does someone suggest me a comparison between different stuffing materials...such as dracon...sheep wool....ecc...ecc
also web link is appreciated
i need to know its listening effects and its range response/frequency.
t.i.a.
also web link is appreciated
i need to know its listening effects and its range response/frequency.
t.i.a.
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What application do you have in mind (i.e. acoustic suspension, transmission line, vented, etc.)?
Your answer will help me direct you to the best on line references.
Have you tried doing a search here at DIY? use search word 'stuffing'....
Your answer will help me direct you to the best on line references.
Have you tried doing a search here at DIY? use search word 'stuffing'....
If you are able to do your own measurements then the best test is to create a test box and drill a hole in one corner to insert a microphone. A one cubic foot, or so, cabinet with a 6 or 8 inch woofer would do fine. Any subwoofer cabinet would also do.
Measure the frequency response inside the (empty) box and you will see all the standing waves of a typical enclosure.
Once the baseline test is done try any materials you choose and try lining any thicknes up to total stuffing. You will see the total effect of the material, and you will have a more revealing view of it than any other view.
My experience with this test is that fiberglass can be equalled but it can't be beat. Many materials such as polyester or BAF (bonded acetate fiber) are close to worthless. Some re-processed wools are good. Some acoustical foams are good.
Fiberglass is the best value.
David S.
Measure the frequency response inside the (empty) box and you will see all the standing waves of a typical enclosure.
Once the baseline test is done try any materials you choose and try lining any thicknes up to total stuffing. You will see the total effect of the material, and you will have a more revealing view of it than any other view.
My experience with this test is that fiberglass can be equalled but it can't be beat. Many materials such as polyester or BAF (bonded acetate fiber) are close to worthless. Some re-processed wools are good. Some acoustical foams are good.
Fiberglass is the best value.
David S.
Home Work
Here is an article that may help you:
Acoustical properties of fibrous absorbent materials
M.E. Delany, E.N. Bazley
National Physical Laboratory, Teddington, Middlesex Gt. Britain
Received 28 August 1969; Available online 19 February 2003.
Abstract
Results are presented of an investigation into the acoustical properties of a range of fibrous absorbent materials. Measured values of characteristic impedance and propagation coefficient are shown to normalise as a function of frequency divided by flow-resistance and can be represented by simple power-law functions. Absorption coefficients of thin layers of material over a range of flow-resistance values are also shown. Supplementary data provide a basis for estimating the flow-resistance of a material from its bulk density.
For more, do a Google Search: "Acoustical Resistance" Properties
Regards,
WHG
P.S.:
1) Try requesting a copy of this or other articles you may find, directly from the authors.
2) Assuming operation well above 100 Hz, lining the enclosure interior with 1" thick Wool Felt works best for your application, but the cost of it is high.
Here is an article that may help you:
Acoustical properties of fibrous absorbent materials
M.E. Delany, E.N. Bazley
National Physical Laboratory, Teddington, Middlesex Gt. Britain
Received 28 August 1969; Available online 19 February 2003.
Abstract
Results are presented of an investigation into the acoustical properties of a range of fibrous absorbent materials. Measured values of characteristic impedance and propagation coefficient are shown to normalise as a function of frequency divided by flow-resistance and can be represented by simple power-law functions. Absorption coefficients of thin layers of material over a range of flow-resistance values are also shown. Supplementary data provide a basis for estimating the flow-resistance of a material from its bulk density.
For more, do a Google Search: "Acoustical Resistance" Properties
Regards,
WHG
P.S.:
1) Try requesting a copy of this or other articles you may find, directly from the authors.
2) Assuming operation well above 100 Hz, lining the enclosure interior with 1" thick Wool Felt works best for your application, but the cost of it is high.
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I have very good results with Memory Foam that is sold at Wal-Mart as a mattress topper. It comes in sheets that roughly match the dimensions of a bed. The version I use is about 1.5 to 2.0 inches thick and has smooth surfaces (as opposed to an egg carton surface). I haven't tried a lot of alternatives but I did prefer this to regular foam, Dacron and polyester sheets. I got the idea of trying Memory Foam from my Spendor speakers which are lined with something very similar.
Rigid fiberglass, rockwool or Bonded Logic cotton insulation. Choose one that best suits your price and needs. Avoid all else if you want maximum results.
Greg
Greg
WSDG - Absorption Coefficient Chart
Bonded Logic - Construction Products - Acoustical Panels
You can also get the Bonded Logic in 3.5" and it is even more effective than those numbers shown in the link. Very good even down below 100Hz.
Greg
Bonded Logic - Construction Products - Acoustical Panels
You can also get the Bonded Logic in 3.5" and it is even more effective than those numbers shown in the link. Very good even down below 100Hz.
Greg
For those of you in the northern region of the US, Menards just started carrying the big bundles of it for a VERY good price. Better than I've been paying from a construction supply house. Listed as "Ultra Touch" insulation.
Greg
Cotton Batting, sold at fabric stores, dirt cheap............about two inches thick. Glued to the inside panels....spread the glue around evenly, front baffle pointed up, cut with scissors to fit each panel, overlap slightly.
_____________________________________________________Rick..........
_____________________________________________________Rick..........
I'm not familiar with this stuff but the numbers look good (comparable to fiberglass). Anything that has had proper acoustical absorption coefficient tests is a legitimate material.
Compare the numbers between materials for samples of the same thickness. Generally doubling sample thickness will shift the absorption coefficients down an Octave.
David S.
Hmmm so I should remove mine then 😉 The foam I am using does definitely make a difference, but I never tested the stuffing "rolleyes"
Tony.
Those of you who have a copy of later editions of Vance Dickason's "LSCB", open them up to the section on closed box systems. Therein you will find an imperical study that was performed with a variety of stuffing materials and densities. A tabular summary of the trials shows effects on a variety of T/S parameters including Qtc and f3. The best performace in Q & f3 reduction from an unstuffed box was FG stuffed at 1 lb/cu.ft. which is my own rule of thumb. "Fill dacron" didn't do much of anything. Neither did Acousta-Stuff. A 0.95 cu. ft test enclusure was used for the study.
I went to Goodwill and purchased a couple ugy wool sweaters.
Cut them into pieces and stuffed my box with that as an experiment.
Cheap and easy for playing.
I used this in the tweeter box and the mid box.
Cut them into pieces and stuffed my box with that as an experiment.
Cheap and easy for playing.
I used this in the tweeter box and the mid box.
Me too!
I use it, gapped about 1" off the enclosure walls, as lining in my "ultimate bass bins". 4.5-5 cubes enclosed, and no enclosure resonances are visible on impedance sweeps.
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