API 3124mb+ - Input Section: Mic;Instrument;Line Preamplifier; Preamplifier Overview and Features; Preamplifier Controls

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4.0 InputSection:Mic/Line/InstrumentPreamplifier
4.1 PreamplifierOverviewandFeatures
Eachofthefour3124mb+preamplifiers(seeFigure5)
is an all‐discrete microphone/instrument/line  pre‐
amplifier designed to provide an unusually good
sounding front‐end for all types of audio recording 
applications.Sonically,itoffersthedistinctAPIsound,
highqualityperformance,andlownoise.
Each preamplifier remains faithful to the
 circuit
designs of API’s founder, Saul Walker. Fully featured,
each carefully preserves the original sound character
that made it so much a part of the early days of
recording.
Offering high headroom and a wide variety of inputs and input access points, each preamplifier is
equallyathomeinthe
commercialrecordingstudioasitisinthehomeprojectstudio.
Features
 UsesAPI2520Op‐Amp
 XLRMicInput
 ¼”UnbalancedInput
 FrontPanelPolaritySwitch
 FrontPanel20dBPadSwitch
 FrontPanelMicSwitch
 FrontPanel48VPhantomPowerSwitch
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4.2 PreamplifierControls
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 
Eachpreamplifierprovidesacomprehensivesuiteofcontrols:
 GAIN:Preampgain
 POL:Preampinputpolarityinverter 
 48V:PhantomPower
 PAD:‐20dBmicrophonepad/‐6dB instrumentpad
 MIC:Mic‐Instrumentinputselector
Figure
6
:Channel1Controls
Figure5:Channel1PreamplifierSection