Bogen M-CLASS AMPLIFIER M450 - Manual (Page 13)

Operation
70V Mono Mode
Placing the 3-position switch to its right most position puts
the amplifier in the 70V Mono mode of operation. The
amplifier supplies a single channel of amplification in this
mode (see 70V Mono Mode Block Diagram). This mode also
mixes the signals from each input module into a mono pro-
gram. Input signals of modules that are assigned to the "A"
bus are controlled by the "A" level control on the front of
the unit and likewise for modules whose outputs are
assigned to the "B" bus. By assigning each module to a different bus, a 2:1 mixer is formed with the front-mount-
ed level controls adjusting the mix. Additionally, one module can be set to mute the other when it is active,
thereby providing an effective paging system (see the section on Module Priority). It is important in this mode to
set the assignment jumpers on the two input modules so that their outputs are on different audio buses (see
the section on Audio Buses). Speakers must be correct for 70V operation. (See section on 70V “Transformer-
Coupled” Speakers).
Dual Mono Mode
Placing the 3-position switch to its center position puts the
amplifier in the Dual Mono mode of operation.This mode is
similar to the 70V Mono mode except that the amplifier
supplies two channels of low-impedance amplification in this
mode (see Dual Mono Mode Block Diagram).This mode still
mixes the input signal from the different modules but a
Channel Balance control is provided to adjust the output
levels of one channel against the other (see the section on
Channel Balance). It is important in this mode to set the assignment jumpers on the two input modules so that
their outputs are on different audio buses (see the section on Audio Buses). Speakers must be low-impedance
type, not 70V type.
Audio Buses
The M-Class amplifier contains two separate audio buses.The "A" bus level is adjusted by the "A" level control
on the front of the unit and the "B" bus is adjusted by the "B" Level control. Most Bogen modules provide a
means to assign their output to either or both of the audio buses.The instructions that accompany the mod-
ules will describe the jumper settings for these assignments.When using the M-Class amplifier in either the 70V
Mono or Dual Mono modes, the module signals will be mixed (see 70V Mono Mode under the Operation sec-
tion of the manual). For maximum control when mixing signals, it is important that each of the two input mod-
ules be set so that the outputs feed different audio buses. Otherwise, proper mixing of the signals will be diffi-
cult. Check that each module is set to a different audio bus before installing it.
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70V Mono Mode Block Diagram Dual Mono Mode Block Diagram