POWER HANDLING LIMITATIONS
The power handling capability of any woofer isYVoice coil overheating and burning due to
related to both its ability to dissipate heat and theoverexcursion are often caused by overdriving
maximum excursion limits of its cone. Once thean amplifier into Oclipping.� A severely clipped
speakerOs voice coil moves outside the magneticsignal, or square wave, contains nearly twice
gap, power can no longer be converted intothe power of a clean sine wave at the same level.
motion and all the amplifierOs power is convertedBass that sounds broken up and distorted at
into heat in the voice coil. This voice coil heatinghigher volumes is usually indicative of an
is the largest detriment to speaker longevity, soamplifier that is clipping and being asked to
overexcursion should be avoided. Since speaker-deliver power beyond its ability.
cone excursion is different for each type of
enclosure, power handling is different for eachY Infinite-baffle or Ofree air� mounting applica-
enclosure.tions allow for greater cone excursion than
subwoofers mounted in an enclosure. In order
Sealed enclosures exert the most control over to compensate, the power handling of the
the motion of a subwoofer because the air insidesubwoofer will likely be half its rated power
the box acts like a spring against the motion ofin this application.
the woofer cone. Larger boxes allow for more
excursion, thus providing more low-frequencyYStudy the excursion curves on the enclosed
output for the amount of power used. WhenReference Series data sheet and note the
placed in a sealed box much larger than the Vasdifferences for different enclosure applications.
of the subwoofer, it will perform as if it were in The type and size of box used will produce
an infinite-baffle installation.different excursion demands on the enclosed
subwoofer and, consequently, different
Vented and bandpass enclosures have the lowestlevels of power handling. As long as the
amount of excursion for the amount of soundrecommended enclosure parameters are
output. This is a result of port output reinforcingused, the subwoofer will perform properly
the sound output from the woofer. The mass ofin its enclosed environment. However, any
the air contained in the port provides an acousticdesign deviation may result in less than
load on the wooferOs cone at the tuning frequency,optimum performance, and may also subject
and this added mass decreases woofer-conethe subwoofer to overexcursion (i.e., where the
excursion. Vented boxes do not provide adequatevoice coil leaves the gap) that can eventually
woofer control when driven below the tuned damage the speaker. For additional help with
frequency (Fb), so proper design is important. Athis issue, please contact your authorized
vented bandpass box will have the lowest overallInfinity dealer.
cone excursion, provided a subsonic filter is used.
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ACEC
