Sonic Farm Tantra USER MANUAL
SonicFarmProAudio,
Vancouver,BC,Canada
Tel310-402-2390,778-863-1613
www.sonicfarm.com
foremail,pleaseusecontactboxonourwebsite
SonicFarmTantra
BassPreamplifier
USERMANUAL
DearAudioProfessional,
ThankyouforpurchasingtheTantra.Wehopeitwilldeliverexceptionalperformanceformanyyearsintothefuture.
Pleasetakethetimetoreadthismanual.ItdescribesTantra’sdesignphilosophyaswellasitsmostimportantfunctions.
DESIGNPHILOSOPHY
Attheheelsofthesuccessofour2DI4Pentodedirectbox,aconversationarosetobuildafull-blownbasspreampwithextensivefunctions
andanoptionalhighpowermodulecapableoffulfillingtheneedsoftoday’sprofessionalbassplayercommunity.
Theideacamefromafellowpro-audiodesignerandalifelongprobassplayerMichaelArnopol.Hethoughtthatthe2DI4,asgoodasit
sounded,neededtobetakentothenextlevel.AftersomeinitialresistanceandalotofbrainstormingbetweenBoris,Michaelandme,we
warmeduptotheidea,andoverthecourseofalmostayear,cameupwiththedesignyouarenowseeinginfrontofyou,theTantra.
Apartfromtheunchangedpentodeinputsectionborrowedfromthe2DI4,thepreamphasanoverdrivesection,centeredaroundanother
pentode,followedbyseveralsolid-statepoweredsections:ahigh-passfilter,a5-bandEQ,acompressoranda2-partharmonicgenerator.
Thereareeffectslooppoints(sendandreturn,balancedorunbalanced)thatfacilitateaddingexternaleffectunitstothesignalchain.
BoththeDIandlineoutputsarestillthere,justlikewiththe2DI4,withsomeimportantfunctionsadded.
ThereisaplacetohouseandconnectanoptionalICE1000ASPclassDpowermoduleaswell.Thismodulewassuggestedtousbythebass
communityastheonewiththebestsound,power,impactandclarityamongstalloftheavailableonestoday.
Allofthesectionswereoptimizedforusewithabassinstrument,althoughtheunitcanbesuccessfullyusedwithothertypesofsignalsas
well.
Theideawastoessentiallyhavea2DI4alongwithalltheseothersoundprocessorsthatwouldhave“nosoundofitsown”andthusnottake
awayfromthedefinitionandrichnessthatthe2DI4isknownfor.Wehopewehavefullysucceededinaccomplishingthat.Inaddition,all
sectionscanbebypassed,andwhentheyare,oneessentiallygetsthebarebone2DI4sound.
Wehopeyouwillputthispreampthroughit’spacesbothinyourstudioandatyourlivegigsandthatitwillgiveyoumanyyearsoffulfilling
performance!
SOMEREMINDERSREGARDINGTUBES
Tubesworkwithveryhighsupplyvoltages.TherearepointsinsideTantrathatmeasureinexcessof350VDC.Iftouched,thosevoltages
couldbelethal!
Makesurethatnopointedobjects(especiallymetal)orliquidspenetratetheinsideoftheunitthroughitscoolinggrillesorotherwise.Ifthat
accidentallyoccurs,immediatelypulltheplugoutofthepowersocketandwaitfortheunittodischarge.Tantramustnotbeoperatedif
moisturepenetratesinside.
Beforeopeningtheunitonemustdisconnectthemainscordandthenwaitseveralminutesfortheinternalcapacitorstodischarge.
Whenmountinginarackenclosure,alwaysleaveanemptyspaceabovetheunittoensurepropercooling.
Pleasedonotreplacethemainsfusewithoneofahighervalue:useonlyslow-blowtypesrated630mA@110-120Vor300-350mA@220240V.
LegalDisclaimer:NeitherSonicFarmnoranybodyassociatedwithitcantakeanyliabilityfordamagetopersonsorpropertycausedby
eitheruse,modificationorservicingthisunit.
HOWTOCHANGETUBES
Thisonlyappliestoafunctionalunit.Pleaseentrustanyrepairstoqualifiedservicepersonnel.
OnlyanEF-86orEF-806/EF-806S(orequivalent,like6267,6CF8orRussian6J32P)pentodecanbeused.
Pulloutthepowercord.Waitforatleast10minutesforallthecapacitorstodischarge.
Thelefttubewillinfluencethetonemorethantheotherone,whichwillonlyaffecttheoverdrivensignal,whenblendedin.Bothtubesareof
thesametypeandcanbereplacedwhenwornoutorifaslightlydifferenttonaltextureisdesired.
RemoveTantra’scoverbyremovingallofthescrewsonthecover.
Pulloutthetubewhileaddingasubtlebutfastleft-rightmotiontoloosenthetubefromatightsocket.Donotbendthetubemuchoutofthe
axisbecauseyoucanbreakthepinsorcauseairtoenterthetubeanddestroyit.Payingattentiontothepinalignment,pushthereplacement
tubeintothesocketusingsamemotionsbutintheoppositedirection.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)orhex
screwdriver(.104”/2.64mmhexx.055”/1.4mmdeep)toadjustpots.
3
ThefirstgroupofminitoggleswitchesstartswiththeDIfeedswitch.ItdetermineswhatgoestotheDIoutput(which,ofcourseis
miclevel).Left:DIisfedfromthepointafterthetubes,andwillbeaffectedbythetubemode(pentode/triode,switch6),LoandHi
boosts(5and7),theattenuation/muteswitch(4),cleangain(8),overdrivegain(17)andoverdriveblend(10).Right:DIisfedfrom
theoutputofthepreampandisaffectedbyallprocessing,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-coloroverdriveindicator
LED(9).Youdon’twantthisLEDtoturnredevenattheloudestnotesplayed.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(5
and7).Thisshouldaccommodateeventheloudestexistingbasses.Ifyoursignal(maybeakeyboard)stillclipstheinputtube,reduce
theoutputlevelontheinstrumentitself.Right(andthisiswheretheswitchshouldnormallybe):OLindicatormonitorsthesignaljust
priortothemasterlevelcontrol.Bypassedsectionsaffectneitherthesoundnorthisindication.Clippingatthosesolidstatestages
soundsnastyandshouldbeavoided.UsethecleanandODmixcontrolstoadjust.
15 PreODhigh-passfilterswitch.Itwillaffecttheoverdriventone.Left:somebassfilteredouttoavoidmud.Middle:onlymidsandtreble
frequenciespassintotheODtube(useforrockandrollcrunchsoundortogetmorebiteoutofyourbass).Right:fullon(thinkLarry
Graham,“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(thelevelwhere
compressionkicksin)withmoreorlesssignal,whichaffectstheoverallloudnessaswellasthepointintime(frompluckingastringall
thewaytodecay)whereloudnessstartstobe“shavenoff”.Forstudioheads,thecompressionratioisfixedtoaround3.5to4,andthe
releasetimeisoptimizedforbassinstruments.Thiscompressoralsofeaturesaspecial,dualtimeconstant,feedbackcircuit.Inplain
words,itwon’tpumporbreatheorsquashyourattackevenathighersettings.Evenslappingwillyieldclean,distortion-free,natural
attack.Itrivalsbeststudiocompressors,andthensome.Itisimportanttopointoutthatthesignalshouldbeniceandstrong(use
controls8and10)togetthemostoutofthecompressor.Justmakesureyoudon’tgetredclippingwithOLfd(14)switchintheright
position.ThedBmarkingsaroundthedialindicatemaximumgainreductionpossibleinthatsetting.
33 Masterlevelcontrol.Affectslineoutput,aswellasthepoweramp,ifbuiltin.
34 2ndharmonicblend.Thissectionallowsgivingyourbassabitmore“growl”.Theeffectislimitedtolowandlow-midfrequenciesonly.
Thenatureofthiscircuitmakesitemphasizeloudernotes.That’swhyweleftthecompressorpermanentlyengagedwiththese2
harmonicgenerators,sothatyoucanregulatenotonlytheblend,butalsotheintensityofharmonicgeneration(evenwiththe
compressorswitchflippedtotheleft).Withcompressordriveatminimum,theeffectwillbesubtler,andyouwillneedtoblendinabit
more.Asyouturnupthecompressordrive,theeffectwillstarttobemoreintense,soadjusttotaste.Thisblendcontrolmixesthe
harmonicgeneratoroutputwiththemainsignal.
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,youcanuseasingle8Ωora4Ωspeaker
cabinet.Themaximumoutputpowerwillbe1000Winto4Ωor500Winto8Ω.
40 Externalpowerampinput.Activewhenthepushbuttonswitch(41)isdepressed.
41 Presstoactivatetheexternalpowerampinputandseparatethepreampfromthepoweramp.Thelinepreampoutputwillstillbe
active.Youcaneveninsertanexternal(balanced,studiograde)processorinbetweenthepreamplineoutput(42)andthepoweramp
externalinput(40).Fornormalampoperation,thisswitchshouldbeout(notdepressed).
42 Linelevelbalancedoutput(electronicallybalanced).(XLRpinconnection:1=GND,2=HOT,3=COLD).Usefulforrecordingordrivingan
externalpoweramp.IMPORTANT:Ifyouwanttodriveanunbalancedinput,youneedtomakeaspecialXLRto¼”cable:Connect
XLR’spin1to¼”plugground(sleeve)andconnectXLR’spin2to¼”plugtip.LeaveXLRpin3disconnected(floating).Youcannotuse
thiscableontheDIoutput,onlyonlineout.
43 Groundliftswitch.Presstopreventhumcausedbygroundloops(onlywhenthelineoutputisconnectedtoanotherunitandyougeta
humasaresult).Thisfunctioncannotremovehumalreadypresentintheinstrumentsignal(forexampleyourbasspickupspickingup
hum).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,ifthatis
notenough,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.
TECHNICALSPECIFICATIONS:
1channel
Frequencyresponse:10Hz-50kHz+/-3dB
Maximumgain:54dBatthelineoutput,32dBattheDI(miclevel)output
Harmonicdistortion:<2%beforeclippinglevel,quicklydecreasesifdrivenless.
Maximumoutputlevel:30dBu
Minimumoutputload:600Ω
Connectors:XLRDIandlineoutput,balancedonly
Instrumentinput:1/4”unbalanced,mono
Powerconsumption:30Wpreamp,max1100Wpoweramp.
WARRANTYINFORMATION
SonicFarmgivesaone-yearwarrantyonpartsandlaborfromthedateofpurchase.
Shouldyouneedtosendinyourunitforwarranty-coveredservice,pleasecontactusforanRMAnumberfirst.
Wewillalsotellyouwheretosendtheunit.
AnyModificationoftheunitvoidsthewarranty.
CONTACTINFORMATION:
SonicFarmProAudio,
Vancouver,BC,Canada
Tel310-402-2390,778-863-1613
www.sonicfarm.com
Foremail,pleaseusecontactboxonourwebsite
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