BiB Vs. iBiB

[motosapien]

Originally Posted by ziocalepino

What do you mean with IIRC?

I've always had difficulty with those pesky online abbreviations too..........
IIRC = "if I recall" (if I'm recalling it correctly)

[Squeak]

Originally Posted by ziocalepino

What do you mean with IIRC?

I've found on Karlson site few examples on how to draw this curve. What about its area? Starting from this data I can begin to calculate the shape.

I really doesn't matter that much. The frequencies you are coupling with the horn won't be able to "see" the difference of small details like the curves exact shape. You could easily just make it a high triangle if that's easier. The basic idea is just to extent the bandwidth of the opening and make it less resonant.
The important thing is, that the combined opening at the exit area of the iBIB should at least be equal to final piece of the horn, just like with a normal ceiling firing BIB. You don't want to narrow the horn after expansion.

If you are doing corner or floor/wall loading (which you should to get the best effect of the iBIB), you should also consider doing a slanted plate at the bottom to help reflect the sound out at the wall and also to avoid standing waves that bounces off the floor back up the horn.

[GM]

Originally Posted by Squeak

You don't want to narrow the horn after expansion.

FWIW, I've periodically posted that all of the few pipe horns I built were floor reflex loaded with Av = Sd with me and their owners being pleased with the results, though this was before there was any really low signal LFE available to consumers. Regardless, some Hornresp sims indicate that doing it and/or capping 'normal' top exit BIBs with a reverse cone will theoretically be a worthwhile tweak in at least some instances, though AFAIK, no one has tried it yet and reported back.

GM

[Squeak]

Originally Posted by GM

FWIW, I've periodically posted that all of the few pipe horns I built were floor reflex loaded with Av = Sd with me and their owners being pleased with the results, though this was before there was any really low signal LFE available to consumers. Regardless, some Hornresp sims indicate that doing it and/or capping 'normal' top exit BIBs with a reverse cone will theoretically be a worthwhile tweak in at least some instances, though AFAIK, no one has tried it yet and reported back.

GM

Well, then you are into the territory of reflex loading or MLTQWT's AFAICT. Something quite different from a real horn like the BIB.

[GM]

Yes, and no, ML-TQWTs (ML-horns) are tuned like 1/4 WL vented or TL alignments, not 1/2 WL as BIB (pipe) horns.

GM

[Squeak]

Originally Posted by GM

Yes, and no, ML-TQWTs (ML-horns) are tuned like 1/4 WL vented or TL alignments, not 1/2 WL as BIB (pipe) horns.

GM

But it's still reflex loading regardless of the resonance of the the box. The sound is quite noticeably different.

[GM]

This far below Fs, I'm betting for the better.........

GM

[Squeak]

Well you get higher efficiency in a smaller box, and the small BR hump before the LF extension falls off a cliff, that gives the illusion of lower extension.
The trade-off is lack of precision and lack of extended smooth roll-off.

[ziocalepino]

Ok, maybe I'll cut a "rounded" triangle instead of an exact Karlson. But I do not have undestood how to estimate its area. And, maybe most important, are there REAL advantages to build Ibib instead of Bib?

[Squeak]

Originally Posted by ziocalepino

Ok, maybe I'll cut a "rounded" triangle instead of an exact Karlson. But I do not have undestood how to estimate its area. And, maybe most important, are there REAL advantages to build Ibib instead of Bib?

The easy way is to just do the triangle area "math" (width x hight (perpendicular lines)) and add a bit of area to account for the curves. Or you can find the area formula for the kind of curve you choose.
The advantage of the iBIB is that you can make it smaller and maybe also get better ear level driver placement which is very important with FR drivers as they beam like crazy. With a normal BIB you want to get pretty close to the ceiling to get good loading. So you need a tall speaker if you have high ceilings. A small driver like the FE126 doesn't really warrant a large box anyway.