Does this box look okay for two 12" HDS3's?

[Justinh722 10+ year member]

I'm trying to design a box for my BMW 325i. I have two 12" HDS3's and an Audiopipe 3k watt amp. I came up with 4.25 net cubic feet with 5.3 gross. I'm going with 50 sq inches of port area. I came up with a 4 inch slot port that is 27 inches long. First port board I have it at 21 inches and the 2nd at 6 inches. I have a tune of 31 hz.

I have a max of 30 inches wide and a height of 14 inches. My depth can range anywhere up to 27 inches.

My design has the subs facing back and the port facing back. That leaves a gap of only .4 inches between subs. Is this an issue?

My dimensions are 30w x 14h x 27d. I initially wanted to do a blow through box with aeroports coming up into my rear deck since I already cut a big piece out of the sheet metal to get sound in the cabin. I also took a large piece out of the rear behind the seats and removed the factory sound deadening between seats. I found that I would need a 4th order bandpass to make it even sound decent.

If someone could look over my measurements I would greatly appreciate it. I used bassbox 6 pro.

12.5 x 30 - back

12.5 x 26 - front

30 x 27 - top

30 x 27 - bottom

14 x 27 - side

14 x 27 - side

12.5 x 21 - port

12.5 x 6 - port

My basic question is will it be a problem with the subs being so close together? Are my calculations right? I had to do bassbox pro as a sealed box and added my port as a misc object for the displacement since there isn't an option for slot port. I appreciate the help.

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[shammyhavik]

You should shoot for 14 square inches of port per foot at 4.5 cubic feet before displacemnet

 

[shammyhavik]

also you should use torres box calculator

 

[Justinh722 10+ year member]

I can't go any bigger than what I'm at and I don't wanna sacrifice anymore room. Right now I'm only at 2.12 cubes each after displacement. To go any bigger with port area, I would have to use a 5.3 inch port and it would have to go out the side of the box. Minimum port area is 12 sq in per cubic foot...which is what I'm at. Is it bad to mount the subs directly next to eachother? Would it make the front baffle weak. I messed with Torres a little bit. I'll see what I come up with in that. I tried winISD pro also.

 

[Jeffdachef 5,000+ posts]

I wouldnt tune them that low unless you like your low low bass enhanced music a lot. I'd go with a center straight shot port thats 12.5 x 4 by 17" long face towards the trunk. With the 14 x 30 x 27 measurements. Or do three 4" aeroports at 14 inches long each.

 

[Justinh722 10+ year member]

The 17 inch slot port would be a 37 hz tune. That's a lil high for my liking. Aeroports would be a 36 borderline 37 hz tone also. Center port would give me 2 seperate boards on each side and the sub would be .2 inches away from the port. I don't even know if that would work. Only thing I could do is make the box smaller.

 

[Jeffdachef 5,000+ posts]

The 17 inch slot port would be a 37 hz tune. That's a lil high for my liking. Aeroports would be a 36 borderline 37 hz tone also. Center port would give me 2 seperate boards on each side and the sub would be .2 inches away from the port. I don't even know if that would work. Only thing I could do is make the box smaller.

its a 37 tune if you dont count common walls You need to add that into the equation too which drops your tuning by quite a bit. Its fine for the subs to be that close to the port.

 

[Justinh722 10+ year member]

I didn't know that I had to add that in. How exactly is that done? Also, my baffle is 30 inches and if the port is 4 inches that leaves me 26. So 13 inches per side. The subs themselves are 12.8. Im just wondering if the structural part of the baffle will hold up with that small amount of space left over? Thanks for the help.

 

[Jeffdachef 5,000+ posts]

I didn't know that I had to add that in. How exactly is that done? Also, my baffle is 30 inches and if the port is 4 inches that leaves me 26. So 13 inches per side. The subs themselves are 12.8. Im just wondering if the structural part of the baffle will hold up with that small amount of space left over? Thanks for the help.

the center port will add A LOT of strength and bracing you'll be fine. Its a better design then an L port structurally. It'll be like having a double baffle in terms of strength wise. Still, add your 45s and the center divider.

 

[shammyhavik]

Center port will make your frequency response better too. frequencies are flatter, less cancellation, other beautiful things too

 

[Justinh722 10+ year member]

A center divider would go through the port wouldn't it? Since I have space issues. Would I need 2 boards for the center port? Shouldn't the port be decent enough for bracing?

 

[CSCStang]

A center divider would go through the port wouldn't it? Since I have space issues. Would I need 2 boards for the center port? Shouldn't the port be decent enough for bracing?

The 2 port walls through the center are the bracing bud. Add 45's to the corners also.

 

[Justinh722 10+ year member]

ok cool. So is it the same concept as an L port? A 17 inch port for the center would be two 8.5 inch walls? This is my first slot port box. Usually do aeroports.