If you are gonna continue to be into car audio... it would be wise to get to learn WinISD, also read about T/S parameters. Jesse gave me this link...

http://www.welcometotheden.8k.com/ca...parameters.pdf



To elaborate on what was said earlier in teh thread by MDIFYTD...
Since the Type-E don't give a flat responce and don't seem to be ported well, you will probably have to tune to a low frequency. The lower frequency you tune the ported box to, the longer the port length have to be since lower frequences have a LONGER wavelength. Making room for that long port requires a much bigger box.

You also have to take into account "port noise" from the air pumping in and out. Speakers with more volume displacement (Cone area x Xmax) require wider ports... and the wider the port the LONGER it must be. So you want the minimium port diamter so decrease the port length. Here is a quote taken from one of Adire Audio's webpage HERE.

For a Helmholtz resonator to work requires two reactive acoustical elements: an acoustical compliance, supplied by the volume of air in the box; and an acoustical mass, supplied by the port. As you may know, the acoustical mass in the port is directly proportional to the length of the port and inversely proportional to the square of the port's diameter. This is why when you increase the diameter of the port, you must increase its length to maintain the same acoustical mass.

But to behave as an acoustical mass, the air in the port must essentially he moving as one. Implicit in this is the requirement, then, that all port dimensions must be substantially smaller than a wavelength of sound. As one of the dimensions starts to approach a wavelength, the port no longer acts as an acoustical mass, but begins to exhibit the behavior of an organ pipe or even a transmission line. Not all the air is moving in the same direction, and the port no longer behaves as a single mass.

So, clearly, we have a set of limits imposed by the requirements that the port act as a single lumped acoustical element. The diameter must be small enough so that it is a tiny fraction of a wavelength in the region of the Helmholtz resonance. At the same time, port length resulting from the diameter must also be a tiny fraction of the wavelength at these same frequencies. Using an arbitrary notion of "tiny" as less than 1/10 of a wavelength, this would suggest that the largest dimension of a port operating at 50Hz (wavelength is 20') would be a 2'.

I would, personally, adopt an even more conservative figure, such as 1/15 or 1/20 the wavelength, suggesting that a port tuned to 50Hz should not exceed about 16" in length. This is because the port is not just acting at 50Hz, but over a substantial range of frequencies above and below this. Imagine, also, that a 2' long port will exhibit its first standing-wave resonance at the low frequency of only 250Hz, where the output of the port increases substantially.


What a Helmholtz resonator is...