vent noise on a ported box

this is my first box and qestion
i recentl managed to obtain a 10" alpine type-e car subwoffer with 600watts peak and 200rms acording to box
well the problem i have is some vent noise at moderate levels on my reciver at a litle over i quarter volume.
the box i had made for it was out of .75" mdf and was 30"L/13"W/10"D
and 4x3"dia. ports and 10' long
any advice would be greatly appreciated thnx:)