polyfill and trying to squeeze more cu ft, maybe different type of ports?aeroports?

[SpeedEuphoria 10+ year member]

I'm looking to make a box for 2 12" Alpine Type R's(new model). I have searched the forum and seems 4ft^3 is about what everyone recommends.

Seems that My trunk:03 Dodge Stratus Coupe can only fit ~30x18x16.5 box which with an L port would be just under 3.5ft^3

So is there another style of ported box where i can make more efficient use of the space. Like maybe Aeroports?(not familiar to it just seen it thrown around here)

I'm new to ported boxes but have a great mechanical aptitude, can build custom stuff, check my car for reference:

http://www.cardomain.com/ride/2641801

Anyway is it going to be possible for me to make this work? Is there a different style ported box other than the "L" port that I have been seeing that will make better use of space?

I plan on using polyfill in the box to help, but I have never used it or made a ported box before. Do you stuff the box completely full? or keep it away from the sub? I have seen here that the port should be free of the polyfill.

Only had sealed box's, my last setup many years ago was 4x JL 12W3's in prefab box's in a trunk/hatch which hit 144.5 or so on 2x memphis 500D's(rated at 2ohms but ran at 1ohm)

As always thanks in advance

Matt

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[bubbagumper6 5,000+ posts]

What size are the subs? That does NOT seem like enough space for a pair of 12's....

 

[SpeedEuphoria 10+ year member]

I was editing the post when you replied, please reread the post for more info/questions.

I can prob make a shorter and narrower box which is really deep and take up my whole trunk that would work if I shoved it in from the pass compartment but I'm really trying not to do that. I could also just go sealed but wanted to try ported.

Basically was thinking if I could use round ports of some sort that stick out of the box near the rear seats, that could be installed after the box was in the trunk. Or something similar??

 

[hispls 5,000+ posts]

Stuffing will help with dampening and low extension a little but will NOT give the efficiency of a larger airspace.

Your answer is doing external ports (if you can fit them) or use passive radiators, which might cost more than your arrghs but will do the same thing as a port and take up almost no volume.

 

[SpeedEuphoria 10+ year member]

Your answer is doing external ports (if you can fit them)

Can you point me to a link or somewhere with info about making a box with external ports please. I have seen a little on it but not much. Was hoping it would be possible to use multiple 4" round ports or similar while keeping there length short but I'm not sure it works that way?

I'm sure your right on the radiators as I picked up 2 new Type R 12" for $220 shipped

 

[hispls 5,000+ posts]

Can you point me to a link or somewhere with info about making a box with external ports please. I have seen a little on it but not much. Was hoping it would be possible to use multiple 4" round ports or similar while keeping there length short but I'm not sure it works that way?
I'm sure your right on the radiators as I picked up 2 new Type R 12" for $220 shipped

External ports is just the port sticking out of the box instead of into it. Depending on the car you can get away with having 8" hanging out of the box....basically saves you the space that the ports would eat up.

Ports eat up space, ports that will be really effective will eat up more space. A wider port(s) needs to be much longer for the same tuning. You can start squeezing down smaller and smaller ports but at some point you'll lose efficiency and begin to get port turbulence.

There's really no free lunch and no "type" of port is really going to be your magic fix.

You might want to state your goals for sound/tuning/power and in the meantime start thinking about a way you can have the port(s) hanging out of the box. Do the math on how much volume ports eat up and it'll be at least half a cube you can save i bet.

 

[SpeedEuphoria 10+ year member]

Thanks for the info.

Well what I would like is to be able to fit a ported box for 2 Type R 12's in my trunk powered by a DSC 1500D. Seems that I can fit either 30x18x16.5 or 35x16.5x13 or prob the least favorite which would be 30x12x30 or whatever depth I need to get the volume but would eat up my whole trunk.

Anyway if I could do the 30x18x16.5 it would be right around 4ft^3 which would be just enough(w/o the ports of course). I have no info at all on what the external ports would look like but was hoping that I could use something like 6"long or so adding multiples in the rear to get the correct port area. Like I said I have no idea how to figure tuning of this kind of port. Well I have found this formula is (radius^2)*(pi)(Length of the pipe).

What is the shortest length of round external port you should use? Like can I use 3x 2" round ports of 6" which would give me ~56.5" of port area on a 4ft^3 box. And how do you find the tuning frequency?

I also bought a Diamond D6 15 and will be making a common 3ft^3 or slightly larger L port box for it and see how it sounds with 1000rms.

I'm not real sure if the 2 type R's sealed would be louder than the 15"? but ported I'm sure they would.

Basically want good sound that bangs, looking for 140db+. I would guess the 15" would be about 140db and the 2x 12's ported prob 145db if done right.(could be off since I'm no expert)

 

[SpeedEuphoria 10+ year member]

Ok so using 28.5x15x16.5 internal dimensions(4.082ft^3 -.2sub displacement)=3.882 cu ft. Then using this calculator and 4" straight port it says 4.625" length this would give me ~58" of port area which is ~14.97 per cube is this too much?. I dont understand this calculator as when I add more ports of the same size I need to make them longer? Can someone explain this to me?

Also would this configuration mentioned with a single 4" port of 4.625" length sound good? or is there something else I need to take into consideration?

Again thanks in advance for all the info

 

[CRXBMPN 5,000+ posts]

a 4" round aeroport is roungly 12.x sq in of port area, you refer to a 4" straight port but not if its round or a square or rectangle in which case you need to tell us the width of it.

you will need 3x of the 4" aero's i'd say for two Type R 12's in that box, unsure of the length. Just my opinion.

 

[SpeedEuphoria 10+ year member]

sorry 4" straight round ports

and I think I see where i was going wrong, that formula that includes length of the port is not correct as its a volume figure not surface area.

So i would need either:

13x 2"diam ports with ~23" length

5-6x 3" ports with ~19-23" length

3x 4" ports with ~19.7" length

and best case for shortest length would be if I could get away with a single 7"port of 18" long

Now my next question which is a stumper. How about if I Make the ports with a smooth radius 90deg bend?? Its hard to picture but it would come out the back of the box take a smooth 90 and continue for the length needed across the back of the box. I'm sure there are no calculators for this but math has always been easy for me and have complete college calculus.

Picture 3x 4" round ports coming out the back corner of the box and turning 90deg and running parallel to the rear of the box for the desired length. I know the tuning length would be a B to figure out but as long as I can get it close it should be fine I think.

Anyway has anyone ever seen a box like this? and yes I like to defy the ordinary check the car I built in the 1st post or in my sig

EDIT: Nevermind I see that its OK to use the 90deg bend in ports so I'll post pice of this beast when done here in the next week.

 

[SpeedEuphoria 10+ year member]

Well built the my 1st ported speaker box. Found that the absolute largest size that will fit in my trunk is 29.5x16.5x17. I made a single L ported box for a 15 Diamond D6. It turned out at ~3.0 cubes net @31HZ with ~36"^2 of port. It barely fit in the trunk(tested before gluing the top just incase), plan to take the router to the outside and the port exit.

I'll post some pics here later when I put some finishing touches on it. Plan to test the sound, maybe add some polyfill and then herculiner the outside.

I plan on making another box for the 2x 12" Type R's and the silly external ports, but seems that using the same outside dimensions it will only gross me 3.77cubes and almost 3.5cubes minus the subs. Speaking of this I've seen it many times but what is the correct procedure for mounting the subs outside the box as in backwards?(to save a little cubes)

Thanks again for this great forum.