What kind of power will you be using to drive those 18's? In a sealed box with the high excursion, should be able to really push them.
The Ultimax UM18-22 driver looks pretty good, especially for the price. I have an open channel on one of my amps, so I ordered one UM18-22, which I received today. Still waiting on the 4.0CF sealed Baltic Birch flat pack. I ordered two flat packs, but no discount for ordering only two drivers, so decided to try one first and then decide if I want to get another one or move up to the SI HST 18.
Very happy with my pair of UM18-22's. I went with the PE flat pack and I'm using an iNuke6000DSP to power them.
Looking good. Mike, quick question. How much did you invest in all of the tools to build your own subwoofers? I assume the ROI is there in the long run, especially if you build more than one. Just curious.
I used to be a commercial general contractor, years ago, so have had all of these tools for many years. Also have a large workshop with large tools. I built my LCR's and I have built a couple dozen subwoofers over the years.