SonicFarmProAudio,Vancouver,BC,CanadaTel310-402-2390,778-863-1613www.sonicfarm.comforemail,pleaseusecontactboxonourwebsite

SonicFarmTantra

BassPreamplifier

USERMANUAL

DearAudioProfessional,ThankyouforpurchasingtheTantra.Wehopeitwilldeliverexceptionalperformanceformanyyearsintothefuture.Pleasetakethetimetoreadthismanual.ItdescribesTantra’sdesignphilosophyaswellasitsmostimportantfunctions.DESIGNPHILOSOPHYAttheheelsofthesuccessofour2DI4Pentodedirectbox,aconversationarosetobuildafull-blownbasspreampwithextensivefunctionsandanoptionalhighpowermodulecapableoffulfillingtheneedsoftoday’sprofessionalbassplayercommunity.Theideacamefromafellowpro-audiodesignerandalifelongprobassplayerMichaelArnopol.Hethoughtthatthe2DI4,asgoodasitsounded,neededtobetakentothenextlevel.AftersomeinitialresistanceandalotofbrainstormingbetweenBoris,Michaelandme,wewarmeduptotheidea,andoverthecourseofalmostayear,cameupwiththedesignyouarenowseeinginfrontofyou,theTantra.Apartfromtheunchangedpentodeinputsectionborrowedfromthe2DI4,thepreamphasanoverdrivesection,centeredaroundanotherpentode,followedbyseveralsolid-statepoweredsections:ahigh-passfilter,a5-bandEQ,acompressoranda2-partharmonicgenerator.Thereareeffectslooppoints(sendandreturn,balancedorunbalanced)thatfacilitateaddingexternaleffectunitstothesignalchain.BoththeDIandlineoutputsarestillthere,justlikewiththe2DI4,withsomeimportantfunctionsadded.ThereisaplacetohouseandconnectanoptionalICE1000ASPclassDpowermoduleaswell.Thismodulewassuggestedtousbythebasscommunityastheonewiththebestsound,power,impactandclarityamongstalloftheavailableonestoday.Allofthesectionswereoptimizedforusewithabassinstrument,althoughtheunitcanbesuccessfullyusedwithothertypesofsignalsaswell.Theideawastoessentiallyhavea2DI4alongwithalltheseothersoundprocessorsthatwouldhave“nosoundofitsown”andthusnottakeawayfromthedefinitionandrichnessthatthe2DI4isknownfor.Wehopewehavefullysucceededinaccomplishingthat.Inaddition,allsectionscanbebypassed,andwhentheyare,oneessentiallygetsthebarebone2DI4sound.Wehopeyouwillputthispreampthroughit’spacesbothinyourstudioandatyourlivegigsandthatitwillgiveyoumanyyearsoffulfillingperformance!

SOMEREMINDERSREGARDINGTUBESTubesworkwithveryhighsupplyvoltages.TherearepointsinsideTantrathatmeasureinexcessof350VDC.Iftouched,thosevoltagescouldbelethal!Makesurethatnopointedobjects(especiallymetal)orliquidspenetratetheinsideoftheunitthroughitscoolinggrillesorotherwise.Ifthataccidentallyoccurs,immediatelypulltheplugoutofthepowersocketandwaitfortheunittodischarge.Tantramustnotbeoperatedifmoisturepenetratesinside.Beforeopeningtheunitonemustdisconnectthemainscordandthenwaitseveralminutesfortheinternalcapacitorstodischarge.Whenmountinginarackenclosure,alwaysleaveanemptyspaceabovetheunittoensurepropercooling.Pleasedonotreplacethemainsfusewithoneofahighervalue:useonlyslow-blowtypesrated630mA@110-120Vor300-350mA@220-240V.LegalDisclaimer:NeitherSonicFarmnoranybodyassociatedwithitcantakeanyliabilityfordamagetopersonsorpropertycausedbyeitheruse,modificationorservicingthisunit.HOWTOCHANGETUBESThisonlyappliestoafunctionalunit.Pleaseentrustanyrepairstoqualifiedservicepersonnel.OnlyanEF-86orEF-806/EF-806S(orequivalent,like6267,6CF8orRussian6J32P)pentodecanbeused.Pulloutthepowercord.Waitforatleast10minutesforallthecapacitorstodischarge.Thelefttubewillinfluencethetonemorethantheotherone,whichwillonlyaffecttheoverdrivensignal,whenblendedin.Bothtubesareofthesametypeandcanbereplacedwhenwornoutorifaslightlydifferenttonaltextureisdesired.RemoveTantra’scoverbyremovingallofthescrewsonthecover.Pulloutthetubewhileaddingasubtlebutfastleft-rightmotiontoloosenthetubefromatightsocket.Donotbendthetubemuchoutoftheaxisbecauseyoucanbreakthepinsorcauseairtoenterthetubeanddestroyit.Payingattentiontothepinalignment,pushthereplacementtubeintothesocketusingsamemotionsbutintheoppositedirection.Makesureitgoesinalltheway.Duetoelectricshockdanger,testingthepreampwiththelidremovedisnotrecommended.Screwthecoverbackinplaceandyou’redone.

TANTRA’SFRONTPANELCONTROLS:

1 Instrument¼”input.Plugyourbass(orguitar,keyboardinstrument)here.Theinputimpedanceis2.2MΩ.

.2 TrimcontrolsdeterminingthelevelofLoandHiboost.Upto9dBinpentodeand5dBintriodetubemode.Thisboosthappensonthe

first,cleantubestage,andwillaffecteverythingelsedownthechain.Useaminislot(.098”/2.5mmØ,.031”/0.8mmwide)orhexscrewdriver(.104”/2.64mmhexx.055”/1.4mmdeep)toadjustpots.

3 ThefirstgroupofminitoggleswitchesstartswiththeDIfeedswitch.ItdetermineswhatgoestotheDIoutput(which,ofcourseis

miclevel).Left:DIisfedfromthepointafterthetubes,andwillbeaffectedbythetubemode(pentode/triode,switch6),LoandHiboosts(5and7),theattenuation/muteswitch(4),cleangain(8),overdrivegain(17)andoverdriveblend(10).Right:DIisfedfromtheoutputofthepreampandisaffectedbyallprocessing,includingthemasterlevelpot.

4 3-positionattenuation/muteswitch,worksatthepointafterthetubesandbeforetheeffectsloop.Left:mute.Mustusebefore

changingtubemodestoavoidaloudclickcausedbyre-biasingoftheinputtube.Mostspeakersaresensitivetosuchclicksaswell.Middle:noattenuation.Right:6dBattenuationofthesignal;usewithstompboxesintheFXlooptoavoidoverloadingthem.

5 3-positionLoboostswitch.Left:Bassboosted(shelvingtype)atfirsttube.Max9dB(pentode)and4dB(triode),dependingonthe

lefttrimpotsetting.Middle:noboost.Right:overallgainboosted,usewithveryquietbassesortogetmoreoverdriveatthe2ndtube.6 Tubemodeswitch.Left:pentode.Moregainandsubtlesaturation.Right:Triode.Lessgainandcleaner,morepolitesound.7 3-positionHiboostswitch.Left:Trebleboosted(shelvingtype,startingatabout2kHz)atfirsttube.Max9dB(pentode)and4dB

(triode),dependingonthetrimpotsetting.Middle:noboost.Right:Trebleboosted(shelvingtype,startingatabout4kHz).8 Cleangainmixcontrol.Thisispostthefirsttubeandwillaffecteverythingdownthechain(notincludingtheODtube).Itisdesirable

tohavethiscontrolashighupaspossiblewithoutclippingthesubsequentstages.Youwillbewatchingthebi-coloroverdriveindicatorLED(9)withtheswitch(14)intherightposition.Youdon’twantthisLEDtoturnredevenattheloudestnotesplayed.Pleasenotethatwhereasthetubefrontendbreaksupverymusicallywhenoverdriven,thisnotthecasewiththesolidstateprocessorsfollowingtheFXloopreturn.Theyclipinaveryunpleasantandjarringway.(Seeexplanationunder14tomakethisevenmoreclear)Alsoseecompressorexplanation.

9 Bi-coloroverdriveindicatorLED(9).Greenforsignalpresence,turnsredtoshowclippingdistortion.Itcanshowaclippingonthefirst

tubeorelsewhereinthechain,dependingontheOLfeedswitch(14),pleaseseeexplanation.10 Overdriveblendpot:mixestheoverdrivensignalcomingoutofthe2ndtubewiththecleanonefromthe1st.ThisODblendcanbe

mutedusingafootswitch,seerearpanelguide.ThesmallorangeLED(11)comesonwhenfootswitchmutingisactive.11 ODmuteswitchindicator(orangeLED).AboveitisablueLEDthatjustindicatesthatthepreampisON.12 OD+switchactivatesthe2ndoverdrivestage(usesFET’s).Left:2ndODstageactivethroughahigh-passfilter.Middle:2ndODstagenot

active.Right:2ndODstagefullon.13 Effectsloopactivationswitch:Left:FXout.Right:FXin.MakesurethisoneispushedtotheleftwithnoFXconnected,otherwisethere

willbenosound.14 Overloadindicatorfeedswitch.Left:Indicatesapossibleclippingdistortiononthefirsttube.Gainpot(8)willnotaffectthis.Goodto

knowifyouareclippingthefirsttubewithaveryloud(highsignaloutput)bass.SwitchtoTriodetoavoidit.Deactivateanyboost(5and7).Thisshouldaccommodateeventheloudestexistingbasses.Ifyoursignal(maybeakeyboard)stillclipstheinputtube,reducetheoutputlevelontheinstrumentitself.Right(andthisiswheretheswitchshouldnormallybe):OLindicatormonitorsthesignaljustpriortothemasterlevelcontrol.Bypassedsectionsaffectneitherthesoundnorthisindication.Clippingatthosesolidstatestagessoundsnastyandshouldbeavoided.UsethecleanandODmixcontrolstoadjust.

15 PreODhigh-passfilterswitch.Itwillaffecttheoverdriventone.Left:somebassfilteredouttoavoidmud.Middle:onlymidsandtreble

frequenciespassintotheODtube(useforrockandrollcrunchsoundortogetmorebiteoutofyourbass).Right:fullon(thinkLarryGraham,“DancetotheMusic”)

16 Compressorswitch.Left:out.Right:in.17 Overdrivegaincontrol,determineshowhardyoudrivethe2ndtube.Goodtokeepthisatminimumifyouarenotusingoverdrive.18 High-passfilterswitch.Left:out.Right:in.ThisisthefirstprocessoraftertheFXloop.19 EQswitch(separatefromtheHP).Left:out.Right:in.EQisthesecondprocessor,followingtheHP.20 HPfilterfrequency:Left:28Hz.Middle:60Hz.Right:40Hz.21 Bassshelvinggain(boostorcut,detentsinthemiddleforflat),partoftheEQsection.22 Centerfrequencyofthefirstparametricbandfilter,34to300Hz.Notethatcontrolsaffectingthesameparametricbandfiltersection

areconnectedbyredlinesforeasyaction)23 Centerfrequencyofthe2ndparametricbandfilter,150to1300Hz.24 2ndparametricbandgain(Boostorcut,flatinthemiddle).MaxboostorcutwillinteractwiththeQ2control(thewidthofthecurveor,

tobemoreprecise,theresonancepeakordipintensity).Thisappliestoall3parametricbands.25 Centerfrequencyofthe3rdparametricbandfilter,690to6000Hz.26 3rdparametricbandgain(Boostorcut,flatinthemiddle).27 3rdparametricfilterband’sQcontrol(resonanceorwidth).Thefilterwillhaveanarrowerandmoreintensepeakordip,dependingon

theG3setting.28 2ndparametricfilterband’sQcontrol(resonanceorwidth).29 1stparametricbandgain(Boostorcut,flatinthemiddle).30 1stparametricfilterband’sQcontrol(resonanceorwidth).31 Highfrequencyshelvingcontrol,boostorcut,flatinthemiddle)

32 Compressordrivecontrol.Forthemainsignalchain,withnoharmonicsblendedin(see34or35),thecompressorswitch(16)needsto

beflippedrightforthiscompressiondrivecontroltobeactive.Youarehittingafixedcompressionthreshold(thelevelwherecompressionkicksin)withmoreorlesssignal,whichaffectstheoverallloudnessaswellasthepointintime(frompluckingastringallthewaytodecay)whereloudnessstartstobe“shavenoff”.Forstudioheads,thecompressionratioisfixedtoaround3.5to4,andthereleasetimeisoptimizedforbassinstruments.Thiscompressoralsofeaturesaspecial,dualtimeconstant,feedbackcircuit.Inplainwords,itwon’tpumporbreatheorsquashyourattackevenathighersettings.Evenslappingwillyieldclean,distortion-free,naturalattack.Itrivalsbeststudiocompressors,andthensome.Itisimportanttopointoutthatthesignalshouldbeniceandstrong(usecontrols8and10)togetthemostoutofthecompressor.Justmakesureyoudon’tgetredclippingwithOLfd(14)switchintherightposition.ThedBmarkingsaroundthedialindicatemaximumgainreductionpossibleinthatsetting.

33 Masterlevelcontrol.Affectslineoutput,aswellasthepoweramp,ifbuiltin.34 2ndharmonicblend.Thissectionallowsgivingyourbassabitmore“growl”.Theeffectislimitedtolowandlow-midfrequenciesonly.

Thenatureofthiscircuitmakesitemphasizeloudernotes.That’swhyweleftthecompressorpermanentlyengagedwiththese2harmonicgenerators,sothatyoucanregulatenotonlytheblend,butalsotheintensityofharmonicgeneration(evenwiththecompressorswitchflippedtotheleft).Withcompressordriveatminimum,theeffectwillbesubtler,andyouwillneedtoblendinabitmore.Asyouturnupthecompressordrive,theeffectwillstarttobemoreintense,soadjusttotaste.Thisblendcontrolmixestheharmonicgeneratoroutputwiththemainsignal.

35 4thharmonicblend.Thesameasaboveapplieshere.Theonlydifferenceisthesoundofthe4thharmonic.

TANTRA’SREARPANELCONTROLS:

36 StandardIEC-typepowerreceptacle.Justmakesurethatthefuseratingscorrespondtothemainsvoltageyouareusing.37 and38:Voltageselectorsforpowerampandpreampseparately.Theseare2differentcircuits;makesurebotharesettothecorrect

mainsvoltage.38 Seeabove.39 and50:Speaker“Speakon”connectors.Activeonlywhenthepowermoduleisbuiltin.UseonlytheproperSpeakoncables.Total

minimumspeakerimpedancenottogounder4Ω(Ohms).Thisisthesameas2x8Ω.Ofcourse,youcanuseasingle8Ωora4Ωspeakercabinet.Themaximumoutputpowerwillbe1000Winto4Ωor500Winto8Ω.

40 Externalpowerampinput.Activewhenthepushbuttonswitch(41)isdepressed.41 Presstoactivatetheexternalpowerampinputandseparatethepreampfromthepoweramp.Thelinepreampoutputwillstillbe

active.Youcaneveninsertanexternal(balanced,studiograde)processorinbetweenthepreamplineoutput(42)andthepowerampexternalinput(40).Fornormalampoperation,thisswitchshouldbeout(notdepressed).

42 Linelevelbalancedoutput(electronicallybalanced).(XLRpinconnection:1=GND,2=HOT,3=COLD).Usefulforrecordingordrivinganexternalpoweramp.IMPORTANT:Ifyouwanttodriveanunbalancedinput,youneedtomakeaspecialXLRto¼”cable:ConnectXLR’spin1to¼”plugground(sleeve)andconnectXLR’spin2to¼”plugtip.LeaveXLRpin3disconnected(floating).YoucannotusethiscableontheDIoutput,onlyonlineout.

43 Groundliftswitch.Presstopreventhumcausedbygroundloops(onlywhenthelineoutputisconnectedtoanotherunitandyougeta

humasaresult).Thisfunctioncannotremovehumalreadypresentintheinstrumentsignal(forexampleyourbasspickupspickinguphum).Undernormaloperation,thisswitchshouldbeout.

44 DI(ormicrophonelevel)output(Transformerbalanced).Balancedconnectiononly!(XLRpinconnection:1=GND,2=HOT,3=COLD).45 Overdriveblenddisablefootswitch.Useastandardlatching¼”footswitchthatconnectstipandsleevewhenengaged.46 Effectssendjack,tip-ring-sleeve.Canbeusedforunbalancedeffects(onlywhenswitch47isout),orbalanced(switch47pressed).You

mustreducethesignallevelwhenyouuseunbalancedstompboxesnottooverdrivethem.Fliptheattenuatorswitchleft,or,ifthatisnotenough,reducethe(8)and(10)controls.

47 Thisswitchchoosesbetweenunbalancedeffectsconnection,likestompboxes,orbalanced(studiounitswithXLRconnectors).Outfor

unbalanced,inforbalanced.Wheninbalancedmode,jacks(46)and(48)areinTRSmode:Tip:Hot,connecttoXLRpin2;Ring:Cold,connecttoXLRpin3,andSleeve:Ground,connecttoXLRpin1.

48 Effectreturn,balancedorunbalanced,dependingontheswitch(47)setting.RememberthattheFXloopisactivatedfromthefront

panel,switch(13).49 Tuneroutput,mono¼”jack.50 See39.51 Preampfuse,630mA@115VACor300-350ma@220-240VAC.Replaceonlywithaslowblowfuseofthesameratingfortheappropriate

mainsvoltage.52 Ditto,powerampfuse.10A@115VAC,6.3A@220-240VAC.Donotexceedtheseratings.53 Preamppowerswitch.Youcanusethepreampseparatelyfromthepoweramp(whenbuiltin).Withtheintegratedversion,always

turnthepreampfirst(beforethepoweramp),andturnitofflast(afterthepoweramp).54 Poweramppowerswitch.Onthefrontpanel,totherightandabovetheF3control(25),thereisasmallredLED.Thisisthepoweramp

clippingindicator.IfthisLEDoccasionallylightsup,itmeansyouaredrivingthepoweramptoohard.Reducethemasterlevel.

Tantra’sFunctionalBlockDiagram:

TECHNICALSPECIFICATIONS:1channelFrequencyresponse:10Hz-50kHz+/-3dBMaximumgain:54dBatthelineoutput,32dBattheDI(miclevel)outputHarmonicdistortion:<2%beforeclippinglevel,quicklydecreasesifdrivenless.Maximumoutputlevel:30dBuMinimumoutputload:600ΩConnectors:XLRDIandlineoutput,balancedonlyInstrumentinput:1/4”unbalanced,monoPowerconsumption:30Wpreamp,max1100Wpoweramp.WARRANTYINFORMATIONSonicFarmgivesaone-yearwarrantyonpartsandlaborfromthedateofpurchase.Shouldyouneedtosendinyourunitforwarranty-coveredservice,pleasecontactusforanRMAnumberfirst.Wewillalsotellyouwheretosendtheunit.AnyModificationoftheunitvoidsthewarranty.CONTACTINFORMATION:

SonicFarmProAudio,Vancouver,BC,CanadaTel310-402-2390,778-863-1613www.sonicfarm.comForemail,pleaseusecontactboxonourwebsite