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The controls for the 548B Routing and Output section function as follows:
PGM (Program): Assigns the channel output to the Program Bus
• The Program Bus is fed post the channel pan-pot
• Illuminates when engaged
FLTR (Filter): Activates the channel output high-pass Filter
• -3 dB at 50Hz
• 6 dB/octave slope
• Illuminates when engaged
• The channel output Filter is located post the Fader wiper and pre the Fader amplifier
Note: An additional band-pass filter is available on channels equipped with 550A Equalizers.
INS (Insert): Activates the channel Insert Return
• The Insert Send is fed pre-fader from the output of the Equalizer
• The Insert Send is always active
• The Insert Send is a balanced, line-level signal routed to the INSERT SEND
(EQUALIZER OUTPUT) 1/4” tip-ring-sleeve jack on the rear panel
• The Insert Return accepts a balanced, line-level signal from the INSERT RETURN
(FADER INPUT) 1/4” tip-ring-sleeve jack on the rear panel
• The Insert Return is located post-EQ and pre-fader
• The Insert Return is active only when the INS button is engaged
• Illuminates when engaged
Trim-pot: The trim-pot below the channel pan-pot calibrates the FADER IN to the DIRECT
OUTPUT stage so the path is exactly at unity gain with the channel fader set to 0dB.
PAN (pan-pot): Provides continuous panning control
• Stereo panning between the Left and Right Program Buses
• Odd and Even panning between Summing Buses (when
engaged)
PAN (button): Activates Odd/Even panning between the assigned
Summing Buses
• The PAN button must be engaged to enable summing bus
panning
• The PAN button only applies to summing bus panning and does
not affect Program Bus Left/Right panning
• Illuminates when engaged
Summing Bus (ACA) Assignment 1-8: Assigns the channel output
to one or more of the eight Summing Buses (Active Combining
Amplifiers).
• Assignments to the Summing Buses can be made on an
individual basis
• Summing Buses are fed post-fader or post the channel pan-
pot when it’s engaged
• Summing Bus assignments are only active when engaged
• Switchable Odd/Even Summing Bus panning
• The Summing Buses 1-4 can be fed pre or post fader from
Echo/Auxiliary Sends 7 and 8