Port...... SMH!!

[bbeljefe]

Everything in enclosure design is based off net internal volume (after ALL displacements), with the exception of finding out how much room you have for a box. So, once you know how much room you have to work with, that's the last time you worry about gross volume.

And as was mentioned, using "port area per cube" is about as scientific as predicting the weather with a horoscope. Port area is calculated using the amount of air the sub(s) displaces (xmax) and the desired tuning frequency. For higher tuning, you'll need more port area than for low tuning and when you use aero ports, you still need a close approximation of the calculated port area. Fifteen to 20% as mentioned above is the most I would reduce port area.

 

[bgowdy 5,000+ posts]

I agree. 113 inches isnt enough unless you have a ton of power to bring the output back up.

So your saying that using aero's it on requires about 15-20% of the port that it would be if you were doing a slot?

Also as far a ton of power, i mean im running 3kw to 2 subs that are rated at 600rms each lol

 

[Notloud00 10+ year member]

So your saying that using aero's it on requires about 15-20% of the port that it would be if you were doing a slot?
Also as far a ton of power, i mean im running 3kw to 2 subs that are rated at 600rms each lol

no, 15 to 20% less than a slot. so you would need minimum around 160sq inch of port. you wont get 3kw of real power unless you know your box rise and account for that when you wire the subs.

 

[Dmac1991]

hm.... well if thats the case, i will have more square inches of port per cube then i thought, possibly to much, but idk. Im running 2 18" OA 18s on 3k. Is 11.48 inches of port per cube to much for a daily driver with potential to put up decent term-lab numbers?

aero port right?

generally speaking, aero's work from as little as 5" of ppc all the way up to 11. You should be fine with 18s

 

[n8skow 10+ year member]

We're going in circles here (no pun intended)...

//content.invisioncic.com/y282845/emoticons/smash.gif.499e08a4a35ffaf54f4c8194fb8fe8ed.gif

Post #16 sums it up nicely.

 

[bgowdy 5,000+ posts]

no, 15 to 20% less than a slot. so you would need minimum around 160sq inch of port. you wont get 3kw of real power unless you know your box rise and account for that when you wire the subs.

I understand the rise and what not, im wiring to .5 ohm to help with rise, but i think a good power number to say would be about 1800, even at 1800 im still overpowering the subs, but of course theres no way to tell with out clamping the amp

 

[bgowdy 5,000+ posts]

aero port right?
generally speaking, aero's work from as little as 5" of ppc all the way up to 11. You should be fine with 18s

thank you, i figured it would be ok. im just going to make a 12" aero

 

[bgowdy 5,000+ posts]

Everything in enclosure design is based off net internal volume (after ALL displacements), with the exception of finding out how much room you have for a box. So, once you know how much room you have to work with, that's the last time you worry about gross volume.
And as was mentioned, using "port area per cube" is about as scientific as predicting the weather with a horoscope. Port area is calculated using the amount of air the sub(s) displaces (xmax) and the desired tuning frequency. For higher tuning, you'll need more port area than for low tuning and when you use aero ports, you still need a close approximation of the calculated port area. Fifteen to 20% as mentioned above is the most I would reduce port area.

thanks for clearing up the "after displacements part"..... as for tuning, im not tuning really low, because i dont listen to slowed music or really low music. Im tuning right at 38hz because it gives me my medium of daily and spl for the music i listen(but thats just me), I know everyone else tunes at like 30 etc but i dont plan to play anything below probly 35hz,

 

[hispls 5,000+ posts]

thanks for clearing up the "after displacements part"..... as for tuning, im not tuning really low, because i dont listen to slowed music or really low music. Im tuning right at 38hz because it gives me my medium of daily and spl for the music i listen(but thats just me), I know everyone else tunes at like 30 etc but i dont plan to play anything below probly 35hz,

12" round is adequate for pair of 18's. You may be able to gain on the meter with more port area but that area and tuning is fine in my book.

 

[bgowdy 5,000+ posts]

12" round is adequate for pair of 18's. You may be able to gain on the meter with more port area but that area and tuning is fine in my book.

thank you for a straight response. //content.invisioncic.com/y282845/emoticons/thumbsup.gif.3287b36ca96645a13a43aff531f37f02.gif