Hello! Long time lurker, first time poster (and recent registration).
Are there any sound dampening materials that I can use to fill a void in a cabinet design that have the same properties as sand WITHOUT the mass?
I understand cat litter is a good alternative (and that's easy to acquire).
I do understand that sand is quite good, especially when dry (and that is also free for me as I live near a beach with a very long distance of sand-to-shore) and plenty of sun... plus I can also access some sand dunes for ultra-fine sand.
My issue, really, is with the mass of these two materials. Given that the enclosure by itself will already be fairly hefty, adding sand in the voids is calculating to be roughly 13kg mass addition to each. This would be fine if I did not have intentions on moving these cabinets to/from some venues and locations, some of which are only accessible by stairs (or in one case, a short mountainous trail).
Are there any sound dampening materials that can fill the voids of an enclosure, similar in properties to sand or litter, but without the mass?
Thank you.
Are there any sound dampening materials that I can use to fill a void in a cabinet design that have the same properties as sand WITHOUT the mass?
I understand cat litter is a good alternative (and that's easy to acquire).
I do understand that sand is quite good, especially when dry (and that is also free for me as I live near a beach with a very long distance of sand-to-shore) and plenty of sun... plus I can also access some sand dunes for ultra-fine sand.
My issue, really, is with the mass of these two materials. Given that the enclosure by itself will already be fairly hefty, adding sand in the voids is calculating to be roughly 13kg mass addition to each. This would be fine if I did not have intentions on moving these cabinets to/from some venues and locations, some of which are only accessible by stairs (or in one case, a short mountainous trail).
Are there any sound dampening materials that can fill the voids of an enclosure, similar in properties to sand or litter, but without the mass?
Thank you.
You might want to consider spray expanding foam. The stuff used to fill voids around windows and the like. It is relatively cheap and comes in several expansion/density types, and is light. I don't know how it compares to sand, sound wise, but it sure deadens sound in the applications that I've used it in.
Hi first time poster!
Sounds like a good suggestion from PJN. I was going to suggest sawdust, although this is mainly used in the manufacture of sound absorbing panels.
The purpose of a sound dampening material is to reduce the amplitudes of resonant vibrations that generate airborne sound and this is best achieved by using a viscoelastic material with a relatively high internal loss.
How big is this 'void' that you have to fill?
Sounds like a good suggestion from PJN. I was going to suggest sawdust, although this is mainly used in the manufacture of sound absorbing panels.
The purpose of a sound dampening material is to reduce the amplitudes of resonant vibrations that generate airborne sound and this is best achieved by using a viscoelastic material with a relatively high internal loss.
How big is this 'void' that you have to fill?
Not really since it's the mass that does the damping, with doubling its weight normally being sufficient. That said, kitty litter/oil dry is my preferred compromise, being good enough to damp horn cavities, while others prefer expanding foam, but beware! Not installed properly can literally blow a cab apart unless it's well braced, fairly rigid/massive to start with.
Another option I used a lot was added mass loading, i.e. placing a removable weight on top that covers at least ~70% of its area, such as heavy plants, concrete slabs/pavers, marble, etc., use your imagination [on an early DIY forum a professional engineer had his doubts, but stacking an armful of vinyl LP albums atop his DIY Voigt Pipes proved the tweak to his satisfaction] or SWMBO's decorative choice; and for safety's sake, attach with industrial Velcro. Again, beware! Experiment a little as IME it's easy to wind up not being strong enough to pull it apart or [ badly] damage one or both of the objects being connected if long/continuous runs are used.
GM
Guess that rules out sitting an aspidistra on top, even though it's also known as the cast iron plant!
Attachments
If you use spray foam, use the stuff that they sell for insulating windows and doors that doesn't expand much.
If you use regular expanding foam, you run the risk that GM mentioned of blowing the cabinet apart.
I've seen the results of using the wrong type of foam on replacement window installations, and it's not pretty.
If you use regular expanding foam, you run the risk that GM mentioned of blowing the cabinet apart.
I've seen the results of using the wrong type of foam on replacement window installations, and it's not pretty.
Interesting - so if I were to source a 'rubber' that can be poured in, that may be a possibility? Rubber Mulch or Granules come to mind. It would be less mass than sand, and even if not fully packed in there would be no resulting vibrations
The voids a similar to those in a Dallas II enclosure.
I have an educational&training background in Architecture, plus I do woodworking - so I’m a making the joints quite solid with some joinery techniques. I'll take a look at my foam options too. That, obviously, could be the lightest option! I may be able to source some melamine foam and just cut it to shape, insert it, and be really precise.
Thanks for the input!
A liquid rubber roof seal may be just the job. Don't know whether it would be cost effective compared to foam though.
This is a top candidate looking at what's available over here in the UK:
https://www.amazon.co.uk/dp/B00180GV4U/ref=psdc_7138592031_t3_B003KA00VQ
I’ve used roof cement mixed with beanbag styrofoam beads (they tiny ones, about 1/8” diameter) to excellent damping effect for coating the inside walls of speakers. Just trowel it on. The beads serve 2 purposes: they add lightness to the otherwise heavy roof cement and allow you to use less material; they also make the roof cement very bumpy and the uneven surface makes parallel walls less parallel.
Hmm, this reminds me, totally forgotten that tires are ground up and used as 'fill' + improving traction in asphalt road construction, though wasn't aware of rubber mulch being used in landscaping, etc., but a quick search says it's ~26 lbs/ft^3 Vs kitty litter's 50 lbs, so maybe the best choice overall and if not enough, then add the removable top mass loader.
GM
The answer to this question is: YES.
The substance is called "glass microspheres".
Glass microspheres are like miniature glass "bubbles". It appears macroscopically as a powder that you can pour. But each particle is hollow and made of glass. They are used IIRC for modifying cement or for use as part of fiberglass resins to change the thickness.
You can find them in the US at Tap Plastics, for instance:
TAP Microspheres • Glass Spheres : TAP Plastics
label closeup:
https://www.tapplastics.com/uploads/miscs/TAP_Microspheres-4oz.pdf
One reference cited the density as 0.6g/cm^3 (water is 1g/cm^3). The density of dry sand is 1.6g/cm^3, so the microspheres are less than half the density. Sand is a lot cheaper, though!
Hmm, are these the same glass beads used in bead Vs sand blasting to clean parts? If so, they are similar, but don't see how they can have the same properties as sand.
GM
That was my first thought, too Charlie.
GM, microspheres are hollow and lightweight, not for sandblasting. You should wear a mask or respirator to be sure you don't breath them.
Often used in hobby work where the weight of glue can be significant- planes, rockets, etc. Mix in hollow spheres and you can still use a good-sized fillet to retain strength with significantly less weight. As Charlie mentioned, you modify viscosity as well.
Guess I need to look up what type glass beads we used to 'sand blast' clean soft materials in a specially made cabinet that didn't require protection, though have full face respirator for installing different filters for various chemicals including sand blasting in the back yard.
Interesting! Built mass quantities of plastic, wood, models until got serious about slot car racing, audio, but don't remember any glues being heavy, though if one used a lot of dope for tissue replicas or rubber band powered, so is this what you mean? I mostly did U-control combat, so would have been a waste if it had been available.
Regardless, will lightweight glass 'powder' make a good cavity damper? Seems like it would have a fairly high resonance unless mixed with a really low material.
GM
Interesting! Built mass quantities of plastic, wood, models until got serious about slot car racing, audio, but don't remember any glues being heavy, though if one used a lot of dope for tissue replicas or rubber band powered, so is this what you mean? I mostly did U-control combat, so would have been a waste if it had been available.
Regardless, will lightweight glass 'powder' make a good cavity damper? Seems like it would have a fairly high resonance unless mixed with a really low material.
GM
GM, I agree about the utility of a lightweight powder for this application.
FWIW- in rocketry, epoxies were the glue of choice for most.
For those competing in contests like flight duration- low weight, minimum diameter, and a low-thrust long-burn motor were usually the winning combo. I was never the expert in those contests, but you'd want good reinforcing fillets to avoid fin flutter or worse. I think most common folks used them (aka microballoons) to add bulk to a glue joint without adding significant weight. 6 fillets per fin is typical for a slot mounted fin, so that's 24 fillets on a 4-fin model.
FWIW- in rocketry, epoxies were the glue of choice for most.
For those competing in contests like flight duration- low weight, minimum diameter, and a low-thrust long-burn motor were usually the winning combo. I was never the expert in those contests, but you'd want good reinforcing fillets to avoid fin flutter or worse. I think most common folks used them (aka microballoons) to add bulk to a glue joint without adding significant weight. 6 fillets per fin is typical for a slot mounted fin, so that's 24 fillets on a 4-fin model.
I'm going to try out the glass microspheres option and see how it goes. It might also be interesting to have the glass microspheres along with some rubber chips/mulch, which would then act as vibration absorption bits.
Amazon has it at large quantities for considerably less price than the first link.
Right now I'm just optimizing the joints of the cabinet so I don't have to use glue... and that might take a while given this is just a side project!
I was thinking this morning about glue and wood. Does glue affect the sound? What about the directions of the fibers? What would be better:
-A solid wood cabinet, CNC milled out.
-A solid wood cabinet composed of planks with intentional fiber directions
-A cabinet made from 18mm birch ply (in this case, every layer of veneer is 90° from the other, with glue in between)
-A cabinet made from OSB or underlayment where the fiber directions are 'random' and short, but quite solid with the amount of glue holding it all together
These are things I keep wondering about, then it brings me to the joinery: how can I minimize the need for metal in the enclosure as much as possible. I can figure out methods to bind all but one side together without metal, but the last panel (side) which needs to be operable in order to replace a driver, wiring, or adjust dampening... getting that side to be tight and strong to structure without screws is an interesting problem to solve.
Amazon has it at large quantities for considerably less price than the first link.
Right now I'm just optimizing the joints of the cabinet so I don't have to use glue... and that might take a while given this is just a side project!
I was thinking this morning about glue and wood. Does glue affect the sound? What about the directions of the fibers? What would be better:
-A solid wood cabinet, CNC milled out.
-A solid wood cabinet composed of planks with intentional fiber directions
-A cabinet made from 18mm birch ply (in this case, every layer of veneer is 90° from the other, with glue in between)
-A cabinet made from OSB or underlayment where the fiber directions are 'random' and short, but quite solid with the amount of glue holding it all together
These are things I keep wondering about, then it brings me to the joinery: how can I minimize the need for metal in the enclosure as much as possible. I can figure out methods to bind all but one side together without metal, but the last panel (side) which needs to be operable in order to replace a driver, wiring, or adjust dampening... getting that side to be tight and strong to structure without screws is an interesting problem to solve.
Nice idea, but they absorb moisture readily. (I use occasionally for reptile terrarium 'wet room')
Glass micro spheres is exactly what I'd have suggested, but will they resonate?
Would that matter if they were mixed in a liquid latex honeycomb?
Polystyrene packing balls is a really good idea though, and probably the cheapest additive
Or....thinking off a tangent some....
Would a thixotropic filler be something worth trying?
(I'm dying to find a way to try it besides filling cavities with Custard)
Constrained layer damping (such as you get when you fill your baffle with sand) can't be replicated when you use damping that is merely elastic, rather than visco-elastic. A visco-elastic substance re-arranges it's structure in relation to stress, shedding energy in the form of heat (just like loose sand would). They are characterized by permanent deformation or hysteresis, even at low amounts of stress.
Glass microballons would be one extreme. They might be a bit too light, certainly no mass damping would occur.
Glass microballons would be one extreme. They might be a bit too light, certainly no mass damping would occur.
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