Park Audio II DF series, Owner'S Manual

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5
FUNCTIONAL FEATURES
Overload and Short-Circuit Protection
Individual per each channel. This protective system becomes active in case of
short-circuited output or overload, caused by reduced load impedance. It disables the
output signal of the respective channel for 0.5 second and then the amplifier gradually
resumes its delivery.
DC Output Protection
The amplifier schematics precludes any clicks or noise occurring during the
power-on/off transition processes without utilizing any relay, commonly used for
connecting the output signal to a loudspeaker. To prevent any DC damage to
loudspeakers, the amplifier incorporates the triak protection system for each channel,
which short-circuits the amplifier output in case of DC voltage or powerful LF
fluctuations.
High Frequency Protection
Should any powerful high frequency fluctuations occur on the output either as a
result of poor contact in the input cable connectors, or being send to the amplifier’s input
by any other device (such as a crossover or mixing console), the protection system
activates the built-in optoelectronic Clip-limiter to reduce the input signal level. Thus the
protection system effectively prevents any damage to tweeters as might be caused by
non-musical signals of powerful high frequency spectrum.
Thermal Protection
The continuous-operation-support protection system is common for four
channels. When the heat sink becomes heated over 50°С, the fan goes into its
maximum speed mode (normally, the fan runs at its minimum at a low speed). If the
temperature of the heat sink rises further to 65°С, the next stage of the thermal
protection system goes active. It is a built-in Clip-limiter, which reduces the input signal
level (for all channels at a time) without distorting the amplified signal. In this case the
thermal protection LED becomes slightly lit (dim). The higher the temperature, the
lower signal level, the brighter is the LED. Such an algorithm ensures faultless and
continuous functioning of the amplifier even in case of overheating.
The amplifier may stop functioning only in case of the fan breakdown or blocked
air flow. In this case upon reaching 85°С, the independent protection system disables
the respective channel of the amplifier. The CLIP LED goes on and the SIGNAL LED of
the affected channel goes off. The amplifier resumes its operation in the reverse order.
As soon as the amplifier cools down, the affected channels gradually regain their
amplification level up to the set value.
Soft Signal Start
During the power-on process, this feature ensures smooth gain from zero to the
maximum level to provide for a smooth rise of the sound level, emitted from the
loudspeakers.