JBL MPA275 - Manual (Page 4)

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The MPA275, MPA400, MPA600, MPA750 and MPA1100 are high-efficiency profession-
al power amplifiers, with two independent channels, respectively capable of deliver-
ing 275, 400, 600, 750 and 1100 watts into a four ohm load (per channel), and
substantially more power into lower impedance loads. Semi-toroidal power trans-
formers (one per channel in the MPA750 and MPA1100) are mounted in each front
corner, as close as possible to the rack ears and rails. The rear panels are 16.9 inches
behind the front mounting plane, so an extra rack depth allowance (i.e., more than
18 inches) will be needed to clear XLR or Speakon connections. The built-in fan
cooling takes air in the rear, exhausting through front vents. Due to the flow-through
cooling, amplifiers may be racked with zero clearance in between, which also helps
support the weight. Rear support within the rack must be used in portable applica-
tions.
Open Input Architecture™ Slots
Provided with each MPA Series amplifier is a standard input module. This module
and the upper input cover panel can be removed, permitting future upgrades.
Internally, a ribbon cable runs behind both of these “slots.” The ribbon cable con-
nects to the rest of the amplifier and carries several levels of DC power, and (for each
channel) the input signals, speaker output monitor, muting status, clip activity, ther-
mal status, and power-on status. These signals are provided to support future remote
control and monitoring schemes as they become available. The JBL Marketing depart-
ment will be happy to entertain suggestions for input modules.
The “standard input board” which is shipped with each amplifier has balanced
XLR and barrier strip inputs, bridging and input-parallel switches, and footprints for
passive rolloffs and popular input isolation transformers (more info is available on
request).
Unit Description
Figure 1. Open Input Architecture Slots.