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| Date: |
March 26, 2008 at 07:57:00 |
| From: |
zoktoberfest, [c-71-193-200-244.hsd1.or.comcast.net] |
| Subject: |
Vas parameter / counter intuitive? |
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I have a pro audio project in the design stage, and Ive been comparing the specs of 18" and 21" drivers. A 21"(18 sound/21LW1400) has a Vas of 13.6 cu/ft and an Xmax of 9.5mm. An 18" Eminence (OmegaPro18) has a Vas of 19.6 cu/ft, with an Xmax of only 4.88mm.
I don't understand how the larger cone (21") with twice the area and more than twice the Xmax can have 3 cu/ft less Vas than the smaller cone (18") traveling half as far. Not to mention the monster motors found on 18-Sound drivers.
I visualize Vas as a driver's ability to displace air when it backs up into a reference box the full extent of its' Xmax.
Obviously, my concept of Vas is overly simplistic. I did note the Qts of the 21" was less than the 18"(.235 / 3.1). The 18" has a slightly lower Fs at 25Hz compared to 28Hz of the 21". Is that enough to cause this perceived discrepency
I need some technical enlightenment.
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Posted with TalkShop version
2.76 BETA |
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