How to measure an aero port?

[Jessica]

So when i rebuild i am going with a 4" aero in each side in a divided box. I want to know if i count from tip to tip on the aeros as length. I've seen this asked before and i can't remember and can't find that thread because there are like 4 jillion threads titled "aero port length". I titled this thread so maybe when others search maybe this will come up and help.

From what i can find it says, "yes, count the flares". Thanks!

also:

sundown sa-12

What i have is 2.04cuft after displacement

one 4" @ 11.25" gives me 12.56in² port area tuned to 34hz

That will put the port exactly 4" from back of box.

That sound about right?

This will actually be a divided box, so this will be X2

[rogue]

I believe the rule of thumb is you count half the radius of each end. Aka the distance from where it starts to flare to the end of the flare divided by two. Them you add that to the rest of the non flared portion. If you have flares on each end you would count them both this way.

[Jessica]

I believe the rule of thumb is you count half the radius of each end. Aka the distance from where it starts to flare to the end of the flare divided by two. Them you add that to the rest of the non flared portion. If you have flares on each end you would count them both this way.

Anyone know the radius on the 4" aero's from parts express?

[certifiednut]

if it is a 4" precision port, it should be 1 inch longer total than what you came up with on torres or wherever

[OrionStang]

if it is a 4" precision port, it should be 1 inch longer total than what you came up with on torres or wherever

This. If you get a 12" length using Torres, for example, your actual aero port should be 13" from end to end.

[Jessica]

Hmmm, ok, thanks. I just took a wild guess while waiting for answers and took and inch off my port length to see. I got a 35.5hz tuning. I could probably live with that. I cant go any longer or else i will be too close to the back of the box.

My only other option is to go out the sides of the box, but that would put the ports in the front right under the subs. i don't know how that will work or sound.

also, Is my port area good enough? it's 12.5 in^2 at 10.5" length.

Thanks again everyone.

[Jessica]

Guess i'll throw this up. This is what i have so far. Tell me what you think. I've done about a jillion different designs in torres and sketchup. It would help if i knew what i was doing. lol

This will be for two sa-12's on a skar 1500.1.

Back of a 87 accord hatch, subs up and port back.

I have to have the ports up high because of the amp rack.

also the port length will actually be 12.75 tip to tip with the flares, and that put the port 4" from the back of the box. I put 11.75 cause you guys said subtract 1" for aero flares.

Help me out here, I really am trying to learn how to do this so i don't have to keep asking for designs. I want to be able to do this myself. It's just kind f hard to find good info.

[rogue]

all looks pretty decent. Im not real familiar with those particular subs but I think you could stand to increase the port area by a good bit like maybe even double the port area. Although in doing so you will need to change much of the current design and you will most likely need to add bends to the ports to account for the extra length they will require to acheive the same tunning with more port area.

Im not saying what you have wont be just fine but you may stand to gain some output with a little more port area.

[Jessica]

I've heard 7-12 for aeros and 11-15 for slots. But it's kind of hit and miss. I can go 4 3" aero's and go longer, but i have to go external with the ports. No big deal but like i said, can't get anything real concrete on what i should be aiming for.

if i go with 4 3" aeros i get 7.13 for the area/ft.

So how much area do I need for aeros?

[john253a]

rule of thumb

aero 9-13sq" per ft

slot 12-16sq" per ft

tihs does not apply to all subs

as a sub with 5mm xmas doesnt need as much port a sub with 20mm xmas in the same net volume

youll need at least 3 4" aeros in 4cuft

also the bracing displacement allows for internal baffle and bracing