Terry Cain's BIB -why does it work and does anyone have those Fostex Craft Handbooks? - Page 528 - diyAudio
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Old 27th October 2013, 09:01 PM   #5271
rka is offline rka  United States
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Default BIB calculator

Quote:
Originally Posted by Godzilla View Post
You can download the BIB Calculator from this link:

https://sites.google.com/site/speake...enclosures/bib

Zilla
Or you can get the BIB calculator at:

Just found the BIB design

then scroll down to post #9

Roger
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Old 22nd June 2014, 12:40 AM   #5272
jhutka is offline jhutka  United States
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Default Terminated BIB?

The BIBs that I have made are generally smaller with 3" drivers. Earlier in this thread, it was mentioned that because of the small size, the cabinets should be down firing with the open end on the bottom.
For those particular speakers, setting them off the floor on milk crates was a good solution.
My question is: How could this elevation be incorporated into the plans?

A) Raise them up on legs?
B) Terminate the cabinet with a large mouth at the bottom?
C) Terminate with open front and back at the bottom?

Here is plans for B with a 10.5" X 7.75" X 5" mouth at the bottom. How do you calculate the height off of the floor? (10.5 was just a guess)

JohnH
Attached Files
File Type: pdf BIB Terminated.pdf (108.0 KB, 47 views)

Last edited by jhutka; 22nd June 2014 at 12:56 AM.
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Old 22nd June 2014, 10:45 PM   #5273
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D) Unfold it. Then it will be tall enough for the ceiling unless you have unusually tall ceilings.
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Old 22nd June 2014, 10:49 PM   #5274
Squeak is offline Squeak  Denmark
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Quote:
Originally Posted by Squeak View Post
D) Unfold it. Then it will be tall enough for the ceiling unless you have unusually tall ceilings.
One of the main ideas in the BiB is vertical excitation of the room. So a sideways mouth would be against the spirit.
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Old 22nd June 2014, 10:58 PM   #5275
chrisb is offline chrisb  Canada
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Well, simply unfolding it would place the diver at only 16" from floor, certainly a full 12" too low, I think - then there's the aesthetics of stabilizing the enclosure.

Raising the downward facing terminus too far above the floor could reduce gain effected by the boundary loading.

The only such design that I've heard (i.e. BIB with downfiring terminus and small driver) had side (& I think back) panels extended to raise the driver to approx 30", and resulted in rather an inordinate amount of coloration.
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Last edited by chrisb; 22nd June 2014 at 11:01 PM.
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Old 22nd June 2014, 11:05 PM   #5276
chrisb is offline chrisb  Canada
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Well, simply unfolding it would place the diver at only 16" from floor! certainly a full 12" too low, then there's the aesthetics of stabilizing the enclosure.

Raising the downward facing terminus too far above the floor could reduce gain effected by the boundary loading.

The only such design that I've heard (i.e. BIB with downfiring terminus and small driver) had side & I think back) panels extended to raise the driver to approx 30", and resulted in rather an inordinate amount of coloration.
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Old 22nd June 2014, 11:16 PM   #5277
Squeak is offline Squeak  Denmark
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Well, either put it on the wall or a simple stand. A real simple idea would be to simply let the side boards continue down until the desired hight was achieved, not cut them off to triangles to fit the horn.

Last edited by Squeak; 22nd June 2014 at 11:18 PM.
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Old 23rd June 2014, 03:45 AM   #5278
GM is offline GM  United States
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In a similar vein, I auditioned this little one and it was pretty anemic until placed on a large, relatively massive 'L' shaped work desk, tucked hard up against a corner. With them on each outside corner, this brought the drivers up to a good height and with the terminus loaded in a quasi-quarter space [1 pi] they proved to have a nice robust [mid]bass line that needed no BSC with the added baffle width.

GM
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File Type: jpg FE126E floor loaded BIB 2.jpg (12.3 KB, 137 views)
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Old 23rd June 2014, 09:17 AM   #5279
xrk971 is online now xrk971  United States
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Default FIB anyone?

Flatten the BIB to the point that you can mount it on a wall. Divide the area into two asymmetric sections with an inverted V and this allows offset mounting for reduced baffle diffraction effects. Mounting on a wall does not require BSC.
Terry Cain's BIB -why does it work and does anyone have those Fostex Craft Handbooks?

Or follow more standard single divider BIB but Flatter is Better (FIB):
http://www.diyaudio.com/forums/attac...s-fib-plan.jpg
Note that plan should be 3 in deep not 4.

Last edited by xrk971; 23rd June 2014 at 09:21 AM.
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Old 24th June 2014, 01:43 AM   #5280
GM is offline GM  United States
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Quote:
Originally Posted by jhutka View Post
My question is: How could this elevation be incorporated into the plans?

A) Raise them up on legs?
B) Terminate the cabinet with a large mouth at the bottom?
C) Terminate with open front and back at the bottom?
A) Yes, with the assumption that they will be hard up against a wall and preferably in a corner in which case the gap would be the same as with ceiling loaded, i.e. > ~75% of ceiling height.

This assumes a low tuned BIB though, so with no actual experience with the BIB per se [my pipe horns were all mass loaded], I’m inclined to take the small BIB’s folded height/3 to maintain the same percentage gap and adjust from there if need be, so working out the pipe tuning would be a function of driver/floor height rather than Fs.

B) A front firing terminus loses much of its loading if spaced up, so better overall to make the pipe longer to space it up even if you don’t continue the expansion, i.e., adding in effect a ducted vent with a CSA = the terminus CSA. That, or design to a lower pipe tuning [Fp] as I noted somewhere in this thread.

C) Any configuration can be used when it has the right amount of open area to perform as well as can be expected, including horn designer Bruce Edgar’s mass loading pyramid ‘phase plug’ used in his large vertical bass horn and my personal choice from both theory and experience.

GM
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