Planning an extended bass cab

[Stub Mandrel]

Inspired by seeing and reading about some really good single 12 bass cabs, I've been looking at how to address the shortcomings of my own setup.

Currently I have a 2x12 Pheonix guitar cab with two Celestions in it, probably 70s greenbacks but I haven't seen them for 30 years and its a lot of screws...

I have a homebuilt 2x12 with two Mackenzie twin-cone PA speakers in it. Adding two modest ports to this has made it a bit bassier than the Phoenix but not as solid as I want. It's 3dB down at about 65Hz, assuming the Mckenzie 12 TCs of ~1980 are broadly similar to the Mackenzie MK Studio 12 100TC of today... I suspect that they are not as good as this!

My thought is to make an 8R 1x12 cab to use with the 'twin mac' where in the past a big 15" cab would probably have been used.This means I don't need something with an extended response beyond 3KHz.

I'm happier to bigger than 50 litres, and something about 700 x  550 x 300 would be about 85 litres and give a solid platform for the twin mac and with only one driver it will weight about the same.

I've found this well specced driver for less than £50 on CPC:

 

This are various experiments in WinISD, the dark line is the above driver - the benefit of using the equivalent 15" is questionable. (It knocks the spots off the slightly more expensive Eminence Beta 12A for this enclosure):

At 150W (more than my amp will put into 8R) the max excursion at 31Hz is = to Xmax of 8mm.

The 'power dip' is down to 55W at 60Hz, but from reading other threads that should be OK because the actual power is spread across many different frequencies.

With four 80mm vents the air velocity stays below magic 11, but needs longer pipes than cabinet depth; I reckon 70mm pipes should be OK as I can 3D print ends flared out to ~80mm that should get rid of any 'whooshing' (Ignore the other plots!)

Do these results look sensible? This is the first time I've use WinISD in anger and I might be making some really stupid mistakes.