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Old 28th March 2004, 12:00 AM   #41
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I seem to remember reading an AudioXPress atricle some time ago that tested various methods of bracing, one of them being a sand filled sandwich. I think the results showed that the sand filled sandwich actually raised the db of some of the resonance frequencies. I'm not sure which issue this atricle was in or even what year, maby someone else remembers this article?
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Old 28th March 2004, 12:04 AM   #42
sreten is offline sreten  United Kingdom
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Originally posted by Vikash
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Perhaps a second PR is the way to go after all.
If the PR has twice the excursion of the driver pointless, sreten.
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Old 28th March 2004, 12:32 AM   #43
angel is offline angel  Norway
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Someone here mentioned the use of flour. I would advise against that, as flour is highly combustible, in fact even explosive, under the right circumstances.

Anyway, as someone pointed out, while mass may help keep a subwoofer from sliding across the floor, bracing is what will matter the most.

On that note, has anyone tried casting a metal chassis themselves? I imagine that would be rather interesting. Or, at the expense of the seamlessness of a cast, and aesthetics (unless you're looking for the ultimate industrial kick), perhaps welding metal sheets for an enclosure?
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Old 28th March 2004, 08:57 AM   #44
Vikash is offline Vikash  United Kingdom
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Quote:
If the PR has twice the excursion of the driver pointless
Pointless? A second PR gives me a little bit more SPL (modeled 106db @25hz in 30l), reduces excursion in all drivers (compression/distortion?) and allows potential force cancellation between passives if I'm to understand correctly.

Was there something other on your mind Sreten?.
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Old 28th March 2004, 12:16 PM   #45
sreten is offline sreten  United Kingdom
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Well Sonus Faber do it, so must be some point.

I didn't know two PR's would reduce the main units excursion
compared to one (with the same tuning frequency).

Your right about distortion being reduced somewhat too.

sreten.
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Old 10th April 2004, 02:05 PM   #46
Vikash is offline Vikash  United Kingdom
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Bracing doesn't appear to be straight forward with this arrangement. Any suggestions?
Attached Images
File Type: jpg 4.jpg (25.8 KB, 148 views)
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Old 10th April 2004, 02:31 PM   #47
sreten is offline sreten  United Kingdom
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All you need is an offset vertical brace with a driver cutout,
or just running up the the back of the bass driver.

You could also make the two sides and front double thickness
which will reinforce all but two of the edges, the front vertical
two edges massively, eight edges very well, the only two not
reinforced would be taken care of by the offset vertical brace.

If you go double layer use larger holes on the inside layer,
also note double layer makes it very easy to stagger the
joints, which is better then butt jointed double thickness.

sreten.
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Old 10th April 2004, 04:02 PM   #48
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My sealed XLS 10 are in double thickness MDF boxes with two crossbraces. They are 60cm tall with one brace at about 20cm up and the other at about 40. these are rock solid even when the XLS shift lots of air.
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Old 10th April 2004, 04:13 PM   #49
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I forgot to mention the lower cavity between teh bottom of the cabinet and the 20cm brace is filled with small stones in platic bags. The crossbraces are shelf braces too. similar to the ones you drew in a your cabient that hold the drivers magnet but mine are perpendicular to the driver. Ie from front to back of the cabinet not top to bottom. A small cube that size made out of 36mm MDF is going to be very rigid anyway, obviously bracing will help increase regidity but I wouldnt worry about it too much.

Nice animation and pics btw
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