appleyard, I ain't going to argue with you anymore, it stops right here, since according to you what I said made no sense. No problem since you're the expert, but maybe you should start reading how you went abt this thread & others promoting the vented box & brahma & xbl2 bla bla bla when the question being asked was a simple setup for Kelisa etc. You keep on mentioning SPL & huge boxes when that was totally irrelevant with what these guys asked. When I do get into SPL , you get defensive & twisting your cerita back to the stroker losing in sq to the brahma. I wouldn't say I disagree with you, but back when we're talking bout the sealed & it's sq qualities, you kept on defending the vented saying it'l go LOUD. C'mon, make up your mind lah. It's not just about the enclosure, yes vented is definitely louder than sealed when loaded in half space, but when you load it into a car it's different, a lot of other things should be considered. A Kelisa has a much smaller acoustic load angle which constitutes a much stiffer load, thus explaining on why the Kelisa or any other small cars that has higher resonant frequency seemingly is " easier to get louder ", coz when the resonant freq is higher, it is easily picked up by our ears. Now the only way you gonna make a vented play lower notes without sounding so stiff is to make the vented enclosure extremely huge which isn't pratical at all in a smaller daily driven car, this is why I kept on saying sealed is better, a lot better in this case. You build a vented enclosure too small, it's going to sound like a walrus or a trumpet, it won't matter though if you want your bass to sound that bad, but I don't think these guys want it. So I ask you again, why don't you build your Brahma 15" in a 1.6 vented enclosure with a 3" port? Coz you have all the space you want & you know it won't sound as good as the enclosure size you have rite now. Look here bud, it's this simple, since you the expert, I bet you know Neville Thiele & Dick Small, the guys who had their parameters named after. In Dick Small's enclosure white paper, there is a small mathematical equation for simple minds like yours.
Efficiency = k * f(3)^3*V(B)
( k is " efficiency constant") ( f(3) is in Hz & V(B) is in cubic meters )
sealed enclosure : k=2*10^-6
vented enclosure : k = 4*10^-6
Check out the EXTREME sensitivity to f(3) in this relationship. A little bit more bass extension costs you a lot of efficiency & enclosure size. Yet enclosure volume & efficiency are traded equally. If you want to reduce the enclosure by half, then the efficiency will be halved too.So this being the case, I would again point out that I strongly disagree with you claiming that a vented would be better than sealed even when it's smaller, coz since you're the expert, than you'd know that one octave of bass extension requires a payment of a factor of 8 in efficiency or box size. Let me make it simpler for you to understand, nanti cakap aku make no sense lagi,. Let's say you have a system that has a f(3) of 80hz & you want to redesign it so that it goes down to 40hz, you could either make the box 8 times larger or have your system being 1/8th inefficient, or you could make the enclosure twice as large & end up with 1/4th the efficiency, thus making your claim of a very small vented enclosure being better baseless. There's no cheating mother nature for the extra octave of bass my friend. Dont't expect concert bass from briefcase style vented,it won't happen. All drivers have definite performance limits. If you, box sifu, understand these limits, you'd be in a better position to fit a particular subwoofer design to the application at hand. Don't exaggerate of what you can't do with a woofer. No speaker will go very deep, yet still maintains efficiency & uses a tiny enclosure. You've been pasting the Thiele & Small parameters to these noobs here, why don't you paste the Australian Loudspeaker Theory written by Thiele & Small. They claim there is a definite relationship between low frequency bandwidth, efficiency & box size. They claim if you want a tiny enclosure, then bandwidth or efficiency will have to be sacrificed. So where does your claim of a vented enclosure being tinier than a small sealed being better? In this case let's assume the efficiency will have to give, wouldn't the smaller vented require more power handling than a smaller sealed? This my friend is the most common scenario where we get the average joe walking to a shop buying a pair of sub, a factory readymade enclosure ( with 3" port ) which is always tiny & amp. They go home & bump only to find their amp " tak cukup kuat ", which half of the time was never the case. I hope this answers the question I received on why I just used a kilowatt amp to drive my Stroker when the nominal power handling is 1.2kw, I just increase the enclosure volume from Cerwin-Vega's recomended 4 cuft vented to improve the efficiency of my amp's shortcomings. & to answer some of the questions being raised on why the sealed is preffered to the vented when it comes to sq it's bcoz of the other tradeoff factor, whilst maintaining the small vented & efficiency ( if you happen to counter it with a more powerful amp ) the bandwidth would give. This does not happen with sealed. Okay we can argue on the fact that why not make the vented bigger than? Again, read the above. Plus, I'm not so sure with sq comps, but I believe the sub enclosure for sq comps does have it's size guidelines that must be followed, pls correct me sq guys if I'm wrong here.
My point is, do not drive these noobs here into settling for less when you yourself won't.
Oh yeah, a Kelisa has an in - car resonant frequency of 74hz, with its in-car SPL response being loudest at 53hz with the backseats intact & 45hz without the backseats ( & oh .. before anyone else cakap saya nonsense abt the backseats, here's a small simple test, if you drive a hatchback than this would be easier, try your subbass with the backseats folded up & folded down, you'll see the difference). This is measured not with your WinIsd, sorry no graph, heh Sorry if I offended anyone here with my boring explanation, but this apple right here likes technical jargons, I just wanted to prove my point as a person who has a 10 year old attitude who talks nonsense,but like I said earlier, it stops now, I ain't going to argue with the "sifu".
Sorry but no offense ya?