Subwoofer Port Ideas

[shawndoggy]

I'm really trying to stay back about 2.5-3" from where the bottom of your front panel "kick plate" is.

I don't think that's possible without removing the seat to get the box in, if you want to get 1.8ft2 and get it under the steering rack, unless you go very trapazoidal towards the hull, and even then...

Did you get the heater core mounted really high up in there?

[Ndawg12]

I don't think that's possible without removing the seat to get the box in, if you want to get 1.8ft2 and get it under the steering rack, unless you go very trapazoidal towards the hull, and even then...

Did you get the heater core mounted really high up in there?

This seat is removed and I modified my riser. I got 18" (real tight) under there before on my last box. The box will probably need to be trapazoidal to say the least after I work arond the heater and steering cable into the floor....

[jk13]

Isn't a .75 port width REALLY narrow? Like if you are going to get noise a really narrow port would be the way to do it?

Just going off the drawing provided answering the question asked.

I'd do at least the 1" port, that's why I posted it. I'd also brace it so the 16.5" side walls don't flex. So really it would end up different entirely.

Edited February 8, 2013 by jk13

[Ndawg12]

Just going off the drawing provided answering the question asked.

I'd do at least the 1" port, that's why I posted it. I'd also brace it so the 16.5" side walls don't flex. So really it would end up different entirely.

Your guys are being helpful and difficult at the same time !!! :pullmyhairout:

[Earmark Marine]

Isn't a .75 port width REALLY narrow? Like if you are going to get noise a really narrow port would be the way to do it?

Yes, that is narrow for a 12" sub. Consider this comparison between a 3"X3" square port versus a 0.75"X12" slot port of the same surface area. There will be more wall friction and less efficiency with the 75"X12" port even though the wall area is the same.

David

[Ndawg12]

Yes, that is narrow for a 12" sub. Consider this comparison between a 3"X3" square port versus a 0.75"X12" slot port of the same surface area. There will be more wall friction and less efficiency with the 75"X12" port even though the wall area is the same.

David

in order to suffice my fixed dimensions ( 16.5" h x 10" d) thats all I had to work with....

[martinarcher]

Building killer boxes in tight spaces is rough isn't it!? My box has to go in with the seat out and the passive radiator has to be installed after the box is under the dash (on top of the box) because the box is exactly the same height as the lowest point on the dash so the R won't clear. Those cubes were worth it. Don't be discouraged Nate....you can do it man!

[Ndawg12]

Building killer boxes in tight spaces is rough isn't it!? My box has to go in with the seat out and the passive radiator has to be installed after the box is under the dash (on top of the box) because the box is exactly the same height as the lowest point on the dash so the R won't clear. Those cubes were worth it. Don't be discouraged Nate....you can do it man!

Doing it right now, cut fit recut fit cut again...hopefully this third box will be good for a while. Btw member MLA, who is local for me, is hooking me up with a 4" aero port, should have it tonight

[Earmark Marine]

Perfect.

Just keep in mind that you have more port surface area with a round 4" I.D. than stated before so the port must be longer if all else is to remain the same. The internal port termination should be around 4" away from the back wall, or side wall if using an elbow. Going from a 0.75" MDF port wall thickness to a 0.125" plastic wall thickness changes the enclosure internal displacement. If you have a proven enclosure template for a given woofer, then you can make all these re-calculations and get it pretty darn close with a simple desktop calculator.

Personally, I like the old calculator/yellow legal pad/pen conversion system once I have a proven design.

David

[martinarcher]

Perfect.

Just keep in mind that you have more port surface area with a round 4" I.D. than stated before so the port must be longer if all else is to remain the same. The internal port termination should be around 4" away from the back wall, or side wall if using an elbow. Going from a 0.75" MDF port wall thickness to a 0.125" plastic wall thickness changes the enclosure internal displacement. If you have a proven enclosure template for a given woofer, then you can make all these re-calculations and get it pretty darn close with a simple desktop calculator.

Personally, I like the old calculator/yellow legal pad/pen conversion system once I have a proven design.

David

That's how I do mine as well.

[nuttyskier2002]

Ndawg, I just completed a ported box for a 12" JL 500W sub. It went under the helm of my 2006 V-ride. The outside dims are

18.5"(H) x 17.375"(W) x 16"(D). My port is 1.375" x 12.5" x 26.125". I used JL's model as a base but adjusted the H, W and D to fit the space available. I don't have a heater so I don't know how much space that takes up. But I can send you my plans and you can see it it will help you. You won't be able to use them verbatim of course, but it will give you an idea of how to construct you port so that it is not too narrow. As stated above......as long as you keep the surface area of the port the same (yours is 12.56 sq in) the length will remain the same.

[Earmark Marine]

Keep in mind that all 10-inch enclosures are not interchangeable, or 12-inch and so on. Each driver requires a different enclosure based on a unique set of parameters called Thiele/Small. Also, there are different alignments for any driver to get a prescribed result based on personal preference or a specific application. With most any enclosure (as with the woofer also) you can elect to go for a wider bandwidth, deeper extension, greater linearity, emphasis towards one or the other extreme of the bandwidth, or greater output over a narrower bandwidth. The summed energy may not be that different but the where the energy occurs is different and the sound is certainly different.

Again, a proven design applies to one driver only for one application only.

David

[nuttyskier2002]

David brings up a very good point here so let me clarify what I'm suggusting above. Due to the issue that Ndawg is running into with his port surface area dimension (the greater of the two not being equal to the height or width of his proposed box dim without making the other too small.....ie .75") I am suggesting showing him my plans. That way he can see how I addressed this issue. His dimensions will be differenent than mine of course.......but the method of constructing the port will be similar.

[Cdoogles]

Wow, this thread is becoming a great resource. So, I fell off on my original response and it looks like it got a little misconstrued. So I am building a vented box from scratch for a Exile 12"Xi12D. Last year I built a sealed box for the same subwoofer and although very happy with it, I wanted to try a vented box this year to see the difference. I will be putting it under the helm of my MXZ in the driver's footwell.

The specs of the sub are here: http://www.exilecaraudio.com/products/xisubs/?tab=specs

I tried using the WINisd program, but honestly I didn't put more than 20 minutes into it before I realized it might be easier to ask the brain trust here on the forums. So the easy part, the box will have a volume of 1.6 cubic feet. (SPL Size) I've got to refine my measurements, but at the moment I am thinking I can get away with a rectangular box. I had some measurements, but I have to check and see how big I can make it since the vent will obviously add to the overall size of the box.

So back to my original question...the specs for the sub list a vent 11" in length with a 4"diameter. I'm using the calculator Shawndoggy referenced and I am having a little trouble figuring out how that converts into a rectangular vent..... any help is appreciated

Edited February 12, 2013 by Cdoogles

[Ndawg12]

A heater significantly cuts down the depth of the box, probably could have gained .2cf by adding a bumpout to fit under the heater but I'm right at 2.1cf. The problem I'm running into is that I can not get the inside flared port end 4" from the back wall, nor can I get it 4" off the side wall (specs from the aeroport). I didn't realize how big an actual 4" port is, the cut out is over 6" !! I'm waterproofing it now so I've got to work with what I've got. I assume my tuning will need to be adjusted since I didn't follow all specs to a "T"...?

Shout out to my man MLA, he went out of his way for a second time for me. If you're in the area give him a shot at your business

[Ndawg12]

Ndawg, I just completed a ported box for a 12" JL 500W sub. It went under the helm of my 2006 V-ride. The outside dims are

18.5"(H) x 17.375"(W) x 16"(D). My port is 1.375" x 12.5" x 26.125". I used JL's model as a base but adjusted the H, W and D to fit the space available. I don't have a heater so I don't know how much space that takes up. But I can send you my plans and you can see it it will help you. You won't be able to use them verbatim of course, but it will give you an idea of how to construct you port so that it is not too narrow. As stated above......as long as you keep the surface area of the port the same (yours is 12.56 sq in) the length will remain the same.

I appreciate the help but I've got it built and need to deal with what I've got.

[jk13]

Is there room to put an elbow on that port to get the length you need Ndawg?

[Ndawg12]

Is there room to put an elbow on that port to get the length you need Ndawg?

good question, the answer yes but is there a distance I need to stay away from the sub? I wish I would have taken pictures before I left but I'm out of town for a week... I do have a photo I can photo shop to show how the cutouts are oriented...

Edited February 13, 2013 by Ndawg12

[jk13]

Bend it straight up and keep it more than 4" from the top of the box. Support it to the floor of the box near the bend and to the back wall if possible for strength.

[MLA]

Wow, this thread is becoming a great resource. So, I fell off on my original response and it looks like it got a little misconstrued. So I am building a vented box from scratch for a Exile 12"Xi12D. Last year I built a sealed box for the same subwoofer and although very happy with it, I wanted to try a vented box this year to see the difference. I will be putting it under the helm of my MXZ in the driver's footwell.

The specs of the sub are here: http://www.exilecaraudio.com/products/xisubs/?tab=specs

I tried using the WINisd program, but honestly I didn't put more than 20 minutes into it before I realized it might be easier to ask the brain trust here on the forums. So the easy part, the box will have a volume of 1.6 cubic feet. (SPL Size) I've got to refine my measurements, but at the moment I am thinking I can get away with a rectangular box. I had some measurements, but I have to check and see how big I can make it since the vent will obviously add to the overall size of the box.

So back to my original question...the specs for the sub list a vent 11" in length with a 4"diameter. I'm using the calculator Shawndoggy referenced and I am having a little trouble figuring out how that converts into a rectangular vent..... any help is appreciated

Im not sure how far along you are, but just a heads up. The helm wall tilts forward (toward the bow, not toward the drivers seat) as it rises from the floor. So to fallow that wall, your enclosure will somewhat trapezoidal. Lats year, we did a 1.8 net ported enclosure for a 12" square sub, without modifying the factory cut opening behind the formed ABS insert. This years wont be a 12, so the opening is getting enlarged a little

[MLA]

A heater significantly cuts down the depth of the box, probably could have gained .2cf by adding a bumpout to fit under the heater but I'm right at 2.1cf. The problem I'm running into is that I can not get the inside flared port end 4" from the back wall, nor can I get it 4" off the side wall (specs from the aeroport). I didn't realize how big an actual 4" port is, the cut out is over 6" !! I'm waterproofing it now so I've got to work with what I've got. I assume my tuning will need to be adjusted since I didn't follow all specs to a "T"...?

Shout out to my man MLA, he went out of his way for a second time for me. If you're in the area give him a shot at your business

Ndawg,

You're very welcome. It was sitting around, so im happy to see it put to good use.

[nuttyskier2002]

Wow, this thread is becoming a great resource. So, I fell off on my original response and it looks like it got a little misconstrued. So I am building a vented box from scratch for a Exile 12"Xi12D. Last year I built a sealed box for the same subwoofer and although very happy with it, I wanted to try a vented box this year to see the difference. I will be putting it under the helm of my MXZ in the driver's footwell.

The specs of the sub are here: http://www.exilecaraudio.com/products/xisubs/?tab=specs

I tried using the WINisd program, but honestly I didn't put more than 20 minutes into it before I realized it might be easier to ask the brain trust here on the forums. So the easy part, the box will have a volume of 1.6 cubic feet. (SPL Size) I've got to refine my measurements, but at the moment I am thinking I can get away with a rectangular box. I had some measurements, but I have to check and see how big I can make it since the vent will obviously add to the overall size of the box.

So back to my original question...the specs for the sub list a vent 11" in length with a 4"diameter. I'm using the calculator Shawndoggy referenced and I am having a little trouble figuring out how that converts into a rectangular vent..... any help is appreciated

In case you didn't get an answer to this question yet....to convert first figure the area of a 4" diameter round port. Formula for this is pi x radius squared. pi is 3.1417....radius is 1/2 x diameter. So 2 squared = 4. 4 x 3.1417 = 12.5668.

You want to keep the smallest dimension of this port surface no less than 1 1/4" for a 12" sub. For this I would choose

1 1/2" x 8 3/8". This comes out to 1.5 x 8.375 = 12.5625 (close enough). Keeping the port surface area the same means you keep the length the same as well.

Edited February 14, 2013 by nuttyskier2002

[Cdoogles]

Does it matter if your port is facing a certain direction? I was going to have a forward facing sub (towards the driver) but was thinking of putting the vent going out one of the sides. Any issue in doing this? Thanks!