General comments
- Your design looks fundamentally fine.
- I would use a lower compression ratio so there is less stress on the cone. The 3:1 you have used is getting up there for “standard” cone materials and designs.
- You don’t need all of those fancy curves for low frequency horns.
- I would select a different driver eg. 18sound 18WL1400, RCF LF18X400, B&C (what ever the equivalent is)
- In most situations the speaker would be used on the ground so I would use 1/2 space loading ( pi) when I model it.
- If you are only going to build 2 of these boxes I would build some good double 18 reflex cabs instead. If it was only 4 cabinets I would shorten the horn to about 8 feet.
- Use a lot of bracing – there is not enough in the LAB.