PDA

View Full Version : A Guide to Aero Ports



7ender
06-16-2009, 04:58 AM
I could never find a guide on using aero's, so I thought i'd write one up. With them seemingly becoming increasingly popular, this is needed!

First off, why use an aero port?
-Boxes using aero's are much easier to construct than boxes using slot ports. Simply build a sealed box, and make a hole for the aero.
-They enable you to retune your box without building a completely new box; some people have multiple sets of aero ports of various lengths to change tuning on demand.
-They are more efficient than slot ports, and therefore can be smaller and take up less space in the box. For people that need every inch of their trunk, this is the way to go since it allows for a smaller overall box.

Much of the slot port-aero port debate is personal preference. Many people still stick to slot ports because that's what they're used to and have had no problems with them. However, because of the advantages listed above, aero ports are appearing more often.

Some people also claim that aero ports are louder, but I have yet to see this. It can vary case by case- some boxes may indeed be louder but others will see no gain.

There are a few disadvantages to aero's, in that:
-They cost more. If you buy a 6" flared aero for example, it'll run you about 30-40$.
-They don't provide the structural bracing that a slot port naturally does. Not that this is hard to add if you need it anyways...

So how do we design a box with aero's? There are a number of things to consider when using them.

First, the aero port itself. These are available at places such as precision sound and parts express. They come in various diameters- the most common being 3" to 6". Some people use PVC pipe available at any hardware store because it is much cheaper. However, they dont' have the flared ends that an actual aero port does and therefore MAY cause port noise and have decreased efficiency. This is not a hard fix at all though, as you can simply get a heat gun and mold the PVC to a flare using a bowl or similar shaped object. I have done this and had great success.

When using aero ports you can generally get away with about half the port area of a normal slot port. Where a normal slot port needs about 12" to 16" of port per cubic foot of box, an aero may need 6" to 8". Again though, your results may vary and I have seen many loud boxes that were well out of this range.

For those that can't figure it out, to find your port area use the formula Pi(r)^2. As a general rule, you want to go with as few ports as possible to get your desired port area. For instance, if you need ~25-30" of port, go with one 6" port rather than two 4" ports even though they have similar areas.

To find the length of the port you need, use the calculator found on http://psp-inc.com/.
As you can see, the length you will need is longer when we use a flared port (as opposed to a straight port), and this is because the air sees the flared port as having slightly more area. Again, I highly recommend using a flare as adding one to pvc is not a difficult process at all.

And for those that haven't taken geometry before, use Pi(r)^2(height)/1728 to find the volume your port is taking up.

A few more rules to keep in mind are that:
-Try to keep the port's end at least a diameter's distance from any wall in the box. Often though this is not possible, so just keep it as far as you can. This will yield the best results as a port too close to a wall can mess with your tuning.
-Also try to keep the port's end as far as possible from the subwoofer itself.


Besides those things, designing a box with aero's is just like that of a slot ported box! There are many ways to experiment with aero's as well. Many people use external aeros or ports that point to the side. This is usually done when attempting to get maximum spl, but try it out for yourself to find the setup you like best!

Hope I didn't forget anything!
7ender

kurrupt
06-16-2009, 06:42 AM
good write up!!! ive been thinking about using aeros in my new builds this will definatly help thanks

Trey803
06-16-2009, 06:58 AM
can somone explain to me the correlation between port area and tunning freq. also why aero ports require less area for same tunning?

and is their any difference btwn an external/internal aero port besides the placement of the port

Xprime4
06-16-2009, 07:09 AM
great morning read. I already made 3 box with aeros and i love them better than my slot port. If need alot of port area, you can use Hardware store Sonotube. They are sold in 8, 10, and 12 inch at my HD. Cheap stuff too

ContourSPL
06-16-2009, 09:25 AM
http://i95.photobucket.com/albums/l125/contourSPL/Big%20Port%20buildup/CIMG0340.jpg

Paaco1981
06-17-2009, 03:20 AM
As much as I hate to sound dumb, when I went to school we didn't have these formulas haha. ( Or I just don't remember it ) I'm not as young as some of you guys :( Can someone tell me the displacement of an 8" port that is 14.5" long?

Pi(r)^2(height)/1728 just confuses the hell out of me. If someone wants to dumb that down for me it would be great. That way I'd never have to ask again :)

Also would a single 8" port be decent for 2 15's in 6.5 cubes? If not please give me suggestions on what you think would be better and why. I am still learning, I have always used slot ports. According to http://psp-inc.com/ 14.5" of an 8" port = 32hz tuning for my enclosure.

Thanks

Something about a huge 8" port just makes me happy. Just seems like it would look beast :)

krainium
06-17-2009, 08:54 AM
Pi(r)^2(height)/1728=
3.14 x (4x4) x 14.5 = 728.48 cubic inches /1728 = .42 cubic feet
Pi = 3.14
r = radius
^2 = equals squared

Hope that helps

Xprime4
06-17-2009, 08:57 AM
i need your take on the port clearance outside of the box. I did search without finding alot of info.

Let's say i want to put a 8 in sono on the top sheet of my box (sig) i could get around 3-4inch of clearance. Would it affect the performance in any way? if so, how? affect tuning or port noise?

And in general, does aero and sub on top works well in hathback? there no other side i could get clearance except the side, near the back

Paaco1981
06-17-2009, 09:23 AM
Pi(r)^2(height)/1728=
3.14 x (4x4) x 14.5 = 728.48 cubic inches /1728 = .42 cubic feet
Pi = 3.14
r = radius
^2 = equals squared

Hope that helps

Thank you very much Kranium. :)

HighTQCummins
07-03-2009, 12:36 AM
Thanks for the write up. Aeros (or things of the like) have always confused me. Now I pretty much understand them. The psp-inc site, has some confusing info on how to install them.

I was thinking about building a ported box for my 8w7 or maybe even 2 sundown E8's. 30hz and roughly 1-1.2 cube. It says with 3" port I need 9.39 inch length end to end. Don't see why I can't just make the thing 9.39 inches long total. The site has all of this cut it to 5" shorter, then make it 1 inch longer etc.

SomeGuyDude
08-25-2009, 06:30 PM
Why isn't this a sticky? Also:


For those that can't figure it out, to find your port area use the formula Pi(r)^2. As a general rule, you want to go with as few ports as possible to get your desired port area. For instance, if you need ~25-30" of port, go with one 6" port rather than two 4" ports even though they have similar areas.

This is EXACTLY what I needed to know.

marcotheclepto
08-25-2009, 11:03 PM
so for 8.6 cubes gross id need 2 or 3 6 inch aeros?

SomeGuyDude
08-26-2009, 12:26 AM
Well they say 10-15sq per cu-foot of box for a slot, so 5-7sq per cu-foot for aeros. 8.6cu means 43-60sq in aero port, so two 6" aeros is 56.5sq of port area. That should be enough.

Just going off what I've read above, I'm no authority.

7ender
09-07-2009, 09:29 PM
bump because I keep reading the same questions over and over...

Though i'd like to add- I actually think 8-10" of port area per cube is a better rule of thumb. Iv'e seen a study that has shown that you can get away with 56% of the port area of a slot with an aero.

Though, iv'e had great success with smaller ports as well.

snb778
09-07-2009, 09:36 PM
YGPM

lots of people on here say to use 1/2 the calculated port area when using FLARED aero's

7ender
09-07-2009, 09:40 PM
Yeah, 56% is a more precise number for the "half" that everyone says to use. This is safer with flared ends because without them you risk port noise.

GI JOEY
01-26-2010, 09:22 AM
Bringing this back, I modded my seat brackets for my silverado and can now fit 3 4" aeros on one side or 2 6" pvc on one side or 1 on either side. The box is gonna be roughly 5 cubes depending on port space. It is 5.6 before PD and after DD. I am not sure if the 3 aero 4"ers will be enough port area.

Buck
01-26-2010, 09:30 AM
Good write up!

GI JOEY
01-26-2010, 09:34 AM
Bringing this back, I modded my seat brackets for my silverado and can now fit 3 4" aeros on one side or 2 6" pvc on one side or 1 on either side. The box is gonna be roughly 5 cubes depending on port space. It is 5.6 before PD and after DD. I am not sure if the 3 aero 4"ers will be enough port area.

What do you think???

BassMechkanic
01-26-2010, 11:54 AM
to be a true aero it mush have the flare on both ends, if not it is just a round port, the aero formulas are for true aeros', if you dont use them your round port length would be different.

Slo_Ride
02-06-2010, 06:18 PM
oops

Ray21
02-06-2010, 06:25 PM
Good write-up!

With the amount of misinformation regarding the use the round ports as Aero's, this should be stickied.

7ender
04-12-2010, 04:41 PM
bump because I still see alot of questions on aero's that I answered here.

And please dont' pm me with questions/requests to design your boxes, as as much as I would like to spend more time on here, I don't logon as often anymore.

O.G. D-Wet
04-12-2010, 04:49 PM
pics of those homemade PVC aeros???

RAM_Designs
04-12-2010, 07:23 PM
I normally do 6-9in^2 per ft^3 for aeros, and ~14in^2 per ft^3 with normal slot ports. I prefer slots more because they're cheap, add bracing, and are easier to tune low. Try tuning at 28hz with adequate port area with aeros and you end up needing two middle sections and a trip to Home Depot for an elbow that hopefully doesn't have any edges on the inside. Whereas with a slot port I can make it as long as I need to with no problem.

bahne
04-06-2011, 03:49 PM
Thanks! Found this thread and just got through designing my first box. Guide was so much help! Can't wait to put my system together :)