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Even BIGGER than Bigger, Badder BIB...
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Old 8th October 2018, 11:28 PM   #31
BHD is offline BHD  United States
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The original "Wilberforce" Jensen corner horns that were the inspiration for this madness.
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Old 9th October 2018, 05:31 AM   #32
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It should allow me to get an idea if the concept works and what it will sound like. Even though they're big they should be a lot easier to build than my Sachikos were.

JBL 2220A drivers have arrived intact and look like new.
Well, if they wind up sounding anything like mine did it will have most of the performance of an all compression horn system except [sub] bass 'attack' won't be quite as 'fast'/'sharp', but still better than standard cabs, so a small price to pay for a smaller cab that's much easier to build/move.

Sweet!

GM
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Old 9th October 2018, 05:37 AM   #33
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The original "Wilberforce" Jensen corner horns that were the inspiration for this madness.
Wow! Don't recall ever seeing these and yet I did multiple postings on the thread.

GM
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Old 9th October 2018, 09:26 PM   #34
ToddD is offline ToddD  United States
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BHD,
How tall are your ceilings?
You might consider building the bib's 8 feet tall if you have room. Besides 8 foot boards are less cuts. I went 8 foot tall but I have 9 foot ceilings.

The sound will be effortless
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Old 9th October 2018, 10:50 PM   #35
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Don't forget, 8 fters can be scalloped out to tilt in place whist providing the necessary pipe vent end correction.

GM
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Old 10th October 2018, 02:51 PM   #36
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I have eight foot ceilings. I was planning on making them just an inch under the height it will take to move them upright. They'll still be pretty close to the ceilings.

At what point do they get to be too close?
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Old 10th October 2018, 05:50 PM   #37
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My SWAG: Terry Cain's BIB -why does it work and does anyone have those Fostex Craft Handbooks?

GM
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Old 10th October 2018, 06:21 PM   #38
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Hi GM,

I looked at the posts from that link and didn't really get any closer to understanding "how close is too close" when it comes to the terminus and the ceiling. Maybe I'm just thick in the head

I think I'll just build the test cabinets, info on the driver says that the fs is 37hz, I put in 40hz because it was too long at 37. If I set the Qts as .17 and Vas as 300 and the Fs as 38 I get 92" height, width of 19.3 and depth of 27.4 which means the hypotenuse of the triangle becomes 94" so I'd have two inches to spare and the terminus will be four inches from the ceiling.

Too close?

A 40Hz Fs entered into the calculator gives me a couple more inches so basically six inches. Is that better than four?
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Old 10th October 2018, 07:33 PM   #39
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Greets!

​For the purposes of this type boundary loading, my SWAG is that this math defines the minimum distance for a ~optimal corner loading and as it decreases, the higher the [sub] bass roll off due to 'compressing/squeezing' the pipe horn's 1/4 WL loading [tuning to a higher frequency] with of course it becoming a leaky sealed alignment once flush against the corner, which at this point will reduce the driver's power handling to virtually nothing since it's tuning will still be way below its Fs and why these types of alignments [> 0.707x Fs] demand ZERO air leaks.

​A greater distance then will lower the pipe horn's Q, extending its roll off BW a bit with of course a rapid decrease in power handling.

GM
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Old 10th October 2018, 08:02 PM   #40
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Quote:
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Greets!

​For the purposes of this type boundary loading, my SWAG is that this math defines the minimum distance for a ~optimal corner loading and as it decreases, the higher the [sub] bass roll off due to 'compressing/squeezing' the pipe horn's 1/4 WL loading [tuning to a higher frequency] with of course it becoming a leaky sealed alignment once flush against the corner, which at this point will reduce the driver's power handling to virtually nothing since it's tuning will still be way below its Fs and why these types of alignments [> 0.707x Fs] demand ZERO air leaks.

​A greater distance then will lower the pipe horn's Q, extending its roll off BW a bit with of course a rapid decrease in power handling.

GM
Okay, so the closer it is the sooner the horn rolls off in the very low frequencies, right? In that case I'll just go with six inches from the ceiling and see how that goes. Right now I'm using a 2W 45 SET amplifier, no worries about power handling. I can also press a pair of Heathkit W4-AM amps into service for parties.
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