Meyer Sound MPS-3 User manual

OperatingInstructions
MeyerSoundLaboratories,Inc.
2832SanPabloAvenue
Berkeley,CA94702
MPS-3
Control
Electronics
Unit
TheMeyerSound
MPS-3 is an active sig-
nalprocessorde-
signedforusewith
MeyerSoundMPS-305
andMPS-355loud-
speakers. It is a ste-
reo device, and occu-
pies a single 13/4-inch
rack space. The func-
tions of the MPS-3
are:
• Loudspeakerfre-
quencyandphase
responsealignment
• SpeakerSense™driver
protection
• Lowfrequencycutfor
systemequalization
Onceallconnectionshavebeenmadeandverified,the
systemisreadytooperate.
• TheMPS-3OutputLevelcontrolsshouldbesetat
minimum.
• SwitchonACtotheMPS-3first,thentothepower
amplifier.
• Setpoweramplifierlevelcontrols(ifany)tomaximum.
Operation • AdvancetheMPS-3OutputLevelcontrolstoset
systemsensitivities. Ifthesystemisnotoperating
properly,recheckallconnections
Note.TheOutputLevelcontrolmarkingsaremerelya
visualaidandshouldnotbeusedtobalancetwosystems.
TheoutputoftheMPS-3iscalibratedonlywhentheOutput
Levelcontrolisfullyclockwise.
TheMPS-3operatesatlinelevel,andisdesignedtobethe
lastcomponentinthesignalchainbeforethepowerampli-
fier. ConnectionstotheMPS-3shouldbemadeaccording
todiagramA.
1. SignalInputstotheMPS-3shouldbebalancedXLR
maleand,forbestsignal-to-noiseratio,haveanaverage
inputlevelofatleast1voltRMS. TheMPS-3willaccept
peakinputsofupto +26dBV.
2. SpeakerSenseconnectionsaremadebetweenthe
outputofthepoweramplifierandtheMPS-3Senseinputs.
Thisconnectionmustbemadeinorderforthe
SpeakerSensedriverprotectioncircuitrytooperateprop-
erly. Thepoweramplifiershouldprovideagainof26dB
(±6dB) foroptimumperformance.
Note.PolarityoftheSenseconnectionsdoesnotmatter,
howeveritisimportanttoverifythattheseconnectionsare
consistentfromSenseinputtoampoutput.(i.e.ChannelA
SensetoAmpChannelAoutput.)
3. SignalOutputsfromtheMPS-3areactivebalanced, at
nominal+4dBVoperatinglevel. Theconnectorsmaybe
wiredbalancedorunbalanced,withmaximumoutputlevels
beforeclippingof+26dBVbalanced,+20dBVunbalanced.
4. Connectionsbetweenthepoweramplifieroutputsand
theMeyerSoundMPS-305orMPS-355loudspeakers
shouldbemadeaccordingtotheinstructionsfortheloud-
speaker. Theseconnectionsmustbeverifiedforcorrect
polarity.
Connections

OperatingInstructions
MeyerSoundLaboratories,Inc.
2832SanPabloAvenue
Berkeley,CA94702
MPS-3
Control
Electronics
Unit
Output Level
Controls and
Mono Switch
TheOutputLevelControlsregulatethegainofeach
channelof the MPS-3. Theirrange isfrom off to0 dB,
with-6dBgainatthecenterposition.
WhentheMonoSwitchisengaged(in), thetwoinput
channelsaresummedandroutedtobothoutputs. While
operatinginmono,eachoutput'slevelisstillcontrolledby
itsrespectiveLevelControl. WhentheMonoSwitchis
disengaged(out),theMPS-3operatesinstereo.
Lo Cut Switch TheLoCutswitchontheMPS-3frontpanelintroducesa
6dB/octavehighpassfilterat160Hzonbothchannels.
Thisfilterisdesignedtoreduceanylowfrequencyempha-
siscausedbycornerplacementoftheMPS-305orMPS-
SpeakerSense™
Driver Protection ThroughtheSenseconnectionsbetweentheMPS-3and
thepoweramplifier,theSpeakerSensecircuitryofthe
MPS-3continuouslymonitorsthevoltagesacrossthe
loudspeakerdrivers. Iftheamplifierouputexceedsthe
safeoperatinglimitsofthedrivers,eitheranRMSlimiter
oraPeaklimiterwillbeautomaticallyactivated,holding
downthepowerleveloftheMPS-3output.
TheoperationoftheSpeakerSensecircuitryisindicated
byasingle,bi-coloredSense/LimitindicatorLEDforeach
channel.
ThefunctionoftheSense/Limitindicatorisasfollows:
•SignalPresenceIndicator. TheSense/Limitindica-
tor lightsgreentoindicatesignalpresence,andveri-
fiesthattheSenseconnectionsbetweentheamplifier
andtheMPS-3aremade. Theindicatorwillflicker
greenatlowsignallevels.
•LimitIndicator. TheSense/Limitindicatorlightsred
wheneverthelimiterisactivated. Amoderateamount
ofredflickeringofthisindicatorisacceptable. The
RMSlimiterhasanattacktimeof60msec,andis
designedtoprotectthesysteminsustainedhighlevel
use.
Limiter Operation Toverifylimiteroperationinthefield:
• Disconnectloudspeakers,leavingtheamplifierandthe
MPS-3intheirstandardconnectionconfiguration.
• Ifyouramplifierrequiresaload,useresistiveloads
sufficienttodissipatethefullpoweroftheamplifier.
• TurnonboththeMPS-3andtheamplifier.
• SwitchtheLoCutout.
• SupplyaninputtotheMPS-3,preferablyasinewave
oscillator. Ifyoudonothaveanoscillator,use a
microphoneandamixertoproducealine-levelsignal.
• Settheinputfrequencyoftheoscillatorto1kHz,or
whistleintothemicrophone.
• BringuptheOutputLeveluntilyouseetheSense/
Limitindicatorlightred. Sincetheindicatorwilllight
redonlyifthelimiteractuallyoperates,itprovidesa
positiveindicationthatthelimiterisfunctioning.
AC Voltage
Selector and
Fuse
Primaryprotection forthe MPS-3is provided bya 1¦4A
SloBlofuselocatedinareceptacleadjacenttotheAC
cord. Beforeexaminingorreplacingthefuse,firstunplug
theAC powercord. Toreplacethefuse,insertaflat-
bladescrewdriverinthefusecapandgentlyturncounter-
clockwise. Thefusewillspringfromitssocket. Replace
onlywithafuseofthetypeandratingspecifiedbyMeyer
Sound.
TheMPS-3musthavethecorrectvoltagesettingandfuse
fortheACpowersource inyourarea. Tochangethe AC
voltagesetting,firstunplugtheACpowercord. Usinga
smallflat-bladescrewdriver,movetheslideswitchtothe
appropriatepositionasindicatedbytheadjacentpanel
legend.
355loudspeakers,butcanalsobeusedtocompensate
fortheproximityeffectofcardioidmicrophones. The Lo
Cutswitchisalsousefulforpreventingspeakeroverload
whenusingMPS-305loudspeakers.

OperatingInstructions
MeyerSoundLaboratories,Inc.
2832SanPabloAvenue
Berkeley,CA94702
MPS-3
Control
Electronics
Unit
Specifications InputType Balanced(active),24kohms
OutputType Balancedactivepush-pull,pin1tochassis=500Ω
MaximumInput/OutputLevel
Balanced +26dBV
Unbalanced +20dBV
HumandNoise -90dBV("A"weighted)
DynamicRange 110dB
SenseInputs 10kohmtruedifferential
DriverProtectionCircuitry RMSlimiter, 60msecintegrationtime,
LFslidingfilter
Indicators
Sense/Limit Bi-colorLED(green/red)
Power GreenLED
FrontPanelControls RotaryOutputLevelcontrols, ACon/offswitch,
Monoswitch,LoCutswitch
Connectors
InputsandOutputs XLR-type(A-3)
SenseInputs Bananajacks
Power 120VAC/240VACrearpanelselectable
PhysicalDimensions 19" W x 13/4" H x 73/4" D
Weight 7lbs(3.1kg)