I went yesterday to a local concrete supply store and finally bought the sonotube I need to build the enclosure for my Blueprint 1803. I bought a 24" diameter tube for the enclosure, and a 10" diameter tube for the vent. The total for both was around 70 dollars (is this what everyone else pays?) Anyways, everyone says 14cuft tuned to 18hz looks pretty good, but I am thinking more around 16cuft tuned to 18hz would be good. My reasons are this. With a 16cuft enclosure, the vent length only has to be 33inches vs 40" with a 14cuft enclosure. This will move the pipe resonance's up higher in frequency, correct? Can anyone tell me what the pipe resonances will be with my configuration? The enclosure is going to be 6ft tall, and I figure around 3cuft will be taken by displacements. The vent alone takes up over 1.5cuft of airspace!!! So the airspace before displacements will be 18.8cuft and after I figure it to be around 16cuft. I have a behringer feedback destroyer so any peaks can be fixed with it. Is thier anything I am missing? I can't think of any downsides with using such a large enclosure, other than the space taken up by it. Thanks!