Question about Infinite Baffle and 411's

[Jim Butler]

I am considering an infinite baffle subwoofer array. My question is whether the 411 is an appropriate driver for an IB install. I have four 411's that I could use but, on viewing the T/S parameters for the 411, I see the xmas is (only?) .28 inches. By comparison, Parts Exress's IB 15 inch driver has an Xmas of .56 inches -nearly double. The IB website recommends drivers with a large xmas. Is the 411's .28 inches enough for this application?

Any info would be greatly appreciated.

Jim Butler

[stpower]

Jim,
Altec recommended a sealed IB enclosure of 4.5 to 8 cu.ft. for the 411. I found about 8 to work best, but anything larger and the 411 voice coil would bottom out at loud levels. It NEEDS that sealed air cushion behind it. I would look elsewhere for a woofer.

stpower

[GM]

Greets!

Yeah, an 825's Vb (~11.3 ft^3 IIRC) is about the limit if not vented. Spaced away from the baffle to allow for the relatively long travel, it's quite the performer in a Hi-Fi app, especially if corner loaded, at least if XO'd at 500 Hz like I tried. Ultimately though, a 416 went back in and the 411 went into the sealed off bottom so that the 511 didn't have to be attenuated so much.

Four 411s should really rock, with gobs of dynamic headroom if box size isn't an issue. Maybe the best of both 'worlds' is an aperiodically loaded IB.

GM