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

[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

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

the problem is the larger I make the hole in the box for the port, then the deeper I will have to make the port, then taking up more airspace that is inside the sub box, so I have to find a happy medium, does that at least correctly tune the box to 33 hz? because I can maybe expand it another inch out with the port if needed, but that is all, otherwise the port goes to far into to the box, I also dont mind having the port come out of the box a bit, maybe up to 4 inches would be fine, let me know what you think about that, I really need to figure this out tonight, because I need to finish the box tomorrow morning before work

[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.

the problem is the larger I make the hole in the box for the port, then the deeper I will have to make the port, then taking up more airspace that is inside the sub box, so I have to find a happy medium, does that at least correctly tune the box to 33 hz? because I can maybe expand it another inch out with the port if needed, but that is all, otherwise the port goes to far into to the box, I also dont mind having the port come out of the box a bit, maybe up to 4 inches would be fine, let me know what you think about that, I really need to figure this out tonight, because I need to finish the box tomorrow morning before work

Man, honestly, your probably going to just have to make a bigger box. Shoot for a bare minimum of 12in^2 per cube, from my experience with the CVX 15's they work really well around 14-15 but you could probably get away with 12". You'll end up with more than 4" external, but at what you've got there output will be severely down from what it should be, and I'd almost guarantee some nasty port noise.

[Ray]

Dont tune to 33. Simple.

Or go ahead and fight it

The f3 will be right at 37 btw.

Just tune to 41 with 9 per.

Untill you can make a bigger box or buy 12's

[Autruche]

That's why you need to design before you build. With a box for 2 15s I usually use about 100-150 square inches of port depending on the woofers used. Would the port need to be long? Yes, but that's the thing about a ported box, a properly built one can be quite large. Sometimes the port displaces more air than there is net volume in the whole enclosure, though that's more of an issue with small boxes.

What subs are you using and how much power will they be seeing?

[dereileak]

you guys dont understand, I built the biggest box that my car allows to fit in the hatch, lmao, I didnt just build a random box, I am perfectly happy with 3 cubic feet per sub, its just I need to get the box tuned right, there is no more room in this hatch for a bigger box, its up against the sides of the wheel wells and the back of the seat perfectly following it, its all I have to work with, on top of that I have to fit a d3100 back there, 3 650.4's and 8 huge ass crossovers, and a 2500.1 in the back of the hatch, ha ha, so I had to balance out, I have seen hair tricks done with 2 12's in a premade box for this car because the cabin space is tiny!! btw what does the f3 of the sub effect ?

[727Designs]

you guys dont understand, I built the biggest box that my car allows to fit in the hatch, lmao, I didnt just build a random box, I am perfectly happy with 3 cubic feet per sub, its just I need to get the box tuned right, there is no more room in this hatch for a bigger box, its up against the sides of the wheel wells and the back of the seat perfectly following it, its all I have to work with

After you get it "Tuned right" You won't have 3 cubes per sub man. I don't know how many more ways to say it for you. Listen to Ray, 41hz with 9in^2 per will be your best bet if you want to keep that box. I'd suggest just selling the subs and going with 2 12's. 2 12's in a GOOD box will do better than 2 15's you made fit.

The F3 is the 3dB down point where the output of the speaker drops to 3dB below the average output. Essentially a fall of point. IMO it should be in the mid 20's or so. Ray feel free to correct me if I'm wrong, would hate to spread any misinformation, that's just always been my thought on it.

[Ray]

Cant tune to 33.

So now what??

[dereileak]

Cant tune to 33.

So now what??

idk what the heck to do, I want to keep these subs, i dont want to go down to 2 12's at all

[Torres]

with such constraints, i'd either run both sealed, or one of them ported.

EDIT: but...down sizing to 2 12's in a proper enclosure will sound better than the 15's in a bad box. so don't necessarily think going to 12's is a bad idea

[Katt]

Cant tune to 33.

So now what??

#1. Sell subs.

#2. Buy new subs.

#3. WALL.