a sealed enclosure

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deegz97

Member - Posts: 21

Joined: June 30, 2008

Location: Missouri, United States

Posted: July 17, 2008 at 11:09 AM / IP Logged

This may be absolutely moronic, but I have a question about sealed enclosures...

I am planning on putting a 10 in a sealed box in the cargo space of a Jeep Grand Cherokee. A sealed box confuses me though. it seems that there would be an excessive amount of pressure inside the box and that the extra pressure could counteract the effectiveness of the sub. ie by making the sub move inaccurately (or against the music) with all the extra air pushing against it from behind...

Sorry if that is incredibly stupid, but just something that I am curious about.

Thanks again everyone!

DYohn

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Joined: April 22, 2003

Location: Arizona, United States

Posted: July 17, 2008 at 12:10 PM / IP Logged

The purpose of a sealed enclosure (acoustic suspension) is to provide the compliance missing from the driver's suspension by adding air pressure "springiness" to it. This acts to increase the woofer's power handling ability and improves its overall performance, specifically by smoothing out frequency response and impedance peaks creating a more 'smooth" or musical sounding system. It also limits excursion helping prevent mechanical damage, and serves to isolate the woofer's front sound wave from its rear sound wave to prevent acoustic cancellation, thus increasing the speaker's effectiveness. Another type of "sealed" enclosure is called infinite baffle, which does not add mechanical compliance to the suspension because the enclosure is too large. This tends to increase efficiency and output in the lowest frequencies but reduces power handling and does not serve to dampen FR peaks. I suggest you might want to Google terms like "acoustic suspension" to better understand how these systems work.

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stevdart

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Posted: July 17, 2008 at 11:41 PM / IP Logged

deegz97 wrote:

it seems that there would be an excessive amount of pressure inside the box and that the extra pressure could counteract the effectiveness of the sub. ie by making the sub move inaccurately (or against the music) with all the extra air pushing against it from behind...

The air pressure inside the box is the same as the air pressure outside the box. It only compresses when (and only to the limit as) the cone moves inward. That's not very much compression, but it's enough to control the cone movement.

Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

haemphyst

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Joined: January 19, 2003

Location: Michigan, Bouvet Island

Posted: July 18, 2008 at 12:00 AM / IP Logged

1: The only stupid question is the one that isn't asked. It's how we all learn, whether we ask the question of somebody else, as you have done, or we ask the question of ourselves, forcing us to simply study to learn more.

2: Here's a good one discussed here in the forum as well... Potentially a bit "over your head" right now, but something that should be read, especially if asking the questions you are asking about sealed enclosures.

It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

deegz97

Member - Posts: 21

Joined: June 30, 2008

Location: Missouri, United States

Posted: July 18, 2008 at 11:05 AM / IP Logged

Thanks for the responses guys! I have only skimmed them as of now - work getting in the way of my fun! Just kidding, I love my job.

I will study them tonight and this weekend. And, Haem - this is ALL over my head, but i am studying as much as I can and can't wait to get started!!

Talk soon...

Jeff

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a sealed enclosure

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