Okay Graeme, thanks for the explanation.
What you are saying is that it might work for over ~400 Hz, but not below.
And thet for the lower freq's it does not really matter, no dispersion control, but no problems either. correct?
The only thing that could be a disadvantage then is that because of the wider dispersion under 400, we have less efficiëncy there too, so the box will go a bit louder (in the narrower field of) over 400 and not under 400?
It might sound "thin" as a result then.
I knew there had to be a catch somewhere,
it was too simple to be true.
But the box is not built yet, and it will take some more time too!
cul8r!