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Athletic wear vs Speaker Fabric for Acoustic Panels. Help!

Discussion in 'Room Acoustics / Isolation / Treatment' started by CRCANPRO, Mar 29, 2016.

  1. CRCANPRO

    CRCANPRO Active Member

    Hello,

    I am building some acoustic panels using Roxul (mineral wool). I am going to buy fabric to cover them and today I was at the fabric store. The girl showed me speaker fabric but when doing the blow test I didn't think it allows a lot of air through. She also showed me Athletic wear and that actually allows way more air when you blow. My only concern is that having little holes (athletic wear does of course) may not be good because with time fibers from the insulation materials will pass through. As you imagine I spend most of my life in the recording/mixing room so I am worried about the health hazards of this. The question is: Do you know about Roxul use in long term? and also should choose Speaker fabric instead? Athletic wear is not only cheaper but allows more air. Any insights are appreciated. Thanks.
     
  2. Kurt Foster

    Kurt Foster Distinguished Member

  3. Brien Holcombe

    Brien Holcombe Well-Known Member

    I cannot believe he said "athletic wear" and "when you blow" in the same sentence.
     
  4. Sean G

    Sean G Well-Known Member

    CRCANPRO likes this.
  5. DonnyThompson

    DonnyThompson Distinguished Member

    If I'm thinking about the same athletic wear material you are describing, the holes are pretty big.
    Along with using a material that would keep those fibers from floating around, fire suppression is also a major factor. I have no idea how flammable that athletic wear material is.
    Burlap that has been flame retarded is what is most commonly used. It's porous enough to allow SP waves to pass, but is woven tight enough so that insulation fibers won't escape.
    It can also be easily dyed to any color you want, to match the aesthetics of your room.

    FWIW
     
    CRCANPRO likes this.
  6. Sean G

    Sean G Well-Known Member

    Tie-dyed burlap anyone?

    http://www.hartsfabric.com/burlap-tye-dye-summer-72275.html

    Real groovy, man...:D
     
  7. paulears

    paulears Well-Known Member

    I've never been that convinced on the blow through test. Hear through is fine, but doesn't a good pop filter let sound pass through and stop wind? Mic windshields the same. Unless you really want to stop wind, an open weave fabric that let sounds through should be the main feature? Where did the requirement to stop wind come from? Seems rather pointless?
     
  8. Sean G

    Sean G Well-Known Member

    There seems to be much said when you google acoustic fabric about this blow through test...but Im of the same mindset that its soundwaves that pass through the fabric.
    I can understand that you don't want to use a backed fabric but WTF?
     
  9. Kurt Foster

    Kurt Foster Distinguished Member

    which is why i always recommend Gulifords fabrics.
     
  10. kmetal

    kmetal Kyle P. Gushue Well-Known Member

    Roxoul, covered with a fire treated, breathable fabric, is generally safe to be in the room with, and hasn't shown any indications health hazards yet.

    That mesh athletic material might be tough to work with when trying to staple it neatly and smoothly on the panel. The burlap type fabrics have some sort of structural integrity to have nice sharp folds, and isn't super stretchy, so it's easy to keep nice straight lines, when stretching the fabric across the panel.

    +1 on GOM
     
  11. Brien Holcombe

    Brien Holcombe Well-Known Member

    If the fabric weave is tight enough, not "breathable" it can reflect rays, the high frequency. Now assuming that you have no issues with high frequency a weave that will not let air thru will reflect rays, again, the high frequency.

    Exposure relates to respiratory since we are talking about particles and dust. So if you have no asthma issues then theoretically it would not specifically be an issue. The problem with long term exposure to dust and particles is that while you did not have respiratory illness before you can develop this as a result of poorly managed treatment development. Also, you can have no way of knowing how this type of particle invasion into the breathable air will affect others in the room.

    What has been suggested for years is to enclose the insulation in either a plastic bag or to encase it in plastic to arrest the particles ability to air-borne transport.

    If you cannot do it for yourself, do it for those that visit your obviously fine establishment.

    I think you should select the jock strap or what ever athlete material you refer to. You deserve it for even considering it.

    Make a statement :)
     
  12. Sean G

    Sean G Well-Known Member

    I have often wondered, how does this effect the absorption of the panels ?

    I'm strictly speaking from the viewpoint that I have often read that backed fabrics, such as those polyester backed fabrics often used for curtains and drapes that block out sunlight are no good for use as a covering for acoustic panels due to their ability to reflect sound.

    Excuse my ignorance on the subject, but would covering the Roxul or similar in plastic or a plastic bag not have a similar effect, even if only partially ?
     
  13. kmetal

    kmetal Kyle P. Gushue Well-Known Member

    Wrapping panels in plastic or using bags will reflect mids/highs back into the room to a certain extent. How much depends on the plastics density, and what fabric your using. Alot of panel designs will incorperate materials that send selective frequencies back into the room. A wall with wooden slats being something we've seen again and again. its not necessarily a bad thing and it can help heavily treated areas not sound too 'dead', this is something that happens by accident or through solid planning or trial and error.
     
  14. paulears

    paulears Well-Known Member

    The physics here is being bent, like light rays. In practice, surfaces are either 100% reflective at one end and 100% absorptive at the other. A barrier layer can have a degree of transparency. Any energy that does not pass through is converted into heat. The same fabric can reflect light, or absorb it - as in white cloth vs black cloth. The wavelength of light is much shorter than sound. I can't find any solid data for the transmission factor of various material, but reflection appears to need mass and rigidity to work. Bolton twill, a very heavy weight popular fabric, even the black colour version can allow a bright spotlight to be vaguely seen through it, and is only transparent to audio at the very low end - HF being absorbed quite well. Hence I guess, why it's commonly used to control sound. I don't know how reflection properties would be measured, because the low frequency sound would pass through and be reflected back from hard surfaces beyond the fabric. Higher frequency waves would presumably be absorbed rather than reflected.

    The actual fabric has a fibre spec, and a 'hole' size - so you could work out the amount of fibre vs amount of 'hole's per square cm or something?

    My point is that this is hugely more complex than just thinking about how breathable it is. Sound waves are wavefronts, aren't they? So behave more like liquid than light. The maths to calculate this is beyond me, but if you cover your sound treatment with fabric the only practical result will be a change in the amount of extra HF absorption. So a membrane type device designed to operate on a low frequency for trapping won't be impacted by the covering to any degree.

    The frequencies of wind, as in the ones capable of being filtered by a windshield, are lower than bass instruments.

    Anyone understand the physics going on here? As in frequency, amount of reduction, size of air path through the fabric/mesh etc?
     
  15. Brien Holcombe

    Brien Holcombe Well-Known Member

    Here is the thing. The problem with living room acoustics is that it was and still is a by-product of arm chair acoustics experts. A typical wall mounted absorber was developed in rooms that are not small bedrooms. A room that will let sound develop has all the hard surface it needs in the wall sheathing,, glass, doors, etc. The problem is that small rooms have low frequency energy issues and then knuckleheads like (fill in your favorite knuckleheads name here) say they room needs bass trapping...lots and lots of bass trapping, And then the "mirror test" comes into play and then the user installs more trapping on the walls, overhead clouds, front/center trapping and more corner or behind speaker trapping in an attempt to get a "good sounding" room.

    Who knows what the room sounded like before but now it is dead with no high energy sizzle.

    A typical insulation filled type absorber is not a pillow with a pillowcase. There is open air space from the face of the insulation to the fabric that covers it. So maybe the rays bounce off. Some of the rays will get into and behind the cloth and strike the plastic and yes they may reflect at angle of incident. But they most likely will not align so as to penetrate the fabric and re-enter the environment.

    But as the frequencies begin to reduce and get longer in length the plastic will have no effect which is what the treatment of this sort was developed for in the first place. Then it is vibration and dissipation of energy from the waves via the insulation from friction and mass.

    In respect to the curtains, that is the incorrect answer. If you are having trouble with low frequency energy it could be effective. Usually, like I already covered, small rooms begin to lose high energy due to the over-treatment. So introducing the curtain as a fabric over an insulation type treatment will work for the area of frequency it is attempting to mitigate, mid/low energy.

    High frequency doesn't have a long shelf life anyway. It bounces around fast and loses energy at every impact and is always eaten up aurally by low frequency so re-introducing the ability for the sizzle to live can only improve the listening enjoyment.
     
    Sean G likes this.
  16. Sean G

    Sean G Well-Known Member

    Thanks for the insight Brien...your knowledge and wisdom in this area is obvious and I'm sure helps dispel many of the myths that permeate the web on this subject.
     
    Brien Holcombe likes this.
  17. CRCANPRO

    CRCANPRO Active Member

    ...do you want a medal?
     
  18. Brien Holcombe

    Brien Holcombe Well-Known Member

    Metal broadband treatments are fine for a small room that has lost high frequency due to the over treating with jockstraps.
     

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