LC Audio Technology Zappulse 2.1 Service manual

ZAPpulse2.1

ZAPpulse2.1SE

COOKBOOK

CreditCardsize

Pulse Field

Technology

200WattRMS8
290WattRMS8(SE)

ZAPpulse2.1og2.1SE PWMHighEnd
DigitalAudioPowerAmplifiermodule.
Balancedandunbalancedlineinput,
ShortCircuitProtection,4layercircuit
boardandcontrolledswitchingslope
ensureminimalEMCemissions.Sound
qualitycomparabletothebestavailable
analogpoweramplifiers.

Dynamics,Soundstage,naturalmusicalperception,clarity,warmth!

LCAudioTechnologyLtd.Denmark

ZAPpulse2.1

DCandproduces200WRMS@8Ohms,
andupto800WRMS@2Ohms.

ZAPpulse2.1SE

andproduces290WRMS@8Ohms
andmorethan1050WRMS@2Ohms.

2.1SEisequippedwithBlackGateVK.

usessuppliesof35-60V

runson35-72VDC

Content.

Bridgecouplingof2ZAPpulsemodules
CompensatedMode
CompleteAmplifier,Schematic
CoolingRequirement
Input-Outputconnections
MechanicalData
MoreZAPpulsetechnology
MinimumSystem
OutputpowerCorrelationwithSupplyVoltage
PassiveVolumecontrol
PowerSupplyConnections

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11
14
17
7
20
4
17
6
7

5
Principleofoperation
Professionaluse
ShoppingList
SurroundSystem
Switchingfrequencyconsiderations
SyncronousMode
TechnicalData
ZAPpulse2.1withActiveCrossover

Furtherinformation:www.lcaudio.com

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ZAPpulse2.1

Copyinganddistributionofthismaterialforpesonaluseisallowed.NocommercialuseofthismaterialisallowedwithoutwrittenpermissionfromLCAudioTechnology.

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PrincipleofOperation.

Inaconventionalamplifiertheinput
signalisamplifiedthroughvarious
analogstagestoaprogressivelyhigher
amplitude.Inthefinalstagesofthe
amplifier,theoutputstage,highcurrent
capabilityisaddedtoenablethe
amplifiertodriveloudspeakerloads.
Whencurrentisdrawnoutoftheoutput
stagetotheload,heatisdissapatedin
theoutputstages,sincetheload
currentmultipliedwiththevoltagedrop
overtheoutputdevicegivesapower
value(ofaverage60%ofthemax.
outputpower)thatneedstodisappate
inheatsinks.60%isnotthepowerloss

Filter

atmaximumoutputpower,butthe
averageheatdisappatedatvarious
outputpowerlevels(exceptverysmall
levelsbelow1W).Soa100Watt
amplifierwillaveragelyneedto
disappate60Wattspowerinto
heatsinks.TheZAPpulseoperatesina
differentway,theoutputdevicesare
eitheronoroffwithnosignificant
voltagedrop,soevenwhentheload
drawlargeamountsofcurrent,thereis
onlyminimalpowertobedisappated.
Tocontrolthesignalamplitude,the
pulsewidthoftheoutputsquarewaveis
controlledveryaccurately.

+60V

Integrator

Differential
Comparator

+

Aftertheoutputdevicesthesquare
waveneedtobefilteredwithachoke
andcapacitor,togetananalogoutput
signalwithoutnoisethatcanbefedto
theloudspeakers.Thechokeand
capacitor'squalityisparamountinorder
togetagoodsoundquality,soweuse
anoversized(1.5kW)ultrahighspeed
ferritecorewithsilverconductorand
TEFLONinsulator.Thischokehasa
verylowimpedanceofonly5milli
Ohms,andallowsforagooddamping
factorinanyspeakerload.Togetan
outputsignalofsay30V,theoutput
devicesaremadetoswitchhigh75%of
time,and25%oftimelow.Inthiscase

Pulse Field

TechnologyGnd

GateDriver

OutputStage

thePulseWidthis75%,sincetheV+­V-is120V,theoutputvoltageseenfrom
V-is75%of120V=90V.90Vontopof

-60Vis30V,aswantedinourexample.
Operatingfrom+60Vto-60Vallowsfor
anyoutputvoltageinthisrange,
including0V.ThusatotalDCcoupled
systemforhighestpossiblesound
performance.PulseWidthModulationis
oftenshortenedtoPWM.Avery
importantstageinaPWMamplifieris
themodulator,thatcanbemadei
variousways,withdifferentproperties.
Wehaveselectedandoptimizedthe
balancedintegratingtype,asitishighly
stable,andhasverylowdistortion.

OutputFilter

Out

Gnd

-60V

ZAPpulse2.1

Copyinganddistributionofthismaterialforpesonaluseisallowed.NocommercialuseofthismaterialisallowedwithoutwrittenpermissionfromLCAudioTechnology.

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MoreZAPpulse2.1Technology!

TheheartoftheZAPpulseamplifierisa
balancedintegratingPWMmodulator.It
basiclyintegratedtheDClevelofon
switchingcycleoftheoutputstage,
includinganyswitchingnoises,slope
differencesetc.Thenthisvalueis
compared,andcorrectedinthenext
switchingcycletocreateanoutput
signalofexactly0Volt.Thiscorrection
isperformedeveryswitchingcycle,
whichisabout500.000timesper
second.

Theinputsignalisinjecteddirectlyinto
theintegratortokeepsignalpathsultra
short.Nosignalconditioning,suchas
DCblocking,HFblockingorother
limitingfactorsarepresentonthe
ZAPpulsemodule.Soifthisisrequired
byyourapplication,youhavetoadd
thesefunctionsoutsidethemodule.
Whensignalisappliedtotheinput,the
integratornolongercorrectstheoutput
signallevelto0Volts,butrathertothe
signalcurves.
Thefeedbackgroupdelayiskeptvery
low,onlyaround2uS,toallowforTIM
freeoperation.Theanalogintegrating
feedbackloophasalowergroupdelay
ofanycompletelydigital(A/Dbased)
feedbackloop.Andsinceoutput
switchingnoiseproductsarethesame
nomatterthemodulatortype,the
analogfeedbackloopgivesamuch
betterrejectionofnoiseproductsthana
truedigitalapproach.It'sallabout
speed,andhowfastthenoisecanbe
cancelled.

Theoutputsquarewavehasabase
frequencyoftyp.500kHz,andrise
timesofsome10.000V/uS.Theslopes
areminimisedtoaround50nStokeep

switchinglosseslowatheavyspeaker
loads.Howeveratlowsignalamplitudes
themainpowerlosscomesfrom
capacitiesintheMOSFET's,so
transitionsareslowedtoreduceEMI,
noiseandidleloss.Thisiscontrolledby
thePulseFieldcircuitintheGatedriver.

Asimplerulesaysthatatnosignal,a
ZAPpulselosessome9.5Wattspower
tocapacitiesintheMOSFET's,andat
fullpoweritlosesanother9.5Wattsto
serialresistance.Soat500Woutyou
onlyhavetodisappatearound19Watts
totheheatsinks.

OnegreatadvantagePWMamplifiers
haveoverconventionalanalog
amplifiersis,thatintheanalogamplifier
itisdifficulttoavoidtheharmonic
distortionproducts,thataresignal
dependent,andthereforeinteractswith
soundquality.InthePWMamp,the
distortionisnon-harmonic,andinde­pendentofsignalcontents.Insonic
performancepropertiesthistranslates
tothePWMamplifiersexceptional
abilitytoexpandthesoundstagewith
addedsoundlevel.Ananalogamplifier
wouldtypicallycollapsethesoundstage
athigherlevels,dependingonthesize
ofthepowersupply(whywehavehuge
powersupplybanksinallouranalog
amplifiers).ThePWMwillplaywithwide
and deepsoundstageatanylisytening
level,evenwithavery(almosttoo)
smallpowersupply.Wehavemade
testswitha2x250WRMSZAPpulse
amp,runningwithonlytwo2200uF
100Vmaincaps.Anditstillhasplenty
ofbasscontrol,definition,widthand
depth.Opportunitiesforinteresting
experimentsinthisfieldareobvious.

ZAPpulse2.1

Copyinganddistributionofthismaterialforpesonaluseisallowed.NocommercialuseofthismaterialisallowedwithoutwrittenpermissionfromLCAudioTechnology.

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ConnectionofPowerSupply.

ZAPpulse2.1

TomakeZAPpulse2.1work,simply
connectatypicalAudioPowerSupply
of+/-35Vto+/-60V(+/-72VforSE
version).Theoutputpowerdependson
thevoltageofthepowersupply.The2.1
standardversionuses63Vcapacitors,
ontheboard,whilethe2.1SEuses160
Vcaps.ThisiswhytheSEcanbe
madetodelivermuchhigherpowers
thanthestandardmodules.Inthe
standardversion,thesoundqualityof
themaincapsmustbeconsidered.

+60V

Power
GND

Power
GND

OUT

-60V

SHORT!

Themidrangeandtreblesonic
propertiesofthesecaps,willinteract
withtheoverallsoundperformanceof
theamplifier,sowerecommendusing
veryhighqualitycapswithstandard
modules.WiththeSEmodulesthemid
andhighfrequencyperformanceisfixed
atthehighestlevelbytheBlackGate
VKcaps(47uF160V).SoPSUcaps
onlyneedtohavegoodbassprops.
Alwaysuseshortandheavywire
betweenPSUcapsandmodules
(<4-5inches).

SHORT!

10.000uF
63V

10.000uF
63V

SHORT!

Thereisnoneedforhugecapacitorbanks,2pcs.

10.000uFwildofineforanynormalspeakerload.At
2Ohmsload,maybe2pcs.22.000uFwillworkperfectly.
Allenergyinthecapacitorbankistranslatedalmost
losslesstoaudiopower.Practicalexperimentsshowthat
evenwithonly2200uFthesemoduleswilldeliver
incrediblehighperformanceAudiosound.(8Ohmsspeakers).

+60V

Power
GND

-60V

ZAPpulse2.1

Copyinganddistributionofthismaterialforpesonaluseisallowed.NocommercialuseofthismaterialisallowedwithoutwrittenpermissionfromLCAudioTechnology.

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LCAudioTechnologyInc.

CorrelationofOutputPowerandSupplyVoltage.

TheOutputpowercanbecalculatedas
aresultofthemax.signalamplitude,
whichdependsonthesupplyvoltage.
At+/-60VSupplyVoltagetheampcan
ideallydeliver120Vpp.Tocalculatethe
outputpowerweneedtheRMSvalue,
whichissimply120/2pi=120/2,82=
42,6Vrms(inthisexample).
Outputpoweristhencalculatedusing
OhmsLaw:

2

U

P=

R

P=OutputPowerRMS
U=RMSVoltage(42,6)
R=SpeakerImpedance(8)

TransformerVoltage
2x24VAC
2x27VAC
2x33VAC
2x36VAC
2x40VAC
2x42VAC
2x45VAC
2x50VAC

DCVoltageafterRect.
+/-32VDC
+/-36VDC
+/-45VDC
+/-49VDC
+/-55VDC
+/-58VDC
+/-62VDC
+/-69VDC

Inthisexample223wattsRMS.
Thiswasidealvalues,inZAPpulsethe

practicalvaluesarecorrectedwitha
seriallossof1-3VDCdependingon
loadimpedance(1V@8Ohms).

At+/-60VDCyouwillgetapractical
outputpowerof:some210WattsRMS.

Seebelowforoutputpowersatother
transformervoltages,andload
impedances.

Bottomtableshowsbridgemode
ZAPpulsemodulesoperatingatvery
highpower!

Poutin8Ohms
60W
78W
119W
144W
180W
200W
230W
286W

Poutin4Ohms
106W
137W
222W
266W
340W
380W
438W
548W

YoucanalsobridgetwoZAPpulse
modulestogetamuchhigheroutput
power.Seehowlaterinthisbooklet.

TransformerVoltage
2x24VAC
2x27VAC
2x33VAC
2x36VAC
2x40VAC
2x42VAC
2x45VAC
2x50VAC

:WecanNOTguaranteethemodulestooperatesafelywiththisload.note

ZAPpulse2.1

Copyinganddistributionofthismaterialforpesonaluseisallowed.NocommercialuseofthismaterialisallowedwithoutwrittenpermissionfromLCAudioTechnology.

DCVoltageafterRect.
+/-32VDC
+/-36VDC
+/-45VDC
+/-49VDC
+/-55VDC
+/-58VDC
+/-62VDC
+/-69VDC

Poutin8Ohms
219W
286W
448W
542W
682W
758W
879W
1100W

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Poutin4Ohms
397W
526W
837W
1019W
1291W
1439W

note
note

LCAudioTechnologyInc.