Allan Clarke DIY Subwoofer

The Ports

Now that the volume of my enclosure was known, I only had to work out the length of the ports. I was looking for a tuning frequency of 23Hz. This was done using winISD software and based on the fact that I was using 90mm OD (86mm ID) PVC pipe. So armed with this information, I was able to calculate that the ports had to be 668mm long each. To fit them into the enclosure, I used 4 PVC elbows to give the ports a ‘J’ shape which would face the Speaker driver. I glued the elbows to the pipe using PVC glue and then glued the pipes into the End Cap with wood glue. I finished them off with a silicone sealant around the ports. To finish, I sprayed the ports with an automotive sound deadener.

With the ports finished and glued into place with wood glue and sealed with silicone sealant, I sprayed the outside of the enclosure black. I had already fitted the binding posts and short length of speaker wire for the speaker, so the only thing left was to fit the wires to the speaker and install the speaker. I used double-sided 6mm foam tape to ensure that the speaker was seated correctly and sealed soundly. I also used screws to hold the speaker in place and put some silicone sealant around the edge as well. Below is the view of the bottom of the speaker with and without the legs.