Originally posted by LoneRanger It's harder to achieve loud bass at lower frequencies, plain and simple.
Think of it this way:
Ever hear a pair of really loud home tweeters? Like they make you feel like your ears are going to bleed? They don't need that much power to get real loud because the higher frequencies have shorter wave lengths. Idealisticaly, the goal in SPL is to find the frequency at which your car produces a full wavelength between the sub an the mic, and tune your port to where it will peak at that frequency. Bass frequencies have huge wavelengths, so this can be very difficult to do, especially in the sub 50hZ range (the lower the frequency, the longer the wavelength. Loyd Lowery (aka the BassGod) has a special box design that gets very loud way down there, but that's a whole new thread.
I hope I haven't confused ya too much //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif