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<blockquote data-quote="Art Welter" data-source="post: 74810" data-attributes="member: 52">Re: SRX718 to &#039;what powered/active sub?&#039;Steve,You are correct, the SRX718 is a ported cabinet, which is why it starts rolling off from it&#039;s 95 dB sensitivity at 50 Hz, while the sealed cabinet using the same transducer starts it&#039;s less rapid rolloff at around 70 Hz.The upper sensitivity is the same for either cabinet, the reason I posted the comparison proving the SRX 718 spec sheet is measured in half space (cabinet on the ground as subs are usually used) rather than free space (non-riggable cabinet suspended in the air).In the half space comparison below of a Lab 2x12<a href="http://soundforums.net/diy-audio/134-free-sub-plan-dual-lab12-front-loaded-welter-systems.html" target="_blank">http://soundforums.net/diy-audio/134-free-sub-plan-dual-lab12-front-loaded-welter-systems.html</a>to a JBL SRX728, which is rated 98 dB sensitivity, note that the 2x12&quot; is within 3 dB of the output at 40 Hz, and 7 dB less at 80 Hz. The 2x12&quot; corresponds well to the Eminence Bass box Pro simulation, which shows the sensitivity of the&nbsp; 2x12&quot; enclosure at around 94-95 dB. The Lab 12 raw driver sensitivity is only 89.2 dB.Both cabinets used exactly the same pink noise signal through the same BW24 filter set to 25 and 125 Hz, microphone was on the ground at two meters.The JBL sensitivity is obviously measured in half space, or one would have to conclude my ported cabinet somehow is another 6 dB more sensitive than Eminence says it could be.Putting the same transducers in a tapped horn twice the size of the ported cabinet does gain 6 dB sensitivity, but that is another story...Art</blockquote>

[QUOTE="Art Welter, post: 74810, member: 52"] Re: SRX718 to 'what powered/active sub?' Steve, You are correct, the SRX718 is a ported cabinet, which is why it starts rolling off from it's 95 dB sensitivity at 50 Hz, while the sealed cabinet using the same transducer starts it's less rapid rolloff at around 70 Hz. The upper sensitivity is the same for either cabinet, the reason I posted the comparison proving the SRX 718 spec sheet is measured in half space (cabinet on the ground as subs are usually used) rather than free space (non-riggable cabinet suspended in the air). In the half space comparison below of a Lab 2x12 [url]http://soundforums.net/diy-audio/134-free-sub-plan-dual-lab12-front-loaded-welter-systems.html[/url] to a JBL SRX728, which is rated 98 dB sensitivity, note that the 2x12" is within 3 dB of the output at 40 Hz, and 7 dB less at 80 Hz. The 2x12" corresponds well to the Eminence Bass box Pro simulation, which shows the sensitivity of the 2x12" enclosure at around 94-95 dB. The Lab 12 raw driver sensitivity is only 89.2 dB. Both cabinets used exactly the same pink noise signal through the same BW24 filter set to 25 and 125 Hz, microphone was on the ground at two meters. The JBL sensitivity is obviously measured in half space, or one would have to conclude my ported cabinet somehow is another 6 dB more sensitive than Eminence says it could be. Putting the same transducers in a tapped horn twice the size of the ported cabinet does gain 6 dB sensitivity, but that is another story... Art [/QUOTE]

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