Dual Type R's 1242Ds - Port in the Middle - Design

[konradac 10+ year member]

So I am building a Ported Box for 2 Alpine Type R's, I'm shooting for roughly 4 - 4.4 cubic Feet @ 35 Hz

I was hoping for some guidance with the design.

I really wish I could just use the free box designs but the boxes are too wide for my car.

My trunk Dimensions are, 17 in (height) x 31 in (total width) and 22 in (depth). (which I wanted to use for the box...still need spare tire access!)

I could make a slanted box and take advantage of more room but being this would be my first box I would be worried I would screw it up.

Here is my Trunk:

here is one of the box plans

Ie, this one is 4.4 cubes @ 35 Hz - Can I manipulate the numbers so it would "fit" and still have the same tuned frequency? (My guess is no!)

And this is what I'm basically trying to build. With either the ports combined or not.

Click to read more...

 

[GAM3OVR 5,000+ posts]

2.2 per type R @ 35hz w/ 30 sq in of port = your best bet

So 4.4 + disp @ 35 w/ 60 sq in of port

 

[konradac 10+ year member]

Thanks for the reply ProjectPechkin!!

Alright so I am running into some confusion.

Here is my plans according to Bass Box Pro.

4.4 + Disp @ 35 roughly

Here are the vents.

But when I plug it into the RE-Audio Calculator. (same Dimensions)

I get 2.8 Sq Ft. @ 43 hz?

If my Bass Box Pro Plans are correct, how would the "Two Flush Ends" look as a port? (How would I cut the MDF?)

 

[DNick454 10+ year member]

I'm confused to the box you have shown in RE Box Calculator. First off... thats more than you need for one sub, but not really enough for two. Second. It's tuned to 43Hz. With the subs in place, it'll end up around 45. Another thing, it's not even wide enough to fit two 12's. Maybe I'm just misinterpreting what you're trying to say.

 

[DNick454 10+ year member]

I just went ahead and made you a quick box design. It's according to the max dimensions in the original post.

17H x 31W x 22D

about 4.5 cubes (4.2 or so once the subs are loaded in the box) with a tuning of 33.85, again once the subs are loaded in, the tuning will rise. Should end up right around 4.2 @ 35Hz with 62 sq. in of port area. Should be perfect for those subs.

If I can offer one warning though, that is to BE CAREFUL WITH THIS BOX WHEN CUTTING THE MOUNTING HOLES!!! A typical 12" driver will have an actual total outer diameter somewhere close to 13" and the front baffle on that box is only 26.25". Figure 13+13 = 26. You'll be cutting it close. Be extra careful when cutting those mounting holes so that the subs don't end up hitting eachother and not fitting or hanging off of the edge of the box or into the port opening. Since the box is 17" tall, I might suggest staggering the subs so that you can move them in towards the center of that front baffle a tad and avoid clipping into the side walls of the port or right side of the box when cutting out the mounting circles.

Good luck with the build //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

 

[konradac 10+ year member]

Wow, Thanks so much DNick! Lets just say I didn't really know what I was doing with ReAudio.

I took a peek at the manual and it says the Mounting Diameter is 10.9", but that is the hole I cut and not the ~13" outer diameter you are referring to?

Will any old speaker terminal work?

And lastly, is it possible to move this Port to the middle or would that screw up the displacement? (I'm assuming yes) Otherwise THANKS so much I really appreciate it. I'm going to get started tomorrow. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

PS. Would staggering the subs have any actual effect on the bass?

I just went ahead and made you a quick box design. It's according to the max dimensions in the original post.
17H x 31W x 22D

about 4.5 cubes (4.2 or so once the subs are loaded in the box) with a tuning of 33.85, again once the subs are loaded in, the tuning will rise. Should end up right around 4.2 @ 35Hz with 62 sq. in of port area. Should be perfect for those subs.

If I can offer one warning though, that is to BE CAREFUL WITH THIS BOX WHEN CUTTING THE MOUNTING HOLES!!! A typical 12" driver will have an actual total outer diameter somewhere close to 13" and the front baffle on that box is only 26.25". Figure 13+13 = 26. You'll be cutting it close. Be extra careful when cutting those mounting holes so that the subs don't end up hitting eachother and not fitting or hanging off of the edge of the box or into the port opening. Since the box is 17" tall, I might suggest staggering the subs so that you can move them in towards the center of that front baffle a tad and avoid clipping into the side walls of the port or right side of the box when cutting out the mounting circles.

Good luck with the build //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

 

[DNick454 10+ year member]

If you were to move the port in the middle, the port would take up more rom because it would split two ways when it takes the turn at the back of the box. Port and sub placemnt in a trunk car will have no effect so long as they're facing the right way. What I meant by the diameter and hole cutout thing is that the hole you cutout is smaller than the actual sub. For example, the 12" type r has a cutout of 11" for the woofer to fit in the hole but the actual outer dimension of the rim of the woofer is larger. Just make sure to keep that in mind when deciding sub placement.

 

[DNick454 10+ year member]

Almost forgot... To answer your question about the terminals, you get what you pay for really. There's the terminal cups that are plastic with little sheet metal spring loaded tabs that accept 14awg wire and then there's the gold plated binding posts that accept 8awg. Me... personally I prefer to drill a hole in the box and run a nice big set of wires straight to the subs and then silicone around where the wires enter the box. No connectors, no weak spots, no leaks, no cost, and no hassle. Granted it may not look quite as nice but it's all tucked behind the box anyways.

 

[konradac 10+ year member]

Almost forgot... To answer your question about the terminals, you get what you pay for really. There's the terminal cups that are plastic with little sheet metal spring loaded tabs that accept 14awg wire and then there's the gold plated binding posts that accept 8awg. Me... personally I prefer to drill a hole in the box and run a nice big set of wires straight to the subs and then silicone around where the wires enter the box. No connectors, no weak spots, no leaks, no cost, and no hassle. Granted it may not look quite as nice but it's all tucked behind the box anyways.

Awesome I think I will use your technique....8 awg would be enough? Or should I go down to 4 awg?

And I'm assuming I should point the sub's back?

And lastly, how to bolt this thing down? I destroyed my last sub because I didn't bolt down well enough. (Did a donut, came loose and screw tore apart the cone)

 

[konradac 10+ year member]

So I had to revamp what I was doing.

I am going with a wedge because the previous box design would not be able to put the sub in and out of the trunk.

I still don't understand how to make a single port in the middle for 2 boxes, so I have come up with the solution of building 2 identical mirrored boxes and having the ports going in the middle.

The woofers will point towards the trunk, while the ports will go through the ski pass.