CONTENTS 1.0DESCBIPTION Introduction Current Dumping Options Variants 2.0 INSTALLATION

Unpacking

Contents lvlains Voltage Selection N4ains Connection lnput Earthing Requirements.. Connectors IECInput Convention NABInput Convention Neutrik Speakon Connectors IECOutput Convention NABOutput Convention Output Connection Requirements Installing Balanced lnputlvlodules Inrush Limiting Module 3.0 OPERATION Protection Fuses
4.0 SERVICE ANDMAINTENANCE ! Warranty Prevenlative Maintenance Repair Packing Spares 5.0TECHNICAL Circuit Description Parts List
Specification CircuitDiagram I I I 8 8

ol528EC

1.0 DESCRIPTION lntroduction power for TheQuad520fis a twochannel amplifier designed professional The including recording public and address. power output users broadcast, into 160W a 4Q loadand 100W an 8!) load. inlo of either channel exceeds of the dumping circuit TheQuad520fusesan implementation current was This topology firstusedon therenowned Quad405 technique. circuit for in of Award Technological amplifier resulted the award a Queen's and lnnovation. is in casewhichis desrgned TheQuad520fseries constructed a rugged to reasonable by users. withstand lreatment professional involves teedforward a error correction technique it and Current dumping associated transistor with amplrfiers.is lt eliminates manyof the problems In dumping there covered patents several by in countries. a current amplifier is in effect bolha lowpower veryhighquality amplifier a highpower and The amplifier controls loudspeakers the at heavy dutyamplifier. lowpower mostof the amplifier provide to alltimesandit callsuponthehighpower rl muscle. is the transistors Thesmall amplifier arranged thatprovided largepower so low of outout current small the candeliver almost fullamount reouired the power and amplifier provide remainder will the accurately completely. quality solely is Therefore output dependent theperformance on the signal and this is to of the small signal amplifier since amplifier onlyrequired deliver indeed. lowpowers canbe made it veryaccurate quiescent adjustment, Theproblems crossover of distortion, current thermal matching dissappear. Current dumping amplifiers tracking transistor and power require internal no or and of adjustments alignment thechoice output transistor typesis lessrestrictive is with option in a tew and TheQuad520tamplifier available onemajor is thefitting an active input balancing and variants. major The of option recommended where Quad520fis to be isolating This the lransformer. is The lines where input isolation required. input is fedfrombalanced or mode voltage range a conventional of module combines highcommon the widebandwidth a lowoutput with input, and transformer a trulyresistive and is impedance. Fitting a simple is operation the onlytoolrequired a rt screwdnver. variants the Quad520fare:Themajor of (520f) supplied unbalanced - 3 female XLR is with Thestandard model and ac inputs, lockable twin level controls wiredtot 2401220v mains. balancing input The520N4 similar thestandard buthasactive is to 520f in The to modules fitted thefactory. 5205slaveis similar the520fexcept so the withlevel controls as to prevent unauthorised thatit is notfitted alteration gain. of which includes - 3 male XLR The521fversion made BBCspecification is to levelattenuators a rearpanel and input modules, balanced inputs, balanced to fromthe chassis. the earth be lifted arrangement allow mains to '1 (a internal The520series alsobe setfor 120/10V ac operalion simple can havebeensupplied to Variants theoutline specifications above change). on to manyclients throughout worldandQuadwillbe pleased consider the requirements. making varianls suitparticular to

CurrentDumping

Options

Variiants

2.0 INSTALLATION
polystyrene and TheQuad520famplifier shipped a protective is in shell packed a heavy in dutycardboard Thepacking case. materials should be retained usein theunlikely for event a return servicing of for being necessary. Thepacking contains following: lhe Main Unit: Accessories: OneQuad520tversion amplitier One2m length IECsocket of terminated mains lead. PartNo.QESOE2A. Onemanual. No.O|528EC. Part TwoNL4FC cablemounting conneclors match to those mounted thechassis on where fitted. PartNo.PPNL4FC. (adhesive labels whichindicate wiring the convention are supplied). Shortages should notified the Distributor the Factory appropriate. be to or as Further supplies accessories be purchased required. of can as

Contents

MainsVoltage Selection
TheQuad520fcanbe setinternally eithet2401220V 120/1 ac tor or 10V working. change The involves replacing on thepower links supply board. Disconnect power the supply before making changes. any Notethatthevoltage the unitas shipped fromthefactory clearly of is marked therearpanel on anda similar clear marking should madeif the be setting changed. is Notealsothatthefuserating should alsobe altered to suit(T6.34 240Vac mains T10Afor 120V mains). diagram for and ac The below indicates arrangementsthelinking theprinted the of on circuit board (pcb) thetworanges mains for of input voltage. TheQuad520fwillfunction for safely mains voltages to 6% of the up nominal 240Vac forwhichperformance beencharacterised. has Thesmall transparant safety cover should refitted. be

Iel ot lel lel Lel

nfl\ // /nlifll'l
/ / /1+lt1+ | lgJ Io or Lq [9J Lol

110- 120V

T;-l E\

MainsInput Connection

plugandsocket. Themains input is connection via a standard CEE22 The ground the mains amplifier chassrs muslbe connected to via supply lead. A simple retaining ensures the mains clip that connector notbe removed can accidentally. power Themains leadsupplied plug should wired the mains be to supply withdue regard thefolowing to colour convention: Brown wire Blue wire wire Green,^/ellow Liveconnection Neutral connection Safetyearth
The Brown wiremustbe connected the plugterminal to marked or L Red. The Bluewiremustbe connected theterminal coloured to marked N or coloured Black. Green/Yellow mustbe connected theterminal The wire to marked or coloured E Green Green/Yellow. or /Vofe.'The amplif mustbe protected a 10A fusewhena 13Aplugis ier by used, if another of plugis used, a 104fuse or in type by either theplug or t lf adapter, at thedistribution or board. in doubt consult qualified a electrician. EarthingRequiremenls Connectors power It is usually safety a requirement the mains that leadearth connection is properly connected theamplifier to chassis. There exists variety Input andoutput connector a of conventions. TheQuad520fis supplied thewiring with convention the input for XLRstyle conneclor marked the rearpanel. markets havestandardised on Certain on theso called NABconvention.should noted lt be thatsomemanufacturers gender chassis haveusedthe alternative of connector. (standard version Chassis mounted mounted socket UK 520f) chassis or plug(521f model only). ChassisMountedSocket or Plud Pin1: Chassis Pin2: Hotor phase Pin3:Cold signal or return pin ,Vote.'On connectors 1 mates XLR before other pinsandthus the two makes safety first. the earth NAB Input Convenlion To soecial order. ChassisMountedSocket return Pin'1 :Coldor signal Pin2:Connectedpin1 to Pin3: Hotor phase

IEC lnout Convention

NeutrikSDeakon Connectors
Neutrik Speakon output for output vollage low convention single systems (supplied standard UK models). as for ChassisMounted Socket Pin1+: Amplifier output Pin1-: Amplifier output return 0V or Pin2+:Notused Pin2- : Notused

IECOutpulConvenlion

plug To special mounted or socket order. Maybe either chassis a Chassis Mounted PIug or Socket P i n1 :N o tu s e d Pin2: AmDlifier outout Pin3: Amplifier return 0V or

NAB OutputConvention

To special order. Chassismountedplug Pin1: Amplilier return 0V or Pin2: Connected pin 1 to Pin3: AmDlifier outout
OutputConnection Beouirements
TheNABconvention loses advantage an independent the of safety earth Also connection theinput to sockets. thesense theoutput of connections arereversed which couldcause amolifier an outout be shorted some to in systems. provides power Theuseof the Neutrik connector Speakon ampli{iers a with hasbeendesigned highcurrent dedicated output connector which for loads. posts It obviates problems with the often associated binding andprovides a sensible outof thequandary XLRgenders wiring way of and conventions. provides higher It additionally rating a current thantheXLRstyles, better a gripandtheoption solderless cable of installation. currently lt is being orooosed a standard as connector the relevant bodies. to IEC performance onlybe achieved theamplifier correctly Optimum will if is grounded. Each channel theamplifier of should treated a lour be as terminal device caremustbe taken ensure thereis no and to that conneclion between coldsides either the of output thecoldsides or of an inDUt related and outout. Thediagram makes philosophy this clear.

(ONECHANNEL)

AN4PLIFIER I\4UST COBRECTLY BE GROUNDED 3 COREAC POWER VIA CABLEOR OTHERGOODEABTH. (SAFETY POINT)
The tollowing points must be observed: 1 Thecoldsideof theunbalanced mustbe at or close input to potential. unbalanced chassis An normally signal source satisfies thisrequirement. Theoutput loadmustbe floating notconnected a separate and to ground. Output cables whichhavethecoldpinconnected thechassis to not should be used. Thecoldsideof the inputs should be connected thecold not to sideof the outputs. Thecoldsideof thetwooutputs not should be connected logether. (as lf a common output is required might required 0V be for headohones) then:

input Balanced floating modules should fitted, for each be or one cnannei. Also a linkwire(0.75 mm'? should soldered ) be between two the power pcb.These supply earth eyelets the power on supply carry orange wires theoutput to connector thechassis. on coloured Whenbalanced input line modules fitted chassis are a connection for if can on thescreen, required, be obtained pin 1 of theXLRinput connector theIECwiring on convention only.
InstallingBalanced Inout Modules
(Quad partnumber provides Thebalanced inputmodule Q52F|NP) each with input. circuit an active and The is channel an isolated transformer one it takesits power fromthe power card Fitting is amplifier whichit feeds. straightforward onlyrequires Pozidrive a screwdriver. such Two and modules be needed. foreach will channel. one whicharefixedby screws the rear Remove topandbottom the covers on panel. Eachmodule fixedontothe heatsink is casting thetwoscrews by point a boss is located which supplied. fixing are The above componentI the pcb. sideof the respective amplifier pcb leads from amplifier (theredandblue Remove input the signal the pcb insulated wires) leaving input the cable screen attached theamplifier to module. order maintain In to andattach themto thetwotagsof the input polarity following signal the diagram shouid observed. be Takethe longtwinleadwhichis attached the input to module plugit and pcb.Thetwoshorter ontotheappropriate tagson theamplifier input individual wires(black red)should plugged and be ontothe power supply polarity the tagson theamplifier card.lt is important observe correct to and wire to supply the and the redinsulated mustbe connected the positive The is black Insulated to thenegative wire supply. module supply made 0V signal connection the module. of through 0V output the

( ooNT AEMOVE)

AMPUFTER |NPUT HOT COLO

DC SUPPIY

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Af -rr-""r"fJ

J or-ao<

HOT COLD MODILE NR'I

InrushLimiting Module

Since serial number limiter module been{itted 6500the inrush has as lts standard. function to control peakcurrent is the which canbe taken from prevents the mains supply whentheamplifier switched Thisprotection is on. fastacting excess current tripsfrominappropriate activity alsocauses and lessstress other whichmight perturbed a temporary to equipment be by dropin theavailable mains voltage. supply Theamplifier switched by thepower is on switch thefrontpanel. two on The green panel front mounted LED's light. gain The should canbe adjusted by gaincontrols thetwochannel eachof whichis fitted witha simple tamper resistant device. Gainis a maximum whenthecontrols rotated fully are clockwise. 0 dBumarking The represents point where maximum the the output an 8() loadcanbe obtained a 0 dBu(0.775V into for rms)input level. point. Thismaybe usedas a convenienl reference

3.0OPERATION

Protection
TheQuad520fseries includes protection full against short circuits, input overload inadequale ventilation. channel fitted Each and is witha thermal sensor which, whena channel experiences excessive temperature any for reason, switches thatchannel theamplifier cooled off until has sufficienlly. power Whenthethermal point beenreached frontpanel has trip the LED willgo out.Theamplifier will channel cycle through process the this until cause overheatingcorrected the input of is or signal reduced. is Theloadis protected damage to component from lailure theamplifier due in by a fusein thepower supply circuit by theelectronic and centring system. pcb. Thisfuseis located the power on supply Thereplacement values fuse are: FSl: FS1: F5100: l\4ains 240Vac supply fuse 20x5mm T6.3A Mains fuse120V supply 20x5 mm T10A ac Internal fuse20x5mm T6.34 orotection
Thereplacement FS100 requires removal thetopcover. of the of
is for in 483 ThermalConsiderations TheQuad520fseries designed mounting a nominal mm (19") (89mm)space. can,of course, lt widerackin whichit occupies 2U a be In caseadequate flowing free ventilation be must usedfreestanding. either provided. enclosed In for whenplaced a rackwithother in spaces, example which wasteheat, equipment alsodissipates signilicant consideration should ventllation. worth lt is be given theprovision forced to of noting when, that into forexample, channels fullydriven 4Q loads anylength are tor both ol will nearly 900Wof waste heatfrom timetheamplifier be asked dissipate to theoutput devices alone. 4.0SERVICE AND MAINTENANCE TheOuad520famplifier is tested inspected all stages and series carefully al packing delivery ensure it willprovide and to thal ol manufacture belore and All for manyyearsof reliable service. amplifiers soaktested at least are 24 hours visit before being subiected a second to thefinaltestarea. to In the rareevent failure Quad520fseries usually serviced of the can be in board andheatsink thefieldby replacing complete a amplifier assembly. Thisrequires pozidrive only. up a screwdriver No setting or eleclronic is alignment required. (which be identified L Replacement modules individual components can and partslistandcircuit fromthe related diagram) should obtained be through lt fromwhomtheamplifier purchased.willbe necessary was thevendor to number. serial ouote amolifier the lf the amplifier to be returned thevendor directly Quadthen has to or to packing. it should sentin itsoriginal be Warranty in TheQuad520fseries guaranteed is against defect material any or workmanship a period twelve for months fromthedateof purchase. of parts Within period supply replacement willbe freeol charge of this the provided thefailure wasnotdueto misuse, that accident negligence. or Freight unless hasbeenlocally this agreed. costs notcovered are Within UKtheguarantee with doesnotlimit the the offered thisequipment customer's statutory rights. guarantee is notsupplied the A card and guarantee period commences thedayon which unitis delivered. on the

Preventative Maintenance There no useradjustable within Quad520fseries. Likeany are controls the fromimmersion liquads if it is in nor equipment itsclassit willnotbenefit of for resident a dampenvironment anyappreciable Bothoperating in time. within range -5'C be the of andstorage temperatures should maintained I workmaybe cleaned using moist a cloth. Strong to +45'C.Thepanel as to organic solvents should avoided theyarelikely havea deleterious be effect the paint on finish. Repair replacing Where repair not,for a variety reasons, matter simply is of a of a module, reference should made thecircuit be to diagram the related and part partslistin order ascertain appropriate replacement number. the to parts be heldby andareavailable Quadandits Distributors. from These will packing that is lf theamplifier returned Quadit is desirable theoriginal is to possible. in where Theequipment be returned thispacking will Ouad used. materials where used. willcharge the useol freshpacking for parts notnormally However supplied partof eachamplifier. as Spare are in anyparticular willbe pleased consider request to any application Quad provision. for or a spares to provide, a givenshipment installation, partslist A Thecontents thiswould negotiated required. spares be as of parts requirements canbe requested is available isolated for spares and or through distributors through Quaddirectly. Quad's

Packing

Spares

5.0 TECHNICAL

Thetechnical details the520fseries oivenin thissection. of are Thecircuit diagram should referred Thedetailed be to. function the parts of of thecircuit should apparent those be to aware discrete of analogue destgn techniques.fewguiding A nolesmayhelp. T100andT101provide synthetic fromthe power the 0V supply output. T1,T2,T3 andtheirrelated form circuitry the input section the amplifier of andwithT5,T6,T7 alsoperforms taskof the highquality power the low correction ier. amplif Theoutput current dumpers Tg to T12andtheydrive loadthrough are the onearmof thebridge tormed C8,R29+R30, andL3.DCcontrol by R24 is provided lC1andtheassociated paths. input feedback by The balancing is circuitry based around useof L200and 1C200. small the A amounl o{ positive feedback used counteract winding is to resistance L200. the of Themains inrush limiting is current circuit based around T300. Whenthe power fedto the mains mains firstapplied is is trans{ormer R300. via This limits current inrush. the However R300canonlyperform rolefor a few this power applied mains cycles it Whenthe mains before willoverheat. is C300 provides charges eventually, theemitter T300, via and of sufficient drive to the relay whichbypasses R300andprovides tullpower the mains the of to thetranslormer. Forthe mostpartthevariants readily employ available components whose provenance notnormally thecause anygreat will be of dif{iculty. Quad parts distributors a comprehensive listo{ allQuadproducts should hold and be ableto giveanynecessary assistance. Thenominal specificationthe5201 is of series givenbelow, certain parameters be affected changes the mains may by in input voltage. Power output 4Q: Power output 8Q: Power response: per 160W channel <0.'1% THD+N 240V, at 20"Camb. per 105W channel <0.1% THD+N 240V, at 20"Camb. 10 Hz-30 -3 dB rel 1kHzat 100W8!) kHz

CircuitDescription

PartsList

Specification

Frequency response: Hz-kHz-0.5dB ref 1 kHz Group delay.:

<6 ps at l kHz

Group delayerror* <1.5 ps rel 1 kHz Distortion: <0.03% THD+N, Hz anylevel to 100W/8o 40 up <0.01% THD+N, kHzanylevel to 100W/8o 1 up <0.'l%THD+N, kHz anylevelup to 100W/8O ?0 -115dB'A'wtdref100W8Q (15.7 bandwidth) kHz
Dynamic range: (hum+noise)
.Group passing delayis a measure thetransit of delay signals of through theamplifier. Group delayerroris a measure thedifferential ol delay passing experienced frequency by components a complex of signal through amplif the ier.

Input sensitivity:

for 500mV (-4dBU) '160W4Q (reduced level by controls)
nominal Input impedance: 20 ko unbalanced, Balanced input: 10 10kQresrstive Hz- 20 kHz.nomnal >50 moderejectron dB 20 Hz-20 kNz Common moderange 250V50 Hz Common
gain: from Voltage to 35 dB max.Adjustable frontpanel <-90dB in with impedance: 0.03c) series 1.5FH Outpul voltage 7 Output oifset: mVtypical 95 terminated Channel separation: dB at 1 kHzinputs Load stability:

any Unconditional load

100W/8o Power requirements: VAwithbothchannels delivering 500 Mains vollage: lndicators: Protection: -220V 125V-1 ac 10V 250V or power) (note will lower supplies reduce output indication eachchannel for LED(green) supply DC Mains inrush; Thermal; Peakcurrent; DCoffset; tuse; DCsupply fuse; Mains
limiter fitted standard as heatsink 85'C internal temperature 12.54peakoutput current limit 0V power supply centring circuit T6.34internal 16.34220/240V 0A 110/1 20V. T1
requires forced ventilation Temperature range: 0'C to 45'C. Highambienl for fulloutput be marntained to Input connector: normally wired IEC XLR-3 chassis socket to pin pin Pin convention. 1=chassis, 2=hot, 3=cold lL
impedance NL4 to Output connector: Neutrik wired lowoutput (2+ 1+ 1convention. = signal, = return, and2- nlc) Weight: packing 11 kg less
x dimensions overall: W483(19"rack) H89(2U)x D320mm Graphof Max.PowerOutput VersusLoadlmpedance

Variants

is subject appropriate to Variations within Quadfamily possible the quantitres.
The ight is rcseNed to alter pedormance and specificalions as rcquircd.

^FF^NCVE\-

OPT IONAL

ACT IVE

MODULE

ONE CHANNEL

SHOWN _ MJ I5OO3 - Z'f)< 542
12556 ALTERNAT IVE MPSA93 ALTERNATIVE

520fseries

Circuitdiagram 2001-6.520 (pcb issue 12828-8)

CHANNE

P. C. B.

t 2A2A-A

X VALUE r I ror

SUBJECT

CHANGE ro I or CHANNEL 2

TNTERNALLY

coNNEcrED