If you only ever plan on running it at 15hz, then yes you can build it with JUST a single port.I'm thinking about building a couple of these subs for my basement theater. I have a cubby space that I can put the subs into that will allow me to effectively flush mount them into the wall. I'm trying to go as cheap as possible so my question is - can I use a single port for each sub and have them tuned to 15 hz? I know the design calls for two ports per sub but this is just to have the flexibility to tune them differently right? If I can get away with buying two precision ports instead of 4 I can save $30 or so. Thanks in advance for the help.
You are correct in that the other port is there to allow for the different tune options.
If it was me, I'd build it in such a way as to be able to add the other port later on, if needed.