GM - here's Abraham Cohen's stubby horn vent cabinet for University Sound's "Diffusicone 8". With a crude attempt to sim it, peaking seemed much worse than the graph below
Diffusicone 8 cabinet article
https://i.imgur.com/3khziku.jpg
https://i.imgur.com/uCEmQ45.jpg
sim
https://i.imgur.com/188ZdgX.png
Diffusicone 8 cabinet article
https://i.imgur.com/3khziku.jpg
https://i.imgur.com/uCEmQ45.jpg
sim
https://i.imgur.com/188ZdgX.png
Thanks for all the info! 
Yeah, the few times my neighbor with the K15 and other projects we built, laboriously did frequency response plots on log paper looked so different even measured outdoors compared to published that he gave up and now with so much more experience that it's obvious they just measured a few key frequencies and only paid any attention to treble response.
GM
Yeah, the few times my neighbor with the K15 and other projects we built, laboriously did frequency response plots on log paper looked so different even measured outdoors compared to published that he gave up and now with so much more experience that it's obvious they just measured a few key frequencies and only paid any attention to treble response.
GM
That BVR / HLR / stub-horn vent (I like that term) above has an 'interesting' expansion profile.
I didn't put anything profound in any of those short talks (TBH I can't entirely remember what I said); mostly pointers or practical hints for relative newcomers that might help until they've learned more, e.g. using slightly undersized vented boxes tuned for a modestly damped response, rather than flat anechoic alignments. More practical for most modest sized UK rooms, and more likely to work 'out of the box' than a more acoustically efficient / flat box alignment. I figure they can move on to working with the latter when they've had some successes & more familiar with box tuning. That kind of thing.
I didn't put anything profound in any of those short talks (TBH I can't entirely remember what I said); mostly pointers or practical hints for relative newcomers that might help until they've learned more, e.g. using slightly undersized vented boxes tuned for a modestly damped response, rather than flat anechoic alignments. More practical for most modest sized UK rooms, and more likely to work 'out of the box' than a more acoustically efficient / flat box alignment. I figure they can move on to working with the latter when they've had some successes & more familiar with box tuning. That kind of thing.