This is for Bass


Box volume
This measurement, listed with each component subwoofer, tells you the recommended interior volume in cubic feet that a box should have to get the best sound from the sub. A variation of 10-20 percent is generally acceptable.

Enclosure types
Sealed Box — A sealed box is simply an airtight enclosure housing your subwoofer. A sealed box is best for any music that demands tight, accurate bass. Expect flat response, deep bass extension, and excellent power handling. A sealed box tends to need more power than a ported box. So, be sure you use an amplifier with ample wattage to get the most bass out of your sealed box.

Ported Box
A ported box uses a vent (called a port) which allows movement of air in and out of the chamber behind the subwoofer. This additional air movement reinforces low bass response. You get more output from a ported box than you would from a sealed box at any given amplifier wattage. Some people prefer the sound of ported boxes for rock, heavy metal, or any hard-driving music because they are a bit boomier than sealed boxes.

Bandpass Box
A bandpass box is a special type of ported box designed for maximum slam. The woofer is mounted inside a dual-chambered box; the woofer fires from the sealed chamber into the ported chamber. Sound waves emerge from the ported side. The sound that comes out of the port is extra loud within a narrow frequency range. Because bandpass boxes are super efficient within that range, they tend to boom. Their aggressive sound is great for rap and hard rock.

Free-air Subwoofers
A free-air system consists of woofers mounted to a board attached to the rear deck or placed in the trunk against the rear seat. The trunk acts as the enclosure housing the subwoofer. Free-air systems save space and have flat frequency response. The woofer must be specifically designed for free-air use, and the trunk must be airtight for the best results.

Frequency Range
The range of sounds from lowest to highest that the subwoofer is capable of reproducing. The figures listed with the drivers are furnished by the manufacturers. The actual range you'll hear can vary depending upon the type of box and vehicle the subwoofer is installed in. Under most circumstances, a typical sub will play deeper than its published figures indicate. So, don't base your choice solely on this spec.

Peak Power
The amount of power the subwoofer can handle as a brief burst during a musical peak. You should not drive your subwoofer continuously with wattage equal to the peak power rating.

Power Range
An external power amp is required to drive any raw component subwoofer. Don't try to drive one with your in-dash receiver's built-in amp. The low number listed is the absolute bare minimum wattage required to get acceptable sound from the subwoofer. For best results use an amp that provides a power level (RMS, or continuous watts) in the upper part of the subwoofer's recommended range (RMS).

Sensitivity
This spec is quoted in dB SPL (Sound Pressure Level) The higher the number, the more efficient the subwoofer is at turning amplifier power into sound. Sealed box woofers tend to be less efficient than those designed for use in ported, bandpass or free-air applications, but they do offer you extended deep bass and high power handling capability.

Top Mount Depth
Tells you the depth of the woofer when it is installed from above the mounting surface. If you choose to mount it from below, the depth will be greater.Dual-Cone
A dual cone speaker, sometimes also referred to as a "full-range" speaker, uses an inexpensive, efficient design. The small "whizzer" cone in the center of the woofer reproduces high frequencies, but not as well as a separate tweeter


This is for non-woofer speakers...tweaters 6x9's ect.

Efficiency or Sensitivity
An efficiency or sensitivity rating tells you how effectively a speaker converts power into sound. The higher the number, the more efficient the speaker and the louder it will play with the same input power. An efficient speaker helps you maximize your available power.

Frequency Response
The range of frequencies the speaker will reproduce (lowest frequency to the highest). The wider the range, the better. Optimal is 20 - 20,000 Hz, the range of human hearing.

Imaging
Imaging describes the extent to which a stereo system reproduces the location of instruments and vocalists as they were positioned during recording and mixing (See also soundstage below).

Good imaging creates a listening experience that seems natural and lifelike. The key to attaining the best possible imaging is equal and unobstructed path lengths between your tweeters and your ears. That's one of the reasons why matched component speakers, with their versatile tweeter placement, sound as good as they do.

Maximum RMS Power Handling
Maximum RMS Power Handling refers to the amount of power a speaker can handle on a continuous basis. not to be confused with Peak Power Handling

Peak Power Handling
Peak power handling refers to the amount of power a speaker can handle during a brief musical burst.

Midrange Speaker
A tweeter-less speaker (ranging in size from 3-1/2" to 6-3/4") dedicated to the reproduction of midrange frequencies. They are used in systems in which the low, midrange, and high frequencies are amplified separately.

Separates or Matched Components
Separates use a superior speaker design to give you the best possible sound. A typical separates system includes a separate woofer, tweeter, and external crossover, all of which are designed to work smoothly with one another. Generally, these components are made of better materials than their two-and three-way cousins.

Separate woofers may be easier to mount in tight places because tweeter protrusion is not a factor. The separate tweeters allow positioning for optimum imaging. Given adequate power, separates deliver phenomenal dynamics and detail.

Soundstage
Individual vocal and instrumental "images" make up your stereo system's soundstage. The better the soundstage, the greater the sense of its definite width, depth and height. See also imaging above.

Surround
The surround is the flexible ring around the edge of the woofer cone. Good ones are pliable enough to let the woofer cone travel freely in and out. The further the cone can travel, the stronger the bass. Surrounds are usually made of cloth, foam or rubber. Rubber tends to last longest.


Three-way
Three-way, or triaxial speakers take the separate woofer and tweeter from a two-way design and add a midrange driver for enhanced warmth and texture. The extra high-frequency energy also boosts overall sensitivity.

Tweeter
Your highs are reproduced by the tweeter, the small speaker perched inside the woofer cone. Cone tweeters are efficient and the most economical. Dome tweeters, the type found in most home speakers, sound smoother and more accurate. Some domes are made of metals like titanium for extended high frequency response. Others are made of a fine cloth like silk for a smoother sound. Some are made from a combination of materials.

Two-way
Your music's high frequencies are reproduced accurately by two-way, or coaxial, designs. These speakers use a separate tweeter to deliver high frequency reproduction that surpasses that of dual-cone models. This tweeter, usually a cone or a dome, is perched inside the woofer.

Voice coil
The voice coil is the coil of wire in a loudspeaker that creates a magnetic field. With the help of other speaker components, the voice coil converts electrical signals into mechanical energy which is used to produce sound. The voice coil former is the part of the speaker around which the voice coil is wound. Many speakers offer a heat-resistant voice coil to prolong speaker life.

Woofer
Your bass and lower midrange are reproduced by the woofer, the speaker's big cone. To operate efficiently, a cone should be made of material that is stiff, yet lightweight. Cones made of polypropylene, or poly mixed with other materials, provide excellent sound, and stand up to the heat, cold and moisture that car speakers face daily. Paper cones treated for moisture resistance also do a great job, and are usually very efficient.

 

here is an example of a free air sub

 

just so everyone knows...a free air sub is something you shouldn't ever do (unless your on a shoe string budget) and wen i say shoe sting i mean you are BROKE....its better to build your own box than to have a free air