Terry Cain's BIB -why does it work and does anyone have those Fostex Craft Handbooks? - Page 129 - diyAudio
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Old 3rd September 2006, 03:56 PM   #1281
McFaBs is offline McFaBs  Italy
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Thanks Dmason

I start to understand.... so "high grade etc.." is a kind of noise absorber for undercarpeting.

Think wuold be hard to find it in Italy. It's usual for that purpose to use a rubber carpet or other materials...I'll try to look after anyway.

Dmason, as owner of Omega Speaker, does your pair have the hole in the dustcup? How is it protected... In the same article Lou said "The driver (Fostex) has a hole in the center etc...., [b]this is covered by a protective screen to repel dust"....[/b]

Any thought?

Ciao. Fab.
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Old 3rd September 2006, 04:10 PM   #1282
GM is offline GM  United States
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Quote:
Originally posted by McFaBs
Thanks GM
I'll see if Google has something to say about, here in Italy.

Talking about stuffing materials, Lou Chochos of Omega Speakers on a Stereophile article was mentioning as using :"high-grade carpet padding - saying - ...it sounds better than everything else I tried...." (Stereophile vol27 n.11 Nov 2004)

I can't figure what kind of carpet is! Can you explain me or suggest a link where exactly I can see it? You know, sometimes It's not possible to find same materials outside USA, or not easy to translate and find the equivalent.....Italy is a strange land.....

Ciao.Fab.

P.s. Just a stupid question.... what YMMV stands for?....


Greets!

You're welcome!

YMMV = 'your mileage may vary': http://en.wikipedia.org/wiki/YMMV

Carpet underlayment (aka 'padding' or felt) comes in three basic grades and each has a range based on various company's marketing strategies, though I've noticed in recent decades that the lower grades are probably all made by just a few companies around the world since they are apparently now only made from scrap foam (aka 'rebond' or 'junk bond') at least WRT what's available in the USA.

When I was young, jute was the norm and how dense/thick it was determined it's grade, being able to quickly assess its quality by its color until unscrupulous folks started dying cheaper grades to fool the casual consumer. You want some serious noise attenuation, then 3/4" - 1" of the best grade will get the job done and under an equivalent quality carpet you don't so much as walk on it as float, but if you have to ask for a quote to do your home you probably can't afford it. http://en.wikipedia.org/wiki/Jute

My last 'update' on this subject was in '94 though, so doing a quick search to see what the 'latest n' greatest' is, it appears that in the never ending search to get more from less, the industry hasn't been 'asleep at the wheel': http://www.acousticalsolutions.com/p...superfloor.asp

Then there's the 'explosion' of engineered foam products.............

Anyway, IMO if you need to use such serious (wide BW) damping on a cab, then the cab's design and/or construction is fundamentally wrong for its intended BW, which sadly is the norm in the consumer speaker industry. That said, if you can beg/buy at a reasonable price some being removed from a commercial or private mansion renovation, it's great for damping anything made from metal, ceramic, etc.. Ditto for damping small machines, 3/4" pads of it were used under typewriters, mechanical calculating machines, etc., so works well damping TTs, CD players, etc.. WRT using it in a FR speaker app, lining a cab with it will 'suck the life' right out of it if >3/8" thick IMO assuming today's offerings are close in its specs to what I've used.

As always though, YMMV.

GM
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Old 3rd September 2006, 04:34 PM   #1283
GM is offline GM  United States
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Quote:
Originally posted by dmason
The padding Louis seems to be referring is the stuff made up of recycled foam-of-many-colors.
Greets!

'Rebond' and 'high grade' carpet padding are mutually exclusive by design, though ~10 years ago I in-home tested a sample of a rebond product that was marketed as a high grade carpet underlayment so I can't call him a liar, but it in no way came close to matching my decades old 5/8" jute in subjective 'feet' performance. That said, the ultra cheap rebond is used extensively in 'el cheapo' consumer speakers to damp the effects of cheap/shoddy materials and/or construction, or at least was back when I was still paying attention to discarded speaker cabs, so for sure it can work well in a 'shotgun' sort of way.

Regardless, thanks for the insight!

GM
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Old 3rd September 2006, 05:58 PM   #1284
renfrow is offline renfrow  United States
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Quote:
Originally posted by McFaBs

I see.... What if I place some sealing foam tape or similar and some dowel screws (like in the front or rear baffle of commercial speakers) until I reach the final tuning? Do you think would be enough?

Thanks. Fab.
Something you might try, that should be available, is sill foam seal. This is used between the top of house foundations and the bottom of the wall to seal against air infiltration. This should have a LONG life span, should you decide to just leave the speaker as-is :-).

Tom.
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Old 3rd September 2006, 06:53 PM   #1285
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Go to a carpet store and look around back on garbage/refuse
collection day. Plenty good size pieces of all that stuff is
discarded. It's still fresh, smells new etc. Just catch it before
it rains.
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Old 3rd September 2006, 07:34 PM   #1286
McFaBs is offline McFaBs  Italy
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Hi!

GM : As usual very exhaustive answers! And luckily, reading between the lines, BIBs doesn't need such damping..... So, another thing rubbed out from the shopping list!

Last but not least THANKS TO EVERYBODY! I really like this forum, I've learned soooooo many things, and for a novice like I am, it's really comforting.

Just sorry If I can't fully contribute in sharing infos; maybe in the future...

Ciao.Fab.

P.s.:
Loninappleton : good hint, and cheap too.

Renfrow : I've glanced that link and sound interesting. Tomorrow I will ask to a friend of mine who's a house builder.
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Old 3rd September 2006, 08:14 PM   #1287
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GM,
What is your view on using cork to line the BIB's?

Ray
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Old 3rd September 2006, 08:48 PM   #1288
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Quote:
Originally posted by renfrow
Something you might try, that should be available, is sill foam seal.
Essentially the same, but thicker, is stuff i salvage from one of local hot tub stores -- it is used for shipping hot tubs in. A quite dense closed cel foam, it should have lots of good uses (besides packing material which is mostly what i use it for.

dave
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Old 3rd September 2006, 09:05 PM   #1289
GM is offline GM  United States
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Greets!

IIRC my cork usage was limited to a decorative form of controlling room and baffle reflections, but it doesn't seem to be space efficient enough for speaker internals. IOW, acoustic fiberglass, felt, foams reduce net Vb much less for the same amount of attenuation, but if you want something relatively rigid, acoustic tile (aka Celotex) like BB uses is a better choice IMO.

GM
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Old 5th September 2006, 12:54 PM   #1290
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Dave has come up with a downward-firing FE108ESigma BIB box. Picture that Dave (P10 -a different Dave! ;-) posted on the FR forum. Early Frugelhorn next to it. Look's pretty impressive. I'll have to look into upward-firing enclosures for the smaller 4 - 4 1/2in drivers again.
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