Does atmostpheric pressure have effect on sealed box speakers ?

[TOGA]

I have this question in mind long ago. Sent question to manufacturer, without getting any reply. Ok I am may be to crazy to think about this, but here it is.

If you notice when aircraft fly high, you see that anything that is sealed will be inflated, like yogurt or snack in sealed plastic bag, during descending water in the bottle will be crushed. That was because of internal air pressure different from external air.

Now let say our sealed box speakers are sealed, the moment they are sealed, they will keep some amount of air pressure inside and no way to contact with outside world anymore. Then what happen if user use it in high elevation town, or speakers experience days to days atmospheric pressure variation.

I guess that pressure difference must have some effect on driver cones neutral position in some way. What keep the cone neutral is the spring force from driver's flexible surrounds, If atmospheric pressure is more than pressure trapped inside the box, then the cones will be tiny bit pushed inside of neutral position, amplifier will also have to work harder to fight with extra pressure to push cones outward with positive signal, but will be easier to pull the cones back in with negative music signal. Will this cause inconsistency in sound between high and low pressure days ?

Also, same speaker models that leave factory on different days will also have
different pressure trapped inside. 10-30 millibars of atmospheric variation is normal through out the year. then each production lots will react differently
to outside air pressure. 21 pound of forced is pushed the 8" driver inside for pressure diff of 30 millibar. (let's say driver is "flat" )

I may be thinking too much, but I have seen plastic bottle crushed before, that is the different of 200 millibar when cabin altitude reduce from 6000 to 0 feet while pressure that is trapped in the bottle remained low even the plane has landed, and that started this question.

toga
Sorry again if this bother you..

[Amfibius]

I don't think sealed box speakers are completely airtight.

The other question is whether the speed of sound is affected by atmospheric pressure. The answer is: no it isn't.

[GaryProtein]

The speed of sound is mostly determined by temperature but also slightly by gas density and humidity.

Warmer air and the presence of water vapor increase the speed of sound. The air surrounding us is not an what physicists call an ideal gas.

I also doubt that a "sealed" acoustic suspension speaker is hermetically sealed.

[Rmac]

Conclusion:

Be sure to listen in a controlled environment...

[TOGA]

Ok, if the sealed box speakers are not completely sealed, then there is no problem.
But where is the holes that allow leaks?
I have seen tweeter diaphram crushed by air transports. One on Stereophile Giya g1, and two on Magico v2 tweeter, dealer said it was dent already when they open the box.

[jfray]

Originally Posted by TOGA

Ok, if the sealed box speakers are not completely sealed, then there is no problem.
But where is the holes that allow leaks?
I have seen tweeter diaphram crushed by air transports. One on Stereophile Giya g1, and two on Magico v2 tweeter, dealer said it was dent already when they open the box.

There are not any holes but since the cabinet in not "perfectly" sealed air pressure will equalize over the journey from location A to B.....

[Face]

Originally Posted by Amfibius

I don't think sealed box speakers are completely airtight.

The other question is whether the speed of sound is affected by atmospheric pressure. The answer is: no it isn't.

http://www.rane.com/pdf/ranenotes/En...d_of_Sound.pdf

[Amfibius]

Originally Posted by Face

http://www.rane.com/pdf/ranenotes/En...d_of_Sound.pdf

Thanks for digging that up

"Eq. (5) reveals the temperature dependence and pressure independence of the speed of sound. An increase in pressure results in an equal increase in density.
Therefore there is no change in velocity due to a change in pressure."

Good that my recollection was correct - a change in atmospheric pressure does not change the speed of sound

[TOGA]

Well, but what i really mean here is that the pressure difference between inside and outside
Will cause extra load to amplifier or not. Rather than concern on speed of sound changes.
toga

[Face]

Nothing to be concerned about.