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Braindead
09-01-2013, 08:25 PM
I just designed a box for 2 ab xd 10's. I'm aiming for 2.5 cubes @35Hz.

My port dimensions are 2 wide*12.5 high*17.5 deep

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Do my calculations match up, and will there be port noise?

AndrewHD
09-01-2013, 08:39 PM
This box only has around 2.2 cu ft internal (when using 3/4" material) not including port displacement

Milk Mayne
09-01-2013, 09:00 PM
I'd suggest a little more port area as well.

Braindead
09-01-2013, 09:23 PM
I'd suggest a little more port area as well.

Could I just widen up the port to about 4 inches and increase the depth to about 15in, or would that do all kinds of crazy **** to my tuning

bbeljefe
09-01-2013, 09:36 PM
If that 25" measurement isn't the full width, like it looks, then you're just under 2.3 cubes before driver displacement. You have 25inē of port, which is a bit too little. You should have about 16inē per foot on that power with those drivers.

If those drivers displace about .10ft then you're at 2.1 cubes and with that port your tuning is ~40.

And yes, you can make the port wider and add depth to the box in order to accomplish your desired volume and tuning. Just remember to subtract port and driver displacements from your gross volume.

AndrewHD
09-01-2013, 10:29 PM
I think you should make the box a bit bigger (deeper to be exact) and then widen up that port to about 2.75-3"

Nutdawg651
09-01-2013, 10:36 PM
If that 25" measurement isn't the full width, like it looks, then you're just under 2.3 cubes before driver displacement. You have 25inē of port, which is a bit too little. You should have about 16inē per foot on that power with those drivers.

If those drivers displace about .10ft then you're at 2.1 cubes and with that port your tuning is ~40.

And yes, you can make the port wider and add depth to the box in order to accomplish your desired volume and tuning. Just remember to subtract port and driver displacements from your gross volume.

Did u get my pm

bbeljefe
09-01-2013, 11:23 PM
Just got it man...

Braindead
09-02-2013, 01:39 PM
If that 25" measurement isn't the full width, like it looks, then you're just under 2.3 cubes before driver displacement. You have 25inē of port, which is a bit too little. You should have about 16inē per foot on that power with those drivers.

If those drivers displace about .10ft then you're at 2.1 cubes and with that port your tuning is ~40.

And yes, you can make the port wider and add depth to the box in order to accomplish your desired volume and tuning. Just remember to subtract port and driver displacements from your gross volume.

Whenever I put my desired measurements into winISD (2.5 cubes, 33Hz, 12.5*4 port) I end up with a port length thats around 40in. Am I doing something wrong?

Braindead
09-02-2013, 01:42 PM
Also the 25" is the full width, I'm not sure why I didn't put the line to the end.

Braindead
09-02-2013, 01:56 PM
AB doesn't list the displacement on their website, would .1ft^3 be a good estimate?

bbeljefe
09-02-2013, 02:00 PM
Also the 25" is the full width, I'm not sure why I didn't put the line to the end.

Oh, well then your box is way too small. And WinISD is telling you to make the port that long because of the area of the port. Less area will net you a shorter port and more area, a longer one. And if you're using WinISD Beta, pay close attention to the vent mach. I don't know why it's not on the newer versions, because it tells you whether or not the port area you've chosen will result in a noisy port.

You'd probably be safe with a 2.5-3" wide port in that application. That would cut the length down to around ~24".

Braindead
09-02-2013, 02:10 PM
Oh, well then your box is way too small. And WinISD is telling you to make the port that long because of the area of the port. Less area will net you a shorter port and more area, a longer one. And if you're using WinISD Beta, pay close attention to the vent mach. I don't know why it's not on the newer versions, because it tells you whether or not the port area you've chosen will result in a noisy port.

You'd probably be safe with a 2.5-3" wide port in that application. That would cut the length down to around ~24".
I'm using the alpha version. So should I just maintain the port width and have it bend around the corners until i reach the correct port length?

Plugging in the dimensions (14H*25W*18D giving me around 2.8 gross) and using .2 as a rough estimate for driver displacement, and a port thats 12.5*3*27.25 I'm getting around 43.7Hz tuning. Makes no sense, I have to be plugging in the wrong number somewhere

bbeljefe
09-02-2013, 05:42 PM
I'm using the alpha version. So should I just maintain the port width and have it bend around the corners until i reach the correct port length?

Plugging in the dimensions (14H*25W*18D giving me around 2.8 gross) and using .2 as a rough estimate for driver displacement, and a port thats 12.5*3*27.25 I'm getting around 43.7Hz tuning. Makes no sense, I have to be plugging in the wrong number somewhere

Yeah, that's 2.8 cubes, but your port volume and your driver displacement reduce that volume. Figure the port at 3.75*12.5*23.25 for a volume of 1090inē plus 346inē for driver displacement and add that to your existing depth measurement. You need to add 4.88" to the depth.... or, about 5 inches and your port length for 35 Hz will be 23.25.

Braindead
09-02-2013, 06:52 PM
Yeah, that's 2.8 cubes, but your port volume and your driver displacement reduce that volume. Figure the port at 3.75*12.5*23.25 for a volume of 1090inē plus 346inē for driver displacement and add that to your existing depth measurement. You need to add 4.88" to the depth.... or, about 5 inches and your port length for 35 Hz will be 23.25.

So in order to reach my desired tuning have all the dimensions basically the same and have a port thats 3.75*12.5*23.25? In order to do that would I need to have the inner part of the port go 13.5in deep then have the port continue at a right angle 9 more inches, giving me a port thats 3.75*12.5*23.25? Also that'd put me around 2.5 net cubes, right? Also thanks for all the help man

bbeljefe
09-02-2013, 07:13 PM
So in order to reach my desired tuning have all the dimensions basically the same and have a port thats 3.75*12.5*23.25? In order to do that would I need to have the inner part of the port go 13.5in deep then have the port continue at a right angle 9 more inches, giving me a port thats 3.75*12.5*23.25? Also that'd put me around 2.5 net cubes, right? Also thanks for all the help man

You need to add five inches to the depth of the box, making it 23" deep. That will get you to 2.8 cubes. Then, you need a 23.25" long port that's 3" * 12.5 inside measurement. The 3.75" I mentioned is the gross displacement of the port, not the actual port dimension. And yes, you will need to make the port L shaped. And remember that when you're laying out the port inside the box, you measure length through the center of the port, not through one side or the other. In this case, that would be 1.5" from the inside wall of the box.

Braindead
09-02-2013, 08:02 PM
You need to add five inches to the depth of the box, making it 23" deep. That will get you to 2.8 cubes. Then, you need a 23.25" long port that's 3" * 12.5 inside measurement. The 3.75" I mentioned is the gross displacement of the port, not the actual port dimension. And yes, you will need to make the port L shaped. And remember that when you're laying out the port inside the box, you measure length through the center of the port, not through one side or the other. In this case, that would be 1.5" from the inside wall of the box.

I don't need 2.8 cubes net, only 2.5. 2.5 net is pushing the upper boundaries of what these subs like, so could I just keep the depth where it is and have the short "leg" of the L a little bit longer? I can't give up 5 more inches of depth, I need that room for cargo.

Braindead
09-02-2013, 08:07 PM
18" deep to be exact

bbeljefe
09-02-2013, 08:13 PM
Well in that case, the port needs to be 26" long. I'm sorry, I thought your goal was 2.8 cubes...

I've been working on several projects today and only stop by the computer to take a break now and then so I guess I haven't been focused too well.

Braindead
09-02-2013, 09:11 PM
Well in that case, the port needs to be 26" long. I'm sorry, I thought your goal was 2.8 cubes...

I've been working on several projects today and only stop by the computer to take a break now and then so I guess I haven't been focused too well.
No problem man, you've been tons of help. So to recap, the box will be 25*14*18 with a port that's 3.75*12.5*26 and that'll land me around 2.5 cubes tuned at 35Hz?

Also, how big should I make the cutout for 10's and do I need to use wood glue or can I skip that since im using silicone caulk to seal all the seams?

bbeljefe
09-02-2013, 10:18 PM
The port should be 3" * 12.5", not 3.75". And please, please, please save yourself a headache and never, ever, ever use silicone caulk on anything but glass and stone.

Silicone does not stick to wood well, contrary to popular belief and it stinks like hell. Use plenty of good quality wood glue (Titebond II or III.. I prefer the latter), make your cuts very accurately and you won't need any sort of caulk on the inside of the box. But... if you want to use caulk, I would use Polyseamseal or plain old painter's caulk, as they are water based, non volatile and, they're made to stick to wood surfaces.