Owner`s manual

PAGE 35 Community Solutions™ Owner’s Manual
13 OPERATING PRECAUTIONS
The following sections detail certain operating precautions for the loudspeaker which 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.
13.1 PowerSense DDP Cautions
The crossovers for the SLS models incorporate PowerSense DDP (Dynamic Driver Protection) circuitry
that automatically provides thermal and over-current protection for the individual drivers. The SBS
subwoofers do NOT have PowerSense circuitry. The PowerSense circuits are designed to work in
conjunction with an electronic controller, or some other type of electronic limiter. Without the
combination of passive and electronic protection, the loudspeaker system is more susceptible to
damage and outright failure. This combination provides significant but not absolute protection from
damage. For example, 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 14: “Effects of Amplifier Clipping” and to SECTION 13.3 “Using Low Power Amplifiers”.)
13.1.1 Operating Modes and PowerSense DDP
The PowerSense DDP circuits function in both the PASSIVE and BIAMPLIFIED modes for all SLS models.
This means that in BIAMPLIFIED mode, both the HF and LF sections have their own PowerSense
protection. The only exception to this is the 12” (305 mm) LF driver in the SLS918.
The SBS subwoofers do NOT have PowerSense circuitry because they do not have an internal crossover.
Protection, as well as the required crossover function, must be supplied by external electronics.
CAUTION:
Do not operate the SBS subwoofers without an appropriate high-pass filter. The high-pass
filter attenuates low frequencies that are below the useful frequency range of the subwoofer.
Such frequencies can cause excessive cone excursion and possible driver damage.
13.1.2 PowerSense DDP Circuit Operation (SBS subwoofers do not have this circuit)
This proprietary circuitry can help ensure that your SLS loudspeakers will perform at their best and
keep performing year after year. It provides not only a measure of protection but gives clear visual and
audible indications to the operator of excessive power input. The PowerSense circuit actually has three
levels of protection (See note below For SLS915 and SLS918).
For short term excessive power inputs occurring at high frequencies, the excess power to the HF driver
is absorbed by HPCCRs (High Positive Current Coefficient Resistors). These are wired in series with the
high frequency driver and convert excessive power to light and heat. When these HPCCRs emit light,
their impedance goes up and thus reduces the power input to the HF driver.
When activated, flashes of light from the HPCCRs can be seen through the bass ports of the
loudspeaker alerting the operator of the excessive power input. Very occasional flashing (once in
several seconds) is OK. If flashing occurs more often than this, it indicates that the volume should be
immediately reduced. This level of protection has little effect on the system output as these HPCCRs
are always in circuit and gradually absorb excessive power in a way that is audibly similar to a
compressor circuit with a “soft” knee.
For longer term or more excessive input, the power to the mid frequency driver or to the entire system
will be reduced by current sensitive relays. These make up two additional levels of protection. One
relay, when opened, puts a set of HPCCRs in series with the mid frequency driver and the other, when
opened, puts a different set of HPCCRs in series with the entire system. These sets of HPCCRs are only
put in series with the signal as a result of excessive current causing its associated relay to open. When
the signal is switched to pass through the HPCCRs, the loudspeaker’s output volume will be reduced