Trying to Tune My Box To 33hz ..... I'm Lost!

[dereileak]

Hey Guys, well I built a box as large as I could fit in my mazda3 hatch, and now I just need a bit of help calculating the port size on it so I can achieve 33hz, subs are gonna be facing up, and the port will be facing up too between the subs

Data:

1: 2 subs Sharing Same Airspace

2: Want tuned to 33hz and need a square port made of mdf, no round ports

3: Subs May Be Put in normal or I may have them firing into the box with the magnet out, depends if they hit the ceiling in my car, lol

4. These are 2 15 inch subs, so the port has to be able to fit between them, the subs are not going to be right up against the edges of the box

5. Thanks for all your HELP!

6. All the measurements in the picture already cut out the mdf wood size, this is the internal measurements of the box, so remember the 3/4 thickness of the wood the port has to pass through

sorry, I have to leave for work right now, so I couldn't get sub displacement

Link to the Subs Manual Specs

Gives you an idea of visually how it looks

[dereileak]

Quick Question, does having 2 subs in the same enclosure effect the boxes tuning? besides that there is more displacement with 2 subs?

[dereileak]

Does this port get me to about 33 hz? If not what should I change?

[TheyDontWantMusic]

problem is the box is a bit small, so to tune it that low, the port needs to be longer than what you can fit.

6.6cuft before displacement, so you might have 5.6cuft after woofer and port displacement (unless you do invert the woofers)

the most space effective ports would be two 6inch round ports, but they'd need to have 90 degree bends as they'd need to be 20inches long for about a 33Hz tune.

[TheyDontWantMusic]

Does this port get me to about 33 hz? If not what should I change?

no, that port equals a 57Hz tune...

[dereileak]

Does this port get me to about 33 hz? If not what should I change?

no, that port equals a 57Hz tune...

what would I need to do to get that down to 33 hz? when you design a box, do you have to recalculate the removed airspace that the port takes out and take that into factor for what tuning it will be?

[dereileak]

Are all these Correct? I used outside box demensions, made the port tune it to about 30 because with the subs in and a little bracing it will bring it to about 33 hz, does this all seem right?

[727Designs]

Are all these Correct? I used outside box demensions, made the port tune it to about 30 because with the subs in and a little bracing it will bring it to about 33 hz, does this all seem right?

Not enough port area. Also you're not figuring for any woofer displacement which would probably be .20-.25 or so.

You're not going to get enough airspace for those 2 subs when you have enough port for them to work properly in that box without doing some external port. Your starting at 6.62 which before ANY displacements only gives the subs 3.31 ft^3 each which is around what they should be seeing net.

[dereileak]

Are all these Correct? I used outside box demensions, made the port tune it to about 30 because with the subs in and a little bracing it will bring it to about 33 hz, does this all seem right?

Not enough port area. Also you're not figuring for any woofer displacement which would probably be .20-.25 or so.

You're not going to get enough airspace for those 2 subs when you have enough port for them to work properly in that box without doing some external port. Your starting at 6.62 which before ANY displacements only gives the subs 3.31 ft^3 each which is around what they should be seeing net.

I am actually going to invert the woofers so they are sticking out of the box, so that fixes that issue, why isnt the port large enough if it gets the box to the right tuning?, its a good amount of area that its going to get to move air freely in and out of the box, dont take this as me being a know it all, I dont know, im just asking lol

[727Designs]

Are all these Correct? I used outside box demensions, made the port tune it to about 30 because with the subs in and a little bracing it will bring it to about 33 hz, does this all seem right?

Not enough port area. Also you're not figuring for any woofer displacement which would probably be .20-.25 or so.

You're not going to get enough airspace for those 2 subs when you have enough port for them to work properly in that box without doing some external port. Your starting at 6.62 which before ANY displacements only gives the subs 3.31 ft^3 each which is around what they should be seeing net.

I am actually going to invert the woofers so they are sticking out of the box, so that fixes that issue, why isnt the port large enough if it gets the box to the right tuning?, its a good amount of area that its going to get to move air freely in and out of the box, dont take this as me being a know it all, I dont know, im just asking lol

Not enough port area will cause port noise. At 3" per cube it'll be performing like a leaky sealed box.