ultimate-guitar-valveking - amp mods - electronics.pdf

20/1/2015 ultimate-guitar-valveking - Amp Mods - Electronics

http://ultimate-guitar-valveking.wikispaces.com/Amp+Mods+-+Electronics 1/26

Amp Mods - Electronics (/Amp+Mods+-+Electronics) Editar 84 (/page/history/Amp+Mods+-+Electronics)

(/page/menu/Amp+Mods+-+Electronics)

AmpModsElectronicsTHISSECTIONISNOTACOMMENTSPAGEMODSONLYManyusersbuytheValvekingandarenotsatisfiedwiththetonestraightoutofthebox.Theseusers(myselfincluded)modifytheampsothatamuchbettertonecanbegainedoutofit.Itreallyisquiteextraordinaryhowmuchofanimprovementcanbemadewithafewsimplemods.HereisanoverviewofthemoretechnicalElectronicsmods.Pleasereadthedisclaimerbelow,wedon'twantanyelectrifiedguitaristsonourhands:).

PleasebesuretoreadtheWarningspagebeforedoinganymodstoyouramp."...Pullingthechassisandpokingaroundinsidetheamphoweverisdangerousdeadlydangerous...."

*DISCLAIMER*Thestandbyswitchdoesnotturnoffthevoltagetotheo/pvalvesanodes(plate)YoucansafelydrainthecapacitorsbyleavingthestandbyONandturningOFFthepower.Theo/pvalveswillcontinuetodrawcurrentastheheaterscooldownanddrainthecapstoasafelevel.RemembertoturnthestandbyswitchOFFbeforeyoupowerupagaintopreventcathodestrippingthevalves,Alwaysremovethepowerconnectorbeforeworkingontheinternals.(recklessrog)

ThecapacitorsinsidetheValvekingChassisareNOTselfdraining.Besuretoletthemdrainefficiently.Becareful!OnemethodIuse(cap47)istopullapowertubewithampunplugged.Useametertocheckthevoltagesofeachpintoground.Ifvoltagesarepresentuseatestleadwithalligatorclipsclippedtochassisononeend.Intheremainingendcliparesistorbyoneendandwraptheresistorwithinsulatingtapeexposingtheremainingendasaprobetoprobethesocket.Probeeachholeforeachpinforapproximatelytensecondstodrainthecharges.Recheckwithameterbeforeproceedingwithyourwork.Ifchargeremainsthenrepeatandrecheckuntilthevoltageisveryloworgone.Recheckvoltageoccasionallyforsafety.Theuseoftheresistoreliminatessparkingwhenthechargedrains.

VK112ownerspleasereadthisfirstbeforemodifyingyouramp.

PleasenotetherearenowtwoversionsoftheVK112thosemadebeforeJanJuneof2011(wecan'tplaceitexactlybutit'sinthatrangeofdatessomewhere)andthosemadeafterthatthathavenowbeendubbedVersion2's.WenowhavePDFschematicsforbothversionshereonthispageWarnings

ThedifferenceisinthecircuitjustafterV2gainstage2andbeforetheleadchannelstonestackwhereResistor173isnowchangedto100kandplacedinserieswithanew

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CapacitoratC105a50volt2.2nfCapacitor.LikethisSignalfromC100>C105>R173>AGND1.C149ischangedfrom50Volt1nftoa50Volt820pf.C100>C149>AGND1Thissupposedlybrightenstheampslightly(needsverification)alatheclipoutC149modinaversion1amp.Thischangemayhaveramificationstosomeoftheampmodificationspostedbelow.IfyournotsurebyallmeansaskeitherhereorattheVKthreadatUltimateGuitars"GuitargearandAccessories"forum.ValveKingThreadMKIIThesecondchangemade...Thecircuitboardtracefromthesend/returnloopsreturnsidetothepowerampcircuitboardhasbeenreplacedwithaplugandashieldedcablerunningfromaplugnearthereturnjacktothepowerampboard.ThischangewasmadetoeliminateaslightlylouderhumsomeuserswhereexperiencingintheVK112.TheVK212andVK100alreadyhavethiscablefromthefactory.

OfcoursePeaveydoesnotofficiallyacknowledgethattherearenowtwoversionsoftheVK112amp.Luckyus::eyeroll::Theonlywaytotellfor100%certainisaskpeaveywhenyourVK112wasmadeordropoutthechassisandcheckforafatcablethatgoesfromnearthereturnjackfromaplugtothepowerampboard.OrlookatR173toseeifitisa100kresistor.Version1boardswillhavea3.9megaohmresistorinthisspot.

AnyonewithinformationonwhetherornottheVK212andVK100havehadtheabovefactorycircuitmodnearthetonestackdonetothempleaseletusknow.

IwonderedwhytherehadbeenatailoffofpostsontheVKthreadabouttheampssoundingdarkandmuddy.

R100modTher100modissaidtoimprovethegainboostcontrolandmakeitlesstrebly,cuttingandoverallharshwhenused.(CreditstratoJim)Ther100modiseasywithminimalsolderingexperience.Justgetaresistor(anywilldo)andusethesolderleadtogofromleadtoleadonresistor100(whichislabeled)therebybridgingtheresistor.Ther100modmadethegainboostfeatureusableandgreatforaclassicrocktonewiththegainlessthannoon.

(Creditilyav)AbouttheR100mod:

Removetheresistorandslama1Mpotthere.

WhatdoyouthinktheNoiseGateonthePeaveyJSXis?

R171cleanboostmod(Credit65SG,submittedtowikibySadisticSponge)

Thismodallowsthegainfunctiontoworkonthecleanchannel.Theendresultisavolume/trebleboostforthecleanchannelthathelpsgiveitabitextrapunch.TodothismodsimplylocateR171andcutit.Thatisall!

Originalthread:http://forums.peavey.com/viewtopic.php?f=19&t=12702&p=84667



Sadistic_Spongenotes:Ihavethemesamodengagedhere,meaningR122isremoved,meaningthatthegainboostisalwaysengaged.ThisdoesNOTimpactthismod'sfunctioningasfarasIknow.ItsoundsgreatandaddsalittlefunctionalityIcanimagineitbeingsuperusefulandit'seasyasallhell.

AnyonedoingThisModmaybeinterestedinalsoaddingaBALANCEpottoequalisethebiastoeachO/Pvalve.Evenmatchedsetscandrawdifferrentamountsofcurrentandastheyagethiscanbecomequitepronounced.IfanyoneisInterestedIwillpostdetailsofhowtodoit.(recklessrog)

BiasPotModThebiaspotmodallowstheampusertoadjustthebiasofthevalvesusingadialthatismoddedintothebackoftheamp.Thisallowstheusertodialoutsomeofthesterilityinthetoneandgenerally"warmup"theamp.(CreditstratoJim)Thebiasmodreallywarmeduptheampandtookoutalotofthegrittinessandincreasedresponsiveness.Itwasverynoticableinthecleanchannelbutaffectedthewholetone.

PeaveyVK112BiasMod(creditcap47)

ByCharlesPeck06/06/2009InthispackageIwilldiscussthestepsItooktomodmyVK112sothatitcanbebiasedmanually.Besidesthepartsthatareshownyouwillneedtoolsforthejob.Belowisalist.1.Goodqualitysolderingiron.2.Cuttingpliers(small)3.17/64drillbit4.Countersinkfordeburring5.Drill6.Multimeter7.BiasRiteorsimilar8.Smalldiameterelectricalsolder(rosincore)9.Ashoehornorpaintcanopenertoremoveknobs10.Cutyourselfsomewoodblockstopropboardon,longenoughtoreachacrosschassisandnottoothick11.WrenchestoremovejackandpotnutsandStandbySwitch12.SmallPhillipsscrewdriverandmediumsize.Smallflatblade.Thispictureshowsthepartsforthebiaspotmod.Youneedoneeach.IftheWeberbiaspotisnotavailibletryMojotone25KLor50KLpot.Also50KTrimmerPot#9010105.Justaboutany25KLor50KLwouldwork,theyarenotlockingthough.6/01/12cap47AlsoWeberWP253slotlockisa25Kbiaspot.



Tostart,Iinsertedmybiasprobesandtookreadingsoneachtubebeforeproceedingandrecordedthosereadings.Ialsotookreadingsacrossthe15kresistortouchedatleftterminalandprobedcenterterminal.Ithenpresettheresistanceforpotwith15kresistorto33k.Sameastheresistoryouwillberemoving.Usingalligatorleadsontheterminalsandyourmultimeterleadssoyoucanadjustsetting.Nowyouarereadytodisassembletheamp.Makesureampisunpluggedleavingstandbyon..DrainsCaps!

Removealltubes,powerandpreamp.Unplugspeakerandreverb.Thereverbhaswhiteplugatthechassissoyoudon'tneedtounplugatthetank.Justpullgently.Takeoutthetwoscrewsunderbackledge.RemovethePeaveylogoatfrontandthemetalplateatfrontjustunderchassis.Nowremovethe4longboltsatthetopoftheampandsupportthechassis.Youthenslidethechassisoutandputonyourworkbench.Nowitistimetogentlyprytheknobsoffeachpotonthefrontofchassisusingtheshoehornasshown.



UseappropriatewrenchtoremovenutsfromStandbyswitch,potsandfrontjacks.Checkstandbyswitchwithmmforvoltagebeforeproceeding.Alwayscheckvoltagesforsafety.Thecapacitorsarenotaccessibleuntilboardhasbeenremovedandflipped.VKisNOTselfdrainingSeeDisclaimerabove.Iassumenoresponsibilityifyouundertakethismod.Ifyoudon'thavetheexperience,don'tdoit.Thereasonthestandbyswitchisremovedistogiveyouroomtoflipthemainboard.Youwillfindaplasticwiretiethatholdsthewiresneartheswitches.Clipandremoveit.Powerswitchstaysin,donotremove.



Nowyouwillfindsmallblackscrewsholdingtheboardin.Approximately7orso.RemovethemwiththeappropriatesizePhillipsscrewdriver.Withthestandbyswitchlooseyoucangentlyliftandslidetheboardoutoffrontpotandjackmounts.LocateresistorR205ontheboard.Thisisthebabyyouwillremove,markit'spositionontheoppositesidewhenboardisgentlyflipped.Withboardturnedslidethewoodblocksundertheboardforsupport.NowyoucancheckvoltageatCapacitors.Shouldn'tbeany.Bewaretho.Ifallisgoodvoltagelevelsyoucanproceedtounsolderthe33kresistoratR205.Notethisprocesscanbefollowedforthe39kresistorfortheVK212andVK100head.Onlydifferenceispresetthepotandresistorinseriesto39k.Useaprobetopullitdownoneachpinuntilitcomesout.Cleanoutthe2holes.Takethenewresistorandcutoneleadabout1/4ononeendonly.Insertthatendthrufarenoughtogetitsolderedtotheboardattheleftholeshowninpicture.Beforegoingtoofarthoyoushouldtestplacethebiaspottodeterminewheretodrillthe17/64holeformountingtochassis.Seepicture.



Theboardisshownherewhereitmountsbutisnotyetscrewedbackin.Onceyouhaveampleclearancetogetpotconnectionssoldereddrillanddeburrtheholeinchassis.Cleanallchipsoutofthechassisandboardareasusingasmallvacuumorblowitoutgoodwithacanofair.Don'twantanychipsshortingthingssocheckgood.Mountthebiaspotasshownandgentlytighten.



Nowinsertthejumperintotheotherboardholeandsolderatthecircuitside.Fliptheboardbacktoitsfinalassemblyspotandgentlybendtheresistorwithsmallpliersuntilitmeetsthepotterminalshown.Putashimundertheterminalsotheleaddoesnotshorttochassisandsolderittotheterminal.Repeatwiththejumperandsolder.Myjumperisactuallytworesistorleadssolderedtogether.Besureyoumadegoodsolderjoints,veryimportant.Damagecanbedoneifitisnotagoodconnection.Noticewhichterminalswereused.Inthispicturethefarrightisnotused.Byusingtheleftoneandthemiddleitgivesyouanincreaseinmilliampsgoingclockwise.IftheotherendterminalwereusedinsteadoftheoneshowntheincreaseinmilliampswouldhavebeenCCW.Checkallyourworkandmakesureitisclean.Putthescrewsintheboardsnug.Putthestandbybackin.Puttheplasticnutsonallthejacksandonlyfingertight.Thenutswillsplitifovertightened.Putthemetalnutsonthepotsandsnugthem,don'tovertighten.Pushtheknobsbackonandreassembletheampinreverseoftakingitapart.Rememberwepresettheohmratingofthepotwiththe15kresistor.NowyouhavetousetheBiasRiteorsimilartosetthebias.Itisbesttouseanoldsetoftubestostartwith.Thepotshouldbecloseenoughtogetitfinetuned.Onceyouareconfidenteverythingworksrightyoucanputinthegoodtubesandtuneitin.

Nowthegoodpart.Playthedamnthing!



BiasTestJacksDonebyJason43onhis212headconversionVK.>Allowseachindividualpowertubebiastobetestedwithease.Testjacks:

Forthis,youneedtoinstalla1ohm,1wattresistoracrosspin8ofeachpowertubeandground.Thereisajumperoneachsocketthatconnectspin8toagroundtraceonthepcb.Removeeachjumperandreplacewiththeresistor.Onceyoumountthetestjacksinthechassis,runawirefrompin8ofeachpowertubesockettoeachoftheredtestjacks.Theblackjackconnectstoground.ThejacksaresoldthroughWeberspeakers.

PLEASENOTE!!!theresistorsshouldreallybe3Wattwirewound.Thisisbecauseifthevalveshoulddevelopashortcircuitanda1wattmetalfilmorcarbonresistorisused,itwillburnoutandgoopencircuitleavingthetestpointatapossiblyHIGHVOLTAGE!!!Apartfromtheobviousshockhazzard,itcoulddamageyourtestmeterifyouhaveitsetonalowrange.IdeallythemainpowerfuseshouldblowBEFOREtheresistor!!!!(recklessrog)

AlternativeBiasPot&TestJackPositionsCredit:NikPlayer(sizzlingbadger)5thFeb2011

Thisallowsthebiastobemeasuredandadjustedviatherearpaneloftheamp.



TipsonbiasCreditGioBos

Measuringthevoltageoftheplate,onmyValveKing,theresultwasof470V.Itshouldbethesameonotherversions.Suggesttheformulaforthebias,basedontheplatevoltageoftheValveKing:

mA=[(0.6*30)/470]*1000

0.7=70%ofthepower(suggestedcalculationfrom50%to70%)



30=Maximumwattagedissipationof6L6

470=platevoltage

Recommendedbias:

Coldbias:approximately31ma(50%poweratidle,suggestedformetaltone,tubelonglife,highheadroom)

Averagebias:approximately38ma(60%poweratidle,suggestedforall,tubenormallife,midheadroom)

WarmBias:approximately45ma(70%poweratidle,suggestedforWarmtone,tubeshortlife,lowheadroom)

Thesedatabasedonacalculationofthecorrectbiasofthe6l6tubesonvalveking.Iwouldrecommendgoingbyearandtaste,from30to45.

StockbiasinmyValveKingwas21,justtoocold!!andmainreasonforthestockcrossoverdistortion.

FootswitchDelayFix(C124mod)(onlyapplicabletooldermodels)Thefootswitchmodisdesignedtofixtheslightdelaywhenchangingchannelsonthefootswitch(thisonlyhappensonoldermodelssouserswhohavenotexperiencedthisproblemneednotcarrythismodout).BelowisacopyoftheemailcorrespondencebetweenaVKuserandPeaveyTechnicalSupport:(creditMathamology)

OriginallyPostedbyme!Hithere,

Iassumethisisthecorrectaddresstosendthismessageto!IownaPeaveyValveking112(serialnumberK0238806),Ibelieveitisoneoftheoldermodels.AsI'msureyouareaware,thereisadelaywhenswitchingbetweenthetwochannels.Afterabitofresearch,IfoundsomethingthatsuggestedtheremovaloftheC124capacitorinthecurcuitwouldsolvethisissue.Couldyoupleaseclarifyif:

A.ThisistrueB.Ifitistrue,doIneedtoreplacethecapacitorwithanything?C.Iknowit'snotreallyassociatedwiththepowersection,butdoesthiscapacitorhavethepotentialtoshock?

Ihopetohearfromyousoon,andmanythanksinadvance,

Hereistheirresponse:

OriginallyPostedbyPeaveyHelloMatt,



Thankyouforyourquestion.

Yesthisdoesimproveswitching.Thechangeisremovalandwillnotneedsubstituted.

Youhavetobeverycarefulwithallvalveampsastheycanstoreextremelyhighvoltagesevenwhentheunitisnotpoweredup.

RegardsBrian

Fixingtheswitchdelay,asadvisedbyPeaveyTheremovaloftheC124capacitorintheValvekingshouldimproveswitchresponse.Thecapacitordoesnothavetobereplaced,socompleteremovalshoulddothejob.Asmallpairofclipperswillbesuffucienttoremovethecapacitor.

(Creditilyavforfinding,PeaveyForumsforsource)Here'swhatI'vedonetoreducechannelswitchingdelayinmyVK100head.

Firstofall,youneedtounderstandwhythereisadelay.Ifyouhavetheschematic,noticeQ101,thisFETisusedasaswitchthattemporarilymutestheaudiosignalwhiletherelaysswitchchannels.Thiswasaddedinordertoremovetheshortpopthatiscreatedwhenswitchingfromcleantolead.Therefore,thetemporarymutingisnecessary,butitdoesn'thavetobesolongasitcurrentlyis.WhatImeanisthatyoucanremovesomemuting,butshouldn'tremoveallofit.

Solet'sgettobusinessthewaythiscircuitworksisasfollows.Wheneitherthefrontpanelswitch,orafootswitch,isusedtochangechannelsthevoltageatR142changesfromgroundto+14V.C131onlyletsthechangeinvoltagereachtheTriacandpullsdownthegateofQ101veryfast.ThisresultsinQ101mutingtheaudiosignalforsometime.ThegateofQ101willremainatgrounduntilitispulledbackupto+14VbyR138.TheexactamountoftimeittakesforR138todothisisdictatedby2factors:TheRCtimeconstantformedbyR138&C130,andbytheVgsoffofQ101.IfyoulookatthedatasheetofQ101(J174),you'llfindthatVgsoffcanbeanywherefrom5Vto10V.Solet'susethemedianvalueof7.5Vforsimplicity'ssake.ThismeansthatthemutingwillbecompleteandtheaudiowillreturnwhenR138haspulledthegateofQ101uptoroughly7.5V,whichisabout53%ofthetotalvoltage.Ifyouunderstandtimeconstants,you'llknowthatR138*C130=timeittakestoreach63%ofthetotalvoltage.Sotakeoutyourcalculatorandmultiply2.2Mby22nandyouget48.4ms(theactualtimeisabitlessdueto63%>53%),thismutingtimeisdefinatelylongenoughforanyonetohear.

Sohowcanyoumakethisfaster,wellyoucanreducethesizeofC130orR138,butreducingC130willaffectboththeturnONandturnOFFtimesofthemutingcircuit,soIrecommendreducingthevalueofR138.I'vechangedR138to1MinmyVK100andfoundthatchannelswitchingfromcleantoleadwasmuchfasterandnotnoticeableanymore.Ofcourse,duetothehugerangeofVgsoffinQ101(5Vto10V),youmightnotgetthesameeffectbyusing1MinR138.Soexperimentwithsmallervalues,470kisprobablythelowestyoushouldgo,butrememberthatifyoumakeR138toosmall,somechannelpoppingmightstartshowingupatthespeakersinceyou'reinhibitingthemutingcircuit.

(creditilyav)"SAGResistor"Modw/bypass



Nosounddifferenceinlowvolumes,Butwhenplayingloud(Powertubesneedmorecurrent)TheresistoractslikeaTubeRectifier.Link:http://studentweb.eku.edu/justin_holton/sag.html

Beautiful.

TheresistorlowersthePlateVoltageby25v(Biasunchanged)likea5V4GA.Alsolowersthebiasfrom40ma(460v,45v)to25ma(435v,45v).ButwhenIrebiasto40mathevoltagedropis50vlikea5R4GYB.

Ohwell...GotmeaTubeRectifierEmulationSagSwitch.

(creditilyav)*AlsomadetheDistortionchanneltighterbychangingstheC103from2.2nto1n.madethebassrolloffat700hz(300hzold).

A/ABPotremoval*RemovedtheA/ABclassPot.(Madetheampalotlouder)noshitinthesignal.Hereiswhatilyavsaidhedid:RemoveA/Bpotandit'swires{leavegroundwireperhisedit)(clip/unsolderthem)ChangeC144to47N(tobe=toC135)oryoucanusetheexistingC144inserieswithunsolderedC1fromtheA/ABboard.Capsinseriesbehavelikeresistorsinparallel.Ex.Cap47inserieswithCap47isCap23.5.Nowsolderasmalljumperfrompin8totheC144legnearit.Editbyilyav:Thereisagroundwireinthe4wiresoftheA/ABpot,leaveitconnectedclipthe3others.

*ModdedthePItothisscheme:http://www.freewebs.co.uk/valvewizard/cathodyne.html

*RemovedtheFXloopmodIdidearlier.

*AddedaMarshallSwitchwhichleavestheDistortionchannelwithonly



2gainstages(insteadof4)andEQ.(likeMarshallPlexi).

(creditilyav)

JCM800modI'vegottopostitguys...My(old)JCM800/Marshallmod.

Whatitdoes:Itbypassesonegainstage.Theonewiththediodes(whichIremovedanyway).Andleavesyouwith3gainstages&theEQonthegainchannel,(justlikeJCM800).*VKhas4gainstagesonthedistortionchannel,thatswhyitstoosaturated&notarticulateenough.TheJCM800has3thenEQ&Plexihas2thenEQ.

AlsoIbypassedtheC149,itwascuttingthehighendotherampshave.*(thisisessentialtotheMarshallsound),(onthephoto).*Notshownonthephoto,butwasaddedlaterontheDPDTswitch,toreturntheVKtoitsoriginalsound.

SoundsBEAUTIFUL!!!!!!!I'vegotamazingCLEANsoundwithgaintill5,YesCLEANsound.VeryPlexilikedrivewithgainon10.WiththeGainboostOn.itsHEAVEN.NoboostingPedalsneededjustarticulatebeautifulROARINGdistortion.

NowIcanactualycontroltheAmpsdrivewithmyguitarvolume.

Hereitis:ClickmyAvatarforSoundSamples.orhere:http://soundclick.com/share?songid=8456721*EverythingwasrecordedONLYontheLeadChanneloftheVK(ontheJCM800mod).*ThefirstfewriffsGainon3,5,7,10(noboost).*OneSM571inchawaysfromgrill,ontheedgeofthecap.

*IactuallyliketheCleansontheleadchannelbetternow.*PlayedwiththeNeck&BridgePUinnoorder(EMG85&81).(mindtheplaying,Itwasonlyforthedemo).



Howdoesitwork:UseDPDTONONSwitch.1.TakethesignalfromtheC106&R106junctiontooneoftheswitheslegs.2.UnsolderR107'sleftleg(onphoto)solderittotheotherleg.3.TheCenterleggoestowhereyouunsolderedtheR107(lefthole).

*ifyouwanttheC149back:SolderC149totheVKsideontheswitch,&tothebottomlegofwhereitwas.SoldertheCentertoground,upperlegofwhereitwas(onthephoto)

Thatsit.Allitdoesisselectsif2(JCM)or3(VK)stagesgoingintothelaststagethenEQ.

Themastervolumeispointlessnow,asIcanhaveanythingfromcleantoCrunchtoFullonMetaljustbyplayingwiththeGain&ModSwitch.Iwantedtoinstalltheppimastervolumetomakethecleanchannelcruch,Don'tneedtoanymore.

ThereisanewJCMmodfromthePeaveyForums.Credit65SG!Usethislinkhttp://forums.peavey.com/viewtopic.php?f=19&t=27933Addedbycap47.Readallforinfoandcomment!

TestimonialbySadistic_Sponge:ImoddedmyVK112withboththeMESAmod(seebelow)andtheJCM800mod.TheJCMchannelfeelsatadthickerwithmoreballstoitbutlessgain,whilethemesamodeisabittighter.BothsoundMUCHbetterthanthestockVKdistortionand



theyhaveMUCHmoredefinitionandthefizzinessofthedistortionisnowgone!

TestimonialbyLivingExperiment:ImoddedmyVK112andALSOmyVK212withilyav'sJCM800mod.CleanchannelstayedthesameandwascompletelyunaffectedwhichIreallyliked.WhenyoucompletethismodallyourfavoriteEQsettingswillhavetochangeforthedistortionchannel.Ifyoucanlivewiththat,dothismod.BothofmyVK'ssoundamazingnow,andIwishIhaddonethissooner.Everythingat12oclockonthegainchannelmakesaniceBushMachineheadtone,butcrankthedistortionandtweaktheEQandyoucannowdometal.VK212hadtobecranked(justlikeanyMarshall)togetthesametonethattheVK112hasatlowervolumes.IhavealsodonetheMESAmod.Whilebothmodsare,nojoke,10xtimesbetterthanstockVKdistortion,IpreferJCM800totheMESAmodsincemybandLivingExperimentdoes"danceablerock"coverbandstuffandsomemetal.IfwedidprimarilymetalstuffI'dgowiththeMESAmod.AddedbyLivingExperiment

Justanote:Idid65SG's'new'JCMmodtoatee,excepttheresistoracrosstheswitchcontactstoeventhevolumebetweenthetwoleadchannel'modes',asIdidn'thavea750kresistorhandy,anddidn'twanttorunanyinseries(extrasolderjoints,potentialforworsesoundjunkinsignal,etc).Anywho,Iputitallbacktogether,trieditout,andforsomereasonmytwomodes(whiletheysoundliketheyshould,whichisAWESOMEnow,thanksto65SG'stutorial)don'thaveadifferenceinvolume,justthedifferenceingain/tone.Iamrunningapeaveyvalveking212(oneofthenewerrevisions).PRS_Tim

(creditilyav)

MESAmodItmakesthegainchannelmilliontimesbetter(exaggerating).MesaandBognerlike(Notexaggerating).

RemoveR122(nojumperneeded).LeaveR124inplace(Don'ttouchit).R116to10k(Wattagedon'tmatterhere).(10Khasmoregain,22Khasless...tightnessoftonedependsonEQandsetup)

Thetonestackcap&resistorarecrutialtoMesasoundC2to470pFR4to47k

Ifit'stoodarkremoveC149(cutonelegofit).

Thecleanisunaffected.You'lllosethelowgainoption(alwayshighgainnow,withlessgain[10k]).*ButstillcanbeveryloworVeryhighgain.Thestructureandarticulationofthegainnowisfenomenal.ThegainbuttonnowcontrollsC115(470n)on/off,Soldano(off),Mesa/Bogner(on[tighter])*Ifyoulikedthegainchannelwithaboostpedal,you'll"Die"fromhappinessonthismod.(ithasplentyofgainnowonthenormalgain,andplenty&tightergainonthegainon.

TheMesamodremovesthelowgainmodecompletely.Anditlowersthehighgainmodeabitandmakesthesoundmuch,muchcleaneranddefinedbut



stillwithplentyofgain.

Thegainswitchnowactslikeafatbutton.Whatwasthelowgain(off)nowhasplentyofgain.Andwhatwaswiththegainbooston,nowisalotmoredefinedandclear.

(creditStefan_L_01)

JustanoteabouttheMesaMod:Thehighertheresistorvalue,thelowerthegain.Itriedonce39kandthisalmostdisabledthisstage,reducingittothe"normal"gainmode.Itslogic,witha100korsoyouwouldhavethecathodyanphasesplitterwithgain1...

Soifyouwantkeepanoticabledifferencebetweenthe3stagegainand4stagegain,idusemax.10k.Thisalreadyreducesgainalot.Youcancompensatewithahighergainsettingofthecontrol,butagain,the2gainchannelsgetclosertogether.

Ifyouneedalowgainrocktoneandahighgainmode(coverband),leaveitthewayitis,orincreaseitslowlyandfindthebestsettingforyourstylemix(2k,4k,10k,20k).

SadisticSpongenotes:AfterdoingbothMesaandJCMmodsIhaddifficultytellingthetwochannelsapart.BasedonStefan_L_01'sobservationschangingR116to5khelpstheissueimmensely.IalsochangedR101to100ktomakethemesamodemoredistinct.Lastly,makesurethatyouuseappropriateresistorvaluesifyouuse65SG'smesamod.Thisvariesdependingonyourtubesetup,soyoumightneedtotroubleshoot.Ihave470kand220kanditworksgreat.

I'vealsoputa20kpotinplaceofR116,whichletsmetakethechannellowergainthantheJCMmodetoultrahighsaturation.Note,however,thatyoushouldputa2kresistorattachedtothepotoritwillsqueallikeastuckpigwhenyouturnitalltheway!

WARNING:Youhavetobeverycarefulwithallvalveampsastheycanstoreextremelyhighvoltages,evenwhentheyarenotpoweredup!Youhavebeenwarned!

___

VK112ExternalSpeakerJackforinternal/externalspeakeruse:Aswealreadyknow,whenusingthe"stock"ext.speakerjackitshutsofftheinternalspeaker...bummer!!!SoIhaveaddedanexternalspeakerjackofmyown...ThisisVERYeasyand...

DOESNOTREQUIRETHEREMOVALOFANYTHING...

Youwillneed:amono1/4"standardjack,asuitablejackplate,a11.5'lengthof16ga.speakerwire,



acoupleoffemalesolderlessspadeconnects,adrilland7/8"woodborebitandscrewstomountthejackplate...

First,DrillaholeinthebottomrearpanelofyourVK112withthe7/8"bit...

Second,Attachthesolderlessconnectstooneendofthespeakerwire,makngnoteofplusandminus...Thenattachthemtothecorrespondingterminalsonthe"stock"speaker...

Third,Threadthespeakerwirethroughthe"guides"ontheinsideoftheVK112cabandoutthroughtheholeinthelowerpanelthatyoudrilled...

Fourth,Solderthethespeakerwiretothejack,againmakingnoteofplus(tip)andminus(shield)...

Fifth,Mountthejacktotheplate...

Sixth,Mounttheplateassemblytothecab'slowerpanel...

Seventh,Vacuumtheinsideofthecabtoremovethesawdust...

That'sit!!!YoucannowpluginandrunanexternalcabwiththeinternalVK112speakersimultaneously!!!

WARNING!!!Thiswirestheinternalspeakerandanexternalcabinparallel..BecarefultoONLYusea16ohmexternalcabwiththisconfiguration!!!PeaveyrecommendsaMINIMUM8ohmloadfortheVK112...

Enjoy!!!

MayGodBless,Luckyman77

_

ThislinkisamodtakenfromaUTubemodandrefineduponbycap47.Thelinktakesyoutotheoriginalpostdetailingthemod.http://www.ultimateguitar.com/forum/showpost.php?p=25566983&postcount=10147



GainStage#3Enhancement(byjdoorn01)Throughamalfunction,IgotalotoftimeinexperimentingwithmyValveKing212.Q103somehowbrokedownandbecamefused,whichseemedtoaffectthebiasofgainstage#2.Whileitwasmalfunctioning,thetoneofthegainstagewasgreat.WhenIfixedit,Ifeltitwaslackingabit.IfoundthatGS3wasagreatstagetofoolaroundwithtoremedythisloss.

Here'swhatI'vegot:RemoveC149(improvesGainChannelbrightness)ReplaceR101(150k)witha100kresistor,Iwentwith1/2wattCF.

Whatthisdoesisdecreasethegainslightlyofthethirdgainstagewhileincreasingtheproportionofevenorderharmonics(gooddistortion).Itsoftensthesoundoftheampslightly.ThisgetsitalittleclosertoJCM800territory.Ifyouwantedtogotheextramile,itmightbeworthswappingthefirsttwogainstagesloadresistors,R103andR104,with100kresistorsaswell.Ididnot,asthiswouldaffecthowglassythecleanchannelis.

NotethatifyouhavetheJCM800modfromilyav,thiswon'taffectanythingin"JCMmode."

SadisticSpongenotes:YoucanalsogetawaywithremovingC117tobrightentheampaswell.I'veactuallyremovedboth,thoughthesoundmightwealittletoosharpforsomepeople.Inthiscaseputa470pFresistorinplaceofC149.

50/100WSwitch(VK100/212ONLY)(jdoorn01)

Here'sanidealiftedfromMesa/BoogieLonestars,verysimple.

IfyouremovetheTextureboard,youcanhavesomethingbetter,imo.Savethe100ncap(C1)andinstallitinserieswiththe100ncap(C144)onthepowerampboard.Thiscloselymatchestheothersideofthesplitter(C13547nF).Alternativelyyoucouldreplacethepairwitha50ncap.YoumustusethissetofcapstobridgethegapleftbyremovingtheTexturecircuit.RefertotheVK100/212schematicfordetails.

Onceyou'veaccomplishedthis,throwaDPDTswitchinitsplace.LocatethecathodejumpersforeitherV7&V6ORV5&V4,pin8.Takealeadfromthepin8sideofthejumperfromeachofthetwotubesyou'vechosenandruneachofthoseleadstotheirowncontactontheswitch.Takethegroundsideofthejumper,orjustsoldertothatfatgroundtraceandbringthattothetwocommoncontactsonyourDPDTswitch.

Whatthisdoesisdisconnecttwoofthepowertubes,onefromeachsideofthepush/pull,anddeactivatesthecathodeground.ThisishowMesadoesitintheLonestar100Wseries.

*Besurethatyouaredeactivatingonetubeoutofeachpairthatformsthepush/pull.ThatwouldmeanyouwoulduseV7&V6ORV5&V4,notV7&V5orV4&V6.

ThisallowsyoutodothesamethingasinaMarshall,whereyoucouldpulleithertheinsideoroutsidepairsoftubestocutitfrom100Wto50W.SincetheVKusesseriesheaters,wecan'tjust



dothat.Thisgetsarounditandisslightlymoreconvenient,IMO.

BufferMod(takeoutannoyingtreble)(CreditGiordanoBoschettigiobos)

PleasebesuretoreadtheWarningspagebeforedoinganymodstoyouramp.Thisisaverysimplemod.Noteveryonelikestheeffectofhighendbufferloop,includingmyself.Infact,especiallyinhigain,feelsveryannoyingtreblethatmakethesoundoftenconfused,andcrossoverdistortionlike.Solution:Lowpassfilter!

Material:oneortwo.010uf50v(103pfor10nf)capacitorSolderonelegofthecapacitortotherightlegofr174,andtheotherlegofthecapacitortotherightlegofr169(thesignalgoestogroundhere),DONE!Soundunbuffered,buffered:witha.010ufcapacitoronsend,thesoundismoreorientedtothemediumfrequencies,thepot"treeble"nowcontrolsthemid/highfrequencies,cuttingthecrossoverfrequency,andgivingcream.Thedifferenceinvolumeisslightlyabovethesoundwithoutthebuffer.withtwo.010ufcapacitorsinseriestothesend(.005uf),equalizationandsoundareverysimilartothesoundwithoutabuffer,butmore"open",cuttingapartofthecrossoverfrequencies.Thedifferenceinvolumeisalmostlikethebufferstock.IusedaDPDTswitchforthis,positionedbetweenthemidrangeandtreblepot,onecapacitorortwocapacitorsinseries(bright),theresultistwoverydifferentsounds.itisalsopossibletosoldera5kpottorightlegofR173withthecapacitor.010ufthatgoestorightlegofr169,soastoallowanfineadjustment.IuseTungsolReissueV1,China12ax7BV2,SovtekLPSV3

A/ABpotremoval(praticalalternative)(CreditGiordanoBoschettigiobos)

First,thankstoilyav&cap47fortheinformations.

Ifoundaconvenientandfastwaytodothis.

Unsolderpottexture,andc1

Cutthecentralpinoftheclip(theleftpinistheresonance,therightpinisground,thecenterpinsareconnectedtothepottexture,ValveKing112)

Solderc1,betweenpin8andtheleftlegC144(C144&C1connectedinseries,ineffectabypassofthepot)

Thepicturesaysitallmuchmoresimply.



Ifinsteadyouwanttochangethecapacitor,wemustactashesaidilyav,changeR144,pin8connectedwithajumperatR144

HalfPowerMod(howtopulltheoutsidetubesonVK212and100)(Creditjmjlai)OneoftheeasiesttrickstoreducethepoweronaABpushpullampistopullthetwooutsideorinsidepowertubes.Thiscanusuallybedonebecausethetwoleftandtworighttubesareinparallel.OntheVK212&100,thiscannotbedonebecausetheheatercircuitiswiredinseries.Simplyput,yourampwon'twork.FollowingiswhatIdidtotakeouttheoutsidepowertubeswithoutpermanentlyaltering/damagingyouramp.IalsosentmymodintoaPeaveyengineerwhoreplied"Shouldbefine....nowarranty,though."Thisbringsthefullpowerto50WandIwouldassumetheclassApoweris25W.



Thekeytothismodisthatheatershavearunningresistancewhenhotwhichmustbematchedto:

1. notoverloadthetransformer2. notoverheatthetube3. notunderheatthetube

A6L6tubeisspec'dtorunat6.3V@900mAwhenrunning.Thereforetheresistancepertubeweareshootingforis7Ohmscapableofdissipatingatleast6W.Iused322Ohm,5Wresistorsinparallelpertube.Imountedthesetoperfboardandwiredtheresistorbankstotheheaterplugsonthetubesocket(DON'TMESSTHATUP!!!)Makesureyoulookatthepinout.Asfortubepins,Ifoundthat440machinescrewsworkgreat.Icrimpedthewirestospadesandusedlockingwasherstoensureasolidconnection.



Ialsoaddedacpuheatsynctotheresistorbankbecausetheresistorsweregivingoutenoughheattoburntheperfboard.Ithenscrewdtheperfboardintothesideoftheampandpresto!Inowhavea50Wamp!

Onethingyouwillhavetoremember.resistorsaremuchmorelinearthanheaterfilamentssoyour2powertubeheaterfilamentswilltake35timeslongertostartglowing.makesureyouleaveyouramponabout5minutesbeforeyoutakeitoutofstandby.havefunbeingabletoturnyouramppast2!Whenpulling2powertubesona4tubeamptheohmsettingofyourspeakershouldbereducedby1/2(16to8,8to4ohmetc.).cap47

KillingExcessHum(Creditto65SG,SubmittedbySadistic_Sponge)

SomeVKshavetoomuchhumwhenidling,whichiscausedbygroundingissues.Thishelpstoeradicatethisproblem.Ihavelinkedthethreadbelowscrolldownabit,thesolutionyouwanthasyouusingsolderingwicktogroundthepotentiometersandinputs.NotethatthisthreadalsogivesdetailedinformationonhowtotestanddrainthefiltercapacitorsontheVKboardwithoutstickingthingsinyourpowertubepins(whichisactuallymypreferredmethod).

http://forums.peavey.com/viewtopic.php?t=11148

PeaveyVK112ModificationsQuickGuideTexturePot/R100conversion

Removewires2and3fromtheP303/313jumper.RemoveC1andR3fromtheoutputbreakawayPCB.FitawirelinkinplaceofC1.RemoveR100andfittwolengthsofinsulatedwireinitsvacantholes.Fittheotherendofthesewiresintothepins2and3positionofP313.RemoveC144andreplaceitwitha47n400vPolyestersimilartothetypefittedatpositionC135.Fitajumperlinkbetweenpin8ofV3andtheterminalofthenewC144nearesttoit.Younowhavecontrollablegainboostandremovalofthenoiseinducing,



AyudaAcercadeBlogPrecioPrivacidadTrminosApoyoElevardecategoraContributionstohttp://ultimateguitarvalveking.wikispaces.com/arelicensedunderaCreative

CommonsAttributionShareAlike3.0License.PortionsnotcontributedbyvisitorsareCopyright2015TangientLLC

powersappingTexturecontrol.ImprovedistortioncharacterRemoveC149,removeC103,fitC149intopositionC103andleaveC149positionempty.RemoveR101andreplacewithvalue100k.DecreasechannelswitchingdelayRemoveC124andleaveitspositionempty,removeR138andreplacewithvalue1M.

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