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| Date: |
December 22, 2007 at 11:17:17 |
| From: |
Petriej, [n148s190.ntc.blacksburg.shentel.net] |
| Subject: |
Re: Help with 12" or 15" down firing seal sub |
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URL: http://www.partsexpress.com/resources/downfire.html |
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I have a downfiring 15" sub. You will want to take care to get a driver that is suitable for vertical placement. There is a formula somewhere that helps you find out, the basics of which suggest that a driver may 'use up' too much of its Xmax just from sagging from gravity, based on the weight of the cone (related to cone area for non extreme cases), the flexibility of the cone, etc. I'll see if I can find it for you.
It also suggests that you need to ensure the driver has sufficient space for air to move around. In my case, I had to calculate the minimum leg length to make sure the surface area (perimeter x height off the floor - area taken by legs) made by lifting the box up with legs was more than the cone area. This should give you enough room to prevent the sub from sounding terrible. You may want to add extra room if you are placing it on a thick carpet.
On a side note, you may want to be careful with a downfiring sub, my neighbors in my apartment below me seem to think it is quite excessive. Especially when my roommates think it is fun to play heavy songs with the gain cranked up.
Percentage of Sag = 24,849 / ( Xmax * Fs²)
I think this should work, though I thought the formula I used incorporated the cone area and a couple other T/S params. Either way, if you get a long through driver it shouldn't be an issue. You will want to make sure your % is less than 5. I have posted the link where I found this.
As for the actual box/table. I would suggest placing the driver closer to the table top than the floor, so you can give it some room to move without having to have really long legs. You could then have open space around the driver that dips down towards the floor, either in a square pattern or circular, depending on how you want your table. You would also want to accomodate struts and supports for the marble top. This sounds like a really nice opportunity to produce a beautiful peace.
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Posted with TalkShop version
2.76 BETA |
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