L-ACOUSTICS LA 24 MANUAL Version 2.2
17/11/08 16
•
PROTECTION FEATURES
Each L-ACOUSTICS amplifier has many advanced protection features that will protect both
the amplifier and the speakers connected to it should a fault condition arise. All protection
circuits are independent and under normal use these features are inaudible. When 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.
Clip limiter
The clip limiter is included to prevent dangerously clipped signals from reaching the speaker
and damaging it. Limiting circuitry 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. Note that if the signal is distorted or clipped before it reaches the amplifier,
the clip limiter will not be activated.
Under normal operation, clip limiting is inaudible. The limiter can be turned On or Off by
depressing the clip limit switch (2).
Clip Limiter ON = switch depressed (IN position)
Clip Limiter OFF = switch not depressed (OUT position)
L-ACOUSTICS recommends leaving the clip limiters switched "on" (button depressed) at all
times.
Thermal protection
When the amplifier is driven very hard into low impedances, the cooling fans go into high
speed. If the conditions that cause this continue, the TEMP indicator(s) will light as an
indication that the amplifier will soon thermal out.
After five seconds the amplifier will go into thermal protect, muting the input signal. After 15-
20 seconds the amplifier will cool the
Intercooler
®
and the cycle will begin again.
Thermal protection starts when the I
ntercooler
®
reaches a temperature above 90
0
C.
VHF protection
When a signal of more than 12kHz at full output power is present at the output connectors
for more than five seconds, the VHF protection circuit mutes the input signal and the VHF
LED will light. This is a useful feature since there are currently no commercially available
compression drivers that can take 1000 watts of continuous power at 12 kHz!! This circuit is
inaudible under normal use, however it can be turned off.
If the VHF protection is required to be turned off, e.g., for studio monitors, please consult the
factory, as this is a non-user adjustment.
