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<blockquote data-quote="TJ Cornish" data-source="post: 59275" data-attributes="member: 162">Re: Subwoofer comparison SRX728 vs Vertec 4883I tried out LAC version 1.2.&nbsp; The same setup as above produces completely different results for the 4883 compared to LAC 1.1:31Hz:109.3dB, 40Hz:115.3dB, 50Hz:116.8dB I also called around inside the JBL mothership and talked to one of the engineers of the 4883.&nbsp; He gave me a graph of the actual measurement of the product.&nbsp; I&#039;m not sure if I&#039;m at liberty to post it, but a couple of interesting things that stuck out to me - the +/-3dB range on the spec sheet is 40Hz - 300Hz.&nbsp; The measured level range over ths band is about 17dB.&nbsp; I&#039;m assuming they are ignoring some of the high-frequency output to focus on the range most folks would consider for subwoofer use.The box appears to be flat from 50Hz to 100Hz, and about 4dB down at 40Hz.&nbsp; Extrapolating this, the peak output for the box should be 134dB at 40Hz, and about 130 at 35Hz.&nbsp; The LAC 1.2 numbers are 19dB less at 40Hz, and about 17dB less at 31Hz.I&#039;m running out of mileage on the spec sheets - time to get a demo.</blockquote>

[QUOTE="TJ Cornish, post: 59275, member: 162"] Re: Subwoofer comparison SRX728 vs Vertec 4883 I tried out LAC version 1.2. The same setup as above produces completely different results for the 4883 compared to LAC 1.1: 31Hz:109.3dB, 40Hz:115.3dB, 50Hz:116.8dB I also called around inside the JBL mothership and talked to one of the engineers of the 4883. He gave me a graph of the actual measurement of the product. I'm not sure if I'm at liberty to post it, but a couple of interesting things that stuck out to me - the +/-3dB range on the spec sheet is 40Hz - 300Hz. The measured level range over ths band is about 17dB. I'm assuming they are ignoring some of the high-frequency output to focus on the range most folks would consider for subwoofer use. The box appears to be flat from 50Hz to 100Hz, and about 4dB down at 40Hz. Extrapolating this, the peak output for the box should be 134dB at 40Hz, and about 130 at 35Hz. The LAC 1.2 numbers are 19dB less at 40Hz, and about 17dB less at 31Hz. I'm running out of mileage on the spec sheets - time to get a demo. [/QUOTE]

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