Terry Cain's BIB -why does it work and does anyone have those Fostex Craft Handbooks? - Page 84 - diyAudio
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Old 12th June 2006, 12:14 PM   #831
fred76 is offline fred76  Philippines
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Quote:
Yeah, the drawing on the left chops off the actual terminus at an angle, thus shortens the recommended pipe length - not right.
Err, correction. I meant the drawing on the 'Right' is wrong.

fred
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Old 12th June 2006, 01:51 PM   #832
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I am about ready to build a pair of BIBs for the Fostex 168ES Sigmas. Using the guidelines, I came up with approx. internal dimensions of 6.5"(w) x 11.5"(d) x 60"(h).

After looking at Terry's latest Inverted BIB, which loads the floor rather than the ceiling, I was wondering on these lines:-

Use a 15" or 18" ELF type of sub and mount the 168 BIB above that to couple with the ceiling better (ceilings are usually 9'-10' high).

I would also like to use a Fountek JP3 ribbon in each BIB.

Set it up for active amplification with an active x-over and make the inputs switchable so that the 168 can be used either as the midrange in the 3-way active setup or as a Full Range.

This way it would be possible to have the best of all worlds ie., a 168 BIB that couples better with the ceiling and a switchable 3-way active system to handle even the most demanding type of music.

One more comment: How is the idea of either starting a thread or putting up the 'internal fill' details for each BIB in the zillaspeak website?

I had posted the above a couple of pages earlier; does anyone want to comment on some of the issues I've raised?

Thanks,
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Old 12th June 2006, 03:56 PM   #833
doggy is offline doggy  Canada
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Default construction

Thanks Scott for your reply. I have had the ff165k in other blh, and the bib not only give excellent low freq. but the midrange comes out better than I have heard it. I was kind of wondering about relections from the baffle to the cone. I can also stuff the top of the "so" to shorten the distance to the driver.

This poplar is 13 ply-$44 can. 4x8 sheet, it has some nice grain, which I put to the sides; chose the clear grain for the front panels. I use the butt joint method with glue and clamps, and cover the end ply with iron-on veneer. I tried a new glue the person at Windsor recomended. It's called bondrite, it is supposed to take stain and sanding. It works the same as regular wood glue.

Will report back after completion.

cheers
doggy
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Old 12th June 2006, 04:12 PM   #834
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Samuel Jayaraj,

Personally if you are going to have a 3 way and are going to use the 15" or 18", I think the BIB may not be the best idea. The BIB is a great way to get the LF and higher gain using a single driver. The 168Sigma BIBs go down to 40hz, a sub would be on a 40hz LP filter. I think that perhaps having the 168Sigma OB would be a good idea having the ribbon on there and using the 15" or 18" similar to the Basszilla. Just my

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Old 12th June 2006, 04:35 PM   #835
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Sam,
I followed Scott's recommended dimensions for my Fe168EZ BIB which were 6 3/4" X 11" internal and a length of 64". Based on the discussions in this thread, it appears that the dimensions are somewhat flexable.

Repeat: I also need sugestions regarding fill amounts.

Dmason--can you share your experience with fill in your 168 BIB?
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Old 12th June 2006, 04:48 PM   #836
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Ray

When I did mine, I put a small piece of heavy fiber behind the driver and what I'd call medium density of fiber fill above the driver. Seemed to work well for me. Left the rest of the line open.

Hope that helps.
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Old 12th June 2006, 04:57 PM   #837
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Thanks ONE1.....that will get me started. I think I will omit the fill in the floor for the initial test; I like the notion of an open line. What is the nature of the heavy fiber behind the driver....carpet pad or something similar?
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Old 12th June 2006, 05:08 PM   #838
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GM and I discussed floor loaded BIBs and stuffing options. One method he suggested was placing grill cloth around the back of the driver. Grill cloth cuts down on high frequencies and by placing it around the back of the woofer, high frequencies wouldn't even enter the BIB. He also suggested perhaps putting a small amount in the tip, but otherwise gain is decreased significantly by stuffing as are the low frequencies.

Josh
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Old 12th June 2006, 06:24 PM   #839
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Quote:
Originally posted by Ray Collins
Thanks ONE1.....that will get me started. I think I will omit the fill in the floor for the initial test; I like the notion of an open line. What is the nature of the heavy fiber behind the driver....carpet pad or something similar?
Well, I actually used a piece of a car seat cover a friend had, a thick piece that had the consistancy of a lambswool. Pretty funny, as this guy has crap everywhere, but something that actually did come in handy. Anyway, just something to help stop reflections coming back into the driver.
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Old 12th June 2006, 06:34 PM   #840
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Josh,

Thanks for the reply. In fact, for a long time I wanted to keep the 168ES 'Open Baffle(d)', for the 3 way active system. I asked for peoples opinions here, but one person replied in this thread saying that the mids/voice sounded much better in the BIB than open baffle.

With the ELF kind of subwoofer, one can easily cover 15Hz to 40 or 45Hz, then let the BIB take over and then crossover to the Ribbon upward of 7Khz. My take is that complex passages and rock music will not suffer.

My idea is to make the preamp/crossover out switchable, so that the 168SE BIB can be used as a true full range, thereby enabling a direct comparison between FR and 3-way active.

Ray Collins,

When you say a length of 64" do you mean 'L' of the BIB drawings or the actual measured height of the enclosure?

Thanks,
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