BIB Bass Horn

 It’s taken a while for these to emerge. Terry Cain mentioned a while back who was simulating BIB subwoofers, but the idea got pushed onto the back-burner as there was a lot going on just with the full-range varieties. The final prod coming from Bob Brines, who, though no fan of the FR BIB, did comment that he thought that they’d be ideal as a nice, simple bass horn.

So, here are a few ideas. Not a massive selection, simply due to time and space considerations –it’s not practical to try simulating every driver under the sun. Rather, we’re going for an interesting cross-section, so there should be something for everyone here. Strictly, these aren’t subwoofers so much as bass-extenders for, say, a couple of small sealed or ported boxes, or open baffles. They don’t plunge the deepest depths as in my opinion, there’s more practical ways of achieving sub-bass.

Speaking for myself, I’ve added a few comments to the usual brief suggested dimensions to explain the driver choice. There are lots of different variations you can try, given that we’re only interested in the bottom end of the response this time. Some of these will appear in the near future, but to get started, we’ll stick with the standard geometry. Note that for the majority of the drivers, I’ve deliberately limited the total line length to 140in to keep the cabinet size vaguely acceptable in the majority of domestic situations.

Scott

Seas CR18RNX - 6 1/2"

Larger will not be needed unless you happen to live in a castle. Lovely doped paper-pulp cone, natural butyl rubber surround, great excursion & nice smooth curve. Good magnet too. 2 options: the tall and the not quite so tall.

Fr plot for the tall one is attached. The shorter gives up ~4db of extension, but the basic curve is the same. Unlike normal BIBs, these do not have to be placed near a rear wall, as they are designed only as bass extenders, and should be crossed over at or around 80Hz or so.

The tall: line length 158in (in practice, 80in tall enclosure), Zdriver 31.75in, Sm=136in^2

The not-so-tall: line length 138in (in practice, yup, you guessed it, 70in tall) Zdriver 31in, Sm=136in^2

Monacor SPH-165CP

Good build, decent price and I like the well-damped carbon fibre cone. Well engineered and a very good set of published T/S parameters.

Line length 140in - Zdriver 28in - Sm=99.75in^2

Monacor SPH-130AL

A decent metal cone is usually worth having. Typical Monacor build and price, and a great spec. Should work nicely in TC’s original enclosure, so ideal for the smaller room:

Line length 140in - Zdriver 31in - Sm=55in^2

Adire Audio Extremis 6.8

Superb engineering, as you’d expect from the source, great reputation and the parameters are spot on.

Line length 140in - Zdriver 28in - Sm=76.375in^2

Seas Excel W18E001

Staggering build and superb technical specification. Magnesium cone, solid copper phase-plug, vented magnet, die-cast zinc basket. Enough said.

Line length 140in - Zdriver 30in - Sm=82.875in^2

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Strange isn’t it how the full-range drivers of Fostex steal the limelight but their ‘normal’ drivers are much less well-known. Here’s a couple.

Fostex FW167

Great cone materials, usual Fostex quality build and engineering. Worth investigating. Oh yes, it’s shielded too.

Line length 140in - Zdriver 28in - Sm=76.375in^2

Fostex FW137

Line length 128in - Zdriver 25.75 - Sm=64.225in^2