Terry Cain's BIB -why does it work and does anyone have those Fostex Craft Handbooks? - Page 499 - diyAudio
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Old 24th March 2012, 05:21 PM   #4981
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I have been throwing around the idea of building a BIB style subwoofer. For example, there is Scottmoose's
CSS TRIO12 design. While reading through the various BIB threads, I found this one, which has the driver
mounted facing into the enclosure. Please see the attached photo. Is there a reason to do ...or not do this?
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Old 24th March 2012, 09:31 PM   #4982
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Quote:
Originally Posted by dobbykins View Post
A couple of quick questions before I start ordering components for my BiB build:
No clue about their mids/HF sonics, though all else equal, I personally would opt for the 166 due to its stronger published motor as it's inherently better damped and also allows a bit more tuning flexibility.

Hmm, thought I posted some thoughts on theoretically optimum terminus/ceiling or floor spacings in this thread, but with my saved docs with links not being available to me for now, no way to quickly check what/where I posted it. IIRC, the rule-of-thumb way is to find the terminus effective radius, then multiply it x 0.613 to get the minimum distance. The more complex way is to calculate its rate of expansion to calculate a proper bend expansion. Done this way, corner loading may not be required.

Regardless, I recommend building it 'stock', but make the terminus with a minor recess such that you can drop in a flanged 'tophat' to both get it closer to the ceiling and mass load it a bit with this simple straight section if you feel the driver needs more loading on some music.

You may want to do it anyway as HornResp indicates it's a worthwhile tweak. I had planned to experiment/post results by now using TC's original 40-1354 BIB, but 'life' keeps getting in the way.

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Old 24th March 2012, 09:38 PM   #4983
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Quote:
Originally Posted by Oscillate View Post
Is there a reason to do ...or not do this?
Without taking the time to research it, I assume the driver is too deep to fit and since it's a 'sub' woofer app, the XO will roll it off long before it gets high up enough in frequency for the frame/motor to audibly affect its sonics.

The only real downsides AFAIK is having exposed wiring, so ideally need some shielding against contact, accidental or otherwise and of course it's hard to dust properly if you're not blessed with a very good home filtration system.

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Old 24th March 2012, 11:48 PM   #4984
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So im thinking of building some of these for a commercial installation, 20ft x 60ft x 20ft.

would using these upside down work, probably wall mount them, or since its not critical listening put them up high in the corners?
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Old 25th March 2012, 06:32 AM   #4985
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Just brought back my BIB from basement storage...it has been a while! re-tuned and really enjoying! Fostex ff165k, external dimensions: 69"x16.25x8.625. I think I copied Scottmoose's BIB and built back then

Last edited by doggy; 25th March 2012 at 06:48 AM. Reason: spelling
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Old 25th March 2012, 10:04 PM   #4986
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Stored? Re-tuned? What was wrong with them?

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Old 25th March 2012, 11:03 PM   #4987
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I added some stuffing below the driver to provide some more loading, helped to bring out the bass. These BIB's are good with the infrasonic bass.

I built these in 2006 for whatever reason I change my audio system. I have some 2a3 monoblocks in storage and not used in years; just using an lm3875 chip amp to power these.
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Old 26th March 2012, 05:39 AM   #4988
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Yeah, pipe horns need a bit of damping in the first ~2/5th of its path-length if used wide range.

These do < 20 Hz with any sort of power?! Must be a lot of room gain.

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Old 29th March 2012, 08:38 AM   #4989
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Click the image to open in full size.

I had to try one this morning.
I need to work some with the stuffing.

J.
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Old 29th March 2012, 04:10 PM   #4990
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Try some stuffing on the bottom to absorb mids coming thru the top. I'd also recommend doubling up the front and back of the speaker so it doesn't resonate.
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