Funk Tonstudiotechnik LAP-2.V3 User manual

OWNER'SMANUAL
ANALOG PREAMPLIFIER

2
TABLEOF CONTENTS
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TABLEOFCONTENTSPage2
IMPORTANT SAFETY PRECAUTIONSPage3
INTRODUCTIONPage4..5
OPERATIONPage6..7
AUDIO SIGNAL QUALITY Page8..10
BLOCKDIAGRAMPage11
INSERTSPage12
ADJUSTABLERECORD PATHPage13
CONNECTIONSand WIRINGPage14..15
MATCHING THE LEVELSPage16..17
POWER SUPPLYPage18
FINISH VERSIONSPage18
INTERIORVIEW Page19
NOISE ANDHUMLOOPSPage20
TECHNICAL SPECIFICATIONSPage21..23
INTERFERENCEEMISSIONand NOISE SOURCES Page24
MAINTENANCEand REPAIRPage25
DECLARATIONOFCONFORMITY Page26

3
IMPORTANTSAFETY PRECAUTIONS
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Thefollowingappliesto all versionsof LAP-2.V3
Alwaysfollow thebasicprecautionslistedbelow to avoidthepossibility of seriousinjury oreven death
fromelectricalshock, short-circuiting, damages, fireorotherhazards. Theseprecautionsinclude, but
arenot limitedto, thefollowing:
CAUTION!:
Onlyusethevoltage specifiedas correctforthedevice.Therequired voltage isprintedonthebottom
plate of thedevice. Standardis230 Volt/50..60 Hz!115 Volt/60 Hz optional
Topreventfireand/orelectricshock, thedevicecan not be exposed to rain ormoisture!
Ifthepowercordorplugbecomesfrayed ordamaged,orifthereisasuddenloss ofsoundduringuse
ofthedevice,orifany unusualsmellsorsmokeshouldappear to be caused byit,immediatelyturnoff
thepowerswitch,disconnecttheelectricplugfromtheoutlet,andhavethedeviceinspectedby
qualifiedFunk Tonstudiotechnik servicepersonnel.
If thisdeviceshouldbe dropped ordamaged, immediately turn off thepowerswitch, disconnectthe
electricplugfromtheoutlet, andhavethedeviceinspectedby qualifiedFunk Tonstudiotechnik service
personnel.
Donot attemptto disassemble theinternalpartsormodify theminany way. Ifit shouldappear to be
malfunctioning,discontinueuseimmediatelyandhaveit inspectedbyqualifiedFunk Tonstudiotechnik
servicepersonnel.
CAUTIONSON INSTALLATION :
Donot install inthefollowingtypesofplaces.Doingsocoulddegrade thesoundqualityand/orcause
malfunctions.
Placeswith significantvibrationsorthatareotherwiseunstable
Near windowsorotherplacesexposed to directsunlight
near heaters orotherextremely hot places
extremely coldplaces
placeswith badventilation orhigh humidity
very dusty locations
BEWAREOF CONDENSATION :
In caseofmovingthedevicefromacoldto awarm place,orused afterasuddentemperaturechange,
avaporintheaircouldcondenseontheinternalpartsmakingcorrectoperationimpossible.Toprevent
this, orif thisoccurs let theunit sit foratleast1houratthenew roomtemperaturebeforeusing.
CLEANING :
Tocleantheunit,wipe gentlywithasoftcloth.Thisparticularlyappliesto theversionwithgoldor
chromeplatedfront.Donot useany benzene,paintthinner,ethylalcohol orotherchemicalagentsto
clean theunit as they coulddamage themetalsurface, orplasticcontrol knobsof theunit.
WARRANTY :
Warrantyforpartsandlabourisgrantedforperiodof 3years. Defectsassociatedwith theproduction or
materialdefect,will be removed free ofcharge duringthisperiod.Thewarrantyisvoidafter
unauthorized openingand/orinterferingwith thedeviceby thirdparties!

4
LAP-2.V3INTRODUCTION
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ANALOG STEREOPREAMPLIFIER / SIGNALSPLITTER
1.0APPLICATION :
LAP-2.V3isultra-linear preamplifierforbothprofessionalrecordingstudios,High-Endaudio users and
enthusiasts,whopraiseneutralityandtransparencyofsound.Itwas designed inorderto choosewhichsignal
shouldbe monitored as well as copyingaudio materialfromonestereosourceto anotherwithoutany loss of
quality. Variousdevicescanbe connectedusingtheLAP-2.V3preamps,likePhono preamp,CD,CD-R, MiniDisc,
DAT, iPod, soundcardorDAB.
TheLAP-2.V3preamplifierwas designed withuseof ourprofessionalreferencemonitoringsystemformastering
labsandit createswhollynewqualitystandardsinitsclass.Besidesabsolutelysuperiorsoundcharacteristics
theLAP-2.V3featuresveryergonomicanduserfriendlydesign.Forexample,signallevelscanbe separately
adjustedforeach stereoinput. Also, each inputcan be connectedto each output.
Thedeviceprovidesreferencequalityofsoundwithexceptional,flatresponsecharacteristics withinextremely
wide frequencyspectrumandrange ofdynamics thatissecondto none.Thelevel ofnon-linear distortionisso
low, thatit cannot be measured usingconventionalmeasuringdevices,becausequalityoftheLAP-2.V3
surpassesthequality of mostaudio measuringdevices.
LAP-2.V3 offersfollowing functions:
1. ECORDING -signalroutingbetween upto six analogsoundsources
2. MONITORING -signalroutingbetween upto six analogsoundsources
3. 2parallel monitoroutforadditionalsubwoofer
4. Signalsplittingfrom1in to 4outsforRECORDpath
5. Level adjustment/matchingforvariousdevices
6. Change of impedancefromhiinputto low Ohmout
7. High quality headphonesout
8. Separate mute switch formonitorandrecordouts
9. „Power-Down“-mute relay on monitorout
10. Inputconfiguration ismemorized afterswitchingoff orsudden power-down
The LAP-2.V3 isequipped with6pairs connectingportsforasymmetricstereosoundsources(cinch/RCA).
Oneof6signalsourcescanbe selectforrecordingindependentfromchoiceformonitorinput (Record-Router).
Thisstereosignalisfed simultaneously to 4pairs of Cinch outputconnectors.
Theaudio matrixoperatesincontact-less mode.Ahighlevel ofstabilityanddistortion-free operationis
achieved bythis.Thedevicecanmatchlevelsbetweeninputsandvarious„hot”devices'outputs,sorapid
changesin levelsduringsourceswitchingareavoided.
LAP-2.V3canworkwithactivespeakers as independentpre-amplifierorwith apoweramp(LAP-2.V3aversion),
oras expansion/upgrade of integratedstereoamp(LAP-2.V3b).
Hiquality, shortcircuit resistantheadphoneamplifieriseasily accessible on thefrontpanel.
Powersupplyoftheunit isexceptionallycarefullydesigned andbuilt,whichensuressuperiortechnical
parameters andstable behaviourof thedevice.

5
LAP-2.V3INTRODUCTION
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2.0SWITCHINGCIRCUIT :
AnalogsignalinputswitchingofLAP-2.V3iscontrolled digitallyandworksinfull contact-less mode.Averyhigh
level ofprecisionandfault-free operationhas beenachieved thatway. Typicaldifferencesoflevel betweenleft
andrightchannelsinthewholesignalpathofLAP-2.V3areless then0,01 dBinfull clockwise,maximum
position of level knob.
Thanksto stepoperation of thevolumepreciselevel recallingisobtained.
Dynamicrange of135 dB, marvellousfrequency(below0,5Hz to over1MHz)andphaseresponseas well as
extremelylownon-linear distortionwithtypicalvalueof<0,0001% THD(<-120 dB)inimportantmiddle
frequency range. Thisallowsforneutralandtotally objectiveevaluation of achosen soundsource.
All analogicalinputsignalsarefed to activematrixbylownoiseinputbufferstages.Thanksto thatveryhigh
impedanceinputsaresupportedandweobtainverylowimpedance,nearly0ohm,fortheelectronicmatrix.
Flimsysignalswithrelativehighoutputimpedancearepassed withoutany distortionorloweringthelevel.
Practicallythesignalsourcewhichisconnectedto theLAP-2.V3seesnoelectricalload.Theimprovementis
20…100 timesfewerloadthan in normalaudio design inputstages.
Bufferingamplifiers beforetheactivematrixensureindependentfromimpedanceofchosensignalsource
valuesofcrosstalkbetweenneighbouringchannels(thisappliesparticularlyto highfrequencies).Suchdesign
giveshighinputchannel separationvaluesoftypically115 dBat1kHz. Small level dropscaused bysplitting
signal(onesignalsplit to monitorandrecordpathsatthesametime),typicalforpassivematrix, has been
eliminatedthanksto activeswitchingmethodused intheLAP-2.V3.Inputsthatarenot selectedarenot
disabledby shortcircuit, as it isseen sometimesin otherdevices.
Anotheradvantage ofthisinputbufferingtechnologyisnon-significant dropofthesignal at all workrangesand
highinputimpedanceof2Megaohmrange.Weakeningoflowfrequencysignalsanddangerofphaseshift
caused byoftenused outputcapacitors arecompletelyeliminatedthanksto hiimpedanceinputstagesofthe
LAP-2.V3.
Signalirregularitiesand/ordistortioncaused bytransientresistancesinwiringandconnectingportshas been
eliminatedto ten timeslowerlevel then typicalinputcircuits.
Normally switchingof theelectronicmatrix in theLAP-2.V3isnot audible. In German Broadcaststationsthey
havethefollowingassumption to say theswitchingnoiseisnegligible:
”theswitchingnoisemustbe –60 dB qp weighteddown fromthenormalaudio level”. If you provide 2Inputs
with thesamesignalwith samelevel andswitch between theseinputs, you will likewisenot hear any audible
switchingnoisewith theLAP-2.V3.
3.0Safetyof operation :
Thedeviceisdesigned forusers whohighlycareforstabilityofaudio parameters throughoutthewholeperiod
of deviceoperation.
Fault-free operationof deviceisensured by activeswitchingmatrix with useof additionalbufferingamps. If you
overloadaninputinany normalaudio amplifier,it ispossible to damage theinputcircuit andsothesessionis
ended.Nowyouramplifierneed tot be repaired.Ifyoudamaged oneinputoftheLAP-2.V3,theother5inputs
will workcontinuingbecausethesummingamplifieras wholewill not stopworking.Maybe yoursession
likewisegoeson.
In caseofturningthedeviceoff orsuddenpowerdisruptiontheinputchoiceandlevelsarememorized and
restored atnextpoweronoftheunit.Thatfunctionisalsousefulforusers,whoworkwithtimertype power
steeringdevices.
4.0INPUT SELECTand MUTINGFUNCTION :
Analog monitor operation :
Central sectionofLAP-2.V3aretwo stereo routers (Monitor-RouterandRecord-Router). Monitorrouter serves
forswitchingsignalsthatareto be monitored orturnsthemoff completely.
Analog record operation :
RECORDROUTER enableschoiceof signalsto be recorded andworksindependentlyfrom choicefor
monitoring. Thesignalappears onall theCINCH outletsandenablessimultaneouscopying onmultiple devices
withoutneed forusingY–cablesorany othercrossingboard.
DIGITAL AUDIO SIGNALS:
LAP-2.V3worksonlywithanalogsignalsources.Ifdigitalsourcesareto be monitored,recorded and/orsplit,
optionaldigitalswitch CAS-2.V3 matched to LAP-2.V3enablesselectionofoneof8 digitalsignalsources
androutingit to externaldigital-analogconverter.Besides,theCAS-2.V3canchooseany signalfrom8inputs
as recordsignalandroute it to any 5 recordoutputs.

6
POWER
FUNKTONSTUDIOTECHNIK
Ser.Nr.
IN3L IN1LIN2LREC.L IN6L IN4LIN5LREC.L MONLREC.L REC.L
IN3R IN1RIN2RIN6R IN4RIN5RREC.R MONRREC.RREC.R
MONL
MONR
LAP-2.V3INPUTSWITCHINGINPUTS/OUTPUTS
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4.1SIGNALSSWITCHING\MUTING:
Analogsignalsourceischosenbydepressingoneofinputselectors - INPUT 1..6.Formerinputselectionis
then replaced by thenew choice.
Turning off themonitorsignal: to turnthemonitoroutpress andholdinputselectionbuttonforatleast1
second.TheLEDlampabovethisbuttonwill be dimmed.Thiswill showtheoutputmute functionison.
Headphoneoutisstill active, though, andchoosingthesignalsourceisstill possible.
Turning themonitorsignalbackon: to turnthemonitoroutputonpress andholdtheappropriate input
selectionbuttonforatleastonesecond.TheLEDlampabovethisbuttonwill gobackto normalbrightness and
theoutputsignalisback on.
LAP-2.V3featuresbothanalog monitormatrix and recordingmatrix.Thanksto thisoneofthesignalsfed to
inputs1..6canbe chosenandused as signalsourceforrecordingonto externalrecordingdevice.Thishappens
independentlyfromcurrentlymonitored signal.By depressing „RECORD“ buttonandsimultaneouschoiceof
analogsource(1..6)the RECORDMATRIX becomesactiveandswitcheschosen signalto all recordingoutputs.
Green LEDdiodesindicate selectedmonitorsource, red LEDdiodesindicate recordsource(blueorwhite LED
diodesarestandardwithchromeorgoldplatedfrontpanels.In caseofotherfrontpanelscolours canbe
custom-ordered). White diodesareoptionalpossible to orderin all versions.
Toturn on record signal: pushrightbutton Record andsimultaneouslydepress oneofinputselectbuttons.
Signalsourcewill be turned on andindicatedby Record LEDdiode.
Turning off therecord path: pushsimultaneouslyandholdforat least 1 secondrightbutton Recordandone
of theinputchoicebuttons. TheLEDdiode Record will gooff andrecordpath will alsobe turned off.
Brightness ofLED diodesadjustment: Brightness ofLEDdiodescanbe adjustedbysmall potentiometer
placed inside theunit.
5.0CONNECTIONS:
Inputs: 6analogasymmetricstereoinputs(RCA sockets).Workinglevel ofsignalis0dBu, input
impedance2M .Alsoveryhighlevel signalsourcesofupto +25 dBu, as commonlyseenin
professionaldevices,will be reproduced withoutdistortion.Formatchinglevelssee also
„Matchingthelevels” chapter.
Outputs: 2stereomonitoroutputs(RCA sockets) foractivespeakers/subwooferorpoweramp.
Outputimpedance:62 .
4stereorecordoutputs(RCA sockets) forrecordinganalogsources.Workinglevel is0dBu.
Outputimpedance:62 .
All theinsandoutsaregoldplatedCINCH sockets.
Headphone output: LAP-2.V3featuresefficientstereoheadphoneamplifierforusewith passiveheadphones.
Back panel

7
LAP-2.V3HEADPHONES and LEVEL
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6.0HEADPHONES
Theintegratedheadphoneamplifiercanworkwithbothlo
andhighimpedanceheadphoneswith6,3mm stereojack.
Headphonesoutiseasilyaccessible onfrontpanel ofthe
device.
TheHeadphoneamplifieroftheLAP-2.V3candrivepassive
headphoneswithrange ofimpedancefrom8 ...10 k .
Optimalimpedanceforheadphoneisbetween70...600 .
Comparingto formerversion(theLAP-2.V2)powerof
headphoneamphas beenincreased by80 %.Depending
onimpedanceofconnectedheadphonesit isapproximately
265 mWperchannel.Dueto internal current limitation,the
poweroftheampislowerwithlowerimpedanceofheadphones.Maximumavailable powerwithrespectto
impedanceisshowed in table below (outputpoweratTHDless then 0.1%)
600 300 200 150 100 70 47 33 22 16
2x200 mW 2x265 mW 2x250 mW 2x235 mW 2x140 mW 2x100 mW 2x60 mW 2x36 mW 2x25 mW 2x18 mW
Attention ! Withuseofcertaintypesofheadphones,dependsfromimpedance,theloudness oftheheadphone
output canbecomequite high.In orderto avoidhearingloss turn down thevolumeknobbeforechangingsignal
sourceand/orheadphones.
6.1VOLUME
Level ofheadphonesignalisset indBandiscommonforbothheadphonesandmonitor.Theknobhas 21 step
positionsandthereforeit iseasyto recall previoussetting.Thispreciseandresistantto wear potentiometer
alsoenablessettingsbetween2steppositions.Therange ofadjustmentisbetween0..-95 dB. In typicalwork
range 0..- 40 dB uniformity deviation between both channelsisless then 0,5dB.
Forspecialusewithconstantlevel ofmonitoringthe LAP-2.V3b versionisavailable. Monitorlevel is
independentfromthelevel knobposition,justlikerecordlevel.Level knobpositionchange bringsonlygain
change forheadphones.In thisversionmonitorlevel canbe adjustedwithexternalstereoamplifierconnected
to oneoftheoutputs.Thisversionmakessenseforthoseusers,whowantto usethedeviceonlyas signal
inputextension fortheirexistingamp.
6.2MODIFIKATION
LAP-2.V3acanbe easily
upgraded to versionLAP-
2.V3b withoutneed for
soldering.Asit isshowed
ondiagram ontheright,
thisisdonebymovingtwo
jumpers ontherightside,
beside potentiometer
inside theunit (jumperJ13
andJ14).In LAP-2.V3a
thejumpers areinposition
„A“,in LAP-2.V3bthey
arein position „B“.
6.3PROCEEDING
Turnoff theLAP-2.V3.All
theCinchcablesandpower
cordconnectedto theback
panel canremaininplace.
Loosen4hexkeyscrews
onthefrontpanel (wrench
size2,5mm).Removethefrontpanel andthenremoveuppercover.Set bothjumpers J13 andJ14 to position
„A“ or„B“. Assemble theunit in reverseorder.

8
LAP-2.V3AUDIOSIGNAL QUALITY
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6.4LEVEL CONTROL
Forlevel control inLAP-2.V3specialmechanicalprecisionregulators areproduced.In comparisonto cheap,
digitallevel regulators theyoffermuchless distortionduringlowlevel signalpass,whichisparticularlynotable
with 16 bit systems.
Qualityof signal incase of using digital level regulators
Purelydigitallevel regulators canbe recommended onlyforlimitedrange ofapplication,especiallyregardinglow
level monitoringandtypical16-bit formats.Atdigitalfaderlevel ofabout -20 dBanaverage signal level will stay
around-30..-40 dB(dependingontheprogram content).However,thebasicnoiselevel will remain
approximatelythesame,regardless ofgainlevel.In consequence,thedynamicrange fallsroughlyinproportion
to preset signaldrop.In caseofsourceswithtypical16 bit resolutionthedynamicrange will be limitedfrom98
dB (atbest)to about58..68 dB.
Thereal problemliesinnon-linear distortion, though (THD), which risesignificantly duringdigitalsignallowering.
In givenexample,distortionrisetypicallybythefactorof10.Moreover,inquieterplacesonCD,wherelevel is
around-20dB, thenon-linear distortionrisesoncemoreto tentimesgreatervalue.Ananalog-digitalconverter,
whichhas THDofaround0,005% atfull level,thenexhibitsthelevel ofTHDatas muchas about0,2..0,5%.
Thisdistortionisstill veryprominentathigherharmonics (k3..k9),whichexcludeslisteningto musicatvery
high fidelity. Athigherbit depthslike24 bitstheproblemisdrastically reduced.
Analogelectroniclevel controllers areoftenused withVCA (Voltage Controlled Amplifier) amps.Theirmainflaw
islimiteddynamicrange andrelatively high distortion when compared to high quality audio electronics. Theflaws
occurmainlyathighlevel differencebetweeninputandoutputoflevel controllerandtheycontainsecondand
thirdharmonic, dependingon thecircuit method.
Likedigitallevel circuitsseparate level controllers withelectronicallyoperatedintegratedcircuits,whichwill not
be realized inD/Aconverter,usuallyhavenoproblems withuniformityofoperation.In simple circuitsandat
higherlevel however,SecondHarmonicdistortionoccurquite often.Also,dynamicrange potentialandlevel
resolution will be limitedin too high degree.
Whyanalog level control ?
Passiveanaloglevel controllerofLAP-2.V3fundamentallydoesnot havethisproblem.Alsoatlowestmonitoring
levels,as inthecasedescribed above,it isimpossible to noticeany significantlimit to resolution.Itdependsin
decisivedegree,though,onamplifyingpath'safterthelevel adjustingpotentiometer.Thereexist
potentiometers,whichtotalinternalresistancedoesnot havepurelyOhmnature.Itiscapacityandinductance
factors, which causemeasurable nonlinearitiesoften.
Abigproblemistrackinglinearityresponseinstereopotentiometers.Trackingnonlinearitiesof2-3db arenot
uncommon,especiallyatlowerlevel settings.Higherqualitypotsensuretypicalerrorof0,5..1dBinthenomal
workingrange from-40..0dB.
Forlevel adjustingpotsoftentoo highvaluesofresistancearedesigned,whichcancauseadditionalnoise
components.Impedanceofvalues50...100 k ormore,whichisoftenseeninHi-Fiequipmentgeneratestoo
muchofown thermalnoise.Thiscanlimit themaximumpossible dynamicrange.Additional,thesehigh
impedancesenabledhigherdistortion in thefollowingamplifierstage through therenon-linear inputimpedance.

9
LAP-2.V3AUDIOSIGNAL QUALITY
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Thisdiagram showstypical,
exceptionallysmall nonlinearities
separatelyforbothchannels.The
dataareforamplification1[0
dB](amplificationinrightfull
position[cw]) andvariousinput
levelsofLAP-2.V3.Bottomscale
showsthelevel,rightandleft
scale showscorrespondingTHD
distortioncalculatedfrom
harmonics k2..k9in%(left)and
dB(right).In amplificationrange
between-10...+14 dBu theTHD
forbothchannelsliesbelow
0.0001%! Evensignalsat-60
dBu, whichcorrespondto the
quietest,almostinaudible places
inrecordingsofsymphonic
orchestra,totalTHDisless then
0,015%.Minimumliesatinput
signalsof+6.0dBu (about1.55
Volts,astudio standardforfull gain),marked bycursor,atvalueofonly0.00005% (-126 dBu).In digitalaudio
devicessuchvaluesarenot obtained involumecircuitstill now. Formost amplifiers used inHI-Fi suchtestsoffer
1..2timesgreaterdistortion.EvenRhode &SchwarzUVP audio analyzerused here,whichbelongsto thebest
audio measuringdevicesforsuch measurments, reachesitsresolution limitsin thistest.
Powerstage influence on signal quality
Alot ofcareandmuchworkweredoneinto designandassemblyofthepowerstage.Thisensuresthateven
leastnoisethatcanbe introduced byapowerstage iscompletelyeliminated.Theintegratedpowerstage
producesexceptionallystable andcleanelectriccurrent(atfull loadnoiseandhumcomingfrompowerstage are
below50µV!).Digitalcontrol systemhaveown powersupplyand,inmajordegree,own leads.„Ultra-Low-Drop“
circuitsforall supplyvoltagesproduceonlyverysmall amountofheat(Ultra-Low-Drop=exceptionallylow
voltage andcurrentlossesbetweeninputandoutputofvoltage stabilizercircuit).Contraryto many other
designs,theLAP-2.V3usesonlysmall amountofenergy, equalto about4.5W. Besidestheenvironmental
protection aspect, it has positiveinfluenceon longevity of thedevice.
6.5AMPLIFICATION PATHS:
TheLAP-2.V3has typicalfrequencyresponseofbelow1Hz...1MHz -3dB. Thereforeevenveryshortimpulsesof
signal withhighamplitude will be cleanlyreproduced andwill not press theLAP-2.V3to itsspeed limit. Thanksto
very fastamplification stagesthetransientinter-modulation distortion ispractically non existent.
Testsignalpicture1:HighsignalfrequencyresponseofLAP-2.V3.Sinusoidalsignalof200 kHz atlevel ofabout
10 VRMS or30 Vpp (correspondsto about+22 dBu gainlevel).Evensoundsignalsofhighestlevel and
frequenciesmuchabovehumanhearingpossibilitiesarereproduced byLAP-2.V3withoutany shape alteration.
Thisdiagram curveshows,thatpreamplifiercanbe anidealmatchfornewestdigitalsoundsources,whichwork
with samplingfrequenciesof upto 192 kHz andbeyond.

10
AUDIOSIGNAL QUALITY
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Amplification paths:
LAP-2.V3isequipped withverywide bandamplificationstages,whichensureexceptionalandsuperstable
reproductionofsignalsanditsphase.Thisclearlyprovesthefollowingmeasurements.LAP-2.V3isdrivenat 0 dB
gain(inputsignalvoltage =outputsignalvoltage)andthesourcesignalissquarewaveimpulsegenerator.
Outputsignalsarerecorded with fast, laboratory standardoscilloscope connectedto monitoroutputof LAP-2.V3.
Limitsresultingfromnarrowfrequencyresponsedueto phaseshiftoftesteddevicearevisible forexample as
irregularitiesintransitionfromverticalto horizontaldirection,oroscillationsonhorizontalpartsofwaveline
diagram.
Testsignalpict.2:1kHz atlevel ofabout1,5VRMS (correspondsto +6dBu gainlevel)withtypicalload
impedanceof10 k .Almost invisible slantsindicate wide frequencyresponseandphasecoherencyinbass range
andclean reproduction of even lowestbass impulses.
Testsignalpict.3:10 kHz atabout1,5VRMS. Oscilloscope loadresistanceinthismeasurementis300 .Very
steepverticalslopesindicate wide frequencyresponseoftheLAP-2.V3inhighfrequencyregion.Eventhefastest
impulseswill be precisely reproduced!

11
LAP-2.V3BLOCK DIAGRAM
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12
LAP-2.V3INSERTS
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6.6CREATINGINSERTS:
LAP-2.V3doesnot haveINSERTinput/outputforexternaldevicesforoptionalusewithmonitorpath.However,
thisfunctioncanbe created(withsmall limitations) formonitorpathas longas onlyupto 5inputsofLAP-2.V3
areused andrecordingpath istemporarily not used.
Picturebelowshowsexample ofconnectingexternalsoundprocessingdevice.Inputs1...5arenormallyused
inputsfor5differentsoundsources.The6-thinputisused foroutputsignalloopofthedevice(suchas sound
processingorDSP FX-type device). Inputof externaldevicewill be fed by any Record-Outof LAP-2.V3, justlikeit
isshown onthepicture.Signalpathfortheexternal deviceisshown inblueorpurple.Attention:Input 6 cannot
be used in recordpath then!
6.7INSERTSETUP :
Tochoosesignalfortheexternaldeviceused as looppress simultaneouslyRecordbuttonandselectedinput
button. The6-th inputwill serveas monitorforany signalpassed through connectedexternaldevice.
Example :if, let'ssay, aCDplayerconnectedto input2ofLAP-2.V3isto be monitored bothdryandprocessed
bytheexternaldevice, then button 2shouldbe pressed forrecordpath. Thisway CDplayer'ssignalwill be fed to
externaldevice'sinput.Signalchanged bytheexternaldevicecanbe monitored byswitchingmonitorpathfrom
button2to button6.Pressingthebutton2will causedrysignalpass fromtheCD,pressingbutton6will pass
thesignalthrough theexternaldevice.

13
LAP-2.V3ADJUSTED RECORD PATH
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6.8HOW TO SETUP „ADJUSTED RECORDPATH“:
Normally, theLAP-2.V3doesnot havelevel adjustmentforrecordoutputsto feed externalrecordingdevices.
Thisfunction,however,canbe createdwithsmall limitations,formonitorpathifonly5inputsareneeded and
common volumeadjustmentformonitorandrecordpath isnot an obstacle.
Belowpictureshowsanexample ofconnectionsfor LAP-2.V3.Inputs1...5will be normallyused as inputsfor5
devices.6-thinput isconnectedwithmonitoroutput signal.Thisadditionalsignalpath isshown in blueorpurple.
Input6can not be used then formonitorpath!
6.9OPERATION MODES :
Forrecordpathinput6will be selected.In orderto enable it press rightbutton“Record”andbuttonforinput6
simultaneously.
Now, Signal for recording ischosenwithinput buttons1...5.Final monitorlevel inthisoperationmode will be set
on outputdevicelikeamplifieroractivespeakers.
Toturn off thismode of operation justpress rightRecordbutton and, simultaneously, sourceinputbutton 1…5.
Audio Block Diagram withoutphoneamplifierandpowersupply

14
LAP-2.V3WIRING
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7.0CONNECTIONS
7.1ASSYMETRICAL ANALOG INPUTS/OUTPUTS
Cablesused with inputsandoutputsof LAP-2.V3should
haveshieldsoldered to Cinchplugchassis.Besides,
attentionshouldbe payed inorderto avoidloopnoise
effectcaused byotherconnectedcablesorbetween
variousstacked devices(groundloopeffect).See also
„INTERFERENCE EMISSION andRESISTANCE TO
OUTSIDE NOISE SOURCES“.Werecommendusing
plugsforunused inputportswithbridged signaland
groundwires.AS-75-Cinch-Connectors with75 Ohm
resistorbetween Signalandgroundaresuitable.
7.2SYMMETRICAL RECEIVERS(active speakersorpoweramplifiersequippedwithXLR inputs)
If asymmetricaloutputsofLAP-2.V3areto be connectedto a
devicewithsymmetricalinputsthepicturebeside shows
optimalconnectionconfiguration(shieldonpin3).Ifground
connectionbetweentheLAP-2.V3andactivespeakers or
powerampsalreadyexists,e.g.viapowercords,thensmall
voltagesdifferenceswill be aligned thanksto differential
amplifierproperties,ifit absorbscommonsignalsufficiently
strong. No groundloop,oftenleadingto soundquality
problems arises.
IfthereisnogroundconnectionbetweenLAP-2.V3andactive
speakers orpoweramp,theusuallymostefficientissecond
connectiontechnique,shown onpicturebelow. Thanksto
connectionbetweenpin1andpin3receivingdevicehas
stable groundreferenceto themonitoringdevice.
In exceptionalsituations,whenproperplaybackcannot be
obtained thisway, thesolutionisto connectintermediate
symmetricalamp.In thisregardwesuggeste.g.SAM-1Cor
SAM-2B, whichareavailable inmany versions.See also
chapter„Noiseandhumloops“.
7.3WIRINGSUGGESTION
Thefollowingpicturenextside presentsanexample oftypicalwiringforLAP-2.V3andastereopoweramplifier
oractivespeakers as well as 6additionaldevices(onlyanalogaudio connectionsareshown).In this
configuration copyingeach sourceonto each receiving(recording)deviceispossible.
Eachofinputs1...6isworkingwell with all asymmetricalanaloghioutputsignalsourcesequipped withCinch
port(cassette tape recorder,phonopreamplifier,tuner,iPOD,CD,DAT, DCC, MOD,DAB, Mini-Diskandsoon).
Thesameappliesto outputs.
In thiswiringexample powerampcanbe used formonitoringany of6connecteddevices(lowerrowofLEDson
frontpanel indicatesmonitored source).
Simultaneously, throughrecordoutputs,regardless ofmonitorchoice,any signalcanbe recorded to DAT-
Recorder,MD-Recorder,CD-Recorderandcassette recorder(upperLEDrowonfrontpanel ofLAP-2.V3indicates
recorded source).
XLR-FEMALE
CINCH
XLR-FEMALE
CINCH
IN3L
IN1L
IN2L
IN6LIN4LIN5L
IN3R
IN1R
IN2R
IN6RIN4RIN5R

15
LAP-2.V3WIRINGSUGGESTION
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16
LAP-2.V3LEVEL MATCHING
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8.0MATCHINGINPUT SIGNAL LEVEL :
Ifotherthenfactory pre-set workinglevelswill be necessary on asymmetricalCinch sockets, then it ispossible to
change sensitivitywithincertainlimits,using20 turnprecisiontrimmerplaced onthemainboard.Asmall,
removable cover(option)ontopofthechassiscanbe removed byunscrewing4small Philipsscrewssize1or,
dependingonversion,ahexkeyscrew1,3mm.Attention:usecareduringtighteningthesmall M2screwsin
aluminumcoverto preventthefragile threadfromdamage.Asfordeviceswithclosed cover: openthedeviceas
described in “HEADPHONES andLEVEL” chapter„6.3PROCEEDING”.
Belowthewindowthereare12 grayrotatingtrimmers,whichcanbe aligned usingscrewdriver.Onlyflattip
screwdrivershouldbe used withtipwidth2...2,5mm.Turningtrimmerclockwiseincreasesgain.Itispossible to
set gain between 0dB..+15 db.
AtfactorytheLAP-2.V3isset at0dBgain.Fullycounterclockwisepositionisroughlystandardgain.Toprevent
damage to trimmertipduringturning,tipofthetrimmerisblocked bygroove.Settingtrimmerabovethis
position doesnot influencegain, butdoesnot damagesthetrimmer.
View fromabove, version with gain adjustmentlid.

17
LAP-2.V3LEVEL MATCHING
_____________________________________________________________________________________________________
8.1 OUTPUT LEVEL :
Outputlevel ofLAP-2.V3andotheramplifiers dependsonused signalsources.Bestsuitedarethosedevices
givingsuchstrengthofsignalthatlevel knobofLAP-2.V3athighestrequired volumesettingsstaysbetween12
and3o'clockposition.Ifthehighvolumeisreached earlier,werecommendmatchinglevelsinpowerampor
activespeakers. In thisregardweofferspecialdimcable DKS which will be specifically matched to yourdevice.
Thislevel matchingcable enablespropermatchofhioutputsourcessuchas preamplifierorotheranalogsignal
sourcesto especiallysensitiveinputsofpoweramporactivespeakersystems.Thematchingcable shouldbe
used when athighestvolumerequired thevolumeknobisfar fromrightmaximumposition. Thefeed level should
be lowered bymutingcable ifthereis15 dBormoreofadditionalgainwhenturningthevolumeknobfully
clockwiseandthemonitorlevel isalready very high, atmaximumrequired level.
Thebasenoisealongwithinterferenceinthecable will be
lowered,accordinglyto strengthofsignal.Thereisbenefit of
increased usable dynamicrange.Besides,thevolumeknob
worksinitsoptimalrange.Thisgivesmorelinear level
adjustmentandalsobetterlevel resolution atlowervolume.
In caseofanalogrecordingdevicesoftoo highinputsignal
sometimesthereisaneed ofsettingthelevel knobinvicinity
of9...10 o'clockposition.In suchcasestheDKScable isideally
suitable.Not onlymuchbettercharacteristics oflevel knobis
obtained,butalsodangerofoverloadinginputamplifieris
avoided.
Voltage dividerinthecable isplaced inside themale CINCH
plug.Thanksto thiscable capacitancehas nonegative
influenceon voltage dividerof thiskind.
DKScable isdelivered as kit consistingoftwosingle cables.
Precisionmetalfilmresistors areused involtage divider,so
level differencebetween both mutingcablesisexceptionally small andtypicalbetterthen 0,02 dB.
DKSmutingcableskit ispassiveandinfluencesdirectlytheinputsofpowerstage.Attenuationdependsalsoon
inputimpedance(inputresistance)ofthepowerstage.However,inputimpedanceofLAP-2.V3isnegligible.
Pleasestate desirable valueofattenuationandinputimpedanceofused poweramplifier,activespeakers or
decoder.
Thecable isalsousable with otherbrandsequipment, as longas inputsandoutputsareCINCH type.
Specialversionsforsymmetricalinputswith XLRconnectors atreceiverside areavailable.
SPECIFICATIONS:
Attenuation :6…-30 dB
Input:Cinch portfemale
Output:Cinch portmale
Cable length :about20 cm
InputImpedance:typ. 5...100 k (variousvaluespossible)
OutputImpedance:typ. 0,1..5k (variousvaluespossible)

18
POWER SUPPLY /BUILDVERSIONS
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9.0 POWER SUPPLY:
LAP-2.V3has built innew, precise„Low-drop”powersupply. Thispowersupplyproducesexceptionallystable
andcleanvoltagesatminimalpowerconsumptionandlowheatemission,comparingto typicalpowersupplies.
Powersupplycanbe loaded upto 250 mA. At highercurrentsvoltage limit will be activeandit will lowersupply
voltage.In caseofshortcircuit betweenoutputvoltagesorground(±20V)thepowersupplywill not be
damaged.
Toavoiddamage to connectamplifiers andspeakers incaseofshort-circuit ofonepowervoltage,thepower
supplyisequipped withoutputvoltage symmetrycontrol system.Ifset bordervalueforsymmetrywill be only
slightlyexceeded,forexample byoverloadingonepowervoltage,correspondingcomplementary outputvoltage
followstheaffected.Sotheaffectedamplifierpowerstageswill be turned off. All stabilized powervoltagesof
integratedpowersupply areshort-circuit resistant.
Thepowersupplycontainsadditionally„Power-Down-Mute“system(turnsoff automaticallyincaseofpower
supplyfailure),whichcontrolled themonitorpathbyrelay. Clicksandnoisesduringpoweronandoff are
avoided bythat,orthoseexistingduringturningonsignalsareeliminated.Ifoneofbothaudio powervoltages
ofLAP-2.V3dropsdown onlyinminimaldegree,thismutingrelaywill be immediatelyactivated.Turnoff time
isequalto single millisecondsafterdropbelow minimumvoltage value, turn on timeisabout10 seconds.
Thedeviceworkswithnoproblemalsowithvoltage fluctuationsbetween210...245 Volt AC currentand
between50...60 Hz. In orderto attenuate thepowerstage interferencestheLAP-2.V3has anti-interference
suppressor(Commonmode inductor) withadditionalX-capacitor,soexternalfilters forpowerstage areusually
not necessary. In caseof LAP-2.V3thoseexternalpowerfilters bringnosoundimprovement!
Powersupplyfuseissituatedinside thedevice.In caseofreplacementuseonlyfuses5x20 mm 50 mAt/250V
(timedelaytype).Justincase,pleaseleaveit to yourlocaldealerorshipthedevicebackto us,wewill help
you fastandin competentway.
10.0BUILTVERSIONSANDACCESSORIES :
Thedeviceisshipped intwopowersourceversions: 230V/50 Hz or115V/50..60 Hz. Changingpowervoltage
can be doneonly by manufacturer.
LAP-2.V3isavailable in2versionsofcover.Standardisclosed cover.Alternatively, opencoverversionis
available.Thisenablesaccess to trimmeradjustingforinputgainstagesofthedevice.Suchcoverversionis
recommended whenthereisneed forfastgainadjustment.Bothcoverversionsarealsoavailable as separate
parts.
Besides, 2coverfinish versionsareavailable :
1. all coverpartspaintedin black, sidesanodized in black
2. all coverpartspaintedin white/grey, sidesanodized in silver
Frontpanel isavailable invariouslooks,andcanbe alsoreplaced laterbyuser.Followingversionsare
available:white coated(RAL7035),anodized inblack, blue,rubycoloured,silver,shadesofgold,as well as
specialversion with goldorchromeplatedfrontpanel, which ismade of brass.
LAP-2.V3isshipped as monitoringamplifierwithcommonadjustmentofheadphoneandoutputpathsas
standard.Forspecialuseit canbe delivered as LAP-2.V3bwithfixed monitoroutputlevel,similarlyto record
path.Pairofjumpers inside ofthedevicecanbe repositioned byuseratany latertime,inorderto turnonthis
function (see alsochapter„Headphonesandlevel knob“).
Specialversionof"LAP-2.V3 MR"withcoupledselectionofmonitorandrecordpathisavailable as option.
Monitorsignalisthenavailable onmonitoroutput(dependentonvolumeknob)andsimultaneouslyonrecord
outputswithfixed,independentlevel.Eachchosensourcesignalcanbe routedto recordoutputs,e.g.canbe
controlled by alevel meterorroutedto anotherdevice. Phonesaredependenton Volume.
ThisLAP-2.V3MRversionisbeneficial forusewithlevel metering.So themeterwill be connectedto Recordout
andmonitors all selectedsignalsindependentfromvolumecontrol.

19
INTERIORVIEWLAP-2.V3
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Insideview ontoaudiomain board with cover removed

20
XLR-FEMALE
CINCH
NOISE AND HUM LOOPS
_______________________________________________________________________________________________
11.0NOISE ANDHUM LOOPS:
Humandnoiseareoftengeneratednot onlyas result ofinterferencewithelectricalormagneticfields.
Differencesingroundpotentialsbetweenconnecteddevicese.g.Dueto double groundconnection,so„noise
loops“cometo existence.Theycancausesignificantinterferencecurrents,especiallywhenlowimpedance
shieldsareused forconnectingthedevices.Thosecurrentsdependingonsystemconfigurationgenerate noise
voltageswhich addsto already distortedaudio signals. Thiscan be preventedby usingsymmetricalconnections.
11.1Noise loops in assymetrical audiocircuits:
Realproblemsolutionliesonlyinsplittingthisgroundconnection(loop)anduseofaudio transformeror
differentialamplifier.
Onpicturebelowinfluenceofseparationwithinthenoiseloopasymmetricintermediate wiringisshown by
connectingsymmetricalintermediate amplifierinput(differentialamplifiere.g. SAM-1C orSAM-2B).
Differentialamplifierorhi-ohm„instrumentationamplifier“ideallytakeinto accountonlythedifferencebetween
thetwoinputs.Ifbothinputsareconnectedto eachotherandthenmodulated,nosignalwill ariseinthiswayat
theoutput.Ifonlyinput minus- will be connectedto groundorto shieldofsending(feeding)deviceandthen
input plus+ to hot inputofthesignaloutput,bothsymmetricalinputsofreceivingdevicewill be modulated
commonphasewithinterferingsignal100 mV. Inputsignal, howeverwill remain equalto 0Volt, becausethereis
noelectricpotentialdifferencebetween input+ and-.
Ifthensendingdevice'soutputwithamplitude of1Vwill be modulated,differenceof1Vwill still existon
symmetricalinputofSAM-1C/SAM-2B, butwithouthumvoltage.Thisrule alsoapplieswhenthetwocores(blue
andred)will be exchanged witheachother.Onlyphaseoftheaudio signalwouldbe changed by180°.So
compensation of phasereversalisalsopossible.
Nodifferentialamplifierworksideally. Typicalcircuitsreachabout1/100...1/10 000 (40...80 dB)ofinterference
signalsuppress.Thereforesmall remainsofinterferingsignalcanbe observed inoutputsignalofdifferential
amplifiers.Thanksto carefuldesign,lasertuned circuitsandinstrumentationamplifiertechniquein
SAM-1C/SAM-2Bdevices,symmetricalinterferenceattenuationhas typicalvalueof1/300 000 (110 dB).In our
example it ismoreby0.3µV(~-130 dB)incomparisonto outlet current,andsobelowthebasenoiseofmost
devices.
In SAM-1C/SAM-2B chassis(groundorprotectivecable shield)andzeroof circuit areisolatedfromeach other, so
they donot create dangerof becomingnoiseloops.
Pictureto therightshowspracticalwayofconnectingsignalsources
containinginterferencewithsymmetricalinputofSAM-1C/SAM-2B.
XLRPin 1remainsopen here, andpin 3isconnectedto shield.