Wool for Fostex Bass Reflex Box

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sean619

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Wool for Fostex Bass Reflex Box
« on: 12 Mar 2017, 01:41 am »
I have built my box and for acoustic absorption material the instructions just say wool with no reference to the thickness or form. I googled a bit and found a wool batting baby blanket. Not sure if I have the right idea.  :dunno: Any help appreciated. It's a little ported box for a 3 inch fostex wide band driver.   
« Last Edit: 14 Mar 2017, 07:54 am by sean619 »

JCS

Re: Wool for Fostex Bass Reflex Box
« Reply #1 on: 12 Mar 2017, 05:06 pm »
I don't much care for wool myself, as it has issues, like attracting Nature's Menagerie. 

I have been quite happy using this:
https://www.parts-express.com/acousta-stuf-polyfill-speaker-cabinet-sound-damping-material-1-lb-bag--260-317
Just be sure to fluff it up good!

Cheers, Jim

mcgsxr

Re: Wool for Fostex Bass Reflex Box
« Reply #2 on: 12 Mar 2017, 05:21 pm »
I recently built up a set of cabinets.

I used the same stuff already linked to.  Picked it up at the local Walmart. 

FullRangeMan

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Re: Wool for Fostex Bass Reflex Box
« Reply #3 on: 12 Mar 2017, 05:47 pm »
I have built my box and for acoustic absorption material the instructions just say wool with no reference to the thickness or form. I googled a bit and found a wool batting baby blanket. Not sure if I have the right idea.  :dunno: Any help appreciated.   
See post one:
http://www.audiocircle.com/index.php?topic=100689.0
If bass is small use this blanket 10mm:

Around the magnet, on top enclosure and behind the driver.

JLM

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Re: Wool for Fostex Bass Reflex Box
« Reply #4 on: 13 Mar 2017, 10:01 am »
I'd ask the vendor for more guidance of how and how much stuffing if you don't want to go the trial and error approach.

There is no right amount/configuration of stuffing.  The Walmart polyfil is the smart/easy option for the stuffing material.

sean619

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Re: Wool for Fostex Bass Reflex Box
« Reply #5 on: 14 Mar 2017, 07:57 am »
Thanks I just added that my box is ported. The Acousta fill looks great for a sealed box.

mcgsxr

Re: Wool for Fostex Bass Reflex Box
« Reply #6 on: 14 Mar 2017, 01:39 pm »
People do still use polyfill in ported boxes.  Care needs to be taken that the fill is not too close to/blocks the port.

Some staple sheets to the walls of the speaker.  Others stuff the box.

DaveC113

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Re: Wool for Fostex Bass Reflex Box
« Reply #7 on: 14 Mar 2017, 02:06 pm »
I'd first line/spray the interior with something to seal it up, maybe a sprayable damping material, then mass loaded vinyl, then sheets of SAE F11 or F13 wool felt, although the ultra touch denim insulation (Home Depot) is just as good and probably less expensive. Acoustistuff works fine too but is harder to keep in place within the box for vented enclosures.

Rusty Jefferson

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Re: Wool for Fostex Bass Reflex Box
« Reply #8 on: 14 Mar 2017, 07:04 pm »
I'd ask the vendor for more guidance of how and how much stuffing if you don't want to go the trial and error approach.

There is no right amount/configuration of stuffing..... 

Agreed that guidance from the builder could be helpful. Type and amount can influence the sound though, imo. 

Some people say "wool" to mean any stuffing the same way people say "varnish" to mean any particular wood finish.

I do use wool (sheep) in my speakers. It's very low bulk. Has no "spring" compared with synthetics. I purchase from this company, and recommend them. http://www.customwoolenmills.com/1_lb_wool_breed_rovings?tag=roving

These 1 lb "ropes" simply pull apart to make a loose fill with excellent damping properties.  I use Liecester.

I pulled some out of the vent on my speakers in the photo.



sean619

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Re: Wool for Fostex Bass Reflex Box
« Reply #9 on: 14 Mar 2017, 10:45 pm »
Some great ideas. Is there an acoustic difference between using loose fill vs using something like wool sheets glued to the walls? I built the standard bass reflex box for the FE-83 SOL per Fostex specs.

 

JLM

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Re: Wool for Fostex Bass Reflex Box
« Reply #10 on: 15 Mar 2017, 10:39 am »
Sean,

I've read that yes, there is a difference between stuffed and lined.  Some DIY instructions call for one or the other while some even describe where the stuffing should go (and of course how much to use).  Decades ago I built transmission line bass cabinets that used sheets of "edge on" foam (to simulate a longer line).

In the same way many ported designs are in actuality functioning (poorly) as transmission lines (like the speakers in your image) in that the driver is at one end of the enclosure and the port is at the opposite end of a rather skinny cabinet (shaped somewhat like a tube, or line).  Think of a flute.  Leave one hole open to get one note, but leave a different hole open to get a different note.