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| Re: Port length on multiple ports [message #33946 is a reply to message #33905] |
Thu, 27 September 2001 09:52   |
AP
Messages: 11
Registered: May 2009
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Chancellor |
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Thinking about a home project related to this. Vas-151L
Qts-.39 Coffee table size box (yes, it would me my coffee table). Internal dimensions 13"x22.5"x34.5" (assuming 3/4" wood). I figure I'd end up around 155L with internal bracing. 4"x12" port. Tuned to 21 Hz. Driver and port on one end. As near as I can tell, it'll stay flat and 3db down would be around 20Hz. What do you think? Thanks man!
Scott
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| PiAlign'ed at 2 cu ft tuned to 20Hz [message #33958 is a reply to message #33957] |
Fri, 28 September 2001 06:27 |
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Wayne Parham
Messages: 18748
Registered: January 2001
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Illuminati (33rd Degree) |
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You have a motor with these specs: Vas=5.33 cu ft
Fts=21Hz
Qts=0.39 So PiAlign equivalents are: Vad=5.33
Frd=21Hz
Qd=2.56 PiAlign recommends a 2 cubic foot cabinet tuned to 20Hz using either a cylindrical 5" long, 1 5/8" diameter port or a rectangular 1" x 2" x 5" long port. You can grab a copy of BoxPlot on the Pi Speakers website to show the response of this cabinet using Thiele/Small analysis. The box you've proposed is about 5 cubic feet, and I suspect that will work just fine. The driver will probably work very well in cabinets from 1.5 cubic feet to 6 cubic feet or so, tuned to 20Hz. You can use BoxPlot to find an alignment that will give acceptable response in this size cabinet.
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