Terry Cain's BIB -why does it work and does anyone have those Fostex Craft Handbooks? - Page 524 - diyAudio
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Old 15th March 2013, 09:23 AM   #5231
xrk971 is online now xrk971  United States
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ST,
I was curious to see how far you could go with your minimal bracing scheme. It may not need as much as I put in but certainly at least 8 or 10 strategically placed braces can help. You may be able to brace it after the fact by sticking pieces in from open end and gluing. Good luck.
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Old 18th March 2013, 12:19 AM   #5232
Spec is offline Spec  Australia
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Small vote, I have been wanting to do a BIB for ages, And well with the Foam board thread and my need for a rear surround speaker Im thinking of doing a small BIB for rear surrounds.

TB W3-1364SA Vs CSS FR125SR

Any thoughts people?
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Old 18th March 2013, 12:41 AM   #5233
xrk971 is online now xrk971  United States
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Quote:
Originally Posted by Spec View Post
Small vote, I have been wanting to do a BIB for ages, And well with the Foam board thread and my need for a rear surround speaker Im thinking of doing a small BIB for rear surrounds.

TB W3-1364SA Vs CSS FR125SR

Any thoughts people?
Have you run these through the BIB calculator spreadsheet? The CSS FR125SR ends up with a 48 in tall cabinet x 7.38 in wide x 9.38 in deep cabinet, driver 21 in from top. You could flatten this and make a FIB as the requirement is a 84 square in cross section. If you made it 5 in deep the cab would be 16.75 in wide and you could wall mount it for a nice out of the way back channel.

The TB W3 is much smaller: only 32 in high x 5.38 in wide x 7.38 in deep, driver 14 in from top. Again, this could be made into a FIB with a 10 in wide cabinet x 4 in deep.

For a rear channel, I think the TB W3 is fine as it keeps it smaller and you don't need the bass as that is from a HT sub.
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Old 18th March 2013, 12:53 AM   #5234
Spec is offline Spec  Australia
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I did run them in the calculator, Infact the CSS driver was already in the one I had.

As I have not used the calculator much I wasn't sure which figure gave me the distance the driver had to be away.

Flattening them out is an awesome idea, I want to get the driver 100mm off the ground to be at ear level when listening.

Downside is looking at the price of foam board, I think making them in 12mm or 16mm will be a heap more cost effective.

What the trick in the caculations withunfolding the design?

Obviously you need to keep the line length the same, but I gather there is some length hidden in the fold?
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Old 18th March 2013, 01:31 AM   #5235
xrk971 is online now xrk971  United States
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You want the driver 100 mm or 4 in off the ground? You mean 100 cm? No need to unfold if 100 cm, move the FIB up or down until driver (Zd) is at height you want. Unfolding is not tricky, just double the length but you are building a triangular shaped box now. Unfolded may be a problem as mouth may bump into ceiling if driver is at ear height. In Australia foam core is expensive I hear so plywood may be better. Just not as easy to work with...
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Old 18th March 2013, 04:26 AM   #5236
Spec is offline Spec  Australia
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oops yeh I meant 100cm from the ground.

Even ply wood is expensive here, MDF is a much cheaper alternative.

Next question sorry, What determines the distance of the opening of the bottom of the "slant" piece at the bottom of the box?
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Old 18th March 2013, 04:37 AM   #5237
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Originally Posted by Spec View Post
oops yeh I meant 100cm from the ground.

Even ply wood is expensive here, MDF is a much cheaper alternative.

Next question sorry, What determines the distance of the opening of the bottom of the "slant" piece at the bottom of the box?
You are trying to preserve the cross sectional area as the sound makes the U-turn. The easy way to look at it is that the edge of the diagonal divider is equidistant from the two walls and the bottom. If you go straight and do not have a bend, then the cross sectional area simply continues to expand. Technically, if you want to recreate the geometry of the U-turn in a straight, it is an expansion (first corner), followed by a contraction, followed by another expansion (second corner). You want to keep the bend as the mouth will end up near the ceiling - which could be good as you get more bass from ceiling and wall loading.
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Old 18th March 2013, 05:53 AM   #5238
Spec is offline Spec  Australia
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Thats what I suspected, I kept reading that my slant piece for the TB drive was going to be 7" but turns out I was reading the base size not the slant size, So now it makes much more sense.
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Old 13th June 2013, 02:05 AM   #5239
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Default What to do with a fat, squatty BIB.

Liked the looks of a Visaton BG 17-8, and wanted to put them in a BIB for my garage. However, after plugging in the parameters, I realized that the cabinet was going to be rather short and tubby:
Internal Measurements
29" X 13" X 19"

A-B-C = 9.5"

When sketching the cabinet up, I realized that mounting the speaker on the side with two slanted baffles, makes more sense.

The "Zdriver" length is supposed to be ~12.25". But, to get the driver to fit between the internal slants I had to drop the driver to 17".

Will this have a huge effect on the sound? Did I miss something in converting to a sideways design?
Attached Files
File Type: pdf BiB standard BG17_8.pdf (7.0 KB, 70 views)
File Type: pdf BiB sideways BG17_8.pdf (7.2 KB, 51 views)
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Old 13th June 2013, 02:44 AM   #5240
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Make the horn wider and shallower. The driver is only 2.24" deep, as a starting point double that to 4.5" internal depth, and re-size.

Be sure to keep the cross sectional area the same.

The A-B-C measurements can be adjusted accordingly.

The horn still starts from -0- csa, and expands conically to the max opening. These could be hung on the wall to put the driver at the optimal height for your listening area....horn opening up or down, loading the floor or ceiling, or even sideways to load a corner.....

John
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