L-Acoustics LA15a, Руководство пользователя

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L-ACOUSTICS LA15a 115V Manual V1.0 27/01/2003 9
MLS positions can be different for each channel and a variety of combinations can be selected as seen in
Table 2. There is no risk for amplifier damage since the LA15a is very well protected (even down to 0.3
ohms). However, if uncertain or where time does not allow, use the default position (MLS = 0 dB).
Table 2: MLS Switch Setting Applications
Channel Impedance MLS Power Comments
A 8 -3dB 200W Power
B 8 -3dB 200W reduction
A 4 0dB 600W High peak
B 4 0dB 600W power
A 8 0dB 370W Power
B 8 -3dB 200W matching
A 8 -3dB 200W Power
B 4 0dB 600W sharing
4.2 CLIP LIMITER
The LA15a Channel A, B, C, and D clip limiters prevent dangerous clipped signals from reaching the
loudspeaker and causing damage. When an amplifier is severely overdriven, the output waveform is
clipped and peaks become squared off, causing a reduction in crest factor. In extreme cases, the
waveform can approach that of a square wave. Normally an amplifier is capable of producing far more
power under these conditions than its normal, undistorted rated output power.
The LA15a clip limiter works by monitoring the output and comparing the distortion produced between
the input and output of the amplifier. If the distortion exceeds 1% THD for any reason (voltage or
current clipping), the limiter reduces the input signal proportionally. Once the amplifier comes out of a
protect condition, the output level has a slow rise time (the effect is like turning the gain up slowly).
Under normal operation, clip limiting circuitry is inaudible.
Note: if the signal is distorted or clipped before it reaches the amplifier, the clip limiter cannot detect
this and will not be activated.
Individual channel clip limiters can be turned on (or off) by depressing (or pressing) the relevant clip limit
switch. L-ACOUSTICS recommends leaving clip limiters switched ON (button depressed) at all times.
Clip Limiter ON = switch depressed (IN position)
Clip Limiter OFF = switch not depressed (OUT position)