Posted by Bill Fitzmaurice [ 152.163.252.199 ] on August 13, 2004 at 12:24:02:
In Reply to: Re: Stuffing thickness posted by manualblock on August 12, 2004 at 20:20:47:
There are some formulas for the amount of stuffing, according to the material, F3 and other considerations, but they aren't terribly precise. The best way to do it is to run an impedance plot. With no stuffing or insufficient stuffing you'll have one large peak at the Fo and a number of smaller ones above it, as I noted before. When a sufficient stuffing density is reached only the high spike will remain, with the rest suppressed, along with the resonances that caused them. With polyester pillow stuffing you'll usually find that sufficient stuffing to throughly fill the line without compresssing it is sufficient.
A line with inadequate stuffing has not only ragged response but the roll off below Fo is at 12dB, the same as a vented box. Properly stuffed a line rolls off below Fo at 6dB, so you have the bass response at Fo of a vented box but the slower rolloff and cone control of a sealed box below that.
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