Owner`s manual

PAGE 36 Community Solutions™ Owner’s Manual
by several dB, quickly and noticeably. How much reduction will depend on the amount and frequency
range of the excessive power.
As a further indication of the operation of either of these circuits, a brighter, steadier light will be seen
through the bass ports than for the HF driver protection. The open relay will then reset itself after
several seconds, depending on the amount of excessive power, and the loudspeaker’s output volume
will return to normal. However, if the excessive power condition continues, the relay will re-open and
reduce the power and volume again. This will have the effect of the system volume cutting in and out
and is a clear warning of excessive power and the need to reduce the input level to the system.
Note: The SLS915 and SLS918 have only two sets of HPCCRs, one for the high frequency driver and one
for the dual 6.5” (165 mm) drivers. The set for the dual 6.5” drivers is relay activated. There is no
PowerSense DDP protection for the SLS918 12” (305 mm) driver.
WARNING:
Continued cycling of the relays can result in their failure. This will either lock the system up in
the reduced volume mode or, if the contacts fuse, bypass the HPCCR protection. Either
condition can result in damage to the loudspeakers or crossover components. When either the
HPCCRs for the HF driver flash, or the mid frequency or overall system protection relay is
activated, it means the loudspeaker is being protected, but only to a point. Therefore, any of
these conditions should be considered an immediate warning that the power input is excessive.
The volume level of the sound system should be reduced to a point where the HF driver
protection is activated only once every several seconds at the most.
13.2 Use Without Electronic Controller
All SLS and SBS loudspeakers will function without electronic control. However, this will provide
neither optimum performance from, nor any protection for the loudspeakers as Community’s
published specifications are established using electronic control. Bear in mind that Community’s
warranty provides insurance against manufacturing defects but does not cover loudspeakers that have
been damaged by excessive power input or other abuse – THIS INCLUDES OPERATION WITHOUT
ELECTRONIC CONTROL.
13.3 Using Lower Power Amplifiers
(Refer to the CHAPTER 8 “Choosing Power Amplification”)
When using an amplifier whose rated power output is below that recommended for the loudspeaker
listed in CHAPTER 9 “Operating Requirements”, the following precautions should be observed.
Driver damage and failure occurs most often when a loudspeaker is used with too small an amplifier.
The amplifier itself will be overdriven before the loudspeaker is or before the protection circuitry in the
controller is activated. The result is that the loudspeaker receives a badly distorted signal known as
amplifier clipping (refer to FIGURE 14). 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. NEITHER THE POWERSENSE DDP NOR THE CONTROLLER CIRCUITRY CAN PROTECT THE
LOUDSPEAKER FROM DAMAGE DUE TO POWER AMPLIFIER CLIPPING.
When operating an SLS loudspeaker with a lower power amplifier and without any sort of electronic
limiting protection, ensure that the amplifier’s limits are not exceeded. Most amplifiers have some
type of indicator that shows when it is clipping. Keeping the signal level below this point will usually
prevent loudspeaker damage or failure. High frequency drivers are very intolerant of clipping.
The SBS models contain no driver protection and must rely on external protection circuitry provided by
an external limiter. If no limiter is present, use an amplifier that is matched to the loudspeaker’s
Program power rating. For the reasons stated above, do not allow the amplifier to be driven into
clipping. FIGURE 14 describes and depicts clipping.