Sealed box too big or amp too small 4 KV2 6.5" subs

[js1 10+ year member]

I recently finished a sealed box for 4 ED KV2. Something short that I could hide and put stuff on top of. I have just over 4 ft to work with behind my seats and planned to use .5" mdf x 8.5" x 48" x 7". I should have factored in poly fill and shot for an even shallower box. For the subs, I was told to use the same calculations as for the newer e3.6 Subwoofer

small 0.2ft³

ideal 0.25ft³ is what I was shooting for.

large 0.3ft³

Displacement .04'^3 (x4 = .16'^3)

200watt rms each

At the home depot, I looked at the 1/2" mdf and decided to go with 3/4" jic.

So now the the box was supposed to be 9 x 48 x 7.5" external with 7.5 x 46.5 x 6" internal/ 1.21'^3 - (4x04'^3) 0.16'^3 = 1.05'^3. Bigger box...

I had them make the 4 main cuts... 2 x 9" strips for top and bottom and 2 x 6" for the sides. Left and started building the box. I just had to cut the two side strips and holes. Put the box together and wired it all up.

I'm running 300+ watts (400watt on birthsheet) from a pdx-5 into 2 ohms. Sounds a little muddy at times and not as tight as I was expecting. As I start installing the box to see if placement would help I notice there is no room between the box and my side panels. I measure it and it's an inch wider than it supposed to be. Still well within spec of .3'^per. I don't think it's leaking. Used liquid nails, a nail gun, and sealed the inside. It's pretty solid all in all. Maybe the subs displace less than I was told? So before I try to build a smaller box (

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[RAM_Designs 5,000+ posts]

Do you have polyfil in the box currently?

 

[RAM_Designs 5,000+ posts]

2x4's would be easy to do to take up some space. When you're putting multiple subs in a common chamber you generally don't need the volume to be that of the combined recommended volume for each sub.

 

[js1 10+ year member]

There's no fill in there. I should made the box 6" deep and used fill I think.

It's a total of 1.24'^3 - .16'^3 (subs) = 1.08' or only .08'^3 bigger than ideal. I'm thinking of gluing strips of extra mdf down to the bottom, but worry it will affect the acoustics negatively.

 

[js1 10+ year member]

2x4's would be easy to do to take up some space. When you're putting multiple subs in a common chamber you generally don't need the volume to be that of the combined recommended volume for each sub.

Whoa. Wish I knew that before making this box. Is there any calculators to how much displacement you add per matching sub? Is there a percentage. Might just build one 9 x 49 x 5.5" if that's the case.

 

[RAM_Designs 5,000+ posts]

Whoa. Wish I knew that before making this box. Is there any calculators to how much displacement you add per matching sub? Is there a percentage. Might just build one 9 x 49 x 5.5" if that's the case.

There aren't and calcs that I know of that factor that kind of stuff in. I generall do 10-15% less when using multiple subs in a common chamber, and it seems to work out fine.

 

[js1 10+ year member]

Thanks for that information... I really wanted something smaller, but will try to fill it 1st and test. If I do build another box, maybe stuff some cheap 8's in this one lol.

 

[pro-rabbit 5,000+ posts]

Fire the subs down..I did 4 of these in a reg cab ranger with all firing down, that thing was crazy for what it was.

 

[js1 10+ year member]

Fire the subs down..I did 4 of these in a reg cab ranger with all firing down, that thing was crazy for what it was.

Thanks for the advice. I originally wanted to build the box with 1" risers to fire downwards, but the box got big... Do you have the specs to your old box?