Power-Handling
Limitations
The power-handling capability of any woofer is related to both its ability to dissipate heat and the maximum excursion limits of its cone. Once the speaker’s voice coil moves outside the magnetic gap, power can no longer be con- verted into motion, and all the amplifier’s power is converted into heat in the voice coil. This voice-coil heating is the largest detriment to speaker longevity, so overexcursion (driving the speaker past Xmax) should be avoided. Since speaker-cone excursion is different for each type of enclosure, power handling is different for each enclosure.
•Voice-coil overheating and burn- ing due to over-excursion is often caused by overdriving an ampli- fier into “clipping.” A severely clipped signal, or squarewave, contains nearly twice the power of a clean sine wave at the same level. Bass that sounds broken up and distorted at higher volumes usually indicates that the ampli- fier is being asked to deliver power beyond its ability.
•Infinite baffle or “free air” mounting applications allow for greater cone excursion than sub- woofers mounted in an enclosure. In order to compensate, recognize that the power-rating value of the
subwoofer will likely be half its rated power in this application.
•Study the excursion curves on the enclosed GT Series data sheet and note the differences for different enclosure applica- tions. The type and size of box used will produce different excur- sion demands on the enclosed subwoofer and, consequently, different levels of power han- dling. As long as recommended parameters are used, the sub- woofer will perform properly in its enclosed environment.
However, any design deviation may result in less than optimum performance, and may also subject the subwoofer to over- excursion that can eventually damage the speaker. For additional help with this issue, please contact your authorized JBL dealer.
