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Community XLT / XLTE Series Owner’s Manual
9 OPERATING PRECAUTIONS
The following sections detail certain operating precautions for the loudspeaker that will aid in achieving and
maintaining its maximum performance and reliability. They also include important information for situations and
usage outside the basic set-up and operation described in the previous sections.
9.1 POWERSENSE DDP
All XLT and XLTE loudspeakers and subwoofers incorporate PowerSense DDP (Dynamic Driver Protection) circuitry
that automatically provides thermal and over-current protection for the individual drivers. This provides significant
but not absolute protection from damage. Neither the PowerSense circuitry nor electronic limiting can provide
protection from continual overdriving or from too small an amplifier being driven into heavy clipping. (Refer to
FIGURE 11 and SECTION 9.2.)
9.1.1 Operating Modes and PowerSense™ DDP
The PowerSense DDP circuitry functions in both the PASSIVE and BIAMP modes for all full-range loudspeakers. This
means that in BIAMP mode, both the HF and LF sections have their own PowerSense protection. The PowerSense
DDP circuitry is also fully functional for the subwoofers whether or not the FULL-RANGE OUTPUT is being used.
9.1.2 PowerSense™ DDP Circuit Operation
The PowerSense circuit has two levels of protection. For short-term, excessive power inputs, the DDP circuit
absorbs excess power using HPCCRs (High Positive Current Coefficient Resistors). Also, these excessive power
peaks will cause the rear input panel POWERSENSE LED indicator to flash red. Flashes of light from the HPCCRs can
also be seen from the front through the bass ports of the loudspeaker. Thus, whether the system is operated from
the rear or from the front, the operator will be alerted to the excessive power input. Very occasional flashing is OK.
If this happens more than occasionally, it indicates that the power to the loudspeaker is excessive and the volume
should be reduced.
For longer-term excessive power inputs, current-sensitive relays will automatically reduce the power input to the
system. This will reduce the output volume by about one-half or 6 to 8 dB. The rear panel POWERSENSE indicator
will glow red. The relays will reset themselves after several seconds and the volume will return to normal. However,
if the excessive power condition still exists, they will quickly reduce the power and volume again. This will have the
effect of the system cutting in and out. This cycle will continue until the power input is reduced to safe operating
volume levels.
WARNING:
Continued operation of the over-current relays can result in the system locking up in the reduced volume mode
and will likely result in damage to the loudspeakers or crossover components. When either the short-term
power protection or over-current relays are activated it means they are protecting the loudspeaker but can do so
only to a point. Therefore, these conditions should be considered an immediate warning that the power input is
excessive and the volume level of the sound system should be reduced.
9.2 USING LOWER POWER AMPLIFIERS
(Refer to SECTION 5.1 and FIGURE 11)
When using an amplifier whose rated power output is below that recommended for the loudspeaker in SECTION 5.1,
the following precautions should be observed.
Driver damage and failures occur most often when a loudspeaker is used with too small an amplifier. The amplifier is
overdriven before the loudspeaker limit is reached and/or the PowerSense DDP protection circuitry in the
loudspeaker is activated. The result is that the loudspeaker receives a badly distorted signal known as amplifier
clipping. (See FIGURE 11). The characteristics of a clipped signal are such that it easily can damage any speaker
component even if the power output is below the power rating of the loudspeaker. THE POWERSENSE DDP
CANNOT NORMALLY PROTECT THE LOUDSPEAKER FROM DAMAGE DUE TO POWER AMPLIFIER CLIPPING.