I found this threadwater about water methods but it is not really helpfull. I now it is not a common concept but I want to give it a try. I have an idea of what I want. Logically it would be a 4th order bandpass sub with the closed section of it filled with water. The magnet would face the port in a big Pvc tube. I still need inputs on tuning and other basic things to know about water and sound. I would use a 6'' driver so a big tube may be hard to find, any idea? I did many tests on cone resistance and it seems that ''plastic'' cones doesn't react to water and moisture. any comment would be apreciated.
(first, I love the profile pic... domo-kun is my favorite 
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I've often wondered about the same thing. I think, however, that getting a suspension that was both waterproof and allowed the cone to move more than .5mm, would be a stretch. I suspect the final solution would be to throw a rave in an olympic-sized pool, and one side of the pool is a wall of woofers... the chamber of the woofers would probably have to be pressurized.
This cold present problems, though. If people get nasty in the water, you have all kinds of liability issues with STDs and the like.
Another alternative would be to hold the party in a pressurized room, just a few atmospheres. This gives the problem that if, for some reason, you need to get out in a hurry, you have to wait patiently for the room to get to normal pressure, or risk getting the bends.
In the end, if you're looking to increase efficiency, look into horn-loading. There's a page out there (can't be bothered to find it--google?) with a floor-horn cast in concrete that gets 110 dB efficiency (that's efficiency, not max SPL) at 10hz... and, IIRC, it's not even that big of a room, I think that would probably be big enough for your needs.
If you can come up with a driver that's waterproof though, I would love to try it...
)I've often wondered about the same thing. I think, however, that getting a suspension that was both waterproof and allowed the cone to move more than .5mm, would be a stretch. I suspect the final solution would be to throw a rave in an olympic-sized pool, and one side of the pool is a wall of woofers... the chamber of the woofers would probably have to be pressurized.
This cold present problems, though. If people get nasty in the water, you have all kinds of liability issues with STDs and the like.
Another alternative would be to hold the party in a pressurized room, just a few atmospheres. This gives the problem that if, for some reason, you need to get out in a hurry, you have to wait patiently for the room to get to normal pressure, or risk getting the bends.
In the end, if you're looking to increase efficiency, look into horn-loading. There's a page out there (can't be bothered to find it--google?) with a floor-horn cast in concrete that gets 110 dB efficiency (that's efficiency, not max SPL) at 10hz... and, IIRC, it's not even that big of a room, I think that would probably be big enough for your needs.
If you can come up with a driver that's waterproof though, I would love to try it...
Having the magnet face the side with away from the water chamber is a good idea.
You really don't need a waterproof suspension.
I have two suggestions.
A) Take a big sheet of Saran or vinyl sheeting-much larger than the cone area-and glue it over the cone. Don't glue it over the surround, just cover the surround-the water pressure will hold it tight-and glue the remainder of the vinyl sheet to the board that separates the two chambers. This will waterproof everything.
Saran wrap is vinyl. Why vinyl? Because it has all the waterproof capabilities of the usual plastic sheeting-plus many, many glues stick to it very well. The usual plastic wrap or sheeting-polyethylene-virtually nothing sticks to very well. Several glue companies have told me this.
For any hobby project where you think of plasic sheeting, think Saran or vinyl sheeting instead. It reallly is important. Vinyl sheeting is easily and cheaply available in several thicknesses from hardware stores, where it is used as dropcloth material. Also "Everything for A Dollar" type stores carry vinyl shower curtains cheaply.
B) Don't bother covering the speaker at all-just put the water in a waterproof bag and put it in the closed chamber. The bag itself will prevent the water from spilling-not the speaker. The pressure of the water against the speaker will guarantee 100% contact between the speaker's cone and the water bag.
Will condensation have water form on the inside of the speaker cone and magnetic structure and eventually cause rust? I don't know. Maybe yes, maybe no.
Let us know how you make out.
You really don't need a waterproof suspension.
I have two suggestions.
A) Take a big sheet of Saran or vinyl sheeting-much larger than the cone area-and glue it over the cone. Don't glue it over the surround, just cover the surround-the water pressure will hold it tight-and glue the remainder of the vinyl sheet to the board that separates the two chambers. This will waterproof everything.
Saran wrap is vinyl. Why vinyl? Because it has all the waterproof capabilities of the usual plastic sheeting-plus many, many glues stick to it very well. The usual plastic wrap or sheeting-polyethylene-virtually nothing sticks to very well. Several glue companies have told me this.
For any hobby project where you think of plasic sheeting, think Saran or vinyl sheeting instead. It reallly is important. Vinyl sheeting is easily and cheaply available in several thicknesses from hardware stores, where it is used as dropcloth material. Also "Everything for A Dollar" type stores carry vinyl shower curtains cheaply.
B) Don't bother covering the speaker at all-just put the water in a waterproof bag and put it in the closed chamber. The bag itself will prevent the water from spilling-not the speaker. The pressure of the water against the speaker will guarantee 100% contact between the speaker's cone and the water bag.
Will condensation have water form on the inside of the speaker cone and magnetic structure and eventually cause rust? I don't know. Maybe yes, maybe no.
Let us know how you make out.
Third suggestion.
Buy a tube the speaker just fits in. If unavailable, buy a slighly gigger tube and cut a circle from wood that creates a tight seal. then cut an opeining in the cicle and mount your speaker to that.
Fill a balloon with water and make sure it is tightly sealed. Baloons are made from lates, I believe, and many glues stick to latex if you want to glue the balloon shut.
Then put that wooden piece on which you have mounted your speaker, stick it in the pipe until it makes full contact with the baloon, put the cap on the pipe which contains a hole with a tuned port, and there you go.
Buy a tube the speaker just fits in. If unavailable, buy a slighly gigger tube and cut a circle from wood that creates a tight seal. then cut an opeining in the cicle and mount your speaker to that.
Fill a balloon with water and make sure it is tightly sealed. Baloons are made from lates, I believe, and many glues stick to latex if you want to glue the balloon shut.
Then put that wooden piece on which you have mounted your speaker, stick it in the pipe until it makes full contact with the baloon, put the cap on the pipe which contains a hole with a tuned port, and there you go.
Water is simply not compressible enough to build a sub like that !
A water-filled balloon that is only taking up a part of the space would have some effect thogh, depending upon placement. If it fits tightly into the tube's diameter and placed closely to the driver, it will increase the driver's moving mass. I do not see the advantage over attaching a solid weight to the driver however.
Because the balloon also represents a compliance it will show a resonant behaviour with a very low resonant frequency.
Maybe that would be usable trick: A passive radiator constructed as some water filled bubble !?
Regards
Charles
A water-filled balloon that is only taking up a part of the space would have some effect thogh, depending upon placement. If it fits tightly into the tube's diameter and placed closely to the driver, it will increase the driver's moving mass. I do not see the advantage over attaching a solid weight to the driver however.
Because the balloon also represents a compliance it will show a resonant behaviour with a very low resonant frequency.
Maybe that would be usable trick: A passive radiator constructed as some water filled bubble !?
Regards
Charles
Hydrolastic suspension components with your name on them??
http://austin1800.homestead.com/Page16.html
I had one many years ago. They work. On the car, that is.
Maybe some of these old suspension thingies could be used for a super-duty high-order LF system?phase_accurate said:
http://austin1800.homestead.com/Page16.html
I had one many years ago. They work. On the car, that is.
I think that there are better ways. Im not quite sure how the water would help as in effect its harder to move than air. A ballon with a gas with different properties from air might work. Whilst i was reading around this subject i came across what looks to be the solution.
http://www.kef.com/technology/acoustic/acoustic.html
It works by the activated carbon being able to adsorb (not absorb) some molecules from the air when the cone moves backwards and releases them when it moves forwards. This gives an effective increase in compliance and hence a better performance from the same size enclosure. Ive looked at the patents and the carbon needs to be treated really to prevent water absorption - but activated carbon isnt too hard to come by and if kept dry enough might be ok to use. I was considering building some speakers using this and a few other tweaks and seeing what i come up with.
http://www.kef.com/technology/acoustic/acoustic.html
It works by the activated carbon being able to adsorb (not absorb) some molecules from the air when the cone moves backwards and releases them when it moves forwards. This gives an effective increase in compliance and hence a better performance from the same size enclosure. Ive looked at the patents and the carbon needs to be treated really to prevent water absorption - but activated carbon isnt too hard to come by and if kept dry enough might be ok to use. I was considering building some speakers using this and a few other tweaks and seeing what i come up with.
If I remember correctly, it was Cerwin Vega who had a speaker containing a gas filled bag. The gas was more easily compressed than air and made the enclosure seem larger than it was. Don't remember the gas.
I've read this entire thread and can't seem to find anything relating to the purpose of a water enclosure except some vague reference to and increase in effeciency.
Could someone clear this up for me?
I've read this entire thread and can't seem to find anything relating to the purpose of a water enclosure except some vague reference to and increase in effeciency.
Could someone clear this up for me?
I don't see any possibility either than lowering the resonance of the driver by adding mass.
But that won't have any advantages over adding mass directly. And I don't see how it should be possible to increase efficiency this way.
Furthermore you can't accelerate water as much as you like. While there won't be much problems "pushing" it - "pulling" might cause cavitation.
Regards
Charles
But that won't have any advantages over adding mass directly. And I don't see how it should be possible to increase efficiency this way.
Furthermore you can't accelerate water as much as you like. While there won't be much problems "pushing" it - "pulling" might cause cavitation.
Regards
Charles
The reason for a speaker's inefficiency is the impedance mismatch between air and the driver. The air has a very low Z, and the driver has a very high Z. (The speaker can act on the air with ease; the air can act on the speaker if wind gets up to hurricane speed.) Thus, the speaker moves back and forth large amounts and gets very little in return.
The idea is that the water could act as an impedance transformer. The area with which the driver interacts with the water could be small (15" woofer as an example) and the water could, in turn, act on a very large area of air.
I don't know that the water-air mismatch would be any better, but you might gain some improvement becuase the water would more easily be expanded to huge surface areas. (Imagine the surface area of a swimming pool moving up and down just 1mm--that's A LOT of displacement!)
The fact is, this is a huge can of worms, and a much easier solution is to just horn-load everything. Horn-loading causes the woofer to act on a much larger area of air, which brings the impedances closer to each other and increases efficiency.
For a permanent installation, a water-loaded sub (BTW, having a horn underwater is nearly useless, because the impedance mismatch is so much smaller) might be a useful and interesting way to increase output, but in the end, I suspect the practical problems would keep it from ever catching on. Horn-loading is a proven design and yes, it has its drawbacks (size, complexity, expense) and like all other things in speakers, there are tradeoffs to be made.
As part of the obligatory "DIY Driver" discussion, I think it would be really cool to make a totally waterproof driver that could be put in a water-loaded enclosure. If the walls of the room had watersubs in them, and the floor were just a grating over a couple inches of water that acted as the main woofer, you might get really good sound. Or it might just be a really expensive failed experiment.
I wonder if there's a grant out there that would pay us to build such a thing, just to find out....
The idea is that the water could act as an impedance transformer. The area with which the driver interacts with the water could be small (15" woofer as an example) and the water could, in turn, act on a very large area of air.
I don't know that the water-air mismatch would be any better, but you might gain some improvement becuase the water would more easily be expanded to huge surface areas. (Imagine the surface area of a swimming pool moving up and down just 1mm--that's A LOT of displacement!)
The fact is, this is a huge can of worms, and a much easier solution is to just horn-load everything. Horn-loading causes the woofer to act on a much larger area of air, which brings the impedances closer to each other and increases efficiency.
For a permanent installation, a water-loaded sub (BTW, having a horn underwater is nearly useless, because the impedance mismatch is so much smaller) might be a useful and interesting way to increase output, but in the end, I suspect the practical problems would keep it from ever catching on. Horn-loading is a proven design and yes, it has its drawbacks (size, complexity, expense) and like all other things in speakers, there are tradeoffs to be made.
As part of the obligatory "DIY Driver" discussion, I think it would be really cool to make a totally waterproof driver that could be put in a water-loaded enclosure. If the walls of the room had watersubs in them, and the floor were just a grating over a couple inches of water that acted as the main woofer, you might get really good sound. Or it might just be a really expensive failed experiment.
I wonder if there's a grant out there that would pay us to build such a thing, just to find out....
i do not see the practical point in this design 
because the mass of water is big. and from my mechanics and physics lessons i remember that
F=m*a (where F is force, m is the mass and a is acceleration ) then the bass speed goes down, or am i thinking wrong
but if you are fighting with the pressure, what the driver gets when it's placed into the water (if you want to use a chamber with air behind the driver), then you should use a U-pipe
like on the added picture
because the mass of water is big. and from my mechanics and physics lessons i remember that F=m*a (where F is force, m is the mass and a is acceleration ) then the bass speed goes down, or am i thinking wrong
but if you are fighting with the pressure, what the driver gets when it's placed into the water (if you want to use a chamber with air behind the driver), then you should use a U-pipe
like on the added pictureAn externally hosted image should be here but it was not working when we last tested it.
Clever lad! Drivers that are waterproof on one side are easier to come up with, methinks, and isobarik loading would make 2 sides waterproof... (Butyl rubber + metal cone = CAR WOOFER THUMP THUMP THUMP) You might have a hard time finding this kind of driver with a low enough Qts so it wouldn't sound like it was going underwater. (Yuck. I bet the water makes Qts+2.)
The seal would still have to be REALLY good, but it could definitely be done. I still want to see someone come up with money so I can build a party hall on this premise.
The seal would still have to be REALLY good, but it could definitely be done. I still want to see someone come up with money so I can build a party hall on this premise.
reply
How about these specially designed speaker which are waterproof and used for shower radios in the bathroom.
With a mylar cone, mylar surrond and mylar dust cap [all one piece,but corrated to make the surround.]Cone only 1 joing and thats joined at the edge,plastic frame.
The only catch is those type of speakers are always fullrange,not bigger than 51/4 inches and not bigger more than 20w rms[also used for burglar alarm bell boxes,and swimming pool speakers].
Also I heard there is a submergeable speaker called Lubell which can be used upto 12 metres underwater used at sealife centres to 'speak' to dolphins.
How about these specially designed speaker which are waterproof and used for shower radios in the bathroom.
With a mylar cone, mylar surrond and mylar dust cap [all one piece,but corrated to make the surround.]Cone only 1 joing and thats joined at the edge,plastic frame.
The only catch is those type of speakers are always fullrange,not bigger than 51/4 inches and not bigger more than 20w rms[also used for burglar alarm bell boxes,and swimming pool speakers].
Also I heard there is a submergeable speaker called Lubell which can be used upto 12 metres underwater used at sealife centres to 'speak' to dolphins.
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