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<blockquote data-quote="Kyle_Keating" data-source="post: 4719593" data-attributes="member: 582385">it does the same thing as a port, its a moving mass with a resonance.for example, a 6&quot; port reaches its compression limit at about 14-15&quot; peak to peak. This is when the air velocity reaches a high level and eddy current/turbulence forms as well as excessive drag on the sides of the port. Drag is not a linear function, it has a squared term.that means the AIR in the port is moving 7-8 &quot; each direction back and fourth with good linearity and will produce lots of SPL (much more than the active driver). It is the air inside a port that is like the cone of the woofer. Its reaches its maximum spl at resonance which depends on the mass of the air in the port and the volume of the box too. Think of a spring mass-system. At resonance is when the most air comes out of the port.&nbsp; This is also why when people say xmax doest mean anything, they don&#039;t understand that xmax is shifting from the active woofer to the port during resonance, and if you&#039;re port can&#039;t displacement air... you&#039;re out of luck for high SPL numbers. its all about displacement one way or another.The PR does the exact same thing, expect its much larger but can&#039;t move as much so here is a quick comparison.A 6&quot; port moving 14&quot; peak to peak is about the same as a 15&quot; passive radiator that can move 2.5 to 3&quot; peak to peak before compression. When they both reach compression, you&#039;re in for distortion and SPL losses, but hte advantage of the PR is you can tune it deep in any box volume, and you can re-tune it later one. Its more dynamic in tha regard.</blockquote>

[QUOTE="Kyle_Keating, post: 4719593, member: 582385"] it does the same thing as a port, its a moving mass with a resonance. for example, a 6" port reaches its compression limit at about 14-15" peak to peak. This is when the air velocity reaches a high level and eddy current/turbulence forms as well as excessive drag on the sides of the port. Drag is not a linear function, it has a squared term. that means the AIR in the port is moving 7-8 " each direction back and fourth with good linearity and will produce lots of SPL (much more than the active driver). It is the air inside a port that is like the cone of the woofer. Its reaches its maximum spl at resonance which depends on the mass of the air in the port and the volume of the box too. Think of a spring mass-system. At resonance is when the most air comes out of the port. This is also why when people say xmax doest mean anything, they don't understand that xmax is shifting from the active woofer to the port during resonance, and if you're port can't displacement air... you're out of luck for high SPL numbers. its all about displacement one way or another. The PR does the exact same thing, expect its much larger but can't move as much so here is a quick comparison. A 6" port moving 14" peak to peak is about the same as a 15" passive radiator that can move 2.5 to 3" peak to peak before compression. When they both reach compression, you're in for distortion and SPL losses, but hte advantage of the PR is you can tune it deep in any box volume, and you can re-tune it later one. Its more dynamic in tha regard. [/QUOTE]

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