Ported Box to Closed Box.........

ZSKCivic01 · 03-02-2003

Hey everyone, I got a quick question. Im fixing to go off to college and I need to carry alot of stuff in my car several hundred miles in my trunk. The sub box that I currently have for my JL 12w3 is built to spec from the jl site. It is pretty big for those who have built it to spec. Well, I was thinking of going with a smaller closed enclosure, since they are so much smaller than the ported box that I have. Will I hear a very big difference in loudness if I go to a closed enclosure? I know that a closed enclosure won't go as loud, but it hits lower notes better.

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ce01cvcex · 03-02-2003

you could buy a jl box, they are pretty small, but they are made for the subs....

WhiteRabbit · 03-02-2003

you will not only lose spl, but you will lose some warmth, might lose some slop, and despite what theory says, you lose a TON of LFE! i can push numbers all day to prove that sealed boxes are louder lower, but numbers mean nothing in teh real world, and the FACT of teh matter is ported boxes play louder, lower.

if space is more important to you than balls out volume, you may as well rebuild that box sealed.

but we should kill that rumor here. ported boxes play lower.

ZSKCivic01 · 03-02-2003

i was looking on the JL site and the closed boxes are suposed to be 1 cubic ft volume. On ebay, I found a nice one that was 1.03 cubic feet, and it is being auctioned for a good price. Will the .03 extra cubic feet make a difference in the way my subwoofer sounds, ignoring the fact that im going from ported to closed?

WhiteRabbit · 03-02-2003

1 cube sealed versus 1.03 sealed, no perforance difference at all

ZSKCivic01 · 03-02-2003

what you said kind of makes me wonder though, so there will be a major difference in the sound quality?

Quote:

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[hr]you will not only lose spl, but you will lose some warmth, might lose some slop, and despite what theory says, you lose a TON of LFE[hr]

I was a little confused by what you said. Please clarify if it is not too much trouble. I also have a JL Audio XR650 component set with my sub and im going to amp them when I get everything delivered, so I can get some bass out of the mids I guess. But for the most part, what im trying to say, will my subwoofer still go pretty loud and sound clean in a closed box with my component set? I am not trying to have the loudest system, just one for my enjoyment that will hit. My sub is running off an alpine M300 if it makes a difference.

WhiteRabbit · 03-02-2003

with XR's, youll have all teh midbass you need.

loss of SPL: ported boxes take advantage of the rearwave of the speaker to in essence doube teh cone area. thats why they are louder in theory. sealing will most likely drop your spl (volume) because now you have halved the theoretical cone area.

loss of warmth : ported boxes, if you ask the average listener sound "warm but sloppy" there are always exceptions, like the tempest and alpine type R sounding very warm sealed, or the HCCA sounding incredibly unsloppy ported, but for JL its definitely true, in my experience. not to say yours sound swarm OR sloppy, but in either case one or the other might be desired, or undesireable.

loss of slop: just like ported boxes are perceved to sound "warm" sealed boxes that arent too small have lots of pressure pullign back on the cone. these boxes have a tendancy to control the cone's movement more thana ported box. woofer dependant, but id gues itll hold true here.

loss of LFE: this is the tricky one. I was writting a great metaphor for it, then realized it was impossible to visualize, so this will be far easier:

green is ported, yellow is sealed. note how the yellow slope is alot more gentle than the green ported slope. thus, eventually, the slope will be too steep for the ported box, and the sealed box will play louder, lower! makes perfect sense, right? now look at what frequency they intersect.

17 Hz? at -15dB? i have to play LOWER than 17 Hz for sealed to play louder? and its already at -15dB? this si of course only one excmple, but in teh USABLE frequency range, a ported box you cna see will play FAR louder, FAR lower. you can do this many many many times, your not gonna find many sensible ported box designs that dont hit far lower than sealed. nope.

EternalVTEC · 03-03-2003

not to mention, the human ear cant hear below 20 Hz, so it would be pointless to build that box unless you were in a competition.

WhiteRabbit · 03-03-2003

competition never reaches below 20, never.

only a fool burps 20 Hz, even. as far as sq, just has ot be flat to 20, not below.

and if you got a ported tempest in yoru car, i guarantee you will percieve lower frequecnies than 20 [IMG]i/expressions/face-icon-small-wink.gif[/IMG]

ZSKCivic01 · 03-03-2003

are you talking about building a ported box for competition?

WhiteRabbit · 03-03-2003

nope, just talking abotu a general rule, going from a ported to a sealed box. I was actually using a daily driver box as an example, teh reason you see the peak in teh curve above is cause the example didnt work for my explanation at all, since the intersection point was at like 3 Hz! just shws theres even more potential than one would think in lowbass frmo a portedbox than a sealed