HELP ME I'M DROWNING; Making my first box

[iiJonathan]

So, to start this thread off, I have a regular cab f150 (2000) which I plan(ned) on installing 3 SA-8 V2's at 33hz. The max dimensions I have behind the seat are 43 Width, 14 height, 9 depth at base, and 5 depth at the top which comes out to 1.65 Cu's. (This is a wedge style design as I have a bench seat)

The problem; I wasn't thinking about bracing, sub displacement, or wall displacement while laying out my audio-build please forgive me, this is my first time. (3) SA's will come out to .24 Cu3 displacement leaving me with 1.41 Cu, already less than minimum for 3 Sa's (1.50) However, I am running a BRX.2000 to them and at 1.37 Ohms, they'll be receiving slightly over their 500 RMS rating. around 570. I'm not sure if that'll compensate for my loss there, but we still haven't calculated the port wall displacement. I've been playing around with torres, and I'm coming to the conclusion that this becoming more and more impossible with my size box and Hz.

Options; Unless someone here has a secret, or knows a builder that could potentially help me (I'm willing to pay) I'm facing downgrading to 2 subs, at 1 Ohm flat they'll receive 1k RMS each which I'm sure they can handle, but I really really really really really don't want to downgrade. I may actually create a box to sit in between the dash and seat on the ***** column.

My thoughts; I'm thinking the 33 Hz is actually what's killing this plan, no matter what I do I can't seem to get my Hz down without killing the air space. What's an acceptable port width? It seems the only way I can achieve 33 Hz is with a 1" port width, but that doesn't seem right. What is an acceptable port length? I technically can make this work, because I can extend the box to a bigger width, but I'll need to extensively modify the plastic bodywork behind the seats which restrict the corners of the box (I'll get back there with a recip. saw) But I'd like to atleast try to not modify the interior too much.

Hopefully someone can help me, and thanks ahead of time if you do!

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[mylows10 5,000+ posts]

might try 2" aero or round ports ,see how that will work for you

 

[iiJonathan]

Unfortunately, I'll have to look into that. I have absolutely no clue on how Aeros work, and how people even figure them out.

 

[NIHL8ION]

You don't have enough space for 3 subs, I'd be looking at going with 2 if I was you, I just built a box for a reg cab 04' F150 for a single 12" sub with about 1.94 cu ft net tuned at 36hz (I went a lot taller than 14") and that was barely even possible keeping it behind the bench...

 

[iiJonathan]

That's what I was really scared of. Atleast I haven't bought them yet!

 

[Better-Action 10+ year member]

Thought about a external Aero?

Plugged the numbers in Torres and if you go with 2 3" aeros 20" long and about 14 of that external you got 1.5cf to work with after the port. That gives you roughly 33hz tuning and around 10" of port per cube.

 

[iiJonathan]

I have looked into aeros, but I have no idea on how they work whatsoever. Externally, Im not sure how I could fit such a long tube, and me being a novice box builder I don't think the results would be good.

 

[iiJonathan]

Thought about a external Aero?
Plugged the numbers in Torres and if you go with 2 3" aeros 20" long and about 14 of that external you got 1.5cf to work with after the port. That gives you roughly 33hz tuning and around 10" of port per cube.

Where would I find said aero?

 

[mylows10 5,000+ posts]

Parts express or just go get some abs pipe at Home Depot

 

[T3mpest 10+ year member]

If the port is facing a boundary that will drop the tuning a few hz as well. If you can get 36hz in a program, you'll be closer to 33 in a car.

 

[Better-Action 10+ year member]

Aeros are simpler than slot ports imo. Less chance to **** em up. Torres has a aero calculator. The way I pictured it was the 2 external aeros on the driver side coming out the top of the box. 14" external so both the ports would go into the box only 6" and the other 14" would be sticking out.

In Torres where you put your slit port dimensions right under it is areo. Just add 2 as the number of ports and 3" as the diameter, and length. Then down by woofer displacement you'll see length of external port. Aero ports are so simple, its kinda hard to mess em up. Plus if you'd like to experiment with different tunings its so easy to just swap out a tube.

 

[bubbagumper6 5,000+ posts]

You have to not only include the port wall displacement but also the port airspace as well, that's not usable airspace for the enclosure and must be subtracted from the gross volume.

 

[iiJonathan]

Aeros are simpler than slot ports imo. Less chance to **** em up. Torres has a aero calculator. The way I pictured it was the 2 external aeros on the driver side coming out the top of the box. 14" external so both the ports would go into the box only 6" and the other 14" would be sticking out.
In Torres where you put your slit port dimensions right under it is areo. Just add 2 as the number of ports and 3" as the diameter, and length. Then down by woofer displacement you'll see length of external port. Aero ports are so simple, its kinda hard to mess em up. Plus if you'd like to experiment with different tunings its so easy to just swap out a tube.

You've actually clarified aero ports so much for me with just that statement. I'm definitely going to look into this, 33 hz isn't as important to me as it is having 3 subs.

 

---------- Post added at 11:02 PM ---------- Previous post was at 11:01 PM ----------

 

You have to not only include the port wall displacement but also the port airspace as well, that's not usable airspace for the enclosure and must be subtracted from the gross volume.

Are you talking about if I use an aero or slot port. If I use an aero there will be no "port wall" correct?

 

[hispls 5,000+ posts]

The volume of air within the port is subtracted from net volume.

2 subs in correct size box will generally be better than 3 subs in too small of a space.

 

[iiJonathan]

Now that I finally understand torres, I plugged in the Aeros, and I see how this can work! Will I have the port "noise" they talk about if I don't flange the ends? and will the 6" internal still need to be accounted for in terms of airspace? I'm not exactly sure if I should brace this style box, I'll probably use some 1x1's, and I won't need the 45's in the corners since its an aero. Bare with me please, these aeros are out of my knowledge range for now.