Fiberfill?
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=48544
Printed Date: April 27, 2024 at 7:11 AM
Topic: Fiberfill?
Posted By: Master Asylum
Subject: Fiberfill?
Date Posted: January 25, 2005 at 7:16 AM
I've seen this a few times and I keep hearing that it makes a sealed box think it is bigger. How does this work? I just can't really seem to think of what it would do.
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1998 Monte Carlo w/
Eclipse CD8454
2xRockford 5.25" Power 2-way T152C
2xRockford 6"x9" Punch 3-way FRC4369
1xMemphis 16-MCH1300 5-channel
2xKicker 12" L5 Solobaric-2 Ohm
Replies:
Posted By: haemphyst
Date Posted: January 25, 2005 at 9:25 AM
Suffice to say, the driver "believes" it is a box that is UP TO 10% larger than it really is. The acoustical calculations are FAR TOO COMPLEX to even think about going into on this forum. I have seen them written out before, and they are indeed, complex. As a general rule, though, never stuff to beyond 1 pound per cubic foot with the actual product Acoutastuff, and never beyond .5 pounds per cubic foot with Dacron pillow stuffing. This is because the Acoustastuff is DESIGNED for use in speaker enclosures, and is designed with very specific acoustical properties, with more even crimping of the fibers. Pillow stuffing, while an acceptable replacement, is not.
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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."
Posted By: DYohn
Date Posted: January 25, 2005 at 10:10 AM
I'd like to add my support for products like Acoustastuff (there are other brands as well) as it is the best material available short of using actual long-fiber wool. It is far far superior to pillow stuffing and far far safer than fiberglass insulation (which IMO should never be used in any case.) A speaker does not "think" its enclosure it larger than it is, because loudspeakers cannot "think." It is pure physics, not some kind of magic. Now while haemphyst is (as usual) completely correct when he says the math to show why it works is far too complex for this forum, I can boil it down in laymens terms for you like this: the added fibers inside the enclosure add surface area and many new "channels" that the air inside the enclosure must pass through. This causes two effects. First, it slows down the air velocity by "getting in the way." Second, since it adds "passages" inside the enclosure the air has farther to travel to get through them instead of simply bouncing straight off the back of the enclosure. Since the air now has to travel farther and has been slowed down, the effect is the same as if the enclosure was physically larger. Does that make sense? ------------- Support the12volt.com
Posted By: heavilymedicate
Date Posted: January 25, 2005 at 11:13 AM
For a added effect... Stuff your ported enclosure with fiberglass insulation! *That way you and your passengers can enjoy that after ride itch! Sort of like the one you get from sleeping with that chick down the block. *Best results with hatchbacks, trucks and station wagons. Results will vary if the enclosure is placed in an enclosed area such as a trunk. ------------- What will you get for Christmas, bad boy? Coal........or Visonik?? - stevdart
Wow, is everyone clueless and lost in the dark? - uthinkuknoaudio
Posted By: Master Asylum
Date Posted: January 25, 2005 at 11:25 AM
Harsh heavilymedicated, harsh. I get it now I'm pretty sure, thanks for the dumbing down. :) ------------- 1998 Monte Carlo w/
Eclipse CD8454
2xRockford 5.25" Power 2-way T152C
2xRockford 6"x9" Punch 3-way FRC4369
1xMemphis 16-MCH1300 5-channel
2xKicker 12" L5 Solobaric-2 Ohm
Posted By: misterjimbo
Date Posted: January 25, 2005 at 11:32 AM
[ A speaker does not "think" its enclosure it larger than it is, because loudspeakers cannot "think." so wait... you mean to tell me that the voices that i hear every time i get out of my car are actually in my head? how unnerving. -------------
Posted By: Steven Kephart
Date Posted: January 25, 2005 at 3:53 PM
DYohn] wrote:
p>I'd like to add my support for products like Acoustastuff (there are other brands as well) as it is the best material available short of using actual long-fiber wool. It is far far superior to pillow stuffing and far far safer than fiberglass insulation (which IMO should never be used in any case.)A speaker does not "think" its enclosure it larger than it is, because loudspeakers cannot "think." It is pure physics, not some kind of magic. Now while haemphyst is (as usual) completely correct when he says the math to show why it works is far too complex for this forum, I can boil it down in laymens terms for you like this: the added fibers inside the enclosure add surface area and many new "channels" that the air inside the enclosure must pass through. This causes two effects. First, it slows down the air velocity by "getting in the way." Second, since it adds "passages" inside the enclosure the air has farther to travel to get through them instead of simply bouncing straight off the back of the enclosure. Since the air now has to travel farther and has been slowed down, the effect is the same as if the enclosure was physically larger. Does that make sense?
That is an awesome discription. You can also see based on the above why you want the fill to be out in the center of the enclosure. Some people just like the walls of the enclosure which has very little effect. You want it placed where the velocity is at it's greatest which is in the center of the enclosure. Steven Kephart Adire Audio -------------
Posted By: stevdart
Date Posted: January 25, 2005 at 4:49 PM
...and since we have the experts convening.......fiberfill in a ported enclosure. Does it change the critical volume? And what is the purpose of lining the walls with it? Would we be more accurate in attaining volume if we used a solid damping material instead, and accounted for its space?
Posted By: DYohn
Date Posted: January 25, 2005 at 5:16 PM
You use it the same way you would in a sealed enclosure and yes, it increases the effective volume by around 10%. A great tool for compensating for driver and brace volume. In a vented enclosure it is important to keep it away from the vent opening(s.) ------------- Support the12volt.com
Posted By: /R7
Date Posted: January 25, 2005 at 5:26 PM
ah an explination to a problem i've had for a long time. Whenever people hear the idea of filling an enclosure with polyfill or stuffing, i've been asked how it actually works. I've bit my tounge every time i say "it makes your speaker think its bigger" it just doesnt clearly explain it, so when i tell them it slows the air down inside the speaker, they get confused. all i need to do is reherse this thread in my head and i'll be set.
Can anyone point me to a thread or website with these calculations. i dont expect to even comprehend it, but im curious is all.
Posted By: DYohn
Date Posted: January 25, 2005 at 5:53 PM
Posted By: DOC_KRACKEN
Date Posted: January 26, 2005 at 11:07 AM
Does this work in doors too? even if you already have treated them with mat , or is that over kill? Thanks
Posted By: heavilymedicate
Date Posted: January 26, 2005 at 11:23 AM
Your door naturally condensate water through the natural process of condensation. Your doors also leak a little inside the doors when it rains, or when you wash the car. Therefore; you cannot place any sort of fill in your doors because it would become a sponge and its dampening abilities would be nullified. Also, it would interfere with the mechanisms in the door (dont ya think)? If you want an enclosure, fiberglass is your answer. ------------- What will you get for Christmas, bad boy? Coal........or Visonik?? - stevdart
Wow, is everyone clueless and lost in the dark? - uthinkuknoaudio
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