By request for Treesive with two SoundSplinter RL-P subwoofers. User was looking for good low end extension (mid 20s) while retaining output. Sound quality was the main concern while keeping low end.
After running the numbers, this design was decided on. A t-line would have been a possibility, though it would have been larger than the user wanted.
Will be placed in a hatch vehicle and has been optimized for a smooth response and low end. The numbers in this design gave the best characteristics for SQ that could be achieved within the working limits and intended design goal.
For anyone wondering, the taper allows me to do a few things. It helps control phase (want to keep it within a limit and as smooth as possible), and shape the response curve. Basically allowing me to pull a few tricks to extend the response without introducing things that generally point to bad sound.
Waiting to hear what he thinks!