Sealing ported enclosure to reduce boom

"Sealing" the port is a bad idea. The drivers and crossover were designed to work with the port open, at least to some degree. The suggestions to play with positioning away from boundaries and partially blocking the port with foam or even a sock are legit.

no one mentioned it unless i missed it but at one time people put soda straws into port to 'control' the air movement. i tried it and never heard a difference and the muticolored straws kept dissappearing as child stole them. i can,t be the only person who endures all these pranks/tweaks recommendations. ha

The straw thing was more of a port noise reducer...port chug, and not boom. Two different things.

Dave

thanks, you are exactly right. can you hear chug? i.m sure it,s there when cheap speaker manufactures like the one in framingham mass use a cardboard tube. ha. the nice looking aerodynamic fluted ports look cool. why is the velodyne ports slotted across the bottom of the cabinet? guess they would claim measurements of response show an advantage. this is why the inventor side of audio is cool to me. so many different ways to try and produce a sound wave accurately. thanks

An in-between solution would be to change the port dimensions and thereby lower the tuning frequency. If you make the port longer, or narrower, the tuning frequency will be lowered and the bass will start to roll off higher up and more gradually. A slightly smaller diameter tube can be inserted into the port (ring the inner tube with electrical tape in two places to get a good friction fit). This smaller tube can be longer than the original port. Or, you can do it with straws, as long as they are likewise longer than the original port. Pack the straws in tightly until they deform into a honeycomb-like shape. You will probably have to remove the woofer if you do the straw-pack, so that you don't accidentally push the straws into the enclosure and end up with a pile of straws at the bottom.

How long should you make the insert? As long as possible, leaving about one diameter of clearance from enclosure walls or woofer magnets (like if the insert is 2" in diameter, you want at least 2" of clearance). If the bass is still boomy, go ahead and seal the box. If you overdid it and the bass is now too lean, the shorten the insert.

Duke
dealer/manufacturer