1231 User Manual

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Input Gain Control: Thiscontrolsetsthesignalleveltotheequalizer.Itiscapableof-12dBto+12dBofgain.Its

effectisapparentbyviewingtheOUTPUTLEVELBARGRAPH.

EQ Bypass: Thisswitchremovesthegraphicequalizersectionfromthesignalpath.(SeeBlockdiagramonPage

8.)TheBYPASSswitchdoesnot,however,affecttheINPUTGAIN,orLOWCUTfilters.

EQ Bypass LED:ThisredLEDlightswhentheEQisinbypassmode.Notethatbypassmodeonlyeffectsthe

graphic equalizer section of the 12 Series EQs. TheINPUTGAIN and and LOWCUT controls remain unaffected

when the EQ is bypassed.

Boost/Cut Range Selection Switch and LEDs: Thisswitchselectswhichofthetwoboost/cutrangestheequalizer

willuse,either±6dBor±15dB.TheredLEDlightswhenthe±15dBrangeisselected,andtheyellowLEDlights

whenthe±6dBrangeisselected.NotethattheBOOST/CUTswitchisslightlyrecessed.Thisistopreventacciden-

talactivationoftheswitch,possiblycausingdamagetoothersoundsystemcomponents.

Output Level Bar Graph: ThesefourLEDsindicateoutputleveloftheequalizer.TheredLEDis3dBbelowclip-

pingandismarkedas+18dBu.Itmonitorsthelevelattheoutputoftheequalizerafterallotherprocessing.

Clip LED: ThisLEDlightswheneveranyinternalsignallevelreaches3dBbelowclippingwhichmayoccurwhen

anyofthefollowinghappen:1)theinputsignalis“hotter”than+22dBu,2)excessivegainisappliedbytheinput

gaincontrol,or3)excessiveboostisappliedusingthefrequencysliders.

Frequency Band Slider Controls: Each one of these slider potentiometers will boost or cut at its noted frequency

by±6dBor±15dB,dependinguponthepositionoftheBOOST/CUTRANGEswitch.Whenalltheslidersarein

the center detented position the output of the equalizer is flat. The frequency band centers of the 1231 are marked at

1/3rdofanoctaveintervalsonISOstandardspacings,whilethefrequencybandcentersofthe1215aremarkedat

2/3rdsofanoctaveintervalsonISOstandardspacings.

Low Cut Enable Switch: TheLOW-CUTswitchinsertsorremovesthe18dB/octave40HzBessellow-cutfilter

fromthesignalpath.WhentheLOW-CUTswitchispushedin,theLOW-CUTfilterisINtheaudiopath.

ConneCtIng the eQ to your systeM

The 12 Series Equalizers have balanced inputs and outputs that can be used with any balanced or unbalanced line-

leveldevice.Formorespecificinformationaboutcablingpossibilities,pleaserefertothesectionentitled

Installation Considerations, Page 5.

To connect the equalizer to your sound system refer to the following steps:





Install the EQs in a rack with the rack screws provided. It can be mounted above or below anything that does

notgenerateexcessiveheat.Ambienttemperaturesshouldnotexceed113°F(45°C)whenequipmentisinuse.

Althoughtheunit’schassisisshieldedagainstradiofrequencyandelectromagneticinterference,extremely

highfieldsofRFandEMIshouldbeavoided.



All three types of connectors for the inputs and outputs can be used for balanced or unbalanced connections.

Theuseofmorethanoneconnectoratatimefortheinputscouldunbalancebalancedlines,causephasecancel-

lation,shortaconductortoground,orcausedamagetootherequipmentconnectedtotheequalizer.Morethan

oneoutputmaybeusedsimultaneouslyaslongasthecombinedparallelloadisgreaterthan600Ω.

switch

Note: Be sure to reduce audio levels at the power amplifiers when changing the setting of this switch as it may generate an audible transient.



ConnecttheACpowercordtotheACpowerreceptacleonthebackoftheequalizer.RoutetheACpowercord

to a convenient power outlet away from audio lines. The unit may be turned on and off from the rear panel

OPERATION MANUAL

12 SERIES GRAPHIC EQUALIZERS

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User Manual - Page 7