Box for two DD 1508's - Got questions..

[westman995 10+ year member]

Ive been using the calculators on the12volt, theyre pretty handy. Ok so after that.. I have one big problem. There is NOWHERE on the box at all that i can do a 22" long port. When DD says on their site to do 22" long i am only assuming that that means how long it is on the outside of the box, not the lenght going inside the box, is that correct?

My only idea so far is, to build the box as shown in my previous pics, except on the drivers side not have the big hump sticking out, and just go straight from top to bottom on that side, allowing me to do a longer port, but even then my box is only going to be 16 max inches tall.

So, i am really stumped on what to do right now. Knowing im supposed to do a 22" long port really messes stuff up, as i cannot fit that anywhere. So i may have to sacrifice something to go with a different size/lenght port or whatever.

 

[westman995 10+ year member]

Sometimes you will find a certain tuning frequency or box shape just flat can't be done, so you need to try something else. You can bend the port around the back of the box sometimes to help. Try messing with this calculator to learn more about how it works...
http://reaudio.com/speaker_box/LPort_Box_Calc.html

The only problem is i cant really fit the subs anywhere else. I think im gona have to go wtih the plan and just do it, but make the port a little different than is recomended by DD. Even if i dont put the subs in that spot, there is no other palce that has more room than that.

I cant really see any of these calculators helping me at all due to my box shape, either that or im just too stupid to figure it out. If i were building a normal shaped box i would have this shit down already.. This is really confusing me.

 

[Fuknmovin 10+ year member]

I hear ya, I am dealing with an odd shape right no as well, can be a pain to get right sometimes, try doing a fiberglass box and still getting it to sound good! LOL!

 

[westman995 10+ year member]

Ok, i hope i am right when i say the 22" wide wont make a ton of difference as long as i have port area the right size?

Ok so 16x1.5=24 which is what i need, 24" port area. Then it says i would need to make it 18" long. I would have the bend the port at the bottom, but i should be able to, just going to take some extra time and work.

No thanks on the fiberglass, too much work for me haha..

 

[DNick454 10+ year member]

Transmission-line box I designed for two 8" drivers...

//content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

Line is 7.7 feet long with port area = two 8" cones and tuned to 36.5Hz

Shame you don't have more room to work with //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif

 

[Fuknmovin 10+ year member]

Ok, i hope i am right when i say the 22" wide wont make a ton of difference as long as i have port area the right size?
Ok so 16x1.5=24 which is what i need, 24" port area. Then it says i would need to make it 18" long. I would have the bend the port at the bottom, but i should be able to, just going to take some extra time and work.

No thanks on the fiberglass, too much work for me haha..

Yeah, the port can (within reason) be any shape as long as there is the proper area, as for the bend, you just do it like the ones you have seen, like the one above. Remember to draw a line in the center of the port to measure the length as its not as simple as it looks to measure them in the bend. I like to draw a diagonal line from the inside corner of the bend to the outside corner, then trace a line in the center of the port from beginning to end and then measure that line for total port length.

 

[westman995 10+ year member]

Nice box dnick, wish i did have some more room. But if i were going with a bigger car or more room, i would prolly go with some bigger subs even tho these subs pound for their size. I havent gotten to see what they can really do yet either tho.

This is going to get quite confusing, as im already pretty confused on what i should really do. I have two ideas. Not sure i really like either of them tho. Here they are.

First is to take off the left side of the box and make it straight top to bottom, and port out to the side. Which i would want to do, as far as output since im told its better to go out the side. And ive tried it with port to the side and it seemed fairly louder. But im not sure i like the look of that. The port would only be 13.5 inches high and i think 1.75 wide to get about 24" port area.

And if i for some reason needed to make the port too long where it would hit the subs, i could possibly do this. Where it has the angle in the front as my car has that shape. Just not sure how much, if any it will help. Due to the subs having a huge magnet, im not sure the magnet will clear the box. I will have to check into that.

And the last one, assuming the subs will clear if i slant the front and move the subs forward a little.. I can get a 22" long port this way.

 

[mmouse57 10+ year member]

west if your in florida and need help making a box lke that id love to build it for you just pay the $30 for sheet of mdf wood screws and some glue 'tips excepted if you like the final results //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

im talking

like this //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif i build so many boxes but i rarely get to build a box like that and my $10k worth of tools in the garage just scream to be used right //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[westman995 10+ year member]

Florida? Says your in st cloud? Haha im in southern Minnesota. And there is a town in minnesota a few hours away called st cloud, unless you used to live here??

By the way, i dont have the wood yet and i was wondering what size they come in? I dono how much im going to need. Maybe more than one sheet?? And how much do they generally cost?

 

[Nut Hair Trick 10+ year member]

What's wrong with building the box the same width, for as deep as it goes? Do you really have to build out at the top? I would have one uniform width, run the port the whole width of the box, (w-1.5) would be your port length. Then just make the port as wide as you have to, to get your desired port area. For cosmetics, you could put make the top baffle flared out to cover the holes on each side of the box. If the box calls for a longer port than you have depth, then just bend it at the bottom.

 

[westman995 10+ year member]

What's wrong with building the box the same width, for as deep as it goes? Do you really have to build out at the top? I would have one uniform width, run the port the whole width of the box, (w-1.5) would be your port length. Then just make the port as wide as you have to, to get your desired port area. For cosmetics, you could put make the top baffle flared out to cover the holes on each side of the box. If the box calls cor a longer port than you have depth, then just bend it at the bottom.

Well that WAS the plan at one point, at the beginning of the thread. But it turns out i do not think that its going to be enough volume with it being that small, thus the reason im trying to build it to get the max volume right now. Otherwise that would be the easiest way to go.

Volume before port and sub displacement would only be about 1.5.. Which is what i need after the port displacement.

How can i figure out just how much area the port takes up? Cuz the calcs i use i enter outside dimensions with the wood size but i dont think taht would work right for the port, would it?

 

[westman995 10+ year member]

Ok guys, i had them in this smaller box which i thought was too small. But i built a (shitty) box, it was the T shape with the one side cut off, subs firing up and port to passenger side. I did it to right about 24" port area, tuned it to 40hz. Now mind the box was a pretty big piece of shit, old wood, leaked alot of air. I only built it to see what it would do and see how it would fit. Not only did it sound like shit it didnt fit near as good as i was hoping.. Well i threw the subs back into the smaller box, and they pound pretty hard in there. So, i think im going to make my design to be much more similar to that box. This box is also pretty crappy, old used wood from another box, but it is sealed up atleast. I had built that box for some other subs just to see how loud i could make them, just wanted to play with making a slot ported box to get better and not waste good wood.

So, the box i have them in is as follows

28" wide, 11.5" high, 12.5" deep..

Brings me to 1.6 cubes according to the calc on the12volt.com

Port is 1.5" wide, 11" high, and 13" long inside the box. That was said to be 40 hz. And then, thats only like what 16" port area? When it was to have about 24".. That going to be much of a problem?

But now, i have some questions on this. I know it pounds pretty hard in this box. But the placement of the woofers is what im concered about, regarding the port and stuff. I have on sub right on the side of the port, and the other is right on the other side of the port.. Well here is a pic to know what i am talking about cuz i cannot explain it. I would think it shouldnt really matter, but i just want to make sure im not going to mess anything up. This is what the current box looks like. Is there any problems with that design, mostly the placement of the port and subs. Cuz they pound pretty good in it, with only 125 rms to each off a rockford 2 channel..

 

[westman995 10+ year member]

By the way, the real box is going to be very slightly different specs i think. Im gona built it just slightly less deep, and a little bit higher instead. And maybe around an inch off lenght only to make it fit in there better. And then ill do the top baffle to also be a trim piece like my original plan. So it sounds like this will work pretty good.

Im not really sure why in the hell the box design before was giving me not that much space, yet this box right here seems to be plenty.. Maybe ive been doing something wrong, but ive done the calculations many times and nothing has changed much.

EDIT: The box i am planning to make is going to be roughly 26x15x10 bringing me again to 1.6 cubes.. The port in that box would now be 13.5 high and 1.5 wide. That will be more like 20" port area vs the 16. Should that make much difference and help? Seeing as how DD wants to have 24" port area. The port would need to be 17" long to be 40hz which i think i want it tuned to, its loud like that to me. May change it up and test later but 40hz is starting point.

The main thing i want to run by you guys is the placement of the subs. The circle on the pics below are about the outside of the subs, you can see it will be close to the port but shouldnt matter. The thing im only asking about is one sub being placed right in front of where the air goes out, and the other behind the port where it doesnt escape. Here is a pic of what the box i want to build will look more like