I currently have a 10" mtx 5500 in a ported box, what is the difference between that and a sealed box?
...an excerpt from my site....
Straightforward in design, the sealed box is nothing more than an airtight enclosure whose purpose is to enhance speaker performance. When a woofer is installed in one, the sound waves that emanate from the front of the speaker cone are separated from the rear-firing waves. This improves bass response, since opposing waves can cancel each other out when they aren't isolated. Superb damping, good power-handling capability, and simplicity of construction make the sealed-box enclosure an ideal candidate for a variety of installations. A sealed enclosure will be the smallest (for a given response shape) and will have good low frequency extension but may not have the best low frequency extension. If space is limited, this may be your best choice.
Vented enclosures – also known as ported or bass-reflex systems – are more complex than sealed boxes, but the extra construction work required to install a vent has its rewards. Vented boxes are more efficient than their sealed counterparts, since they channel sound waves from the front and rear of the cone into the listening environment. Other virtues of the vented design include better reproduction of low bass, a reasonably flat response curve, and low distortion – provided the box is properly constructed. A vented enclosure will generally have a better low frequency extension for a given response shape (alignment) but would require a larger enclosure. If you made the enclosure as small as the sealed enclosure but ported it to gain the low frequency response, the output would deviate from the desired flat response.
A bandpass enclosure can sound good and give you a flat response but most of the generic bandpass enclosures are not designed for a flat response. They are designed to impress you in the stores. This means that they are built to produce a large peak at some frequency near 60hz. These enclosures will work well with something like rap music but generally won't sound good with other types of music. If you use a bandpass enclosure, it should be designed specifically for your speakers.
If you're building your first system, I'd recommend a sealed enclosure. It is the simplest enclosure and will be the easiest to get right. A sealed enclosure only needs to be the right size and well sealed. Alright... Enough of my opinions.
Rap music - sealed
Rock + Roll music - ported
..all you need to know =)
Sealed boxed dont allow for air to escape, thus there is a pressure change inside upon excursion, tending the subwoofer to return to normal. Basically that means you get better response with a sealed box, so your bass will be tighter, but less efficient dB wise.
Ported means air can go in and out, so there is no vacuum or high pressure force acting on the sub during excursion, giving it worse response, but better volume performance, and better deep bass (due to being able to move more air at lower frequencies with the same power).
ported boxes are usuall more complex and larger, while sealed are simple and smaller.
www.howstuffworks.com has some good info on the subject.
A ported box doesnt make a "deeper" bass note. That all depends on the "tuning" of the enclosure. Generally a sealed box usually "goes lower" If its big enough. If a ported box plays a freq. far below the tuning freq. the woofer will move out of control. Almost "oscillate" if you will. A sealed box will generally not experience this effect. But if the box is to small for the woofer it will sound terrible and not hit low frequencies.
Small boxes are "easier". Thats why theyll "sound better" to most people. Because most people dont know about car audio, and use wrong ported boxes, subs not made for ported boxes, wrong alignments, etc.
I like ported boxes because they offer increased volume and better efficiency. But, I am currently running a JL 8w6 in a sealed box, because of space.
A sealed enclosure is easer to build and is more forgiving if you choose the wrong internal volume. The constant pressure inside the box prevents the cone from traveling to its furthest extremes (excursion), and so the cone returns to its neutral position faster. We hear this as "tighter" bass. Likewise, sealed enclosures are generally smaller that a ported enclosure for the same speaker. The problem with a sealed enclosure is that it shifts the speakers passband up in frequency. If, in free air, the speaker can pass, say, 30 hz at -3 dB (where output is down 50%), inside a sealed box that frequency will be shifted up to 55 hz or higher. In most popular music (rock, metal, hip-hop, most techno) this isn't a problem. But, if your playing alot of classical music, the music where the deepest bass usually happens (the fundemental tone of the lowest note on a pipe organ is 16 hz, which is below the range of human hearing) a sealed box is going to miss alot of that.
A ported box, on the other hand, is more complicated, and should only be built by someone who actually knows what they are doing (if you don't own a copy of Vance Dickeson's Loudspeaker Design Cookbook, you don't qualify). There are various alignments that exist, some of which will suit a particular driver, while others will not. There are no simple guidelines I can quote to tell you which to use, even knowing the T-S specs of your drivers. A ported box will generally have a lower power output, but that isn't universally so. A ported box will generally pass lower frequencies, but again, this isn't always the case.
Ultimately, there is no ultimate type of subwoofer. There is only a question of which subwoofer best suits your needs. The only way to know that for certain is for you to experiment, trying different alignments until you find what's right for you.
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