slot ports vs. aero ports.

[valin 10+ year member]

I have been doing some searching and was considering going with some aeroports in my new setup, which is two loaded BTL 18's off of two Memphis Mojo mc-2000d's in 12.5 cubes total airspace before displacement.

I have read so many contradicting things about aeroports that I am forced to ask some questions.

Is it true that with aeroports you need 1/2 the port area as a slot port to be just as efficient? ie. 200 sq. inches of slot = 100 sq. inches of aeroport?

If this is so, I am going to either run three 6" aero's, at 11" long for 33Hz, or two 8" aero's at 15" long for 33Hz.

Where can I purchase 6" or 8" aeroports?

Click to read more...

 

[Lakota 5,000+ posts]

http://www.psp-inc.com makes 6" aero's, but I don't believe that any companies make 8" aero's as of now. Those with 8" aero's probably had to make them themselves.

Yes, you can get away with less port area, I'm running 3 4" aero's on my 15.

 

[valin 10+ year member]

bump about the ratio of port area of an aero vs. that of a slot.

 

[Lakota 5,000+ posts]

bump about the ratio of port area of an aero vs. that of a slot.

Your original plans should work fine, but another 6" would probably be better.

 

[jake the ssnake 10+ year member]

bump about the ratio of port area of an aero vs. that of a slot.

I'm interested in this also. I just recently heard that they are around 50-60% more efficient than slot ports. I would like to get some more input on this or test results.

 

[IgnoreMe 5,000+ posts]

use the search button and search for

"aero port area"

you will find what you need.

 

[newusername 10+ year member]

The amount you cut down velocity will depend on the mouth radius, throat radius, and flare radius. 50-60% is not at all an unreasonable assumption.

I did some of the math on flared ports here:

http://www.soundsolutionsaudio.com/forum/index.php?showtopic=7546

You can see that in the example I listed in that post, velocity at the mouth was decreased by approximately 56%.

 

[J31Rob 5,000+ posts]

Is it true that aero's are more "peaky"..?

 

[newusername 10+ year member]

It is possible. The reason a flared port works in the first place is because the flare causes the air in the boundary layer (air close to the walls of the port) to expand and loose speed in a controlled manner, the amount of expansion obviously depending on the various radiuses I listed above.

The problem is that the flare effect is most predominant on the boundary layer and has little to no effect on the air in the center of the port. As the velocity increases, this air becomes increasingly turbulent (for a given diameter port) and the flare does nothing to help this. This is port compression at it's finest, where there is a little loss of output and the helmholtz resonator shifts in frequency (the tuning frequency of the port changes).

For a given port diameter and throat velocity, you will encounter problems regardless of the flare radiuses.