liquid absorption of baffle/enclosure vibrations?

[JinMTVT]

just a quick idea

what if we would use some sort of liquid filled area within an enclosure to help absord mechanical vibrations???

has it been done ?

just thought of that trying to guess how i would be desiging my next OB loudpseaker for nearfield in wich baffle noises could be more of a problem i believe

i thought about having some type of container with a liquid of a determined viscosity attached to the back of the baffle in an indentation ..probably glued to it

another of my compeltly ridiculous ideas ?
i believe so

lets hear what you say now

[cheapskate]

I don't think this would work terribly well with anything with a lower viscosity than molasses. Molasses might work but if it was in a sealed space you might get fermentation then an explosion then an amazing mess to clear up.

Remember, sound travels more readily through a liquid like water than it does through air. Perhaps you need a vacuum rather than a liquid? Hard to implement though.

Sand is probably a better bet. I made some spherical speakers that were essentially a sphere within a sphere. The space between the two was filled with sand. This has worked well. I think Gutta-percha fortified with fine lead granules would make a good sound deadening medium though I have never tried it.

[JinMTVT]

hi cheapstake!

i was more thinking about mechanical movement of the baffle than sound itself
i believe that all drivers induce some vibrations to the enclosure they are fastened to while moving nah ??

so i thought that a freely moving mass as a part of the enclosure/baffle would absorb some of the movement
forces ...

[cheapskate]

Yes, the drivers certainly excite the enclosures.

Liquids don't necessarily 'absorb' the induced vibrations. Get a s/steel bowl, fill it with water and bang it. It will vibrate like a bell quite nicely.

I think that to loose the energy in the vibration the material has to convert the energy into another form - heat?

A mass of viscous liquid, I think, will just slosh and re-excite the baffle, converting only a small fraction of the energy into heat.

You want something that converts mechanical vibration into heat readily or a great deal of mass that would require more energy to excite than ithe drivers can produce 8-)

[JinMTVT]

Originally posted by cheapskate
Yes, the drivers certainly excite the enclosures.

Liquids don't necessarily 'absorb' the induced vibrations. Get a s/steel bowl, fill it with water and bang it. It will vibrate like a bell quite nicely.

I think that to loose the energy in the vibration the material has to convert the energy into another form - heat?

A mass of viscous liquid, I think, will just slosh and re-excite the baffle, converting only a small fraction of the energy into heat.

You want something that converts mechanical vibration into heat readily or a great deal of mass that would require more energy to excite than ithe drivers can produce 8-)

Superb answer!!!
i will try to seak another path then ..

thanks much!

[sreten]

Hi,

Sand sounds like a far better bet than viscous liquid.

/sreten.

[Brett]

Originally posted by sreten
Hi,

Sand sounds like a far better bet than viscous liquid.

/sreten.

I think you're right. Bitumen hotmix was suggested in an earlier thread I found, but no one tried it because of concerns over fumes.

[noah katz]

I think you'd get better damping with less volume using CSD (constrained layer damping).

[phase_accurate]

This one uses liquid bitumen:

http://users.skynet.be/accupulse/manger_head.html

Regards

Charles