Round Port Tuning - Port area?

[scoob8000 10+ year member]

I'm going to build my first ported box but I'm a little confused with all the info that's out there.

Is enclosure volume and port area the only thing that effects the tuning frequency?

I have a sub with no TS specs, but the manuf suggests a 1.25 cuft box tuned to 40hz with a 3.5"x10.4" port.

If I understand right, I have a few other options that could work:

3" Port 7.33in long

2 1.5" Ports, each 3.6" long.

Am I thinking this thru right?

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[mcsoul 10+ year member]

Those other options you listed would tune the box correctly.

However the MACH rating (whistle/port noise) would be to high.

 

[Alex JB 10+ year member]

Like mcsoul said, going smaller can cause wind noise, go biger with the port and take the port area up - will mean longer port though.

Fluid dynamics dictate less contact surface area is better for smoother (laminar) flow.

Go for one big port if you can, not lots of smaller ones giving the same area.

 

[scoob8000 10+ year member]

Think a 3" Aeroport would give me too much port noise? Because like an idiot I already ordered one before posting this. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

I guess if it does, I can always cut the hole bigger and put a 4" one in. With a 4" port, length gets to be a concern though. (Box is only 16" OD wide)

 

[Alex JB 10+ year member]

how long can you make the port with the location for it you have?

 

[scoob8000 10+ year member]

how long can you make the port with the location for it you have?

Actually I have exactally 16" wide at the deepest point.

I figure 4"x14.4 long will give me the recommended tuning. How close can the inside opening of a port be from an inside wall?

 

[skmfkr 5,000+ posts]

4" aero needs to be 4" from the wall

 

[scoob8000 10+ year member]

Scratch that idea then. Unless I can get away with an elbow in the port.

I think I'll give the 3" a shot, worst case I can make the hole bigger. (Actually I'm retrofitting a sealed box that happens to fit the bill perfectly).

 

[scoob8000 10+ year member]

After doing a little more reading, should I even bother with the 3" Aeroport?

The manuf suggests 3.5, but will the flares help make up for the half in in diameter?

 

[mazdakid 5,000+ posts]

If you use an aeroport then you can get away with using less port area. If that 3.5" they recommend is a round port then the 3" aero should be fine

 

[scoob8000 10+ year member]

If you use an aeroport then you can get away with using less port area. If that 3.5" they recommend is a round port then the 3" aero should be fine

Sounds good, and if it doesn't I'll just build another box. I need practice anyway. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[ThaPath]

i have a question...dont mean to steal this thread or anything

im building a box for my two 18 inch bls that is 12.64 ft^3 and i was gonna use 3 4" ports for each cabinet at 15" long...is that alright

 

[skmfkr 5,000+ posts]

i did 4 4" aeros for my 6.5cube box... i would suggest using 4 of them each for you also. 3 4" is what you would use for like 4-5cubes or 1 15