L-ACOUSTICS LA15a 115V Manual V1.0 27/01/2003
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Refer to Sections 5.1 and 5.2 concerning amplifier mounting and cooling considerations.
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Make sure that the AC mains voltage is correct and the same as the one printed on the rear
panel of the amplifier. See Sections 5.3-5.7 concerning operating voltage, grounding and
power consumption for more details.
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Make sure that the power switch is set to “off” before making any input or output
connections or operating the switches on rear panel.
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Make sure that the switches on the rear panel for clip-limiters and the MLS™ switches are in
the correct position. See Section 7 concerning operation modes, Section 8.1 about clip
limiters and Section 4.1 concerning the MLS switches.
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It is always a good idea to turn down the gain controls during power-up to prevent speaker
damage in case a high signal is present at the input.
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Remember the old saying: “amps on last, amps off first”
7.3 POWERING UP – SOFT START
When you power up the amplifier it takes a few seconds to check its circuits (this is known as the soft or
slow start sequence). The fans blow at high speed before going into idle and the two bottom green
LEDs illuminate to show the amplifier is operational.
7.4 INPUT ATTENUATORS
The four input level attenuators on the front panel adjust the signal level for their respective amplifier
channel in all modes. Input level attenuators are calibrated in dB to assist in setting up active loudspeaker
systems or cutting down unwanted noise from the input signal.
In bridged mode, both controls must be in the same position so that the speaker load will be shared
equally between the channels.
7.5 INDICATORS
Figure 13: LA15a Front Panel Detail
The two bottom green ”ON” LED’s indicate that the output circuits are receiving the correct rail
voltage.
The ”-25 dB” LED’s illuminate if the output signal is greater than -25dB (with 0 dB referenced to full
output power). These LED’s also act as signal present indicators.
The rest of the green LED indicates -10 dB below clip.
