I've never heard of marble (or any rock) having good damping properties. Again, any enclosure made of a single material is not going to be optimum. By constructing a light/rigid enclosure and utilizing constrained layers you can achieve fantastic damping and therefore a 'high performance' speaker enclosure.
Constrained layers contain a centre layer of viscoelatic type material that shears when flexing occurs in either of the surrounding layers. This shearing action is very effective at generating heat, which is what you need to do. A slab of MDF, Concrete, Marble, Plywood is NOT effective at generating heat from vibration, and is therefore not well damped.
Constrained layers can be very thin by simply gluing two materials together, but there are is always an optimum. An enclosure within an enclosure can work fantastic as well, as you are reducing the efficiency of vibration transmission from the inner box to the outer one. Filling that gap with sand may or may not improve things. A vacuum would probably be the best thing to use. This type of construction is tricky as well, and can end up being bulky and heavy. Each system has some trade-off.
Constrained layers contain a centre layer of viscoelatic type material that shears when flexing occurs in either of the surrounding layers. This shearing action is very effective at generating heat, which is what you need to do. A slab of MDF, Concrete, Marble, Plywood is NOT effective at generating heat from vibration, and is therefore not well damped.
Constrained layers can be very thin by simply gluing two materials together, but there are is always an optimum. An enclosure within an enclosure can work fantastic as well, as you are reducing the efficiency of vibration transmission from the inner box to the outer one. Filling that gap with sand may or may not improve things. A vacuum would probably be the best thing to use. This type of construction is tricky as well, and can end up being bulky and heavy. Each system has some trade-off.
Quite right, MartinQ, mable and granite are not very good damping material per say which is why I use it on the outside because of it's one good quality, dissapating the heat generated in the tar layer. If you see my my post you'll notice I use a rigid inner cabinet with a gap filled with sand that dampens almost all mid-bass to midrange frequencies. The remaining low frequencies are dampened by the tar/granite sandwich. Oh yeah and high frequencies are dampened inside the cabinet by having varying densites and/or dampening materials used.
Ahh.. it's all clear now. Thanks, and good effort on that box!
I guess for the ultimate outer layer you could use black annodized aluminum heatsink extrusion! The ribs could contribute to rigidity, and would be one of the best heat dissipators you could use, not that there is any noticable heat.
I guess for the ultimate outer layer you could use black annodized aluminum heatsink extrusion! The ribs could contribute to rigidity, and would be one of the best heat dissipators you could use, not that there is any noticable heat.
marble and other rock'n'roll
nice discuss.
let's considering the fact's only. damping factor (DF) I mean is reaction of material for outside mechanical (acoustical) force. this is sound pressure. moreover we talking about subwoofer, low end range, less than 120 hz, plunger mode till 80 Hz will be better.
so, like I knew in the university, in particular a marble has an ideal DF. response to sound pressure within bass range is optimal. marble cubical box isn't emissive any, exept effective, original sound. his durability allow us do not use additional facility of rigidity. marble sub have not chanse to mutter. it's ok.
next thing is composit layers. I wouldn't make sandwinch. it's realy difficult and it's not necessary. anyway we have to place any smooth materil inside. paste it over with glue.
apropos, I used special epoxide resin for marble. it's absolutely effectively connected panels, thick 25mm.
satelites, I'll make another way. marble front panel and wooden others.
nice discuss.
let's considering the fact's only. damping factor (DF) I mean is reaction of material for outside mechanical (acoustical) force. this is sound pressure. moreover we talking about subwoofer, low end range, less than 120 hz, plunger mode till 80 Hz will be better.
so, like I knew in the university, in particular a marble has an ideal DF. response to sound pressure within bass range is optimal. marble cubical box isn't emissive any, exept effective, original sound. his durability allow us do not use additional facility of rigidity. marble sub have not chanse to mutter. it's ok.
next thing is composit layers. I wouldn't make sandwinch. it's realy difficult and it's not necessary. anyway we have to place any smooth materil inside. paste it over with glue.
apropos, I used special epoxide resin for marble. it's absolutely effectively connected panels, thick 25mm.
satelites, I'll make another way. marble front panel and wooden others.
Attachments
Cloth Ears said:
not exactly Cloth. but thank's for opinion.
my Alto has 32 litres only. and it force me to make port 75mm length 250 mm. it means frequency of port is about 40 Hz as well.
new model of Alto has exponential port and I'll tune it to 16 Hz.
remember mi, E string of bass gitar has fr about 11 Hz. how does we hear it?
pity. will work about it, but I couldn't make sub bigger, then grand piano.it's Kostya, my son
I'm within Taiwan business trip
kiding. but Taiwan a realy excellent country. lot of business people, but they don't make DIY and don't interesting of audio also. probably they very busy....
about temperature inside sub. of course it's active. original amp, used MOSFET made my partner Samod (200153104 ICQ UIN)
you can find him in the suitable DIY forum. it's perfect amp's. now he work about amp, without feedback. it will be the best. I hope you know why.
so, his amplifire has cooling, from port blast. it's realy enough.
kiding. but Taiwan a realy excellent country. lot of business people, but they don't make DIY and don't interesting of audio also. probably they very busy....
about temperature inside sub. of course it's active. original amp, used MOSFET made my partner Samod (200153104 ICQ UIN)
you can find him in the suitable DIY forum. it's perfect amp's. now he work about amp, without feedback. it will be the best. I hope you know why.
so, his amplifire has cooling, from port blast. it's realy enough.
In my experience it's best to avoid any issues with cabinet materials - all you have to do is eliminate the cabinets.
http://wun.smellthecolors.com/currentopenbaffle.htm
http://wun.smellthecolors.com/currentopenbaffle.htm
I'm very impressed by some of the construction ideas and photos.
For a completely closed box, sand and that sounds like a good plan. It sounds extremely complicated though. I bet that the ruffer the surfaces of the marble, the better the heat conduction is. And probably the price.
Is it better to use soundproofing foams and acrylic wool than layers of sand and tar? the heat transfer of the air and marble combined with the springiness of sound proofing materials should be ample. Certainly easier.
The best way to make marble even more conductive, which should be fairly easy to do, is to drill holes in it and knock in rivets of aluminium. Or melt it in.
For a completely closed box, sand and that sounds like a good plan. It sounds extremely complicated though. I bet that the ruffer the surfaces of the marble, the better the heat conduction is. And probably the price.
Is it better to use soundproofing foams and acrylic wool than layers of sand and tar? the heat transfer of the air and marble combined with the springiness of sound proofing materials should be ample. Certainly easier.
The best way to make marble even more conductive, which should be fairly easy to do, is to drill holes in it and knock in rivets of aluminium. Or melt it in.
For subwoofers, damping is not very important. In the bottom octaves you are mostly concerned with stiffness. The stiffness will raise the panel resonance out of the operating range quite easily and effectively. The more limited the sub range, (and if the sub is separate from the main/satellite) the easier it is to deal with.
Proper damping is critical within the range that the human ear is most sensitive and that's around 300 - 5000Hz (give or take), and that's primarily the midrange. Most cabinet resonances will live in this range too, as high up as 10000Hz for a rigid cabinet.
The combination of high frequency resonance which is within the range of hearing sensitivity is a bad mix. This is where damping is most important.
Open baffles are a sure way to help deal with the rear wave and pressures within the cabinet, but they do not address the mechanical transmission of vibration from the driver chassis. Also, open baffles are often less rigid than a full enclosure due to the lack of walls which act as braces. This can all be overcome if you know what to look for.
Each system has it's own strength and weakness.
An excellent page that deals with the construction of a complete sound system:
http://www.silcom.com/~aludwig/contents.htm
Specifically, the Music Room:
http://www.silcom.com/~aludwig/My_Music_Room.htm
... and the Loudspeaker Construction:
http://www.silcom.com/~aludwig/Loudspeaker_construction.html
Proper damping is critical within the range that the human ear is most sensitive and that's around 300 - 5000Hz (give or take), and that's primarily the midrange. Most cabinet resonances will live in this range too, as high up as 10000Hz for a rigid cabinet.
The combination of high frequency resonance which is within the range of hearing sensitivity is a bad mix. This is where damping is most important.
Open baffles are a sure way to help deal with the rear wave and pressures within the cabinet, but they do not address the mechanical transmission of vibration from the driver chassis. Also, open baffles are often less rigid than a full enclosure due to the lack of walls which act as braces. This can all be overcome if you know what to look for.
Each system has it's own strength and weakness.
An excellent page that deals with the construction of a complete sound system:
http://www.silcom.com/~aludwig/contents.htm
Specifically, the Music Room:
http://www.silcom.com/~aludwig/My_Music_Room.htm
... and the Loudspeaker Construction:
http://www.silcom.com/~aludwig/Loudspeaker_construction.html
see the difference
see the difference - marble and other stown. granite - work using rock hammer drill, but marble - using simple drill.
I've used not any marble. she best - is Carara. optimal thickness, compactness, solidity. generous view. easy to work. nice get on glue.
lot of colors, not expensive.
http://www.artmaydan.org.ua/sub4.html
see the difference - marble and other stown. granite - work using rock hammer drill, but marble - using simple drill.
I've used not any marble. she best - is Carara. optimal thickness, compactness, solidity. generous view. easy to work. nice get on glue.
lot of colors, not expensive.
http://www.artmaydan.org.ua/sub4.html
Three quick thoughts.
Foamed metal panels. I don't know the costs, but rigid and light and energy absorbant.
Scotchbrite scrubbing pads soaked in melted plasticine clay (the kind that never dries) as interior coating or constrained layer.
Silicone rubber 'noodles' as an interior coating or constrained layer.
A couple or more tubes of goo, a caulking gun, squirt onto a bed of talcum powder, let set.
No graphs or charts or experience, just my brain noodling about.
Foamed metal panels. I don't know the costs, but rigid and light and energy absorbant.
Scotchbrite scrubbing pads soaked in melted plasticine clay (the kind that never dries) as interior coating or constrained layer.
Silicone rubber 'noodles' as an interior coating or constrained layer.
A couple or more tubes of goo, a caulking gun, squirt onto a bed of talcum powder, let set.
No graphs or charts or experience, just my brain noodling about.
http://www.mission-usa.com/index1.htm
mission being made Pilastro using Granitech. why not marble?
couse it's expensive. I don't know, but Pilastro has price about $40000.
mission being made Pilastro using Granitech. why not marble?
couse it's expensive. I don't know, but Pilastro has price about $40000.
VvvvvV said:
I don't have access to it anymore since I don't study at the university anymore. But all my test where done with a mirror attached to the surface and then a laser reading the distance to that for extreme accurate measurements.
I did a huge amount of test and the best that is feasible for DIY'er is the above described.
You can use foam instead of sand but it's actually better to leave it filled with air (or a vacuum) if you're not going to use the sand. Either way (except for the vacuum one off course) you'll get a moderately worse result.
I suggest you do not leave out the tar as that is the reactive component of the sandwich described and it doesn't work without it or another kind of non-setting glue, but I found tar to be the best.
The sandwich works when it has a layer of vicious material (in this case the tar) between two layers of high mass, one being extremely rigid (the marble or granite, the later is better) and the other being (at least somewhat) flexible (in this case the HDF).
The absolute best results I had was when I used a 6 mm (1/4") copper plate instead of the HDF. But that is certainly out of reach for most DIY'ers to even consider when making a whole speaker.
Btw, I didn't even study engineering of any kind, I studied english but I hung around the lab a lot.
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