10in L7 sub box construction.

NorCalChris

NorCalChris

NAXJA Forum User
Location
Central Coast, Ca
Im planning on building a sub enclosure for a kicker L7 in the 10inch flavor. 1200/600 max power/rms. Im gonna use a 1100watt class D Pioneer amp I picked up for 40 bucks off CL. It has a 600 watt rms @2ohms. Im gonna wire the sub for 2ohms. Kicker recomends .66-1.0 cu. Ft of air space for a sealed enclosure. What is better: to be on the smaller or larger side? Also, should I use .75 or 1.0 thick mdf? What about poly fill, should I use it and how much?
It's a lot of questions, and I thank you in andvance.
-----NorCalChris
 
1.0 MDF if you can, if it fits where you want it. Slightly larger is better as you can fill it, if necessary. I may have some mdf if you are interested. Not sure when exactly I will be heading up that way tho.
 
After looking at the tech manual for it, it calls for a 1.25 cubic ft box with 2"x2" triangular bracing between panels for support.

http://www.kicker.com/Product_Manuals

There's the link to go download the tech manual, when selecting it there's one for 2011 multilingual at the bottom of the selection that I looked at. They have the sealed compact at 1 cubic ft and the sealed SQ at 1.25 cubic ft.
 
Johnnie Walker said:
1.0 MDF if you can, if it fits where you want it. Slightly larger is better as you can fill it, if necessary. I may have some mdf if you are interested. Not sure when exactly I will be heading up that way tho.
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3/4" is plenty strong. I've never had a problem with it. I have even went so far as to use 1/2" in places to save weight and size. If you really don't care how much room it takes up, I guess you could use 1". If you're really worried about strength, you could use 3/4" thick 11 ply Russian Birch plywood. There are no voids in that, unlike traditional oak plywood. The only downside to the Russian Birch is price. It costs about $70 for a 4'x8' sheet. Ouch.

If you have the room for it, it sounds like you want to aim for 1.25 cu ft. If you end up with a little less, it's not the end of the world. When doing your box design, don't forget to take the volume of the driver into account.

Good luck and be sure to post pictures of the final product.
 
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dave92cherokee said:
After looking at the tech manual for it, it calls for a 1.25 cubic ft box with 2"x2" triangular bracing between panels for support.

http://www.kicker.com/Product_Manuals

There's the link to go download the tech manual, when selecting it there's one for 2011 multilingual at the bottom of the selection that I looked at. They have the sealed compact at 1 cubic ft and the sealed SQ at 1.25 cubic ft.
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Okay, for the 2008 manual that I looked at before posting they recomended .66 for compact and 1.0 for SQ. Remember I am building a sealed box, not a ported box. The specs you listed match the specs I have for a ported box. Im going to shoot closer to 1.0 cu. ft. Now I need to find some materials. As there any downside on creating a perfectly square box? meaning all dimensions are the same?
 
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Which model of the L7 are you getting the 08 or 11? If it's the 08 model then go with what the manual for the 08 says otherwise the manual for the 11 states that it's 1-1.25 cubic ft sealed.

http://www.kicker.com/sites/default/files/2011 L7 Multilingual Rev B.pdf

Page 4-5 is where it shows the sealed requirements on the left side 1.0 for compact 1.25 for SQ, ported is 1.25 compact and 2.25 for SQ.

Just make sure of which model you're getting to build the right size enclosure as that will make all the difference in the world.
 
Like I said, 3/4" will be fine. Predrill and countersink your screw holes and seal the joints.

$33/sheet is a typical price.
 
Ok wasn't sure if you had an older one or were planning to buy the brand new one. If you look at the tech manual for the 08 where it shows the specs the next page I believe gives you a basic cut sheet for what size to cut the panels to.
 
I use 3/4" mdf and fiberglass the inside of the box when I'm trying to push big spls without blowing the sides out of the box :D I got tired of cracking boxes and leaking air.
 
Home Depot also sells 2x2 and 2x4 panels, so you don't have to buy a full sheet if you don't need it. $5-9 per locally. Easier to throw in the Jeep than a full sheet too.
 
dave92cherokee said:
If you look at the tech manual for the 08 where it shows the specs the next page I believe gives you a basic cut sheet for what size to cut the panels to.
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thanks, im going to design off that.
GrimmJeeper said:
I use 3/4" mdf and fiberglass the inside of the box when I'm trying to push big spls without blowing the sides out of the box :D I got tired of cracking boxes and leaking air.
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do you fiberglass the whole inside or just the seams?

littleblackxj said:
If you are going ported, check out RE L box calculator.
http://www.reaudio.com/speaker_box/LPort_Box_Calc.html
and check out the port area calculator
http://www.carstereo.com/help/Articles.cfm?id=31
If you build your box according to manufacture volume specs and using the port size according to the calculator, and tune it to 30hz or even a little lower you will have one hard hitting sub that sounds pretty damn good.
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I wasnt planning on building a ported box, but I've been considering it. If I have enough materials left over I might build a ported box as well and see which box I like better. when you say "tune it to 30hz or even a little lower" what exactly are you refering to?
Starboard M said:
Have you tried Homedepot or Lowes? Our local HD had 1'', 3/4'' and I think 1/2'' MDF in stock.
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I went to HD yesterday and they went up to 3/4" and it was $30 for a 4x8. So I am gonna go there for my sheet.

hubs97xj said:
Home Depot also sells 2x2 and 2x4 panels, so you don't have to buy a full sheet if you don't need it. $5-9 per locally. Easier to throw in the Jeep than a full sheet too.
Click to expand...
thanks for the info, but I rather buy a whole sheet.
 
norcalchris said:
do you fiberglass the whole inside or just the seams?
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I seal the seams with silicone, then use my fingertip the push the sealer into the seam and wipe up excess. Let it dry overnight, then get an old sheet or something similar, just a thin piece of fabric, anything will do. then I mix the resin and hardener, put the sheet in the box, and work from the bottom center out with a 3" paintbrush, out to the sides and up around and back towards the hole the speaker goes in. make sure it's completely saturated but not runny. once you get it done trim off whatever excess is overlapping the speaker hole with a razorknife, or let it dry and use an angle grinder.

You'll never break the box again, and the guy who taught me to do this said the sub will be punchier because the box won't flex as the sub creates pressure inside of it.
 
GrimmJeeper said:
I seal the seams with silicone, then use my fingertip the push the sealer into the seam and wipe up excess. Let it dry overnight, then get an old sheet or something similar, just a thin piece of fabric, anything will do. then I mix the resin and hardener, put the sheet in the box, and work from the bottom center out with a 3" paintbrush, out to the sides and up around and back towards the hole the speaker goes in. make sure it's completely saturated but not runny. once you get it done trim off whatever excess is overlapping the speaker hole with a razorknife, or let it dry and use an angle grinder.

You'll never break the box again, and the guy who taught me to do this said the sub will be punchier because the box won't flex as the sub creates pressure inside of it.
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So I dont need to buy any fiberglass huh? Just use some fabric with fiberglass resin + hardener.
 
That's what I do, the matting makes it heavy but I suppose it would be stronger. You can keep the weight down by using thin fabric, I've found fleece works the best for big subs because they move so much air the pressure in there can be pretty intense. For a smaller sub that won't be driven really hard though a simple bedsheet works just fine.
 
norcalchris said:
So I dont need to buy any fiberglass huh? Just use some fabric with fiberglass resin + hardener.
Click to expand...

Fleece holds lots of resin, if I am just doing a glass box I will use fleece to shape it and use FB Matt on the inside to strengthen. With the power and sub you are talking about you don't need to glass the inside of the box.

Just 3/4 MDF and silicon and it will work great, then if you’re worried about deflection or splitting the box, just brace the box. It’s about 400 times faster and just as affective. With the box size you’re talking about there is no need to glass or brace.

Lots of people use screws but I have always just stapled or nailed the box together with a brad nailer. If you use screws, be careful screws will strip DMF quickly, glue all the edges, silicon the corners, carpet and call her done.

Here is a carpet trick that works great,

Cut the carpet so you wrap 4 of the 6 sides of the box with one piece you can go any direction but I like to have the smallest pieces on the sides, now cut the side pieces, make sure you overlap each edge with a good amount of fabric.

Take the long piece and spray your glue on the box and the carpet and let it tack up. (don't do the sides yet) Once tacky lay the long piece around the box and make sure to smooth it out (this piece normally covers the speaker hole) Your overlapped pieces should end up at the bottom rear edge of the box make sure and push both overlapped pieces tight together and to the edge. At the edge you want to have the overlaped pieces create a seam right on the bottom rear eadge making a flap of fabric. Here I will take a Plastic dead blow hammer and while pulling the carpet flap one to one side tap along the edge, pull the carpet flap to the other side and tap all down the edge again.

Next at each corner cut a slice from the overlapped edge down to the point of the corner this should make 4 flaps overhanging on each side.

Next spray glue one side of the box and one side piece of carpet and let tack up. Once it is ready to apply take the 4 flaps from the main carpet piece and fold them out so you can place the side pieces on without the flaps getting in the way. Smooth out the side pieces working form the center out.. at each edge you want to have the overlap from the main carpet piece and the overlap from the side piece create a seam right on the edges. Do the other side the same way and let it dry up. do the same thing you did with the bottom rear edge and take a plastic dead blow hammer and while pulling the carpet flap one to one side tap along the edge, pull the carpet flap to the other side and tap all down the edge again.

Let it dry

Once everything is nice and dry, take a good pair of scissors and cut both pieces a carpet right along the edges and remove all the overlap. Get as close as you can to the corner edges. After you cut it you will have a little seam that will show. To blend this take your plastic dead blow hammer and tap along the seam, the two pieces will blend in.. No more seam.
 
I recently did my VW's box with this stuff. I've never done carpet before, but I wouldn't change anything about how that stuff laid down. It was very forgiving. Spray on some 3M Super 77 and slap it down.

Here are the results.
166483_923759366752_9120626_48275081_7336234_n.jpg


Excuse the glue overspray...
168126_922938127522_9120626_48259509_4632241_n.jpg


There are several seams on the top, front, and sides that you can't even see unless you look for them.
 
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