Cerwin-Vega CXA series, Руководство по эксплуатации

Страница: 6 / 9

PROTECTION
Every model in the CV-Series incorporates protection features.
The front panel Protection LED indicates the activity of the
speaker connection relay circuitry in each channel.When the
protection LED turns on, this circuitry is active, and all connected
speakers are muted.
Initial power-up : For approximately five seconds after initial
power-up, the protection circuitry is activated and the speaker
outputs are muted. If everything is operating normally, you will
hear an audible click at the conclusion of this brief period, as the
protection circuitry is deactivated and the unit begins delivering
signal to the connected speakers. It is normal for the Protection
LED to fade gradually after the amplifier is powered off.
Thermal Protection : Abnormally high heat sink temperatures
will engage the protection circuitry for the overheating channel
only. An output relay disconnects the speakers until normal
temperature range is restored. The Protect indicator will light to
show the protection circuit is active. To guard against this
problem, make sure the unit receives adequate ventilation on
all sides and that both the front and rear panels are
unobstructed. If the power transformer gets too hot, its thermal
switch will disconnect all of the secondary power and disconnect
both channel outputs.
Short circuit : If output is shorted due to faulty wiring, the
thermal circuitry will automatically protect the amplifier. If this
occurs, the load will be disconnected by the thermal protection
circuitry.
DC Voltage Protection : If an amplifier channel detects DC
voltage at the speaker output, the output relay will immediately
open to prevent speaker damage.
Subsonic Frequency Protection : The built-in High Pass Filter
provides subsonic frequency protection for each channel.
Current limiting Protection : At the amplifier’s full power limit,
or clipping point, the limiter circuitry will be activated. This is
indicated by illumination of the Clip LED. The channel gain is
automatically reduced, protecting the speakers from high power.
Uncontrolled feedback, oscillations, or improper equipment gain
setting may activate this circuitry, which is virtually transparent
in operation as full signal bandwidth is maintained.
There is reason to be concerned any time the Protection LED
lights up (except for initial power-up during approximately five
seconds). If this occurs, turn the amplifier off immediately and
check all wiring and external equipment carefully in order to
locate and correct the condition.
SETUP
Clipping is the result of an amplifier running into power supply
limitation. The maximum output voltage that any amplifier can
produce is limited by its power supply. Attempting to output a
voltage (or current) level that exceeds the power supply limit
will result in a flattening effect on the signal. A clipped waveform
exhibits extreme harmonic distortion, making it sound harsh or
dissonant. The clip limiter detects this and reduces the gain to
minimize the amount of overdrive. To preserve as much of the
program dynamics as possible, limiting reduces the average
program level until peaks barely clip. Each channel has its own
clip limiter, which can be switched on or off. When driving full-
range speakers, clip limiting reduces high frequency distortion
caused by bass overload. It also protects higher frequency
drivers from excess overdrive and harsh clipping harmonics.
Also known as a low-cut filter, a High Pass Filter rolls off signals
below 40Hz. The reproduction of the signal’s bass portion is thus
optimized, since ultra-low, distracting frequencies are
eliminated, and more power is available for the reproduction of
the wanted segment of the signal.
You should set up the filters so they best suit the frequency
response of your speakers, since some speakers are particularly
sensitive to over-excursion. The 40Hz filter works well with most
compact full-range speakers.
Clip limiter HPF (Hi-Pass Filter)
4