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Safety
6
Speaker Protection
All loudspeakers have electrical,thermal and physical limits which must be
observed to prevent damage or failure. Too much power,severely clipped wave
forms,low frequencies applied to high frequency drivers and DC voltage can all
be fatal to cone and compression drivers. Crest Audio CKi Series amplifiers
automatically protect speakers from DC voltages and subsonic signals.
Be sure that the low and mid bands of an electronic crossover are connected
to the correct amplifiers and drivers,and not accidentally connected to those
for a higher frequency band. The amplifier’s clipping point is its maximum peak
output power,and some of the higher-powered CKi Series amplifiers can deliv-
er more power than many speakers can safely handle.Be sure the peak power
capability of the amplifier is not excessive for your speaker system.
To ensure the speakers never receive excessive power and that the amplifier
never clips,use a properly adjusted external limiter (or a compressor with a
ratio of 10:1 or higher) to control power output;in systems with active elec-
tronic crossovers,use one for each frequency band. The clip limiter will auto-
matically limit the duration of squared-off,continuous wave forms applied to
the speakers.The amplifier will,however,allow normal musical transient bursts
to pass. When the amplifier does clip,it is at its maximum output power.
Some speaker systems are packaged with processors that have power limiting
circuits and should not require additional external limiting. Fuses may also be
used to limit power to speaker drivers,although as current-limiting rather than
voltage limiting devices. Some poor quality fuses have a significant series resis-
tance that could degrade the amplifier’s damping of the speaker’s motion and
may even deteriorate the system’s sound quality. If you elect to use fuses,
check with the speaker manufacturer to determine the proper current rating
and time lag required.
Do not drive any low frequency speaker enclosure with frequencies lower than
its own tuned frequency;the reduced acoustical damping could cause a ported
speaker to bottom out even at moderate power. Consult the speaker system
specifications to determine its frequency limits.
The wire gauge charts in Appendix D will assist you in determining the opti-
mum copper wire gauge for speaker cables in direct output systems.Speaker
cable resistance robs amplifier power in two ways:through power lost directly
to resistance (often referred to as I2R loss),and through increased total load
resistance,which decreases the amount of power available from the amplifier.
Appendix D gives cable length figures in feet/AWG wire gauges and in metric
values.
User Responsibility
Your CKi Series amplifier is very powerful and can be potentially dangerous to
loudspeakers and operators alike.It is your responsibility to read all precau-
tions and make sure that the amplifier is installed,wired,and operated properly
as instructed in this manual.
Many loudspeakers can be easily damaged or destroyed by overpowering,espe-
cially with the high power available from a bridged amplifier. Always be aware
of the speaker’s continuous and peak power capabilities.Crest Audio is not
responsible for damage to loudspeakers for any reason.
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