Need a little help on this sub

[Cj Kumz]

Ok so I'm working on a building for 4 spl dynamics 300d1a www.spldynamics.fi/products/subwoofers/SPL-series/spl-300d1a-e.html Now I need a little clarification over the xmax to use in winisd. I have seen 3 xmax types people mentioning. Linear Xmax, linear peak xmax and peak to peak xmax. So on this sub is that peak figure representing linear peak or peak to peak. Thanks guys

[Triticum Agricolam]

There are basically two "correct" ways to determine Xmax that I know of, the first is the mathematical way which is (coil height - top plate thickness)/2, this is how far the cone can move before part of the coil starts to leave the gap. The other way is how much excursion it takes before BL drops to a certain amount (usually 70%). Both of these measurements are one-way.

Any time you see anything about peak-to-peak Xmax that's just the manufacturer trying to pull some stupid marketing shenanigans in an attempt to make the Xmax seem bigger than it really is. In the case of the sub you linked above it looks like the real Xmax would be 11.5 mm, though that does seem low for that sub. You could email the manufacturer and ask them for clarification.

[Joe X]

If you have a peak to peak specified Xmax just divide by two to enter in modeling software, anyways Xmax doesn't change modeling results, it serves as reference and help figuring out port area, however Xmax is very important to parameter to consider in a design and knowing which method was used to obtain it not only for driver safe operation but for the quality of sound you are going to get if it is relevant to the application.

[Cj Kumz]

Yah I have used the 15 inch version of this sub but next really paid attention on the excursion. But in all honesty it's way to much of an spl oriented sub and not musical could that explain the short xmax? Yah in my experience port area is a major factor especially when pushing a sub to its limits