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spydyplayer
05-27-2005, 09:46 PM
Is there a drawback to having too much airspace in a sealed subwoofer box besides maybe a sloppy sound? Reason I am asking is because I made a box for two fifteens that is sealed and has 5.6 cubes of air before woofer displacement.

squeak9798
05-27-2005, 09:52 PM
Actually too much airspace wouldn't result in a "sloppy" sound, quite the opposite really; you'd normally end up with a "critically overdamped" alignment, which may sound "dry" or "lifeless". Other effects would be decreased output, lower mechical power handling and possibly not too pleasing low frequency extension.

Anyways, can't tell you if 5.6cuft gross is too big or not, since you haven't said what subs you were using ;)

spydyplayer
05-27-2005, 10:56 PM
Oh sorry, I am using the 05 Type R 15"s.

squeak9798
05-28-2005, 12:46 AM
Should an enclosure that's "too large" give you better low-frequency extension ? Also, wouldn't it be underdamped ?

Overdamped = low Q alignment = box too big. Qtc of .5 is considered "excessively taut and overdamped", whereas Qtc of 1.2 would be considered underdamped.

Lower Qtc does give you better low frequency extension to a point, beyond which you will start loosing LFE again. Lowest F3 is at Qtc .707, and the further you move either north or south of that, the more LFE decreases (higher F3).

squeak9798
05-28-2005, 01:03 AM
Oh sorry, I am using the 05 Type R 15"s.


Looks like your box will be slightly above Alpine's recommendations even after sub displacement.

My box program is fvcked up right now, but according to actual by hand calculations using the subs specs, it appears that a 1.37cuft box gives a Qtc of .707