Building box for single X-12

[King_N9ne]

Im looking to build a daily pounder, no comps. I have a SAZ-2500 and the electrical to boot, so power is no issue.

Not sure on the port area, or tune I should look for. I read somewhere around 18-20 in/^3. Id like it to still be musical for rock and easy listening, but mostly for murderous lows.

The car is a 97 grand prix so space is a bit of an issue. The max I can go is 14x36x22. I had planned to use 1"material, and an L port.

So far with a 4.25x12 port 46" long, it gives me 51in of port area or 20.9 in/^3 at 32.9 Hz.

Would this be too much port for the power at hand? Should I tune lower?

Note; this is w/o sub displacement since I can't seem to source the specs. Also, at some point I might decide to upgrade to a Zv4 so Id like the box to suite both drivers. However, I may go to a 15 rather then a 12, but just to keep in mind. Not sure how different the specs would be for both 12's. The Z has 5mm more xmech and handles 500 more watts. I believe it has a stiffer spider too.

As of now I have it in a 2.5^3 @ 32 with 12 in/^3. For my first spl type driver, Im liking it, but I want more. There's A lot of port noise as you can imagine. So Im looking at building a different box.

That said, Id really appreciate some incite being these drivers are still "new-ish" and info is sparse.

Thanks

[Triticum Agricolam]

I think your 51 sq. in. of port area certainly will not be too much. That driver has so much excursion that, if anything, you may want more. I think you will be fine with what you have planned though. The tricky part is that port is already pretty long. Any more area and its may start to get hard to implement since it will be so long. As far as tuning to 32.9 Hz, its kinda a personal preference thing. I like low tunings (< 32 Hz) because they hit the lowest stuff better and have a more even response so they don't sound so boomy. Since you listen to rock music I would guess you would like it that way too, but again I can't tell you what you will like.

[slowfkncar]

Your probably looking at 4-4.4 ft^3 gross /2.6-7 net and around 19-22square inches p.foot^3. These things love port and I actually have not hit the "too much port" mark yet.

[King_N9ne]

I think your 51 sq. in. of port area certainly will not be too much. That driver has so much excursion that, if anything, you may want more. I think you will be fine with what you have planned though. The tricky part is that port is already pretty long. Any more area and its may start to get hard to implement since it will be so long. As far as tuning to 32.9 Hz, its kinda a personal preference thing. I like low tunings (< 32 Hz) because they hit the lowest stuff better and have a more even response so they don't sound so boomy. Since you listen to rock music I would guess you would like it that way too, but again I can't tell you what you will like.

I guess 1" material is not common so 3/4 it is... With a 4.25 wide port, I can go 63" long. But that cuts my net volume down 2.2 with 24 in/^3 of port area @ 30.5 Hz.

If I cut it down to 56" long, that gives me 2.55^3 w/ 20.83 in/^3 @ 30. Seems like the best medium and an ideal tune. I can't go any wider then a 4.75 port and keep the net vol above 2.2 w/ tuning bellow 34.

Seems 4.3-4.5 is the ideal width. I sure don't wanna sacrifice anymore volume for port area. 2.5^3 would probably be the minimum. That said, a 15" Zv4 ain't gonna happen lol.

[King_N9ne]

Id like to do a kerf flare with as small of 45's possible. However Im not sure what the ideal radius is for a kerf or understand how to figure out the volume of 45° corner braces. The formulas I did find are in cm, so that just adds to my confusion. Basically they'll measure .75x.75x1 and 12.5" long.

I can't figure out how to post pics. There seems to be no toolbar for image links. But this is a sketch of what I have in mind. Just don't know how to figure out the kerf radius and volume of the 45's or how to add the 45's to the port length, or if they would have an effect on port width.

http://carphotos3.cardomain.com/images/0016/33/38/16363383_large.jpg

[Triticum Agricolam]

About the smallest outside radius you can do for a kerfed corner is a little under 2" with 3/4 material. I'd shoot for a 2" radius.

When you do your 45 is the corner you want B to equal A.

To calculate the volume the 45 takes up multiply C times D times the internal height of your box and then divide by 2. In this case the volume of the 45 doesn't really matter because you already lost that volume to the port anyway so it isn't going to reduce the net volume for the sub any more.

[King_N9ne]

About the smallest outside radius you can do for a kerfed corner is a little under 2" with 3/4 material. I'd shoot for a 2" radius.

When you do your 45 is the corner you want B to equal A.

To calculate the volume the 45 takes up multiply C times D times the internal height of your box and then divide by 2. In this case the volume of the 45 doesn't really matter because you already lost that volume to the port anyway so it isn't going to reduce the net volume for the sub any more.

Thanks for posting my sketch, for some reason using my phone I have no toolbar even in desktop view... I kinda figured the corners have to maintain the port width, however not sure how Id figure it out what the distance is on paper. I want em small as possible as to not sacrifice too much port area. That's why I was trying to figure out the bracing displacement. I forgot so much from algebra/geometry its sad lol.

So, if I cut the braces to fit in the corners as snug/small as possible by making 2x 45° cuts out of 3/4" material, what would c&d equal? Would it be 1x1 with a cross section of 1.5? Also, I was thinking of radiusing the outside of the inside 45° corners (if that made sense). Or would it just be easier to router the edges of the back port wall, and overlap the side walls? Id think the 45's radius'd would be more efficient, since they'd have a larger radius?

Im using the "box tunning calculator" (BTC) app for my modeling. A lot of people say its accurate. Would you mind double checking my numbers?

22x36x14 w/ .75 material = 5.12 ft^3 gross

4.25x12.5x56 port = 2.57 ft^3 port area

5.12 - 2.57 = 2.55 net @ 30Hz

Ignoring the kerf and 45's, my first port wall from the front of the box would measure 19.125, and back wall would measure 30.25, and inside wall would be 8.125. Those measurements are from corner to corner. So obviously the cut lengths for the side walls (if the back wall overlaps) would be .75 shorter. Pretty simple math, however never hurts to have a second review.

I sure appreciate the help btw, this is my first box so I need all the help I can get .

Thanks

[Triticum Agricolam]

OK, I'm going to try to go after your questions in order.

First off, when making the 45s for the corners there really isn't much to gain by trying to make those as small as possible. They just don't take up much space. What I do is I make them so the long side is 1-3/4" long. This leave a little gap behind the 45. You want this because you will probably have a little bit of glue squeeze out back there and if your 45s come to a sharp point that glue squeeze out will keep you from being able to get them in there tightly. You could make them so that they come to a point but you would want to glue them to one of the side pieces first before you glued that side piece to the front/back. You wouldn't have to deal with the glue squeeze out issue this way, but I think it would be a lot harder to get a good joint than to just make them a little bigger and put them in after you glue the front/back and sides together. I guess it comes down to how you want to build but that's how I would do it and the difference in how much volume they take up is literally like 8 cubic inches, which is nothing.

For your second question I would use a 3/4 radius on the outside corner in your port, but I wouldn't mess with trying to radius the 45 piece. Just make it the same distance from the radiused corner as the width of your port and call it good. Also any performance you may gain by trying to get too fancy with radiusing stuff in the port you could get a lot easier by just making the port bigger, which you might consider doing. Accord to Small's formula for proper port size you need to have 59 sq. in. for a 32 hz tune. Now you can cut that down a bit by flaring the ends of the port, but still I wouldn't want it to get too much smaller.

I checked your math and it shows your port taking up more volume that it should be. I calculated your port to take up just over 2.0 cubic feet. Giving your box a net size of 2.95 cubic feet net after you take out .12 cubic feet for driver displacement and a little bit more for bracing. You might want to think if you really want the box that big. I looked at the box Sundown recommends for the X-12 and it comes out to about 1.85 cubic feet net. The larger you make a ported box the more gain you get around the tuned frequency. If you make that box 3 cubic feet net I think it might make it WAY too boomy. I know it would be too boomy for my taste. Of course Sundown also show a port with only 28 sq. in. of area to which I say, LOL. If you can, I'd try modeling it in WinISD just to see for yourself what difference box size makes.

[King_N9ne]

OK, I'm going to try to go after your questions in order.

First off, when making the 45s for the corners there really isn't much to gain by trying to make those as small as possible. They just don't take up much space. What I do is I make them so the long side is 1-3/4" long. This leave a little gap behind the 45. You want this because you will probably have a little bit of glue squeeze out back there and if your 45s come to a sharp point that glue squeeze out will keep you from being able to get them in there tightly. You could make them so that they come to a point but you would want to glue them to one of the side pieces first before you glued that side piece to the front/back. You wouldn't have to deal with the glue squeeze out issue this way, but I think it would be a lot harder to get a good joint than to just make them a little bigger and put them in after you glue the front/back and sides together. I guess it comes down to how you want to build but that's how I would do it and the difference in how much volume they take up is literally like 8 cubic inches, which is nothing.

For your second question I would use a 3/4 radius on the outside corner in your port, but I wouldn't mess with trying to radius the 45 piece. Just make it the same distance from the radiused corner as the width of your port and call it good. Also any performance you may gain by trying to get too fancy with radiusing stuff in the port you could get a lot easier by just making the port bigger, which you might consider doing. Accord to Small's formula for proper port size you need to have 59 sq. in. for a 32 hz tune. Now you can cut that down a bit by flaring the ends of the port, but still I wouldn't want it to get too much smaller.

I checked your math and it shows your port taking up more volume that it should be. I calculated your port to take up just over 2.0 cubic feet. Giving your box a net size of 2.95 cubic feet net after you take out .12 cubic feet for driver displacement and a little bit more for bracing. You might want to think if you really want the box that big. I looked at the box Sundown recommends for the X-12 and it comes out to about 1.85 cubic feet net. The larger you make a ported box the more gain you get around the tuned frequency. If you make that box 3 cubic feet net I think it might make it WAY too boomy. I know it would be too boomy for my taste. Of course Sundown also show a port with only 28 sq. in. of area to which I say, LOL. If you can, I'd try modeling it in WinISD just to see for yourself what difference box size makes.

Yeah I tried winisd and I can't seem to model a box w/o the sub parameters. I put in what I could, but it gave me an error when I tried to save. However I did model a box using Torres'. I now realise the btc app only models with zero common walls. So that's why the port area is so far off.

Now I need to refigure everything. I got a lot more room for port area then I thought. I'll cut 45's so that it keeps the port width (a& equal. So do you think I should still keep the vol around 2.3-2.5 w/ 20-22 in/^3 of port area @ 29-30Hz?

[King_N9ne]

I actually found some specs and recommendations from Brian. For the X-12

FS 30Hz

14 in/^3

42in^2

.12 displacement

3ft^3

Kinda interesting, yet frustrating. Now I have no idea what to build....

Here's the link

http://www.stevemeadedesigns.com/board/topic/176883-x12-d2-box-design/page-2