VAC Phi 300 Setup guide

300.1
TheVACPhiThree Hundred
Stereo/MonoBeam PowerAmplifier
Operation&MaintenanceInformation
ValveAmplificationCompany
Manualissued03/06/2007

1
CAUTION-SAFETYNOTICE
THEAMPLIFIERCONTAINSNOUSERSERVICEABLEPARTS. DONOTREMOVETHEBOTTOMPLATES
OR CHASSISCOVERS. LETHALVOLTAGESAREPRESENTWITHINTHECHASSIS. DONOTOPERATE
THEUNITSIFTHEYAREWET.
VACUUMTUBESBECOME HOT ENOUGHTOCAUSESERIOUSBURNS.NEVERTOUCHATUBEWHEN
THEUNITISON.ITMAYTAKESEVERALMINUTESFORTHETUBESTOCOOLDOWN AFTERTHEUNIT
ISSWITCHEDOFF.ITISSTRONGLY RECOMMENDEDTHATTHETUBECOVERSBELEFTINPLACEATALL
TIMES.
THETUBECOVERSWILL BECOMEHOTINNORMALOPERATION.DONOTSETORSPRAYANYTHING
ONTHEM.
Never touchatubeiftheglass isbroken.Theinternalstructurescarry highvoltageandcouldpresent
aserious,possiblylethalshock.Ifatubebreaks,unplugtheamplifier andwait30 minutes,then
removethetube.
Keepflammableobjectsawayfrom theamplifier.
DONOTLEAVETHEAMPLIFIER UNATTENDEDINOPERATION.
THEAMPLIFIER IS HEAVY. ITISADVISABLETOHAVEASSISTANCEINUNPACKING,MOVING,AND
SETTINGUP. BESURETOUSEPROPERLIFTINGTECHNIQUESTOAVOIDBACKSTRAINAND INJURY.
BECERTAINTOINSTALL ITINASECURELOCATIONFROMWHICH ITCANNOTFALL OR TIPOVER.

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INDEX
Introduction
Installation
Installingthefrontglass andtopbars
Inputconnectors
Operation
Feedback
Triode&Ultra-LinearModes
IlluminatedLogo
InstallingNewOutputTubes
Biasing&CheckingOutputTubeCondition
ReplacementofLowLevelTubes
Care OfChassis
TipsandAdvice
AWordAboutTubesinGeneral
OutputTubes
LowLevelTubes
ImpedanceMatching
Grounding
TuningYourSystem
Specifications
Footnotes
Warranty&RegistrationForm

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INTRODUCTION
ThePhi300 isauniquepower amplifier,andthemostpowerfulanddetailedinVAC’s history.
Featuringanewdirect-coupledinput&driver circuit, extremelyfastandvividsoundisachieved
from bothsingle-endedandbalancedsources.
ThePhi300 maybeusedasa150 watt/channelstereoamplifier,orasa300 watt monophonic
amplifier,asdeterminedbytherearpanelswitch.Ineither mode,frontpanellevelcontrolsmaybe
selectedorbypassed;thesecanbeusefulinbalancingroomacousticsortrimminglevelbalance
inbiampapplications.
Thefrontpanelmutecontrolisusefulwhenexchangingcablesormakingchangestoyoursystem.
Triodeswitchesare providedforthosewhowishtoexplore thatoperatingmode.
Thechassisismachinedfrom thickaluminum, finishedinametallicbasecoat/clearcoatfinish.
ThePhi300 isdesignednottothelatestfadbuttosubstance,forthehighestpossiblesoundquality.
Timespentfamiliarizingyourselfwiththismanualwill bewell rewarded.

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TubePlacement-VACPhi300
V9V10V11V12KT88
V1V2V3V46SN7
V5V6V7V8KT88
INSTALLATION
001)Install thevacuumtubes.Eachtube
oritsboxhasa“V”number,which
correspondstothelabelsonthetop
plateoftheamplifier;theseindicate
where eachtubeshouldbeinstalled.
Fiteachtubeintothematching
socket.
Wheninsertingandremovingtubes,
handlethembytheirbases,notby
theirglass bulbs.
Notethatthere isalocatorpinon
theoctal(eightcontact)tubesthat
indicatesproper alignment.
02)Verifythatthetwo“UltraLinear/Triode” switchesare settothedesiredposition.The
ultralinearsettingwill deliver thebestsoundqualityinmostsystems.
03)Carefullyinstall thefrontglass andtoprails(see detaileddirectionsinthenextsectionofthis
manual). Takecare nottochiporscratchtheglass.
04)Settherearswitchtomonoorstereoasdesired.
05)SettherearpanelattenuatorswitchtoDIRECT(bypassingthefrontpanellevelcontrols)or
VARIABLE(engagesfrontpanellevelcontrols)asdesired.
06)Connectthespeaker cables;theblackleadgoesto“-“or“Ground”.Theredleadgoesto
“+” or“Positive”. Followthechartofthebackoftheamplifier fortheimpedancethatbest
matchesyourloudspeakers.
07)SettheinputtypeswitchtoXLR (forbalancedinput)orRCA(forsingle-endedinput).
08)Connect12 volttrigger inputcablesintotheappropriatesocketsonthebackpanelif
desired;either will slavetheoff/onfunctiontotheexternalconnection.
09)Provideadequateventilation-allowatleast3inchesaboveandtoeachside.

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10)Donotplaceinacompletelyenclosedcabinet.Donotstackother equipmentontopofthe
VACunit.
11)Donotoperateoncarpetoranyother surfacethatmightblockairflow.
12)Thechassisandglass will becomehotinnormaluse.
13)Donotallowthechassistotouchanymetalparts,suchastheframeofanequipmentrack.
Thismightcreateaparallelgroundpaththatcoulddegradethesoundofyoursystem.
14)Connectthepower cordtothepower sourceindicatedontherearpanel(will beeither
100, 120, 220, or240 voltsAC). Voltageconversionsmustbedoneatthefactory ofby
anauthorizedVACimporter.
15)Avoidpower conditionersthatfloatthegroundpin.
16)Power requirementsare approximately1000 watts.Paycloseattentiontopower quality,and
beaware thatdifferentpower cordscanalter thesound.
17) Checkthebiassettingsoftheoutputtubeswhentheunitisfirstinstalled andwhenever a
tubeischanged.Itisalsoagoodideatoverifythesettingsperiodically,suchasoncea
week. Followthebiasprocedure outlinedlater inthismanual.
18)Notethatthere isafrontpanelMUTEswitch; thisfunctioncausestheinputsignal(s)tobe
muted.ThePhi300 will onlybemutedifyouselectit.Thismaybeusefulifyouare changing
cablesorsourceequipment.
NOTE:Donotremoveandconnectinputcablesorspeaker cableswhileisamplifier isrunning.
Doingsorisksdamagetoyourloudspeakersortheamplifier.
Donotoperatetheamplifier withoutaloudspeaker orloadresistorattached.
Donotoperatewithoutthefrontglass andtoprailsinplace.
Takecare tokeepeveryone, especiallychildrenandpets,frombeingabletoreachand
touchthetubes, whichbecomeextremelyhotandcauseseriousinjury.
Never touchatubeiftheglass isbroken.Theinternalstructurescarry highvoltageandcould
presentaserious, possiblylethalshock. Ifatubebreaks, unplugtheamplifier andwait30
minutes, thenremovethetube.
Keepflammableobjectsawayfrom theamplifier.

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INSTALLINGTHEFRONTGLASS AND TOPRAILS
Youramplifier hasbeenshippedwiththefrontacrylicglass andthetoprailsromoved.
Thefollowingstepsshowhowtheseare installed.
Theglass installsinthegrooveatthetopofthefascia.
Insertitataslightangle, asshown.
Handletheacrylicglass carefully,anddonotscratchit.Scratcheswill show
stronglywhenthepanelislightedinnormaloperation.Yourpanelwas
carefullyinspectedpriortopacking.
Thepanelwill restsecurelyinthegrooveasshown.
Thetoptubecagebarshaveaspringpinineachend.
Toinstall,placeoneofthespringpinsintooneofthesmall dimples
machinedintooneofthesiderails.
IntheIllustration, thepinhasbeenlocatedintotheleftsiderail.
Tocompletetheinstallation,press thebarinthedirectionofthepinalready
inserted, andmanoeuver theother endintothecorrespondingdimplein
theother siderail.
Inthisillustration, thebarispressedtotheleft, whiletherightspringpinis
setintothedimpleintherightsiderail.
Theamountofprotrusionofeachpinmaybeadjustedslightlyifneeded.
REMINDER:Donotremoveandconnectinputcablesorspeaker cableswhileisamplifier is
running. Doingsorisksdamagetoyourloudspeakersortheamplifier.
REMINDER:Donotoperatetheamplifier withoutaloudspeaker orloadresistorattached.

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OPERATION
Bytimedelay, soundwill beginapproximately60 secondsafter turnon.
Aswithall highfidelityproducts,thesoundcharacteristicoftheVACchangessomewhatasitwarms
up.Weadviseagainstleavingtheequipmentonatall timesforsafetyreasons,andbecauseofthe
attendantaccelerationofoutputtubewearandpower consumption.Lifeoftheoutputtubes
averages3,000 to8,000 hours.Forbesttubelife,turntheamplifier off whenyouare notlistening.
AnytimethattheVACPower Amplifier hasnotbeenusedforafewweeksthesoundmaybe
different.Thisisalsonormalforhighresolutionaudioequipment.Optimumsoundshouldreturnafter
afewhoursofoperation, preferablywithanaudiosignal.
PleasenotethatalthoughyourVACSystem hasbeenrun for48 hoursatthefactory, thebreak-in
timeofhighresolutionaudioequipmentisinfuriatinglylong.ThePhisoundwill continuetoseason
forapproximately200 hours.Theearlysoundoftheamplifier will beless extended,dynamic,and
coherent.Thenthesoundwill improvenoticeably, followedbyaperiodofdarker sound,finally
givingwaytothedesiredmusicality. Patienceisavirtue.
Alsobeaware thatmanycomponentsdisplaytheneedforanewbreakinperiodafter being
transportedinunheatedcargoaircraft.
ILLUMINATEDLOGO
TheilluminationofthefrontVAClogomaybeturnedoff viaaswitchonthebackpanel.

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TRIODE&ULTRA-LINEAR MODES
Triodeamplificationistheoldestformofamplificationknown,whilepartialtriode("ultra-linear")
operationofpentodesandbeampower tubesdatesbackto1937.Bothmodesofoperationare
availablewithyourVACPhiamplifier viaasingleswitchonthetopplate.
Althoughthemodemaybechangedwiththeamplifier inoperation,westronglysuggestthatyou
turnonlyoperatetheswitchwhentheamplifier isoff andthetubeshavecooleddown [VACUUM
TUBESBECOME HOT ENOUGHTOCAUSESERIOUSBURNS.NEVERTOUCHATUBEWHENTHEUNIT
ISON.ITMAYTAKESEVERALMINUTESFORTHETUBESTOCOOLDOWN AFTERTHEUNITIS
SWITCHEDOFF.] Turntheswitchtothepositionindicated, thenpower theunitupandlisten.
Less power isavailableinthefull triodemode,butdistortionbefore clippingmaybereduced,as
isoutputsourceimpedance.Experiencerevealsthatthetriodemodewill soundsomewhatleanon
somesystemsandbetter definedonothers.Inmanywaysthisisanissueofsystemmatching,and
universalrecommendationsdonotexist.Listentoboth,andselectthemodemostpleasinginyour
system.
Notethatthebiascurrentwill typicallyreadslightlylower inthetriodemodethanintheultra-linear
mode.SimplyfollowtheBIAS procedure ifnecessary torestore thecorrectreadingforeachtube.

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INSTALLINGNEWOUTPUTTUBES
First, see theSAFETYNOTICEearlier inthemanual.
Outputtubesare typeKT88.ReplacementoutputtubesshouldbepurchasedfromVAC.Itis
desirablethattubesbeinmatchedquartetsforeachchannel,andbeclosetothe"bogey"values
forthemajorparameters. Makecertainthateachtubefitsfirmlyinitssocket.
ALL POWERMUSTBEOFF.Removethetopcagerodsandtheoldtubesafter they havecooled
down(THECAGERODSBECOMEQUITEHOTINNORMALUSE;TUBESBECOMEHOTENOUGHTO
CAUSESERIOUSBURNSWHENINOPERATIONAND MAYTAKESEVERALMINUTESTOCOOLDOWN).
Install thenewtubesfirmlyandfullyinthesockets,observingthatthetubewill onlyfitintothesocket
inoneorientation,determinedbytheplastic“keyway” inthecenter ofthebase.Donotuse
excessiveforce. Replacethetoprodsbefore operatingtheamplifier.
Adustthebiascontrolfullycounterclockwise.
Switchontheamplifier andfollowthebiasprocedure outlinedlater inthismanual.Biasmustbe
checkedandadjustedwhentheamplifier firstturnson,at60 seconds,90 seconds, twominutes,
andfiveminutes.Intheearliestchecks,setthebiassothatthemeter readabittotheleftofcenter.
Finalsettingshouldbemadeafter 15-30 minutes. Rechecknewtubesdailyforthefirstweek.
Whenever atubeischanged, thebiassettingsmustbecheckedandadjusted.
Aslightvioletglowinthetubeisnotcauseforconcern.Ifatanytimetheplate(theoutermostmetal
structure)oftheoutputtubesbeginstoglowbrightorangeorredSWITCHOFF IMMEDIATELY.The
redglowindicatesthatthetubeis"runningaway",beingdestroyedbyconductingexcessive
current. Tubesmayrun awayforseveralreasons:
1)Thetubeisnotfullyinsertedinthesocket.
2)Thetubefitslooselyinthesocketandthuscannotmakecorrectcontact.Suchatubeis
unusable.
3)Thetubeisdefective.
Intheeventthattroubleisencounteredcheckconnectionsand/ortry another tube. Stopifthe
problem persistsandconsultwithyourdealer orVAC.
Forfurther information,refer toTips&Advice:TubesinGeneralandTips&Advice:OutputTubes.