need help building a subwoofer box for my subs

[Siikdude]

hi there.. so i have 4 x skar zvxv2 d2 subs and i have a jeep wrangler 10' the max diamentions in m jeep is a width 42in x length 26 1/2in would like less like 23 length or less if possible to have some space in my jeep, and the height i can do max 17in or i can do a Wedge Enclosures that measures 18 1/2in length max by 42 width max by back height max 25in and front height max 17in. i have some some models of what i was thinking. but i believe it has to much volume in it ill post it btw i like to listen to trap, rap, dubstep, house music, hiphop, edm

drivers recommendation is as followed by skar audio
Recommended Enclosure Specifications
Recommended Port Area 38.0 in² ,
Recommended Ported Volume 3.00 ft³
,Sealed Volume Not Recommended
Recommended Tuning Frequency 34 Hz

Subwoofer Measurements
Total Height 11.39"
Mounting Depth 9.89"
Magnet Diameter 7.85"
Cut-out Diameter 11.25"
Outside Diameter 12.62"

T/S Parameters
Bl- 21.8 n/a, Fs 44.0 Hz, Re Dual 2 Ω, Sd 510.0 cm2, Cms 0.04 mm/N ,Mms 341.0 gr, Qes 0.50, Qms 6.10, Qts 0.45. Vas 25.6 L. Nref 0.15%. Xmax 29 mm (one-way), Sensitvity 83.7 dB

box max dementions
24 length x 42 width x 25 height back panel with front panel 17 height, or 17 height max
volume displacement of my 4 subs should be 33.84 liters im not 100% sure on this.

this was my initial idea, and the middle has plexiglass.

pictures are in link below

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[Doxquzme Premium Member]

Assuming the driver displacement is .25 ea. that means you are going to need a box that is around 13.25 internal cubic feet (Vb of 12. to 12.15 Cu feet) with a port that is large enough to handle that air, so lets say 6x10x5 inches. I'd lose the Plexiglas, you'll need a piece that is around .75" thick to withstand that kind of air pressure and anything larger than 12x12 is going to run you in the $125 to $200 range (just for that piece of plastic) not to mention what it will take to seal and secure it in the making of that box. I calculate that the box around 13.25(internal) gross cubic feet, that is HUGE!!!

You might consider getting exotic, like doing a 6.625 cu foot box, load the drivers out of phase, face to face, in a compound load or an in-phase isobaric loaded box.

 

[Doxquzme Premium Member]

You might consider going with a couple of 15's instead. A 13-14 cubic foot nbax, is going to need substantial bracing, at leas double thick walls and a tipple thick baffle, unless you use like 13 layer birch ply, that could be $3-$400 dollars just for the wood alone. If you end up using MDF, you will need an engine hoist to load that into the jeep as it will likely weigh in at around 4-500lbs!

 

[Siikdude]

oh god. yeah thats getting expensive. i already have 4 12s and not looking for 15s. im also going to be running a taramp smart bass 8k.. btw i have both measurements of the outer and inner of the box.. perhaps u could take another look at the numbers?
Box with pexi in middle inner dimensions 40 1/2 W by 23 1/2 L, 13 1/4 height 2. height 1= 21
measurements of Outer box with thickness 3/4 wood= 14 H ,25 3/4L ,42 W ,2H= 22
Second box that's smaller inner dimensions= 22 3/4 L , 30 3/4W , 15H ,2nd H 21 19/32
Outer box diamensions with thickness 3/4 wood 16 1/2 2nd H ,24 1/4L , 31 1/2 W * 1st H 23 1/2..

you will need an engine hoist to load that into the jeep as it will likely weigh in at around 4-500lbs!

is that including the subs? lol.. only 1 weight about 53 lb. if the box weights 300 lb i could do that

You might consider getting exotic, like doing a 6.625 cu foot box, load the drivers out of phase, face to face, in a compound load or an in-phase isobaric loaded box.

what does that mean?

 

[djdilliodon!]

I have no idea why they would use a 4 layer spider making the suspension that stiff on a sub that only handles 1500 rms . You will need every bit of that 3 cubic feet per sub and with the max dimensions you have along with port displacement and double 3/4” all around, I don’t see it happening .

 

[Siikdude]

I have no idea why they would use a 4 layer spider making the suspension that stiff on a sub that only handles 1500 rms . You will need every bit of that 3 cubic feet per sub and with the max dimensions you have along with port displacement and double 3/4” all around, I don’t see it happening .

i see.. but why?

 

[Siikdude]

that means you are going to need a box that is around 13.25 internal cubic feet (Vb of 12. to 12.15 Cu feet) with a port that is large enough to handle that air, so lets say 6x10x5 inches.

Well I could make the Box 12 cubic feet and also the port is on the outside of the box that measures out to 36in 1/2 W by 2.5 H 24 L and that height can be adjusted to Max 4 in the length could be shortened as well as the width.. and the plexiglass size I will be needing would be 26 with 12 length that's if I do the plexiglass and yes it would be 0.75 thick. Most likely I'll be doing it out of birch that's 0.75 thick with a double baffle in the front and the top.

 

[1aespinoza 10+ year member]

max diamentions in m jeep is a width 42in x length 26 1/2in would like less like 23 length or less if possible to have some space in my jeep, and the height i can do max 17in

These are your max dimensions and they equal to 10.95 cubic feet. The 4 subs need 12 cubic feet for optimum performance. This is not even accounting for wood thickness, sub displacement, bracing volume, or port volume.
djdilliodon! is a subwoofer builder so he knows how subs will perform based on the materials used to build them. 4 layer spiders are usually needed for high power subs to bring the cone back to center point without ripping off. 1500 watts will struggle with that stiffness hence the big box volume to make up for the lack of cone travel.
Doxquzme suggested an isobaric setup. That was my thought as well when I saw the box volume requirements. Basically you build the box for two subs, mount two subs, then mount the other two on top of them face to face. You then wire the outer subs out of phase. This will help overcome the stiff spiders issue and need less power and box space for good performance.

 

[Siikdude]

These are your max dimensions and they equal to 10.95 cubic feet. The 4 subs need 12 cubic feet for optimum performance. This is not even accounting for wood thickness, sub displacement, bracing volume, or port volume.
djdilliodon! is a subwoofer builder so he knows how subs will perform based on the materials used to build them. 4 layer spiders are usually needed for high power subs to bring the cone back to center point without ripping off. 1500 watts will struggle with that stiffness hence the big box volume to make up for the lack of cone travel.
Doxquzme suggested an isobaric setup. That was my thought as well when I saw the box volume requirements. Basically you build the box for two subs, mount two subs, then mount the other two on top of them face to face. You then wire the outer subs out of phase. This will help overcome the stiff spiders issue and need less power and box space for good performance.

Ohh okay thanks for clarifying I appreciate it. I can actually go bigger in my jeep but those are the max dimensions I would like. My jeep is 45 W but without bumping into the sides the best would be 42 W * Legnth is 26 * H I could do 27... But it can go higher but wouldn't look. Nice in my opinion. And if the port is in the front it will have about have inch before it's cut off by the jeeps door.. If face to face subs would get me the best performance then I'll go that route. But if I can get that much volume needed in the jeep then I'll perfer that I believe. I was looking at Birch at my local shop.. And it's roughly 86$ for

3/4 in. x 4 ft. x 8 ft. PureBond Birch Plywood. What specs dimensions should I have for that 12 cubic ft.. And for the other way the Face to face what size would I need?. I would like to learn and know how to calculate these things aswell like you guys.​

 

[Siikdude]

Would any of this work? With double baffle of 0.75 each? Birch wood

 

[Doxquzme Premium Member]

That 2nd 13.26 cu ft is workable. That accounts for .25 cubic feet per sub for each their displacement. as well .26 for bracing and port area. You mentioned you are going to put the port outside the box, how so? It can be done and if you are going to do this, then it does not count against the internal volume displacement. A box with that kind of power and subs, will need substantial bracing, regardless of what you build it out of. Here are some bracing ideas to incorporate into your design.

Implementing Bracing

UPDATE! - I added a bunch of pictures as examples of bracing Ive done, see page 3. Bracing is a very important part of building a stiff and strong enclosure. There are lots of ways to do it, each with their own advantages and disadvantages. I have developed my own ways for doing bracing and they ...

www.stevemeadedesigns.com

Remember the total area that the braces can use up is .25 cu ft in that 13.26 cu ft box (provided each woofer only accounts for .25 ea.) . It's important you find out from the manufacturer what each subs displacement will be too. If the port is out of the equation, with a 13.26 box, you only have 1.26 cu ft to deduct begore it starts to impact the overall volume needed for an optimal box size ( again, if the displacement is .25 per woofer). Technically if you're off by 10%, you should be okay, 12 cu ft being optimal after all is said and done. Additionally, adding double or triple baffles will increase the outside dimensions relative to the number of baffles added.

Isobaric is a little more tricky to build but will save you 50% in over all volume needed. Here are examples of isoberric configurations.

Cone to cone or magnet to magnet are out of phase, cone to magnet (center) is in phase. Ultimately, you want to insure that the finished product has both cones moving in the same direction These are pretty simple to build but as anything, there are compromises such as the box has to have breakdown capability if you want to be able to remove the isolated subs in both the non- face to face designs. That one face to face design can just have a a 1-2" spacer between the baffle mounted sub and the top mounted sub..
Here an example of a 6 order bandpass compound loaded enclosure.



If you are new to building enclosures, these are most likely beyond what you're going want to try, they are not easy to do correctly.

 

[Siikdude]

That 2nd 13.26 cu ft is workable. That accounts for .25 cubic feet per sub for each their displacement. as well .26 for bracing and port area. You mentioned you are going to put the port outside the box, how so? It can be done and if you are going to do this, then it does not count against the internal volume displacement. A box with that kind of power and subs, will need substantial bracing, regardless of what you build it out of. Here are some bracing ideas to incorporate into your design.

Implementing Bracing

UPDATE! - I added a bunch of pictures as examples of bracing Ive done, see page 3. Bracing is a very important part of building a stiff and strong enclosure. There are lots of ways to do it, each with their own advantages and disadvantages. I have developed my own ways for doing bracing and they ...

www.stevemeadedesigns.com

Remember the total area that the braces can use up is .25 cu ft in that 13.26 cu ft box (provided each woofer only accounts for .25 ea.) . It's important you find out from the manufacturer what each subs displacement will be too. If the port is out of the equation, with a 13.26 box, you only have 1.26 cu ft to deduct begore it starts to impact the overall volume needed for an optimal box size ( again, if the displacement is .25 per woofer). Technically if you're off by 10%, you should be okay, 12 cu ft being optimal after all is said and done. Additionally, adding double or triple baffles will increase the outside dimensions relative to the number of baffles added.

Isobaric is a little more tricky to build but will save you 50% in over all volume needed. Here are examples of isoberric configurations.

View attachment 55549
Cone to cone or magnet to magnet are out of phase, cone to magnet (center) is in phase. Ultimately, you want to insure that the finished product has both cones moving in the same direction These are pretty simple to build but as anything, there are comprises such as the box has to have breakdown capability if you want to be able to remove the isolated subs in both the non- face to face designs. That one can just have a a 2" spacer between the baffle mounted sub and the top mounted sub..
Here an example of a 6 order bandpass compound loaded enclosure.



If you are new to building enclosures, these are most likely beyond what you're going want to try, they are not easy to do correctly.

I can make the box a bit more higher.. But remove one ich from Length and i can go two inches up, and if the bracing and port inside will only take up 26 cu ft then i can put it inside instead unless that's only counting one bracing. What would be the best internal Cu ft Vb needed for the subwoofer?.. Like that I can tweek the dimensions till I get that number obviously subtracting the port if inside along with the bracing and the subs

 

[Doxquzme Premium Member]

The golden ratio for box design is not expected in a car, you do have other considerations/limitations. That said, you can tweak it anyway you like, within reason as long as the internal volume is within spec (no more than a 10% deviation, preferably less than 5%).

 

[Siikdude]

The golden ratio for box design is not expected in a car, you do have other considerations/limitations. That said, you can tweak it anyway you like, within reason as long as the internal volume is within spec (no more than a 10% deviation, preferably less than 5%).

Man, that's all Chinese to me..

 

[Doxquzme Premium Member]

Let me make it clear as mud...

While making an enclosure with no parallel sides is possible, it's very difficult for the home constructor making only a pair of enclosures. The vast majority of speakers use conventional parallel sides, front and back, top and bottom. This can still produce a very good box, but there is one thing that can make it 'better'.

There's something known as the 'Golden Ratio', signified by the Greek letter φ (Phi). There are many claims as to its inherent advantages (including aesthetics), but it does have an important characteristic ... no side is a multiple or sub-multiple of any other, so a box using the golden ratio cannot set up single-frequency standing waves across more than two panels. The ratio is defined as ...

φ = (1 + √5 ) / 2
φ = 1.61803398875...

For example, if the baffle is 400mm high, the width (or depth) should be 247mm, with the remaining dimension being 153mm. Note that these are all inside dimensions. These dimensions are not harmonically related, so there is less chance of reinforcement of particular frequencies or overtones. In reality, it probably doesn't make a great deal of difference one way or another, and it's just as easy to build a box using the 'golden ratio' that sounds bad as any other box shape (excluding a perfect cube with the driver smack in the centre of one face of course

).

The ratio can also be described as 0.618 : 1 : 1.618. Which side you choose for the baffle is largely irrelevant, but ideally it would be the narrowest side (so for the example above, the baffle would be 400mm high by 153mm wide (internal). However, this does limit the size of speaker that can be mounted on the baffle - typically to no more than 150mm (6"). If the enclosure has a sub-enclosure (for a midrange driver for example), the problem gets a bit harder. There are probably far more commercial speaker boxes that don't use the golden ratio than there are that do, so to some extent it's always going to be a moot point.

Now that it is perfectly clear, don't worry about it!