’tubelife.
TheMP1isdeliveredwithadetachablefoot.Thiscanberemovedbygentlytwist-
ingthefootcounterclockwise.Withoutfeet,twoMP1’scanbeconnectedtogether
toformastereo1U19”unit.AnMP1generatessomeheat.Whenusingastereoset
ofMP1’sina19”rack,itisadvisedtokeeponefreerackspacebelowandaboveto
provideoptimalcooling.
Technology
TheMP1featuresaspeciallydesigneddiscreteshunthigh-voltageregulatorfed
fromacurrentsourcetomaximisesuppressionfrommainsinducedanomalies.It
alsooffersverylownoise(typ.-96dBVor16uV20-20.000Hzunweighted).More
importantly,thisshuntsupplysoundsmorenaturalthanthemorecommonlyused
modernseriesregulators,duetotheabsenseofelectrolyticcapacitorsattheout-
put.
Itwouldhavebeenquickandeasytorelyonindustrystandardvoltageregulators
fortheheatersupply.However,inquiteafewclassicalmicstheheatervoltageis
alsousedtobiasthegridoftheamplifyingtubeinthemicrophone,implicating
anopengatewayfromheatersupplytothesensitiveinputofthemic’samplifying
stage.Wethereforechosetodesignacleanandultralownoisediscretevoltage
regulatorfortheheatersupplyaswell.Itfeaturesaverylowdrifttoensurethe
heatervoltagealwaysremainswithinspecs.
Boththehigh-voltageandtheheatersupplieshaveanextra‘crowbar’protection
circuitthatwillswitchonincaseoneofthesuppliesbreaksdown.Thisisanextra
lineofdefencetoprotectthevaluabletubeinyourmicrophone.

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2. Modifiying factory settings
YourMP1isfactorysettothesupplyvoltagesofthemicrophonespecifiedinyour
order.IncaseyouneedtoadjusttheMP1tothesupplyvoltagesofadifferent
microphone,therearevariousinternalsettingstofacilitatethis.Wehavetowarn
youhoweverthatselectingawrongvoltagewillveryprobablyleadtodamageof
the(sometimesveryexpensive)tube.Sounlessyouareanexperiencedengineeror
likelivingdangerously,wedonotadvisetochangethefactoryvoltagesettings!In
anycaseGrimmAudiocannotacceptliabilityfordamagetomicrophones.Forthose
peoplethatstillwanttochangetheinternalsettings,pleasereadthefollowingin-
structionscarefully.
Inappendix1alistcanbefoundofknownmicrophonetypeswiththeirfactory
advicedsupplyvoltages.Shouldyourmicrophonenotbelisted,pleaseconsultthe
originalmanufacturer.PleasealsocheckthisMP1manualonGrimmAudio’sweb-
site,itmighthavehadanupdateofthemicrophonelist.Threepresethighvolt-
ageareavailablefromtheMP1:120,145and210V.Thesearesetinternallyusing
jumpersandnotbyexternalcontrols,toavoidcostlymistakeswhileamicrophone
isconnected.Atrimpotallowssome(+/-8%)adjustmentofthesevoltages.TheHT
supplyisinherentlyshort-circuitproofasitisashuntsupply.Asanextrasafetya
“crowbarcircuit”willshutdownthecurrentsourceincasetheoutputvoltageex-
ceedsthenominalvaluebymorethan12%duetomalfunctioning.However,Grimm
Audiocannotacceptliabilityincaseofdamagetomicrophonesshouldeventhe
protectioncircuitfail.
Fortheheatervoltagetwopresetvaluesareavailable:6.0and3.9V.Thesevalues
arechoseninconjunctiontowhatisprescribedformostclassicalmicrophones.
Theytooaresetbyinternaljumpers.Athirdjumperpositionenablesatrimpotand
allowstheheatervoltagetobesetatanydesiredvaluebetween3.6and7.0V.In
addition,theoutputpolaritycanbereversedassomemicsrequirenegativeheater
voltage.Noiseisverylow:typ.<-120dBV(<1uV),animprovementofatleast
30dBoverindustrystandardvoltageregulators.Theoutputisshort-circuitproof,
thecurrentlimitsat0.5A.Asanextrasafetyacrowbarcircuithasbeenaddedto
protectthemicagainstunforseenfailuresshouldtheheatervoltageexceedthe
nominalvalueby10%(incaseofthevariableheatervoltagesettingasecondtrim-
potallowstheusertosetanappropriatethreshold).However,GrimmAudiocannot
acceptliabilityincaseofdamagetomicrophonesshouldeventheprotectioncircuit
fail.
Check the voltages output of your MP1
HowtheMP1isset,caneasilybemeasuredfromtheoutside:abluetestsocket
allowsthemeasurementoftheheatervoltage,aredsocketgivesaccestotheHT
dividedbij10(forsafetyreasons);ablacksocketpovidesagroundreference.These

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are2mmsocketssomultimetertestpinsfitdirectly.Pleasecheckthesevoltages
beforeconnectingthemicrophone.Markthattheheatervoltagewillmeasureap-
proximately0.1Vhigheratthissocketthanindicatedabove.Thisisonpurposeto
compensateforcablevoltageloss.
Tominimizetheriskofaccidentaldamagetomicrophonesequipedwith3.9V
tubesbypluggingtheseintoa6VMP1supply,GrimmAudiohasdecidedtodeliver
its3.9VversionwithanXLR6socketandthe6VversionwithanXLR7socket.The
factorysetvoltageisindicatedontheback.Ofcourse,ifauserchoosestochange
theinternalvoltagesettings,theXLRpincountnolongergivestherightindication!
Thisisoneofthereasonswedisencouragethechangeoffactorysettings.
TheMP1featuresarotaryswitchtoallowachoiceofpolarpatternonmicrophones
equippedwithsucharemotecontrolinput.ThecorrespondingpinontheXLR6or
XLR7microphoneconnectorcanbevariedbetween0Vandthe120or145HTvolt-
agesorbetween0VandHT+40V,dependingontheinternaljumpersetting.For
example:ifHTissetto120V,itcanbevariedbetween0and120Vor0and160
V.(The40Vover-voltageisnotavailableatthe210Vsettingastherearenomicro-
phonesthatrequirethat).
Changing the internal settings
OpeninguptheMP1andchangingitsinternalpresetsortrimmingsisbestlefttoa
trainedtechnician.Whenswitchedon,therearepotentiallydangerousvoltagesas
highas300Vinside.GrimmAudiocannotacceptanyresponsabilityfordamages
toeitherpersons,ortheMP1itself,ortoanymicrophoneconnectedbyunwittingly
chosenvoltagesorpolarities.
BeforeopeningtheMP1,switchoffthemainspowerandremovethepowercord.
Alsoremoveanyaudiocables.Wait30secondstoallowtheHTontheelectrolyt-
icstoreachasafevalue(<40V).Removethe2screwsfromonesideofthecover
aswellasthe2screwoppositeofthemontheotherside.Carefullyslidethecover
backwards,awayfromthewoodenfront.Theelectronicswillthenbecomevisible.
Anoverviewofsettingandtrimpotsofthepcbisgiveninfig.1onthenextpage.
High Tension (HT) settings
Jumpers7to10settheHT(highvoltagetothemicrophone)to120,145or210V.
Thejunperontheleft-handrowsetsthevoltage,thejumperontheright-handrow
setsthecrowbarprotection.Theyshouldalwaysbechangedinpairs:bothinthe
120Vposition,orbothinthe145Vposition,orbothinthe210Vposition.Failure
todosomayshuttheMP1down,orincriminatecorrectprotectionagainstover-
voltage.

10
Inaddition,J4mustbesettotheupperpositionwhen210VHTischosen.(Failure
todosowillstilloutput210Vbuttheshuntsupplywillnotbeabletofunctionop-
timally,possiblydegradingsoundquality).
ChoosethelowerpositionforJ4ifyouwantawiderrangeof0-160Vavailablefor
polarpatterncontrolinthe120VHTcase.Thiswillalsoworkforthe145VHT,
resultingina0-184Vvariablevoltage,althoughnomicrophoneisknowntousthat
needsthissetting.
ThetrimpotallowssomeadjustmentoftheHToutputvoltage.Thecrowbarprotec-
tionthresholdsremainfixed.Trimmingtheoutputvoltageclosetothetreshold
valuesisnotrecommendedasthisincreasestheriskofill-triggeredshutdown.
ToresetacrowbaractionitsufficestoswitchoftheMP1,waitafewsecondsand
switchonagain.
Heater Voltage Settings
Thejumperssettingtheheatervoltagearelocatedtotherightinfig.1.
FirsttakealookatthetwojumpersJ2&J3intheright-handtopcorner.Theyset
theheatervoltage’soutputpolarity:||ispositive.Changetheirorientationby90
degrees:==isnegative.Checkwiththered(plus)probeofthemultimeterinserted
intothebluetestsocket(nomicconnectedyet!).
 Fig1.VoltageadjustmentjumpersinsidetheMP1.

11
Lowerinfig.1tworowsofheaders,andtwotrimpotscanbeseen.Theright-hand
rowsetsthevoltages,theleft-handrowchangestheaccordingcrowbarprotection
levels.Again,thejumpersinbothrowsmustbemovedinunison,failuretodoso
mayshuttheMP1down,orincriminatecorrectprotectionagainstover-voltage.Both
jumpersaresettotheupperpositionif6,0Vheatervoltageisdesired.Inthelower
positiontheMP1delivers3.9Vheatervoltage;thevalueisintentionallychosenas
deviatingfromthenominal4.0VfoundinthedatasheetoftheAC701(+/-0.2Vis
allowed),asmanymanufacturersspecifyaslightlylowervalueforlongertubelife
orforthesubtlechangeinmicsoundreportedbysomeusers.However,iflongmic
cableswiththinwiresarebeingused,thevoltageatthemicendofthecablemay
belowerthandesired,soiftheexactvalueisconsideredcriticaltheactualresult-
ingvalueshouldbemeasuredatthemicrophoneitself.Normaltubemicrophone
cablesof10metertypicallyshowa0.1Vlossatthemicrophone.Atthefactory,the
voltagesarethereforesettoslightlyabove6.1and4.0Vrespectively,whichcanbe
measuredatthemultimetersocketsonthebackoftheunit.
Withthejumpersinthemidpositionbothtrimpotsbecomeactive.Thisallowsto
setanydesiredheatervoltagebetween3.6and7.0V.Onecanusethisfortubemi-
crophoneswithunusualheatervoltagerequirements,orincaseofverylongcables
toadjusttheheatervoltageatthemicrophonetoanexactvalue(e.g.5.8Vor3.8
V).Thebestprocedureisasfollows.Firstdisconnectthemiccable.Decidewhat
thevoltageVxshouldbewhichwouldsetoffthecrowbarprotection(asarule10%
higherthanthedesiredworkingvoltage).Turntheprotectiontrim(left-handone)
totallyanti-clockwiseuntilsoftclicksareheard.SwitchtheMP1on(nomicconnect-
ed!).Adjusttheright-handtrimuntilVx+10%isreachedatthebluetestsocket;
anti-clockwisewillincreasethevoltage.Nowslowlyturntheprotectiontrimclock-
wiseuntilthecrowbarstepsin:aredledwillglow.Backtothevoltagetrim(R-H)
again:do10clockwisehalf-turns(5fullrotations)tolowerthesettingofVout.Re-
settheMP1byswitchingitoff,andafterafewsecondsonagain.NowtrimVoutto
thewantedVx(doNOTtouchtheprotectiontrimanymore)andmakesureyouhave
settherightHTaswell.SwitchtheMP1offagain,connectthemicrophone,switch
on.Ifdesiredmeasuretheheatervoltageatthemicrophoneandmakefurthersmall
adustmentsifnecessary.Thismakessenseforinstanceifoneuseslongercables
orcableswithoutathickerheaterwiring.Theheatervoltagecanbeadjustedtoan
exacttargetvaluebymeasuringthevoltageinthetubemicrophoneitself.Needless
tosaythisadjustmentisbetterlefttoatrainedtechnician.

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3. Specifications
HighTensionvoltage:adjustable120/145/210V,with8%trim.
VariableHighTensionvoltageforremotepolarpatterncontrol:HT+0V/HT+40V.
Heatervoltage:adjustable6.0/3.9/3.6-7V
Voltagesfactorypresetformicrophonetype,indicatedontheback.4Vheatersup-
plyMP1’sarefactoryshippedwitha6pinXLR,6VheatersupplyMP1’sarefactory
shippedwitha7pinXLR.
Maximumambienttemperatureforoperation:40°C.
Lifeexpectancypowersupplyelectrolytics>45.000hours.
Powersupplyvoltagerange+6%/-10%
Fuses:
120V(USA): fuse500mA-T
100V(Japan):fuse500mA-T
230V(EU): fuse250mA-T
Weight:2.3kg
Dimensions:215x175x44mm
Powerconsumption:20W
Woodtypeoffront:Cherry
XLRpinning(ofboth6and7pinXLR’s):
Pin1:GND
Pin2:Audio+
Pin3:Audio–
Pin4:Heater
Pin5:HighTension
Pin6:VariableHT(forremotepolarpatterncontrol)
TheXLRaudiooutputisinternallyhardwiredtothecorrespondingpinsofthe
multi-pinXLR.

13
4. Appendix 1, Microphone voltages list
AKG
C12,C12VR:120V&6.3V,HT-var+0Vposition
C24:120V&6.3V,HT-var+0Vposition(thismicrophoneisstereoandneedstwo
powersuppliesandacablesplitter).
(Telefunken)ElaM250,ElaM251,USversion:120V&6.3V
(Telefunken)ElaM250,ElaM251,EUversion:120V&3.9V
C12a:120V&5.2V,HT-var+0Vposition
C28A,C29A,C30A,C60/CK28,C60/CK26:120V&3.9V:theMP1cannotbeused
withthesemicrophonesbecausetheiroutputtransformerismountedinthesupply.
MicrotechGefell
CMV563:120V&6V
UM57:120V&6V,HT-var+0Vposition
UM92,UM75:120V&5.8V,HT-var+40Vposition
M990:120V&5.8V
Neumann(Telefunken)
KM(2)53,KM(2)54,KM(2)56,KM(2)64,KM(2)66,M50,M250:120V&3.9V
M49,M249,M269:120V&3.9V,HT-var+0Vposition
U67:210V&5.8V
SM69,SM23:120V&3.9V,HT-var+0Vposition(thesemicrophonesarestereo
andneedtwopowersuppliesandacablesplitter).
U47,U48:thefilamentsupplyofthesemicrophonesisderivedfromtheHTsupply.
PleasebuyourMP47insteadoftheMP1,becauseitisespeciallydesignedforthis.
M147,M149,M150:thesemicrophonesarepartlysolidstate.Theyneed+and-70
Vand32VandcannotbeusedwithanMP1.
Schoeps(Telefunken/Philips/Siemensequivalent)
CV60,CM61:145V&-5.7V
M200,M201:150V&-6.3V
M221b:120V&3.9V
M222:theMP1cannotbeusedwiththismicrophonebecausetheoutputcircuitryis
mountedinitspowersupply.
Sony
C37A:theMP1cannotbeusedwiththismicrophonebecausetheoutputtransform-
erismountedinitspowersupply.
C800,C800G:Thesemicrophonesneed276VwhichtheMP1cannotdeliver.The
C800Galsoneedsanadditional6VforthePeltierelement.
Forpowersupplyvoltageinformationofother(contemporary)tubemicrophones,
pleaseconsulttheoriginalmanufacturer.TheMP1willmostlikelysupportthem.

14
Grimm Audio contact information
GrimmAudioCV
Strijpsestraat94
5616GSEindhoven
TheNetherlands
+31(0)402131562
Email:[email protected]
Website:http://www.grimmaudio.com

15
5. Grimm Audio Limited Warranty
GrimmAudioCV(“GrimmAudio”)warrantsthisproducttobefreeofdefectsinma-
terialandworkmanshipforaperiodofone(1)yearforpartsandforaperiodofone
(1)yearforlaborfromthedateoforiginalpurchase.Thiswarrantyisenforcable
onlybytheoriginalretailpurchaserandcannotbetransferredorassigned.
DuringthewarrantyperiodGrimmAudioshall,atitssoleandabsoluteoption,
eitherrepairorreplacefreeofchargeanyproductthatprovestobedefectiveon
inspectionbyGrimmAudiooritsauthorizedservicerepresentative.Inallcases
disputesconcerningthiswarrantyshallberesolvedasprescribedbylaw.Toobtain
warrantyservice,thepurchasermustfirstcallorwriteGrimmAudioattheaddress
andtelephonenumberprintedbelowtoobtaininstructionswheretosendtheunit
forservice.Allenquiriesmustbeaccompaniedbyadescriptionoftheproblem.All
authorizedreturnsmustbesenttoGrimmAudiooranauthorizedGrimmAudio
repairfacilitypostageprepaid,insuredandproperlypackaged.Proofofpurchase
mustbepresentedintheformofabillofsaleorsomeotherpositiveproofthatthe
productiswithinthewarrantyperiod.GrimmAudioreservestherighttoupdate
anyunitreturnedforrepair.GrimmAudioreservestherighttochangeorimprove
designoftheproductatanytimewithoutpriornotice.
Thiswarrantydoesnotcoverclaimsfordamageduetoabuse,neglect,alterationor
attemptedrepairbyunauthorizedpersonnel,andislimitedtofailuresarisingdur-
ingnormalusethatareduetodefectsinmaterialorworkmanshipintheproduct.
InnoeventwillGrimmAudiobeliableforincidental,consequential,indirector
otherdamagesresultingfromthebreachofanyexpressorimpliedwarranty,in-
cluding,amongotherthings,damagetoproperty,damagebasedoninconvenience
oronlossofuseoftheproduct,and,totheextentpermittedbylaw,damagesfor
personalinjury.
©2011,GrimmAudioCV.Allrightsreserved
Reproductioninwholeorinpartisprohibited.
Specificationssubjecttochangewithoutnotice.
Grimm Audio MP1 manual v1.0, 11/17/11