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Subwoofer Enclosures, Second Order, Acoustic Suspension

Second Order Subwoofer Enclosure These enclosures are usually the easiest enclosures to build and are the most forgiving of many constuction and design errors.

Other characteristics include a shallow roll off on the low end (12 dB), great low frequency power handling, the best transient responses, and smaller enclosure sizes than most other designs. However, magnet structures will not cool as well as they do in some ported enclosures, and distortion in the upper bass frequencies is more noticable than ported enclosures, but can usually be compensated for by lowering the crossover frequency or using a steeper cut-off filter.

Remember, none of these enclosures are shown to scale. Please refer to your driver's specifications for recommended/optimal enclosure volumes.

Second Order / Acoustic Suspension / Sealed Enclosures:
Isobaric - Sealed
Isobaric - Sealed (Compound Loading)
Isobaric - Sealed (Back to Back)
Isobaric - Sealed (Planar Loading)
top of page Sealed Enclosure
Here is a basic sealed enclosure. Often these are construsted with the face or rear wall of the encloser angled to prevent standing waves within the enclosure, but since many sealed enclosures are so small this is unlikely to occur and may be a simple box shape as shown, but lining the walls with an acoustic damping material is still recommended.

sealed enclosure

top of page Isobaric - Sealed
When enclosure space must be at a minimum, sealed isobaric designs work very well. These usually require half the space of a basic sealed enclosure, but require twice as many drivers and will acheive the same acoustical output as the single driver show above in the larger enclosure.

isobaric sealed enclosure

top of page Isobaric - Sealed (Compound Loading)
Another isobaric enclosure with the drivers facing the same direction. Obviously this will require a larger enclosure than the one shown above, but again, output will be the same.

isobaric compound sealed enclosure

top of page Isobaric - Sealed (Back to Back)
Another variation of an isobaric enclosure. It doesn't matter which way the two drivers face, but if you have the space to use this enclosure, you should be able to use a simple sealed enclosure instead (only one driver reguired!).

isobaric sealed back to back enclosure

top of page Isobaric - Sealed (Planar Loading)
Odd spaces will require unique box shapes. This isobaric enclosure can be a great solution for such a space. Remember, the volume of air space between the two drivers is not crucial to the design of the enclosure, (however, you do not want to make it too small) only the volume of the main section of the enclosure (that of the rear enclosed driver).

isobaric sealed planar loaded enclosure
<< Previous - Second Order / Infinite Baffle / Free Air Next - Fourth Order / Bass Reflex & Bandpass Enclosures >>

Subwoofers, Enclosures, & Calculators:
Second Order / Infinite Baffle / Free Air
Second Order / Acoustic Suspension & Sealed Enclosures
Fourth Order / Bass Reflex & Bandpass Enclosures
Sixth & Eighth Order Enclosures
Parallel & Series Calculators
Subwoofer Enclosure Calculators
Subwoofer Wiring Wizard
Thiele - Small Parameters
Help and Additional Resources:
Car Audio Forum
Car Audio Home
Car Audio Hot Topics
Car Audio Manuals
Passive Crossovers
Stereo to Bridged Mono Switched Outputs
Switch Series to Parallel and Back
Switch Stereo to Bridged Mono & Series to Parallel

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Thursday, May 24, 2018 • Copyright © 1999-2018 Support Privacy Policy Top of Page
Disclaimer: *All information on this site ( ) is provided "as is" without any warranty of any kind, either expressed or implied, including but not limited to fitness for a particular use. Any user assumes the entire risk as to the accuracy and use of this information. Please verify all wire colors and diagrams before applying any information. spacer spacer spacer
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