First Box Build WinIsd Question.

[SpydreX]

The transfer function magnitude is just a graph of the frequency response of the sub & enclosure.

Where your box peaks at and where its tuned to are not the same thing, as the graph is showing. Ported boxes are a resonant system and the tuning is the frequency at which the system resonates. Where you get peak output is going to depend on a lot of different factors, box size and tuning being some, but not all, of them.

WinISD only shows you raw output from your sub, once you put it in a vehicle cabin gain is going to change the frequency response significantly. Most likely shifting your peak frequency down.

Oh ok that makes a lot more sense now, thanks for the help. This box should do the trick then.