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Flipx99
08-31-2005, 10:45 AM
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.

PhatTonyDeMarco
08-31-2005, 10:49 AM
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
08-31-2005, 10:59 AM
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
08-31-2005, 11:15 AM
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
08-31-2005, 11:29 AM
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...



wheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee eeeeeeeeee :peace:

Flipx99
08-31-2005, 11:32 AM
I don't have 6.5cf to build that box. I drive a 89 Cutlass Ciera.

Flipx99
08-31-2005, 11:56 AM
bump

mrray13
08-31-2005, 11:59 AM
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...




wheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee eeeeeeeeee :peace:

tRiGgEr
08-31-2005, 12:14 PM
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
08-31-2005, 12:22 PM
did i not jsut say that??? yes, yes i did...


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



wheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee eeeeeeee :peace:

Flipx99
08-31-2005, 12:25 PM
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
08-31-2005, 12:29 PM
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.


wheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee eeeeeeee :peace:

Flipx99
08-31-2005, 01:17 PM
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
08-31-2005, 01:19 PM
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...



wheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee eeeeeee :peace:

Flipx99
08-31-2005, 01:28 PM
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.

Flipx99
08-31-2005, 01:28 PM
Is Vas the same thing as displacement?

mrray13
08-31-2005, 01:48 PM
what are u trying to figure out exactly?

vas is something more complex then vb...




wheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee eeeeeeeeee :peace:

Flipx99
08-31-2005, 01:59 PM
I found it listed finally.

I am going to take your advice and do the ported box thing. It doesn't bother me really and I may be able to use the sub as a replacement or something so it isn't hurting anyone just sitting there.

I looked into one site that does boxes. I belive it is by beerman. When I look at the pic, it is a bunch of lines that go up and down and I don't see where you are supposed to put the sub. It also has a port lenth that is longer than the box. I am not sure what I am looking at here. Here are my specs:

Width- up to 42"
Height - up to 16"
Depth- up to 24" (also depth isn't an option on the box)

12" sub
xmax - 12.7mm
driver displacement - .083cf
reccomended volume - 1.75 cf

qts - .33
vas - 1.22 cf
fs - 30 htz

What is the difference between the teal bars and the violet ones?

hoss
08-31-2005, 01:59 PM
the volume of air that is the equivelant to the suspension...

an easy way to think of it is this, if youre box volume in a sealed enclosure is equal to the VAS, you might as well be running infinite baffle.

Logikalliquid
08-31-2005, 02:00 PM
im slow, ignore this

mrray13
08-31-2005, 02:06 PM
the volume of air that is the equivelant to the suspension...

an easy way to think of it is this, if youre box volume in a sealed enclosure is equal to the VAS, you might as well be running infinite baffle.

u put it into words alot better then i could've..lol....which is why i didn't try...



flip...basiclly, ur going to need a 3.5ft^3 NET enclosure for a pair of twelves.


i'd suggest tuning around 34-36hz to achieve the best compromise of sq and spl..


40in^2 of port should be plenty for two of those subs...



and if u get a port length longer then any inside box dimension, u bend it..lol..either "L" shaped, or labrinyth style...u can, of course, use round ports and get away with less port area, say two 4" round ports, and they will also be a touch shorter...




wheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee eeeee :slayer:

Flipx99
08-31-2005, 02:07 PM
When I said depth isn't an option, I meant on the utility. I car build it as deep as necessary.

Flipx99
08-31-2005, 02:10 PM
I see. I beleive the "labrynth style" is what the pciture is depicting. Now if I can figure out what the colors mean and where the subs go I'll be all set. Thanks for your help. Here is a link to what utility I am using.

http://www.accelerator-pedal.com/ported-box.asp#

mrray13
08-31-2005, 02:23 PM
here's on u can build....


15" tall x 35.75" long x 16" deep, with two 4" round ports x 12 3/8"long (assuming shd 40 pvc), gives ya 3.5ft^3 net, tuned to 35hz



or if u slot port it....

15" tall x 38.75" long x 16" deep, with a slot port 13.5" tallx 3" wide x 18.75" long with net u 3.5ft^3 tuned to ~35hz




hope that helps a bit.....and this assumes no bracing and 3/4" mdf...

wheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee eeeeee :peace:

Flipx99
08-31-2005, 02:37 PM
How do you make the " L " for creating depth in the ports. L brackets? Or screws, but it looks like it would make it wobble.

Here is an attempt on what I am trying to explain:



|
|
_______|*_______________________
/\
| --- is all I have to is put a screw here or do I also need L brackets at the *

Or do I have it all wrong and port does not have depth?

Flipx99
08-31-2005, 02:38 PM
The line should be even with the *, for some reason it did not come out right. If you give me your e-mail I can send you a pic of what i am trying to explain.

mrray13
08-31-2005, 02:43 PM
ummmm, well,when finished, u won't need any brackets as teh box will hold it in place..(u'll screw into the top and bottom of the port wall from the outside)

i take it u've never built an enclosure? or at least a ported one?



u might be better off having someone build it for u.....




wheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeee :peace:

Flipx99
08-31-2005, 02:47 PM
I can structurally build things if I know how they come together. I built a sealed one before and it works out fine.

I see how it works now...I believe....I am going to see if I can find some pics of ported enclosures from the inside.

It may be easier to do the round ports...because they sell them.

mrray13
08-31-2005, 03:22 PM
I can structurally build things if I know how they come together. I built a sealed one before and it works out fine.

I see how it works now...I believe....I am going to see if I can find some pics of ported enclosures from the inside.

It may be easier to do the round ports...because they sell them.


correct, but flared ports figure differently then just round ones...



and i'm not trying to doubt ur building ability, but just making a suggestion..no offense intended.

finding such pics will be helpful...



wheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee eeee :peace:

Flipx99
08-31-2005, 03:25 PM
I found some pics and see more how the vent extends the depth/height of the box, not just a dimple. Is there advantages/disadvantages to placement of the port?

mrray13
08-31-2005, 03:27 PM
for daily driving, no, not really.


there are some quirks to it, but none that are really noticeable to the ear...


so are u going slot or round?


wheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeee :peace:

Flipx99
08-31-2005, 03:33 PM
Well, I now that I kinda understand how they work, I don't know. The round seems more popular in pre-fab, but the slotted looks very popular in sounddomain/cardomain. What about other shapes? Wouldn't they cause port noise?

Which do you belive is easier?

Looks like round may have an issue being straight, whereas slotted you would need exact same cut or else your box would be warped.

Flipx99
08-31-2005, 03:35 PM
Why would I tune to 35-37 hertz when my "characteristics" graph shows max spl @ ~40 hertz. Lower frequencies improve SQ?