blackfox Posted October 5, 2009 Share Posted October 5, 2009 (edited) well i'm currently looking at speaker dampening, many speakers i'v come accross they have a heashen/wool weave like removalist blankets but about 15mm thick, cotton stuffing like pillow insides or even nothing! I have a thread on my speakers in DIY section so u can look for a better understanding, really want something that has a high coefficient from 30hz to 500hz for inside my boxes. I have found some 45mm egg carton shaped foam and 100mm fairly dense foam, they don't have the coefficients so i don't know how good it is..was used in a band room, wanting to know others peoples experience, price vs quality is the key, like all i don't want to spend too much (say up to $150 for two 140lt boxes) but want the best i can...any ideas? the cheaper the better Heres a quote i read "The absorption coefficients that are typically published for acoustical materials are found using the reverberation chamber method. This method yields random incidence absorption coefficients, which are not percentages. Normal incidence absorption coefficients are percentages. The two are often confused in the literature. A material that has a random incidence absorption coefficient of 1.22 is simply a better absorber relative to a material with a random incidence absorption coefficient of 0.67 for the same frequency band, all other factors being equal. The numbers should not, however, be treated as an indicator of the percentage of sound absorbed by the material." all help considered (with backup reasoning please rather than only opinions...) also i'v heard puttng deadening inside changes the internal volume that the speaker "sees", i was lead to believe u put some in and it makes it think the box is larger? is this true? included below is the image of the foam i was looking at, Edited October 5, 2009 by blackfox Link to comment Share on other sites More sharing options...
kye Posted October 5, 2009 Share Posted October 5, 2009 hi blackfox I wouldn't get too hung up on speaker stuffing - the pro stuff is basically the same as pillow stuffing (not completely, but inside a speakerbox the differences aren't much at all).. I would just use pillow stuffing, but if you're up for the absolute best results then you should captialise on what australia does best and use long fibre wool - it's one of the materials of choice for cost-no-object speakers. Link to comment Share on other sites More sharing options...
blackfox Posted October 5, 2009 Author Share Posted October 5, 2009 (edited) so the 45mm ripple foam and flat 100mm foam in predescribed manner will make no discernable audio difference? as it wil only cost me $75 for two sheets ripple and 1 100mm foam, (with heaps 100mm left over...) Edited October 5, 2009 by blackfox Link to comment Share on other sites More sharing options...
Bilbo Posted October 5, 2009 Share Posted October 5, 2009 Cheap way out... I recently bought a 1.8x1.8m blanket from Bunnings - the type used by removalists. At $9.95 it's much cheaper than felt and stapled or glued to the interior of the cabinet provides a good cheap method of dampening. Adding some long fibre wool as kye suggests will finish it off nicely. Link to comment Share on other sites More sharing options...
Mick35 Posted October 5, 2009 Share Posted October 5, 2009 I prefer the white pillow stuffing type (Dacron is the trade name I think) It's easy to use and it's easy to remove or add as needed at a latter date. You may find you have to play around with the quanities, to get it just right. I've always listened to the speakers for a good 100hrs before changing the stuffing, so your ears become use to the sound, that way if you want to add or remove stuffing, picking up the differences will be easier. Link to comment Share on other sites More sharing options...
blackfox Posted October 5, 2009 Author Share Posted October 5, 2009 i was thinking stuffing one and not the other for instant comparison? both woofers came out of another set of speakers i made so are already warmed in so would be a good rule to start from? i'll get the sheeting, even if in the end it doesn't help i can always use in other room tweeks i'm sure, never the less anyone have any scientific evidence of testing that would assistance this venture? Link to comment Share on other sites More sharing options...
Guest Posted October 5, 2009 Share Posted October 5, 2009 Black Hole 5 Link to comment Share on other sites More sharing options...
blackfox Posted October 6, 2009 Author Share Posted October 6, 2009 Black Hole 5 and that is? Link to comment Share on other sites More sharing options...
rob323 Posted October 6, 2009 Share Posted October 6, 2009 It is a really good panel dampening material, amongst other things. Do you want this stuffing to absorb reflections, or to dampen panels, or to increase enclosure volume? Link to comment Share on other sites More sharing options...
blackfox Posted October 6, 2009 Author Share Posted October 6, 2009 The speaker walls are 25mm mdf, I have bitchumen coated them, and they also have bracing, so wrapping your knuckles on the outside sounds like a hammer on a brick wall, Just want to Asborb reflections internally btw rob how are the elsinores treating you? I'm actually thinking of making a pair next, would two parasound HCA-1000 (400w rms monoblocked) be fine to power the pair? Link to comment Share on other sites More sharing options...
ENIGMA Posted October 6, 2009 Share Posted October 6, 2009 and that is? Proper speaker dampening material, google it and you will see. Beware, it is expensive. Link to comment Share on other sites More sharing options...
naggots Posted October 6, 2009 Share Posted October 6, 2009 To damp the panels you can use wavebar or soundpaint (pyrotek), you could also try melamine foam for high frequencies combined with wool or dacron. Link to comment Share on other sites More sharing options...
rob323 Posted October 6, 2009 Share Posted October 6, 2009 Just want to Asborb reflections internally As others have suggested, consensus is that long fibre wool or dacron with a high % of natural wool is preferred. btw rob how are the elsinores treating you? They hate me cause I still haven't finished them off.I'm actually thinking of making a pair next, would two parasound HCA-1000 (400w rms monoblocked) be fine to power the pair?That would be heaps, they have surprised me with what they can do on the end of an 18watt valve amp and the designer only uses valve amps. Link to comment Share on other sites More sharing options...
Jim Smith Posted October 12, 2009 Share Posted October 12, 2009 long fibre wool. Artificial materials may work reasonably well, but the OP said "best" in the title of this thread. So, without any consideration for cost, I'd agree on the long fibre wool. Best, Jim Smith Link to comment Share on other sites More sharing options...
Guest Posted October 14, 2009 Share Posted October 14, 2009 and that is? Sorry for the late reply http://www.orcadesign.com/products/blackhole/blackhole_five.htm Cheers Link to comment Share on other sites More sharing options...
gainphile Posted October 14, 2009 Share Posted October 14, 2009 To damp cabinet/structure resonance: Asphalt + Sand mixture. To damp standing waves: wool fibre. Link to comment Share on other sites More sharing options...
bensl Posted October 14, 2009 Share Posted October 14, 2009 i used this http://www.jaycar.com.au/productView.asp?ID=AX3694&CATID=&keywords=650gsm&SPECIAL=&form=KEYWORD&ProdCodeOnly=&Keyword1=&Keyword2=&pageNumber=&priceMin=&priceMax=&SUBCATID Link to comment Share on other sites More sharing options...
Guest Posted October 14, 2009 Share Posted October 14, 2009 To damp cabinet/structure resonance: Asphalt + Sand mixture. Water based or solvent based . Cheers Link to comment Share on other sites More sharing options...
Andrew Steel Posted October 15, 2009 Share Posted October 15, 2009 black fox where in qld are you? I have all of that stuff at work and you could try some .... Link to comment Share on other sites More sharing options...
greenmatt Posted October 22, 2009 Share Posted October 22, 2009 I would use a mix of grades of dacron/tontine. Acoustisorb 3 I have used in room treatment and is a good absorber. I would put a lighter grade in front of it for better HF absorbtion. This layering method obviously with a bit more control has been used where I work for anechoic linings. It is much cheaper than most custom speaker absorbers. http://www.spec-net.com.au/company/tontine/acoustic/index.htm Link to comment Share on other sites More sharing options...
planet10 Posted October 22, 2009 Share Posted October 22, 2009 We've started using this -- UltraTouch. We use the denser 1/2" for wall lining, and the les dense bat (3.5") for volume fill in addition to polyfluff. Trying to damp any panel with something that adds mass without stiffeness is not a good idea. It both lowers the resonant frequency of the panel and decreases its Q. This means that more energy is avialable to excite the resonance and that it becomes more audible. dave Link to comment Share on other sites More sharing options...
Andrew Steel Posted October 22, 2009 Share Posted October 22, 2009 I have no direct experience but think that Green Glue would be a great cabinet damper. You would need to build a box and then add another layer of material, MDF or whatever, with Green Glue in between. A bit of extra work but should be worth it. If someone in Brisbane wants to try it I'll donate a tube and make some measurements with an accelerometer afterwards as I am dying to know how it performs. C'mon, don't make me make a box just to test this :-) As for standing waves in side a cabinet and, if any exist they would be quite high frequency wouldn't they? I think the material inside the box is to make the conditions adiabatic rather than isothermal. The layering method works great on walls and should in principle do the same in a box, hut it would need to be very thin layers and takes a fair bit of working out to get right. I know on walls layers in the wrong proportions can be detrimental. Link to comment Share on other sites More sharing options...
planet10 Posted October 22, 2009 Share Posted October 22, 2009 I Green Glue. http://www.diyaudio.com/forums/multi-way/153419-constrained-layer-damping-mdf-ply.html dave Link to comment Share on other sites More sharing options...
rob323 Posted October 22, 2009 Share Posted October 22, 2009 Andrew, I reckon this is something a mate and I would be very interested in assisting with. We have even discussed buying a small accelerometer to do some testing with on the enclosures we are building at present cause at the moment, all we are going off is a lot of theory but being Engineers, we like to see empirical data too. If you are not in any great hurry I'm sure we could knock something up. I guess the next question is what? What driver? (Full ranger?, bass driver?) What frequency range are we looking to test? What enclosure type (I'm guessing sealed would the most problematic, not to mention it's the easiest to build)? Link to comment Share on other sites More sharing options...
Andrew Steel Posted October 25, 2009 Share Posted October 25, 2009 Hi Rob, I think it would be informative to test the broadest range possible. That being said, I don't know that HF is really going to matter, so maybe a decent mid/bass driver. I have the accellerometers and associated gear. We should make a GG box and a control. I think that a ported box would be just as bad but as you say, closed is so much simpler to make. Sounds like a Christmas project :-) Link to comment Share on other sites More sharing options...
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