Volume Question

[Flipx99 5,000+ posts]

When a company posts there reccomended specs on a box, does that included with the sub in it? The sub displaces some of the air. Therefore, is the reccomended size before or after the sub. If it is before, how do you calculate the volume of the sub in the box?

Reason being: I have 3 TSW2000SPL. I am moving from sealed to vented. Vented/Ported needs a 1.75 box. It would seem to me if I put them in individual boxes, then I could make them in any dimensions, as long as the total volume of each box is 1.75. Is there much more to it? I would assume that there is because of all the expensive box building software.

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[PhatTonyDeMarco 5,000+ posts]

I believe that number is BEFORE port and driver displacement. You do not have to go by this number all the time though. You could go larger, or smaller, depending on the tuning you would like. 1.75 cubes is pretty small already though, so I wouldnt reccomend going any smaller. And porting them all in seperate boxes might not be the best thing to do. Human error will cause each box to be tuned to different frequencies, giving you an effect that you will not like... If you have room for it, go for one big box, or wall it off (if you have an SUV.)

 

[tRiGgEr 5,000+ posts]

It is AFTER all displacment. So the box needs to be 1.75ft^3 after your port/speaker displacment. The manufacturer lists the speakers displacment.

So you're looking at 5.25ft^3 not including port and speaker displacment. The box is going to be around 6.5ft^3 total...

 

[Flipx99 5,000+ posts]

That's a huge box. I guess I am going to stay sealed. Are there advantages to 1 large box vs 3 smaller boxes when going sealed?

 

[mrray13 10+ year member]

That's a huge box. I guess I am going to stay sealed. Are there advantages to 1 large box vs 3 smaller boxes when going sealed?

as in one big chamber as opposed to three individual ones?? i'd do one large box with individual chambers, as ur bracing is built in. also, in theory, individual chambers will offer a measure of protection in the event one sub blows, it won't take the other two with it.also, if one goes, u can still have bass....

teh downside is that with individual chambers, u have to be careful on measurements so as to not make three different sized chambers...the one larger chamber is an easier build...

but i'd build one large chambered ported box...regardless of size...

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[Flipx99 5,000+ posts]

I don't have 6.5cf to build that box. I drive a 89 Cutlass Ciera.

 

[Flipx99 5,000+ posts]

bump

 

[mrray13 10+ year member]

well, that could be a problem...

u could always just drop one sub and then build a smaller ported enclosure for two subs, which would equal or do better then the three subs sealed...

or better yet, sell ur three subs, buy one type r and smoke those three subs!!! cuz we all know cone are means nothing...

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[tRiGgEr 5,000+ posts]

I would choose to just port 2 of them. The box will be much smaller, and get just as loud if not louder than the 3 sealed.

Why run 3 subs anywayz???

 

[mrray13 10+ year member]

did i not jsut say that??? yes, yes i did...

come up with ur own advice once in awhile, eh???

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[Flipx99 5,000+ posts]

I don't know but it sounded like a good idea to compete with my friends 2 15s. He has 2 HE2s and I wanna be around where he is. He is hitting around 141 dB.

It sounds strange that 2 can sound louder than 3. I know it will be easier from a wiring standpoint. That way I get to 1 ohm.

 

[mrray13 10+ year member]

back to real advice..lol..

2 12's in the right ported enclosure will indeed compete with 15"he2's...which aren't all that great (especially if he's only grabbing a 141)

and i u can wire down to one ohm and that's where ur amp makes it's rated power, then u will for sure see more output then 3-12's wired off the amps impedence.....not taking into consideration box impedence rise, which u needn't worry about it.

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[Flipx99 5,000+ posts]

Last question: How do you calculate Vb? I am looking at one of these online tutorials and I need Vb to calculate box dimensions.

 

[mrray13 10+ year member]

Vb is the net internal volume of ur enclosure..that's what u end up with after doing the math and subtracting the sub/port displacment...

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[Flipx99 5,000+ posts]

I had no idea there was this much math involved...I see now why those programs must cost so much money. Looks like I got a lot to learn.