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Old 26th April 2013, 06:22 AM   #11
GM is offline GM  United States
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Quote:
Originally Posted by hoz816 View Post
Obviously I have some more reading to do, but how critical are the corners to this implementation?
Corner loading in most rooms just means it will increase low distortion power handling below ~100 Hz with ~1 mm Xmax drivers and reproduce the lowest pipe organ symphonies with a bit of authority with higher Xmax rated drivers.

As already noted, the standard BIB will be tall enough to get good ceiling loading, but the trade-off may be a too high a driver position, so inputting a higher Fs to lower it will of course reduce ceiling loading and where the corners become a good plan, though a simple rectangular 'top hat' can be added for mid-wall positioning to help somewhat.

I'm also a big proponent of wide, flat cabs to keep from having to use any baffle step compensation [BSC] as an acceptable trade-off to maintaining a relatively smooth transition through the fold.

GM
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Old 26th April 2013, 06:30 AM   #12
GM is offline GM  United States
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Originally Posted by lowtherdream View Post
BLH........
Wiring's a bit tacky looking, but a beautiful horn!

GM
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Old 26th April 2013, 11:39 AM   #13
Philfr is offline Philfr  France
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Hi,
I build MLTL (MJ King), but with port at rear and add a variable BSC..
So I can "adjust" mid level according room or amp.
In a small room, it's work's very well on jazz, acoustical music, or classic.
Phil.
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Old 26th April 2013, 01:07 PM   #14
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I fully agree with GM's arguments.

Build my BIB's in 2008 for lowther dx3 ; reduced size : 30x47x157cm outside dimensions.
Wasn't pleased with the sound of the lowthers , even with BSC.
Put the FE207's in and Great result , even without BSC.
They def. need Corners or at least a side wall!
Good luck with your choice!
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Old 26th April 2013, 08:20 PM   #15
hoz816 is offline hoz816  United States
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Quote:
Originally Posted by Philfr View Post
Hi,
I build MLTL (MJ King), but with port at rear and add a variable BSC..
So I can "adjust" mid level according room or amp.
In a small room, it's work's very well on jazz, acoustical music, or classic.
Phil.
Yes, I agree. Currently my 207's are in MJK's Project 5 (MLTL) with BSC and phase plugs from Planet10, and they do sound good, especially with jazz and acoustic music. Vocals, especially female, are magnificent.

As I mentioned earlier, I used to move frequently, and I didn't have the forethought to install a variable BSC. Rather, I settled on a moderate value for the setup they were originally designed for. To compensate for room irregularities when I would relocate, I implemented a digital room correction filter (using BruteFir to apply the filter before the flac stream is sent to the Squeezebox). The results are significant, but it is a real pain to measure the room response and generate the filters every time I moved or redecorated. Also, the DRC obviously doesn't work when I use an analog source, but that doesn't stop me.

I am intrigued by the BIB's and have some more reading to do, but that particular thread is HUGE! I am still curious about the Chang/Half-Chang as well. Can anyone offer a subjective comparison between these?

Also, the link to the BIB designs on zillaaudio.com is dead. Is it possible that this info is currently being hosted elsewhere and I just haven't found it yet?
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Old 26th April 2013, 08:35 PM   #16
xrk971 is offline xrk971  United States
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The BIB calculator is rather hard to find in that massive thread. I re-posted GM's spreadsheet here: Just found the BIB design
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Old 28th April 2013, 04:00 PM   #17
hoz816 is offline hoz816  United States
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Quote:
Originally Posted by xrk971 View Post
The BIB calculator is rather hard to find in that massive thread. I re-posted GM's spreadsheet here: Just found the BIB design
Thank you! That helps a lot.

Quote:
Originally Posted by xrk971 View Post
The BIB will still work fine without corner loading if you have it near a wall you will get wall and ceiling bass enhancement. As the BIB for this driver will be quite tall - you will be close to the ceiling anyhow. The BIB calculator says the box is 87 in tall x 11.5 in wide x 14 in deep (ext dim). This puts you within 9 inches from the ceiling - definitely will get lots of ceiling bass enhancement. This is a relatively slender cabinet due to the low Qts and moderate Vas. If you have the room and the WAF, BIB is the way to go. You might try flattening the BIB to make a FIB and mount the driver on the longer 14 in wall if there is room. A FIB can be made by changing the aspect ratio to 6 in deep x 25 in wide (internal dim) (preserves CSA) and placing the speaker next to wall where it hardly takes up any floor space. It could be made to look like a built-in wall column and painted to match wall trim.
OK, after spending many hours reading through the forum and linked material, I've decided to give BIB a go. Budget is tight at the moment, and three sheets of good plywood is not inconsequential, so I'll need to save some nickels for a while. In the meantime, I have some more decisions to make and could use some guidance.

I like the FIB concept, and I do have the room for the 14", but the 25" implementation would interfere with the windows. Also, In considering the "wall column" implementation, I got to thinking about positioning. Currently, my MLTL's are significantly toed in, so they cross directly in front of the listening position. Would this also be necessary with the BIB? If so, that may make the "wall column" less desirable?

Also, I had a good read through Bob Brine's thread "A cabinet out of thin material". As big as these cabinets are, they will be quite heavy if constructed from 3/4" plywood, or even heavier if I cheap out and go with MDF. I wonder how these BIB's might respond to a thin/lighter cabinet, say maybe 1/4" plywood attached to 1/2" expanded polystyrene or some such? Thoughts?
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Old 28th April 2013, 04:46 PM   #18
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If pressed to reduce cost, I might use OSB for the back, bottom, and divider board--no real need for beautiful veneers there.

There are differing opinions regarding build materials, with strong feelings both for and against MDF. Personally, I'm a plywood kinda guy. Don't want anything to do with MDF.

As always: YMMV

Cheers, Jim
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Old 28th April 2013, 04:46 PM   #19
xrk971 is offline xrk971  United States
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Thin material can work well if braced sufficiently. Laminate of 1/4 in ply and foam sheathing can work well too. I make all my speakers out of foam core but nothing this big. If you want low cost but good looking ply, try the Sureply 1/4 in underlayment. Good luck.
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Old 29th April 2013, 07:42 PM   #20
DrBoar is offline DrBoar  Sweden
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BBC have publications regarding thin walled cabinets. I have done an interpretation of their designs (One BC, homage to a classic vintage design)
OSB is light but a bit scruffy with its uneven surface and tendency to fray at the edges.
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