enclosure help

[deadgame1]

i have four MA121XQ subs that I want to build a ported enclosure for. The manual recommends 3 cu ft. for one sub so am I correct in assuming that i need an enclosure with 12 cu ft ? Also it recommends 25 sq/in. port area and port length of 14 inches so does this mean i could do 1 port that has 100 sq/in of port area. i am a little confused because when i punch all of my measurements into the Torres box tuning calculator i have to use different dimensions for the port to tune to 35Hz. These are the outer dimensions that i have and will be using 3/4 mdf

Height 23"

width 36"

depth 32"

Port dimesions

Height 20"

Width 5"

Lenght 9"

This will be in a full size K5 Blazer if that matters at all . Any help you guys could give would be greatly appreciated.

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[Trancer 10+ year member]

This makes things much simpler RE AUDIO - Box Calculator

 

[deadgame1]

thanks i will give this one a try

 

[Danometal 10+ year member]

I love the RE Box calculator, except in cases when I need to bend a port more than once, and then it's pen and paper and port length calculators online. Do note that you need to design the box to have a slightly lower tune than your target, as the sub's displacement, braces, 45s in the corners of the port, etc. will raise your tuning frequency by a slight margin.

 

[THATpurpleKUSH 5,000+ posts]

Do note that you need to design the box to have a slightly lower tune than your target, as the sub's displacement, braces, 45s in the corners of the port, etc. will raise your tuning frequency by a slight margin.

This.

The RE calc does not take these into consideration and this can throw off your tuing by 2-3hz.

 

[Danometal 10+ year member]

This.
The RE calc does not take these into consideration and this can throw off your tuing by 2-3hz.

There is some other good news concerning RE's calculator. I've done calculations and confirmed that it actually takes end correction into consideration when projecting the total port length and subsequent tuning frequency. That impressed me for sure. Heck, I'll go ahead and say RE does everything right IMO as a subwoofer manufacturer (Well, I'm not crazy about foam surrounds, but I digress).

 

[on1wheel01 10+ year member]

I love re calc. But now IM using aeros more and have no idea about what length to calc them at lol

 

[deadgame1]

This may be a newb question but why is there such a big difference in the various calculators that you find on the net. If I put my measurements into the torres calculator it gives me a net volume of 12.42ft but the RE calculator gives me 10.37. That is of course if i am entering my measurements right.

 

[kyle3194 10+ year member]

This may be a newb question but why is there such a big difference in the various calculators that you find on the net. If I put my measurements into the torres calculator it gives me a net volume of 12.42ft but the RE calculator gives me 10.37. That is of course if i am entering my measurements right.

My take on this is that the torres calculator is not taking into account the driver displacement from your subs. When you only have a couple, you really cant notice it, but put four subs in a box, and all that driver volume will really add up on you.

 

[deadgame1]

The torres calculator gives you the option to add sub displacement to the figures. Do the port deminsions i gave above look right for tuning to 35Hz