Terry Cain's BIB -why does it work and does anyone have those Fostex Craft Handbooks? - Page 453 - diyAudio
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Old 13th June 2009, 09:44 PM   #4521
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Quote:
Originally posted by jamikl
If I understand you correctly Briso, why not make the first expansion of the BIB the tower sides and then the centre could be the combined mouth halves or if you like the combined expansion after the bend. Have no idea what it would sound like though.
jamikl
Yes. Well that might be the next step beyond the simple clustering I suggested.

Doug
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Old 13th June 2009, 11:39 PM   #4522
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Default Re: coral 4A-70 project - sound absorbing stuff

Quote:
Originally posted by arustyrednail

should make tuning the bib a little easier with a range of panel damping and stuffing stuff to try,
Greets!

You're welcome!

Yes, they've got some good stuff, but didn't see anything suited for damping a BIB.

GM
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Old 13th June 2009, 11:46 PM   #4523
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Quote:
Originally posted by jamikl
If I understand you correctly Briso, why not make the first expansion of the BIB the tower sides and then the centre could be the combined mouth halves or if you like the combined expansion after the bend. Have no idea what it would sound like though.
jamikl
Yeah, this makes more sense to me. This would in essence be an inverted re-entrant horn turned up on end with the mouth loading either the ceiling or floor.

GM
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Old 16th June 2009, 01:51 AM   #4524
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Default coral 4A-70 project - sound absorbing stuff

hi,


regards allproof product line and its application to my experiment...

can get samples of the various materials and had thought selective application of 'quietwave ... flexible visco-elastic, constrained layer, self damping' rubber and chalk sheet to inside of panels if they seemed too lively; and take a few sharp tools to an 'acoustic pyramid' tile - maybe a few peaks at the ' u-bend ' and a flat slice on the surface behind the driver and maybe applied near the mouth ....

also, for space below the driver, have been offered surplus 'green' polyester wall insulation material and, as this is sheep country, shouldn't be to hard to find long hair wool as an alternative (not keen on handling fibreglass, haven't enjoyed previous encounters)

suggestions welcome,

thanks,

adam
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Old 16th June 2009, 06:31 PM   #4525
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Hello Guys,
Please excuse me but I need some opinions. I built my BIB using Fostex 168EZ sigma drivers and while the highs and mids are excellent, the bass is anemic. I followed the chart religiously when building the cabs. I tried the stuffing suggestion in Jeff's website but still the bass is not to my liking.

I'm suspecting that the loss of bass is due to my oval secondary baffle (from 1 1/2 inch sugar maple) on top of the front plywood piece where I mount my driver is adding too much space between the driver and the slant hence the no loading.

I'm tempted to connect the lower half of my Linkwitz Orions to fill out the bass. Thanks. Godspeed.
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Old 16th June 2009, 07:16 PM   #4526
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Assuming we are talking a standard (i.e.upfiring) BiB... what's the distance between the terminus (mouth) and the ceiling?
Also... isn't much mids leaking through the terminus ?

Gaston
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Old 16th June 2009, 08:07 PM   #4527
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Docjr,
I have the same drivers in my BIB and they are bass heavy; something is wrong. Mine are in corners and I have 10' ceilings in my house (which is a little high for maximum effect). Maybe yours are out of phase?

Ray
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Old 16th June 2009, 09:57 PM   #4528
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Another cause of low performance in the bass is sometimes leaks in the seal between the driver and the enclosure. In your case, having a secondary baffle there are double opportunity for leaks.
I made the walls of the driver hole tight by applying pva to them. Before that they leaked through the ldf/hdf combination I used. The bad side of scrap material

I also used the seal tape that came in the box of the drivers (mine are FE166E so not much different from yours) and they have adequate bass when driven from a flea power amp and plenty of it when driven witha a 15+15W amp.

My ceilings are 8' high.
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Old 17th June 2009, 12:01 AM   #4529
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Thanks for replying guys. I have to measure the distance from the mouth to my ceiling when I get home tonight. My secondary baffles were sealed with silicone and the drivers were mounted with weather strip gasket between the flange and the maple suprabaffle. There might be leaking because one side panel for each cabinet were not permanently glued yet for I'm experimenting on the stuffing.

Out of phase? Oh My, maybe, let me check that too. I remember that the speaker terminal with the red marking is the positive side for the drivers but let me re-check. Thanks a lot guys and Godspeed.
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Old 17th June 2009, 03:50 AM   #4530
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Quote:
Originally posted by Doc Jr 8156
Thanks for replying guys. I have to measure the distance from the mouth to my ceiling when I get home tonight. My secondary baffles were sealed with silicone and the drivers were mounted with weather strip gasket between the flange and the maple suprabaffle. There might be leaking because one side panel for each cabinet were not permanently glued yet for I'm experimenting on the stuffing.

Out of phase? Oh My, maybe, let me check that too. I remember that the speaker terminal with the red marking is the positive side for the drivers but let me re-check. Thanks a lot guys and Godspeed.

Phase check is done with a couple wires and an AA battery. The Positive end of the battery to the positive (red) terminal and Negative end to the negative. You'll hear a noise which is suddenly loud. Watch the cone for movement outward rather than inward. If not so, the reverse is actually the positive.
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