How to stop car speaker static?

Why does my car system sound better with the trunk open?

• i have two 12" pyramid subs and a 1600 watt pyramid amp. I built my own speaker box with 7/8" plywood and the speakers are facing the rear of the car. ( my speaker box has 2 ported holes in the back) Car: 1993 Oldsmobile Cutlass Cieara S When i am driving around i have the trunk closed obviously. and my licenses plate rattles like crazy and that's all you can really hear, you can hear some base out side the car and can barley hear or feel the base while in the car. ( it honestly doesn't even sound like i have a system, its complete ****) Now when i am sitting in my driveway i open my trunk and it sounds at least 10x better, i can defiantly hear the base while in the drivers seat and can feel it. What i want to know: How to stop my license plate from rattling? How to make my system sound as good as it does while the trunks open? ( make it sound the same way closed) Does it make a difference where the holes are in the box? What are your general suggestions that will make my system sound better? :D thanks!

• Answer:

  You're experiencing phase cancellation. If the ports (or "holes" as you call them) are facing the front and the woofers are facing the rear then the sound waves coming from each are reaching your ears at different times (roughly 180* later). That's why it's always highly recommended to position the ports on the same side of the enclosure as the woofer. Plug the ports somehow and I bet is sounds better.