Best dry sand for filling speaker cabs?

[rcavictim]

I am making some speaker cabinets that will use dry sand in an air gap between the cabinet walls. My last attempt to damp something audio with sand was way too much work. I bought 'play sand' at the building supply and discovered the stuff was soaking wet, Half a day's work later, a badly discolored frying pan and about $50.00 added to my electricity bill I had processed a 50 lb. bag of sand. Since I need a lot this time I am NOT prepared to do this again. I know that sandblasting (silica?) sand which is available to me locally comes dry as it won't work otherwise. It has very sharp edges though, not rounded like beach sand, Is the sandblasting sand going to cause me any problems that I am not aware of?

As sands go I know the dust from this particular one is kind'a nasty healthwise if inhaled. This won't be a problem once built as the cabinet spaces will be sealed.

Baking the sand myself assures sterilization. I am assuming I will not have a fungus or mold problem with dry silica sand from the bag. If you know otherwise please do tell. Should i be adding a anti-fungal powder or something? I wouldn't want my speakers to develop athlete's feet someday and run off with my best SET amp!

Jokes about how my speakers may have a sharp edge to the sound are anticipated. 😉

Thank you for any suggestions.

Rob

 

[Zaph]

I use Kitty litter. I'm serious. It's cheap, dry, heavy and clean.

It's even better when it's unused. Oh, sorry, back to being serious. It does serve the purpose nicely, and obviously there's no need to pay the extra money to get the clumping type. Depending on what kind you find, it's only about 50% as dense as sand, but in general it's still heavy enough and does a great job. Some types are heavier, almost gravel based. Possibly 75% the density of sand. See what you can find if interested.

 

[rcavictim]

Zaph,

That isn't a bad idea. I have two cats...doh!, so I am familiar with the properties of both the new as well as the used stuff. I only left a 5/8" thick gap for the sand though so I'd probably best stay with sand this time for maximum effect, besides...wouldn't want my cats using my speakers for you know what!

 

[wunhuanglo]

Hi

All sand is silica (silicon dioxide) so I don't know why blasting sand would be particularly noxious, except for the fact that it is very dry and therefore more likely to become airborne. It is in use that silica dust becomes a problem. The dust forms as the grit shatters during blasting creating dust clouds.

Typical blasting grit moisture specification is less than 0.5% by weight:

http://www.enviroabrasives.com/images/EA_PDS_Ceramic.pdf

It's also probably not very subject to hosting mold either. Molds thrive on moisture, not in a dry environment. Blasting sand is dry, I believe, because it's dried artificially, so the heat used ought to kill any mold spores that were present prior to processing.

You could always fill roasting pans or cookie sheets and bake it off in the oven for a couple of hours to make sure.

 

[454Casull]

What you can do is build two enclosures, one inside the other, with the "front" baffles of each secured to each other so that the front is like a double-thickness baffle (the bottoms can be glued together also). Then you can pour kitty litter or liquid bitumen or even something like this:

http://www.latexite.com/pr-aptgrade.html

in between the walls.

 

[Overd0se]

The silica sand should work just fine. You might consider mortar sand as well. I think it is denser than silica, not sure though. It should be available from home depot, lowes , etc.

 

[rcavictim]

Thank you all who gave your opinions and helpful information.

Man, double walled cabinets are a lot more work!

 

[Dr. ODD]

HI
I used Sand they sold for the Roof of Bird Cages. It worked good for me.😎 😎 😎

 

[rcavictim]

HI
I used Sand they sold for the Roof of Bird Cages. It worked good for me.😎 😎 😎

You studied all your options and took the one that was ....cheep...cheep....cheep.

😀

 

[Bas Horneman]

bought 'play sand' at the building supply and discovered the stuff was soaking wet, Half a day's work later, a badly discolored frying pan and about $50.00 added to my electricity bill I had processed a 50 lb. bag of sand. Since I need a lot this time I am NOT prepared to do this again.

LOL..you have even less patience than I have..I will use play sand. Should be no problem if left to dry in the sun...??? The sun is a much cheaper source of heat!

Cheers,
Bas

 

[urapnes]

fill them with cement

 

[rcavictim]

fill them with cement

I doubt the MDF would survive the exposure to water without serious impairment. Cement while attractive in adding density is prone to physical resonance as are other materials. it would merely lower the resonant frequency of the cabinet wall. Sand actually converts mechanical vibration into heat, thus damping cabinet vibration. Cement does not do this.

I would certainly consider casting a speaker cabinet in cement but the wooden (or whatever) form would be removed once the cement cured.

 

[Ed LaFontaine]

bead-blasting shot

What about steel (or iron) beads used for shot-blasting concrete floors prior to epoxy coating? Is a ferrous material a problem? You would have a heavier balast.

In order to avoid the drying you found necessary with play sand, look around for a new or recently delivered load of it. It is not bagged wet and only becomes that way after being in the rain.

 

[audiofan]

I would keep away from steel grit an others stell stuff, there will be steel dust and it will find a way to speaker magnet an gap.......
I would dry sand in the oven at moderate temperature keeping the door craked open wit a wodden block to let the water escape.

 

[urapnes]

what about simply filling them with cement powder. Dont mix the cement with water, just dump it dry right into the voids.

 

[Overd0se]

what about simply filling them with cement powder. Dont mix the cement with water, just dump it dry right into the voids.

I don't think that would have any advantage over just sand, as cement is mortar sand, gravel, lime, and other additives to aid the reaction. The large percentage of gravel in the mix is probably undesireable as well. The kitty litter idea is probably the easiest/least messy. I would either go with that or dry mortar or silica sand. Also, play sand is usually dry if you buy from a fresh shipment. It gets wet when its stored outside as mentioned earlier in this thread.

 

[tiroth]

Kitty litter is designed to absorb moisture, unlike common sand which is supposedly not terribly hygroscopic. From what I've read "kitty litter" is either composed of or has large amounts of silica gel in it. This would make me leery of using it for this purpose, if the fear is moisture content.

Silica gel is form of silicon dioxide, SiO2, the material that occurs in nature as sand. The difference between silica gel and sand is that sand is a crystalline, non-porous form, whereas silica gel is non-crystalline and highly porous.

http://www.dcchem.co.kr/english/product/p_basic/p_basic07.htm

EDIT: I did a little more digging and most conventional (non-clumping) litters may also be composed of large amounts of clay, which is also quite hygroscopic.

 

[planet10]

LOL..you have even less patience than I have..I will use play sand. Should be no problem if left to dry in the sun...??? The sun is a much cheaper source of heat!

I had potting sand on hand, so i used it. Put it on a plastic sheet out in the sun, on a hot dry day, and let it get real hot, kept sweeping it around. (obviously this only works in climates where it gets hot & dry).

dave

 

[Overd0se]

I had potting sand on hand, so i used it. Put it on a plastic sheet out in the sun, on a hot dry day, and let it get real hot, kept sweeping it around. (obviously this only works in climates where it gets hot & dry).

Thats a good idea. Last time I had to dry some sand for sand blasting I got impatient and used a metal pan and a propane torch 😱

 

[jewilson]

Maybe you can use some old lead fishing weights or one heck of alot of be bee of is it bb's.