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Old 19th November 2007, 04:35 PM   #1
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Default BIB and ceiling height

Hi,

I'm considering building a Fostex 206e BIB but I'm worried about ceiling height. The BIB for 206 is 221cm high, and my ceiling is only 250 or 260cm (2 rooms).
So the question is what would be the minimum and/or optimal ceiling height for a 206 BIB ?
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Old 19th November 2007, 06:02 PM   #2
GM is online now GM  United States
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Greets!

Well, the closer to the ceiling it is, the greater the slot loading, so from this POV it would have to be very close indeed to be too close. If you mean to keep it from being slot loaded, then at minimum it has to be beyond the pipe's acoustic length at whatever the driver's max low distortion excursion is, so no set distance.

BIBs typically have a large enough terminus and use low enough suspension limited (Xsus) drivers though that a pipe's end correction formula is probably sufficient, so calc the mouth's effective radius, then Dmin = > radius*0.613 and > 3*radius if you want no doubt.

GM
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Old 20th November 2007, 03:56 PM   #3
kaan is offline kaan  Denmark
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I'm in a similar situation so ill just join in here.

I take it that slot loading is a good thing then?
Sorry for being a noob

I guess that everything more than ~40mm is really enough?

-Klaus
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Old 20th November 2007, 05:23 PM   #4
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??? The 206E BIB calculates 10.16 cm minimum to the ceiling.

Yes, slot loading can be a good thing, though it will sound considerably different to a ceiling loaded BIB that has enough distance to 'breathe'.

GM
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Old 20th November 2007, 06:35 PM   #5
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Hi all, that same question has been on the back of my mind also. The top of my 206ES-R BIB's are just 10" from the ceiling.
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Old 20th November 2007, 09:20 PM   #6
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Quote:
Originally posted by GM
??? The 206E BIB calculates 10.16 cm minimum to the ceiling.

Yes, slot loading can be a good thing, though it will sound considerably different to a ceiling loaded BIB that has enough distance to 'breathe'.

GM

Would you elaborate on this, for all us noobs in this thread.
Could you describe what effect sound wise, slot loading has ?
I've read BIB has a "dipole" bass, will slot loading affect this ?
What would be "enough distance to 'breathe'" in the above example.

And another question for that can help. How could you describe the difference in bass of a BIB and BLH (Dallas for example). I've had a chance to listen to a Dallas II, but it's a hard build for a beginner, so I'm looking around for a easier build.

BTW coming from a BR box (Mirage m-390is) I was amazed with the quality (speed, body, everything) of bass in a Dallas.
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Old 21st November 2007, 03:49 AM   #7
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Greets!

You're asking the wrong person in that I know how slot loading, dipole bass, and the type of pipe horns I've built sound (which are a bit different than BIBs), but I've never built/auditioned any of the BIBs based on T.C.'s design, I just know how to design them. Anyway, I was pretty surprised when some folks described them as sounding like bass dipoles as I figured they would sound very close to my version, which has a fairly focussed presentation like one gets from a corner loaded BLH.

Slot loading is best for low tunings since it controls the driver better, increasing its acoustic efficiency, lowering harmonic distortion, but being essentially a bandpass (BP) alignment, it rolls off much of the higher frequencies coming out of the vent/horn mouth, which may/may not be desirable depending on the application (app).

In theory, the >10.16 cm I calculated.

I have no experience with the Dallas either, nor have I reverse engineered it, but at a glance I imagine it's going to be more refined, focussed ('tight') sounding while the BIB is going to have a bigger, more open presentation that goes much lower, so a somewhat 'fuller', more life-like one when the source material is truly wide BW.

Yeah, just about any decent TL, pipe or BL horn is going to outperform any BR, consumer or DIY. BR's advantage for a given Fb is small size compared to the others.

GM
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Old 21st November 2007, 07:58 PM   #8
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Ok thanks, can anybody who has listened to both types of enclosures (BIB and BLH) comment on their sound?
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