User’s Manual
K&F Self Powered Subwoofer Systems ‘SP’
KLING & FREITAG GMBH ©2003 - 2014
Version 7.0, 09.09.2014
Page 12 of 48
6)
LED POWER ON (GREEN) and LIMIT / PROTECT (RED)
The LED is dual-purpose:
a)
When the LED is green, the speaker is connected to the supply voltage and
ready for operation
b)
The LED will turn red if…
…the input signal is so high that the internal limiters reduce its level.
The limiters consist of a peak limiter, which limits the peaks of the signal,
and an RMS / thermal limiter, which continuously regulates excessive levels.
During normal operation the red light may occasionally illuminate briefly. It
does indicate that the level peaks are limited by the limiter circuit. The peak
performance of the speaker has then been reached.
Should the red light come on more frequently or remain illuminated, the
output level of the mixer should be reduced. When speakers with and
without SP module are in operation simultaneously, the gain control on the
SP speaker can be turned down, provided the level is sufficient for the oth-
er power amplifiers. The limiter protects the speaker from damage due to
excessive levels.
c)
The LED stays permanently red, if…
…the protection circuitry of the integrated power amplifier cuts in and as a
result no further signal reaches the speaker (Protect Mode).
The protection circuitry switches off the integrated power amplifier,…
−
…if the temperature of the amplifier module is too high. As soon as
the temperature falls below the critical value, the amplifier module is
switched on again automatically. Excessive temperatures can be
caused for example by inadequate ventilation of the heat sink. Make
sure that the air vents are not covered or positioned directly against a
wall.
−
…if the output impedance is too low or in the case of a short circuit,
caused for example by a defective chassis or a faulty component on
the crossover.
−
…if the amplifier has an internal fault. The SP amplifier module checks
that all is functioning correctly during operation. As soon as a fault be-
comes apparent the module switches into protect mode. If only one
module of the SW 215E has a fault, the input signal is attenuated by
70 dB, to prevent damage to the other module.
Measures to be taken when LED is red:
Fault
Measure
Function
LED remains red or flickers
continually during opera-
tion
Reduce output level on mixer until LED
goes out or flickers only occasionally.
Limiter
No or too low output sig-
nal, LED shows red in spite
of reduced mixer level.
Allow to cool. The amplifier module
switches itself on after a few minutes.
Provide sufficient ventilation.
Temperature
protection
No or too low output sig-
nal, LED stays red after
cooling down.
Have loudspeaker checked by
authorized repair technician.
Other
protection
SW 215E:
Output signal is
too low
Have loudspeaker checked by
authorized repair technician.
Other
protection
