Enclosure Types 101

The simplest enclosure type is an infinite baffle or free air system.
In this system the woofer has the front of its cone isolated from the back of its cone by mounting the woofer to the rear deck or on a board placed across the back of the rear seat.

Advantages of this design include simplicity, minimal occupation of space and lower cost due to not having to create a box type enclosure.

Disadvantages of this design require a larger power , difficulty (sometimes extreme) in completely isolating the two sides of the cone from each other, and slightly less accurate sound reproduction.

Sealed Enclosure
The simplest box type system is a sealed enclosure. Here a woofer is mounted in a completely sealed box that isolates the front and rear waves of the woofer.

Advantages of the sealed design include ease of assembly, smaller box size requirements, excellent transient characteristics, high power handling, and a typically smaller enclosure.

Disadvantages are less efficiency (requires more amplifier power) than vented enclosures and less low bass as compared to a properly tuned vented enclosures above the port tuning frequency.


Ported (Vented) Enclosure
Vented enclosures are similar to a sealed enclosure in design except that they add a “port” that is a certain length and a certain area around. This port, usually a length of PVC pipe, is tuned to a certain frequency by variation in the two parameters of area and length. By adding this port, the rear wave of the cone motion is used to reinforce the front wave. When done properly the subwoofer system becomes more efficient than a comparable sealed enclosure above the port's tuning frequency. However, below the port tuning frequency the woofer will become unstable and "unload" causing the woofer to oscillate violently, leading to premature woofer failure when driven with excessive power.

Advantages of this design are increased efficiency and a lower frequency extension above the port tuning frequency.

Disadvantages are a more complex design, a larger enclosure as compared to a sealed design, lower power handling, and slightly less transient accuracy.


Single Reflex Bandpass
(4th order) Enclosure
The most complex design of the common enclosures is a band pass system. The purpose of the band pass system is increased efficiency over a small range of frequencies. This design also helps filter out unwanted midbass and upper frequencies. There are variations on the band pass design known as orders. The simplest design is the single reflex (4th order) in which a woofer in a sealed enclosure fires into a vented enclosure.


Dual Reflex Bandpass
(6th order) Enclosure Series Tuned Dual Reflex
Bandpass Enclosure
There are also dual reflex designs (6th order) in which both enclosures are vented and series tuned designs in which the woofer and first vent fires into the second vented enclosure.

Advantages of this design are a high efficiency over a small range of frequencies and some filtering characteristics.

Disadvantages are decreased frequency response, less accurate reproduction, extreme complexity in design and assembly, larger enclosure size, greater woofer unloading and decreased power handling.


Isobaric Loading
Another enclosure design that you may hear of is isobaric. Isobaric is not actually an enclosure type but a woofer loading method. Isobaric loading can be used in conjunction with any of the enclosure types, except perhaps infinite baffle. Isobaric loading consists of two woofers coupled together by a short enclosure which is only long enough to prevent the two woofers from striking one another. The woofers may be mounted face to face, back to back or front to back. It is important however to have the woofers firing in phase with one another. In order to accomplish this with the woofers firing front to front or back to back one of the woofers speaker leads must be reversed with respect to the other woofer.

Isobaric loading is usually used when space is at a minimum or a maximum number of woofers wish to be used in a certain volume of space. By isobarically loading the woofers, a box of only half the size of a one woofer box is needed. For example, if a 12" woofer requires a two cubic foot box, the same 12" woofer isobarically loaded only requires a one cubic foot box. The cost of this design, other than doubling the woofer cost, is a reduction in the subwoofer system efficiency by three decibels (if both woofers are given the same power as a single woofer), which is equivalent to halving the amplifier power. New, small box subwoofer designs have all but negated the need for isobaric loading in car audio and it has fallen out of popularity.

Advantages of this design are increased linearity in the speaker movement, lower space requirements, and increased power handling.

Disadvantages are increased cost, increased design and assembly complexity, and decreased efficiency.

Imageshack givin some probs so ill post the pics of each enclosure when its in good working order

nice thread here....thanks lon...i've added this to the sticky collection

great infor...

so lon does it really depend on the type of speaker or the space that you are working with?

when it comes to enclosures?

not always eh, most times it depends on the purpose u use it for ...eg, spl, low power, high power.... in my personal experience power and purpose is what it all boils down to

however, subwoofers come with a minimum enclosure volume and port spec....some ppl do some unrealistic things like put a 15" sub in a 2 cubic ft box and expect it to play good, using a sub in an enclosure not sufficient and powering it as recommended can be dangerous, u can damage the cone and then your coils will become damaged after

my advice, if its even the minimum recommended u have to work with, use it and power it adequately..... this way youll be satisfied and safe

very good advice there.....

Wow ,you know a lot

thanks, only 13 years in the biz though

ok to small or big of a box can affect the performanceof the sub. what about breaking in a new sub how do u do that.

Wao..... That is great info

although i thought u weren't goin 2 finish than ks 4 the info

ohhhhhhhhhh!! interestin!! lol nice!!

Woo.. Thanks For De Info There Soldier.. Now Only If Someone Could Build A 4 10" Box For Meh To Play Loud Bass.. Lol

^^^u call d man wah ah tell u to call as yet???...wuh he say?

well im an installer too, where u from and what vehicle u got, ill be happy to help