What Is The Difference Between Slot VS Circle/Round/Aero Ports? A Confused Car Audio Subwoofer Question That Many Ask:(

When you are building a custom made ported enclosure for your subwoofer driver, you need to create a port and tune it to the bass frequency you want your sub to play. A port is used in a enclosure to increase the spl output of the sub and is vital to get it correct.

There are two types of common port designs that most car audio enthusiasts use for building a port subwoofer enclosure, which are a circular shaped port, made from cheap plastic (PVC) and the other port design is a mdf wood fitted on the end of the subwoofer box, that is used to create a slot, so the air can vent itself out.

They are both designed to increase spl, but the slot port is likely to create port noise, this is when you turn up the volume. Port noise will occur when the friction of air is moving through the port. Slot ports are likely to have rough edges, so that will increase the friction moving through the port, resulting in terrible port noise, this will reduce sound. So use sandpaper and sand the 4 corners in the port, smooth. Also the benefit using a slot port is that you have no limitation on the area of the port, this can lead to more spl levels.

The circle port is a simple item to install, all you do is cut a hole into the subwoofer box, tune the port length for the sub's requirements and place the port into the hole, job done. But on the downside they cause massive amount of turbulence reduces the spl gain of the enclosure. But the good thing about using a aero port for your subwoofer enclosure is that later on if you do decide you want to lower the tuning frequency, you simply reduce the size of the port. However it will be extremely difficult to make that modification to a slot port.