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View Full Version : Aero port once more.



robertoyoung08
09-07-2009, 09:16 PM
aah here it goes again.
need some final help with aero port.
been doing some MORE numbers, but i want to make sure i have it right.

4.5 cubic foot box. need tunning to 33 hz.

- i can do one 6 inch aero at about 12 inches in length (but would end up being really close to sub because where exactly i want both the aero and sub to go they happen to meet up)

- or two 4 inch aeros at a little under 12 inches in length.

someone give me some advice. which would work best for my box also considering trying to avoid port noise.

thanks a lot, so far i've gotten a lot of help from you guys on here. didnt know nothing when i first started out with this box and im working my way up there. however since i dont know much about how to calculate all this please try to give me some straightforward answers. i keep reading and being told about "the rule of thumb" when it comes to aero ports and how much sq inch of port should be put in per cubic feet, but im completely new at this so i hardly know how to apply that to my calculations.

must be annoying to help a rookie but thanks again. really appreciate it!!!!!!!!!!

7ender
09-07-2009, 09:20 PM
That's a very small port, even for an aero. Iv'e used a 6" aero on my 4.1 cube box, but that's the absolute smallest i'd go.

The rule of thumb you hear of is how many inches of port are you'll want per cubic foot of box. For aero's, i'd try to stick with around 8-10" per cube.

If you're trying to avoid port noise, i'd definetely go bigger. My current box has a 7.5" aero and it's 4.5 cubes, and it's probably my favorite box so far. It comes out to a little under 10" per cube of port.

If you're wondering where I got the odd size aero...go to home depot and look for sonotube. They make it in an 8" diameter, but they vary in size (the 8" sono's go from 7.5" to 8.5").

robertoyoung08
09-07-2009, 09:54 PM
hmm okay.
looks like now i have to reconsider everything lol
but thats alright, im trying to get it right.

i found some 8 inch with flares on ebay so maybe i could get one of those.

but which of the ports would you say is too small, the one 6x12 inch? or the two 4 x12? or both?

figuring out aeros is harder and it seems like they take up more room than a slot port. aero is my only way though, since im trying to place it at the top of a box so it will fire upwards into the cabin of the car.

i havnt been able to figure this out. i figured out the numbers i got with precision sound prodcuts (psp-inc) tool calculator. and i emailed them and they said to use that, a few other people told me that was one of the most accurate too, but i did find the number to sound a little sketchy a lot of the time. i did use car stereos round port calculator and it gave me a minimum diameter of i think 7.3 inches, or something like that, so i do think your right on needing at least a 7.5 diameter.

what do you have your box tuned to?

7ender
09-07-2009, 09:59 PM
Did you read my guide? Aero's take less volume than slots, because you dont' need as much port area.

Both those ports are too small. A 6" aero gives you 28" sq inches of port, and two 4's gives you 25".

mazdakid
09-07-2009, 10:14 PM
an 8" aero would be nice for a box that size

7ender
09-07-2009, 10:16 PM
an 8" aero would be nice for a box that size

that's what i'd go with as well.

mazdakid
09-07-2009, 10:22 PM
the guy thats selling the ones on ebay is on the forum and sells them here.

robertoyoung08
09-07-2009, 10:39 PM
alright, im getting somewhere now.

im getting some really good suggestions, thanks everyone.


so how many sq inches of port would i need.
im not sure how i would figure how many square inches of port im getting per cubic foot. if i go with 9 inches of port per cubic foot, how do i figure length/diameter of aero?

well at least to try and make it easier, if i was to go with that 8 inch aero, what would the length be? about 13?
my box is odd shaped, where i will place the aero is only 14 in in height, so that might present a problem. which is why i was trying to figure out smaller ports, maybe 3+ 4"aeros

i want to get this down soon. im installing a whole system in my car car, box is the only thing keeping me from installing it all.

perfecxionX
09-07-2009, 10:49 PM
I have been told that port area is never determined by box volume. People develop these 12-16" per cube rules of thumb for the ease of it but port area is better determined by the air displaced by the driver. So to answer your question without knowing what type of sub or power is being used would be a pretty hazardous guess.

With that said, in my personal experience one 6" aero should be enough for a single 15. what kind of sub is this box for?

7ender
09-07-2009, 10:51 PM
Again, have you read my guide? Alot of your question have been covered in it already. It's a few topics below yours in this forum section...

robertoyoung08
09-07-2009, 11:12 PM
have you guys read perfecxionx's response?

i havnt read your guide, i cant find it. i will look again.

robertoyoung08
09-07-2009, 11:14 PM
I have been told that port area is never determined by box volume. People develop these 12-16" per cube rules of thumb for the ease of it but port area is better determined by the air displaced by the driver. So to answer your question without knowing what type of sub or power is being used would be a pretty hazardous guess.

With that said, in my personal experience one 6" aero should be enough for a single 15. what kind of sub is this box for?



yeah, i keep getting different things. a six does seem big enough, but ive never done aero so i really wouldnt know. what would you say?

its a 12 inch RE audio MX
will be pussing about 1500 watts rms.
in a 4.5 ft^3 at 33hz

robertoyoung08
09-07-2009, 11:15 PM
Again, have you read my guide? Alot of your question have been covered in it already. It's a few topics below yours in this forum section...

ha okay nvm
i found it. was looking way too far.

perfecxionX
09-07-2009, 11:45 PM
yeah, i keep getting different things. a six does seem big enough, but ive never done aero so i really wouldnt know. what would you say?

its a 12 inch RE audio MX
will be pussing about 1500 watts rms.
in a 4.5 ft^3 at 33hz

why so big? you realize thats more than 2x RE's recommended size?

http://reaudio.com/specs.html#sp_mx

robertoyoung08
09-07-2009, 11:48 PM
now im getting even more confused.

okay, just tried that formula again and nope cant come up with ANYTHING that looks reasonably right.. AT ALL.

i would like to get the answer to this box already.. but now im also more interested in actually understanding this.

robertoyoung08
09-07-2009, 11:52 PM
why so big? you realize thats more than 2x RE's recommended size?

http://reaudio.com/specs.html#sp_mx

yeah, re recommends 2.5 cubic feet for an mx.
but that seems way too small for such a huge sub.

but either way, minus sub displacement as well as the aeros.the 4.5 includes the subtraction of the wood displacement, but at the end of the build it will probably turn out smaller. its an odd shapped box so i dont even think the sub will see some the box

snb778
09-07-2009, 11:55 PM
8" sounds about right... dunno if sub size matters at all with that amount of port

robertoyoung08
09-07-2009, 11:57 PM
8" sounds about right... dunno if sub size matters at all with that amount of port

okay, 8" aero. bout how long?
il try psp, but idk if the numbers will come out right.

let me know what you think

thanks!

perfecxionX
09-08-2009, 12:04 AM
yeah, re recommends 2.5 cubic feet for an mx.
but that seems way too small for such a huge sub.

but either way, minus sub displacement as well as the aeros.the 4.5 includes the subtraction of the wood displacement, but at the end of the build it will probably turn out smaller. its an odd shapped box so i dont even think the sub will see some the box

so youve admitted that your new to this and dont really understand it, yet your ready to go so far against the manufacturers recommendations?

according to their website re recommends 2 cubes. you should do 2@33 with two 4" aeros. after displacement that will gross around 2.7 cubes

psp-inc's length calculator says that each 4" aero should be 29" long (if you actually give the port a 12" length the tuning will be at like 50hz)


is there a reason why you dont just do a slot port?

robertoyoung08
09-08-2009, 12:20 AM
so youve admitted that your new to this and dont really understand it, yet your ready to go so far against the manufacturers recommendations?

according to their website re recommends 2 cubes. you should do 2@33 with two 4" aeros. after displacement that will gross around 2.7 cubes

psp-inc's length calculator says that each 4" aero should be 29" long (if you actually give the port a 12" length the tuning will be at like 50hz)


is there a reason why you dont just do a slot port?

yeah id be ready to drop the aero and do a slot with a quickness. except im trying to get the aero standing up height wise with the box so it can fire through where my stock sub was and get bass into cabin. otherwise too much of it is retained in the trunk.

im not new at car audio, just completely new at aeros so its confusing as hell for me.

with that being said, im going against the manufatures recomendations, because just like every other manufature, they recommend box sizes smaller than they should. re recomds like a cub and a half optimal for the xxx afterall, but just as caraudio magazine reviewed, they give smaller enclosure sizes to be conservative for people. 2.5 ft^3 seems decent enough as recommended by re audio, but after all displacements i should be okay i figure

perfecxionX
09-08-2009, 12:41 AM
I think you'd be wrong to say that all, or even most, manufacturers recommend excessively small boxes. RE recommends 2.2 optimal for the xxx. and btw 2 cubes is a pretty standard size for a 12, so i wouldn't hesitate to trust their recommendations.

why do you think that a "huge sub" requires a huge box and port?

robertoyoung08
09-08-2009, 01:07 AM
I think you'd be wrong to say that all, or even most, manufacturers recommend excessively small boxes. RE recommends 2.2 optimal for the xxx. and btw 2 cubes is a pretty standard size for a 12, so i wouldn't hesitate to trust their recommendations.

why do you think that a "huge sub" requires a huge box and port?

i dont mean any sub needs a big box.
and port size i wouldnt give my opinion on because i know that goes specifically by tunning.

well i guess i worded myself wrong, while i do think this sub is big, i wasnt trying to say any big sub needs a big box, im just trying to give it more space than what is recommended. i called re and they told me 2.5
i had the box measurements for exactly the box i wanted and the largest i can fit. it ended up being 4.3 and i figured id give it a try like that.

i am highly cosidering going down, but either way i still have the problem that i cant figure out the tunnin with aeros for any box size. so im stuck either way

snb778
09-08-2009, 01:12 AM
3x 4" aeros 18" long.. tuned at 35hz.... done

robertoyoung08
09-08-2009, 01:19 AM
3x 4" aeros 18" long.. tuned at 35hz.... done

you make it sound a lot easier than it actually is for me

and thanks, only thing now is that my box height is only 14 inches. so those 18"s definitely would not fit

perfecxionX
09-08-2009, 01:29 AM
http://www.ncbigsweep.org/elbow.JPG

snb778
09-08-2009, 01:49 AM
you make it sound a lot easier than it actually is for me

and thanks, only thing now is that my box height is only 14 inches. so those 18"s definitely would not fit

should never port out the top of the box... go out either side, or the back

robertoyoung08
09-08-2009, 02:06 AM
so youve admitted that your new to this and dont really understand it, yet your ready to go so far against the manufacturers recommendations?

according to their website re recommends 2 cubes. you should do 2@33 with two 4" aeros. after displacement that will gross around 2.7 cubes

psp-inc's length calculator says that each 4" aero should be 29" long (if you actually give the port a 12" length the tuning will be at like 50hz)


is there a reason why you dont just do a slot port?

ooh by the way, i would like to know why you say that if i use two 4" aeros at about 12" length it would be 50hz tunning. i got those number right from psp. unless you did the math on your own. but i dont see why psps numbers come out different.

robertoyoung08
09-08-2009, 02:09 AM
should never port out the top of the box... go out either side, or the back

why do suggest i shouldnt port out the top of the box?

snb778
09-08-2009, 05:20 AM
you want the port to be the ports diameter away from the closest side-wall... you'd be limited to about 10" length for each port... wouldnt work...

and B... nobody does it because it doesnt give optimum results

robertoyoung08
09-09-2009, 06:05 PM
well the whole point of me putting the aero was cus of how i want the box.
if i cant put the aero upwards then its not useful for me. id just make the slot port. i cant make a slot port in the middle of the box, which is wehre i want the aero to be.