Port Area

[CleanSierra]

OP, amount of port area can also determine how flat or peaky your box is too. It's a delicate balance.

Not really. Frequency response is determined by box size and tuning vs. driver t/s parameters.

Only way port area will affect frequency response is if it is undersized to the point of not operating correctly (air velocity too high).

This is interesting because I was always under the impression that on average, a port with too much area could give a peaky response. It's more the driver in question whether or not it will be like that huh? VERY interesting...

[bkolfo4]

If too large of a port created peaky response, what would happen if I designed a port to support a sub with 50mm of excursion and then played it at low volumes? When the sub is barely moving, the port is "too large"

[CleanSierra]

I realize youre taking huge Xmax numbers in your example, but there's a limit to what is too much. Couldn't too much port give the feeling of a big leaky sealed box? I know that too small of an opening can cause compression of the wave and do that, but can't too much port do the same thing?

[bkolfo4]

Don't forget as the port area increases, the port gets longer. If you make the port larger without making it longer, then if course you will have issues.

The port would have to get large enough and long enough to have resonance issues other than the tuning frequency. It is possible, but not likely for the sizes used in even what people are calling "SPL" boxes in cars.

The point of my example was just that you design a port for the maximum condition, but it still works great when played way below that condition.

It is like the argument that under-powering blows subs. All you have to do is stop and think about the fact that any time you are not playing the sub at max volume, you are "under-powering" it, even if you have an amp that is double the rated RMS of the sub.

[Jessica]

If too large of a port created peaky response, what would happen if I designed a port to support a sub with 50mm of excursion and then played it at low volumes? When the sub is barely moving, the port is "too large"

Port area isn't the only thing to consider here either. Port ratio is critical as well, you can have a port with 100 sqin of area, and if it's 3X33 it will probably sound horrible.

But i wonder if port area has more to do with air space. what i mean is if you build at the lower end of recommended specs, or at the larger end then would you adjust port area to compensate for the effects of those changes?

hmmmm....

[bkolfo4]

If too large of a port created peaky response, what would happen if I designed a port to support a sub with 50mm of excursion and then played it at low volumes? When the sub is barely moving, the port is "too large"

But i wonder if port area has more to do with air space. what i mean is if you build at the lower end of recommended specs, or at the larger end then would you adjust port area to compensate for the effects of those changes?

Not if it is for the same speaker. . .