Does this make sense? When i roll, or crack my windows, the bass definitely gets louder. I dont know if it has something to do with cabin airspace..... does anyone else notice this?

 

I do, it has something to do with air flow

 

Think of your car as a box. It's sealed with wondows up but when you crack the windows or open them it becomes ported and you are sitting in the port. That's probably why.

 

I believe you're right; with windows up the subwoofer cone's excursion is limited because it is pressing against the air pressure inside the car... with windows open, the backpressure is eliminated and the subwoofer cone can reach it's full excursion... by the way everything i've just said is total BS that I just made up on the spot.

 

^ HAHA. That's exactly what I did but you made it sound a little more official. NICE. . You must be in sales.

 

The vehicles resonant frequency has a little to do with it, as well as trapped sound waves. The lower the note the longer the wave. Having a completely sealed car has 'some' cancellation effects, which is why when you let your windows down, the bass notes (sound waves) can (in laymens terms) escape, stretch their legs, breathe a little easier, etc., etc., and thus the increase in sound levels.

for reference, higher notes have shorter wave lengths, and having windows up, or more appropriately 'the vehicle completely sealed', builds more pressure inside the vehicle, which = higher SPL.

This is why Team Gates dominated for so long using 80hz and higher bass tracks in their Bronco...which is also why those higher frequencies have been banned in Major SPL competitions. They even use mic's that filter out these higher bass frequencies now. It was almost cheating, since sub bass is technically 20hz and below (the average threshold of an adult).

 

well, that appears to be the answer im looking for. However, I was thinking it had something to do with the "ported box" explanation as well

 

A port or vent reinforces the REAR wave of the sub INSIDE of an enclosure...the air in front of the sub is already being compressed/excited outwards inside of the cabin its playing in (the vehicle). It cant technically be compared to a port.

 

im not gonna give some long technical explanation, im just gonna say YES, i have the same effect when rolling down my windows

 

Mine actually hits harder with the windows up with an ALL JL Audio set up and an Eclipse deck.

I have a sealed box and my trunk lid is Foamed and Matted. My Sub is facing up with a 15 degree angle towards the front cabin.