Port Design

[a1161979 3]

I remember reading somewhere about the relationship between a box's port area and potential output. The reason i ask is i have been looking at the IXL drivers from Mach 5 and in order to tune low in such small boxes the port needs to be quite large in order to avoid port noise.

I was looking at a 2cf box with a fairly large port (roughly 50 inches) my question is will such a large port casue a loss in output? i was looking at tuning at 30Hz for a daily setup that would hammer out the lows. Is there a general rule of thumb regarding port size compaired with box volume? Could someone point me in the right direction (i haved tried to search)

I was hoping some of the experienced guys could give me some advice

[Adrian_D 520]

The general "rule" is 16 square inches / cu ft. I personally use 1/3 up to 1/2 of the cone area for port area.

[a1161979 3]

So if your ports are larger then you will lose output? I am interested to hear more becasue i have noticed SPL guys seem to run really large ports.

The main problem i am having is building a box for the IXL's which is tuned low enough with a port then will not chuff. Currently im looking at 2Cf with a port that is 12 inches by 4 inches and roughly 60 inches long according to WinISD this is a cross area of 47 inches

Is a 1st port resonance of 120Hz too low?

Thanks for any help guys

[Duran 387]

So if your ports are larger then you will lose output? I am interested to hear more becasue i have noticed SPL guys seem to run really large ports.

Not necessarily. Large port area raises efficiency, which competitors really need to win.

A lot of guys on here have tons of port, they use all of it for competitions and plug some of them for daily listening.

[DeeCee 0]

I range my ports between 12 - 16 inches per cu ft. The reason is that if the port is too large, then the sound can be very drony if there is a reasonable amount of internal resonance inside the box. Using a flared port will decrease port noise.

You could potentially lose output if the port is too large. The sub will essentially think its playing free air. Finding a good ratio of port to box with given sub and power is a fine balance.

Look at making a modular system with a removable port. That will allow you to change up and tailer a sound for competition and sq and daily street beating as long as the box can accomodate the various port lengths.

Tip - lower tuning isn't always better I frequently tune my boxes to 35 - 37hz instead of the more common 30-32hz. The reason being that it offers a slightly higher output while being tighter than a lower tuned box and not sound drony and hollow.

[Duran 387]

I range my ports between 12 - 16 inches per cu ft. The reason is that if the port is too large, then the sound can be very drony if there is a reasonable amount of internal resonance inside the box. Using a flared port will decrease port noise.

You could potentially lose output if the port is too large. The sub will essentially think its playing free air. Finding a good ratio of port to box with given sub and power is a fine balance.

Look at making a modular system with a removable port. That will allow you to change up and tailer a sound for competition and sq and daily street beating as long as the box can accomodate the various port lengths.

Tip - lower tuning isn't always better I frequently tune my boxes to 35 - 37hz instead of the more common 30-32hz. The reason being that it offers a slightly higher output while being tighter than a lower tuned box and not sound drony and hollow.

Exactly, or something similar to 95honda's 8 8" RE subs ha did a while ago, he used all of his port for competitions at 50 Hz. , plugged two of them to yield 40 Hz. for rap, and plugged two more at 30 Hz. for all other music.

[DeeCee 0]

There you go

To make a system more modular, it takes more work on the calculation side, espec. since you have to rework the volume that the sub is playing into as that will affect power handling ability.

Overall, you should be able to figure something out that has the best of a lot of scenarios by being a bit different and making things interchangable.

[a1161979 3]

Thanks for the advice guys, my origional plan had way to much port so i will go back to the drawing board and try to design something that will allow me to change the tuning of the Box so i can experiment