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Date: March 22, 2003 at 19:14:02
From: norman bates, [oproxy2.rockwellcollins.com]
Subject: hey


If you put a driver in a sealed and ported box of the same size, the sealed excursion increases until fsb then doesn't travel much further (same power at all frequencies. The ported excursion follows the sealed almost exactly until about 2/5 an octave above the tuning frequency. Then the excursion decreases to almost nothing (if you have a large enough circle port based on the amount of air flowing through the vent ). I like to see for a 28hz tuning a 6" port for 1 12", a 8" port for 2 twelves or 1 eighteen, and 1 twelve inch port for 2 eighteens. If tune lower you'd need a bigger port.

Take your .5 qtc, port it to 18hz. If the sealed bottoms out at 60 watts at 35hz so will the ported. The drivers will mover further and further till fsb on the sealed box. As frequencies are halved, excursion is quadrupled. At 25 hz the sealed may need 38 watts while the ported may need 90 watts. Speaker programs can be used to figure this stuff out.

Anyway my subs are parallel 8 ohm 96db 1w/1m, making a 4 ohm load with 102db 1w/1m.

I don't believe in stuffing.

I'll email again near 7:00 iowa time.


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