Is that really happening in practice?

How about mounting a simple solid baffle around the pole-mounted box? This pic below shows two half baffles (in red) which could be mounted both sides of the box (blue).

A total width of one meter would already move the step F3 downwards to below 115 Hz.

In fact that's what the old Altec (and other brand) cinema speakers did:

Also, putting multiple boxes together will also cause a similar effect. Line array units probably also do.

I agree that adding flaps around a pole mounted speaker may not always be practical (wind shield!) but you still can easily obtain more lower frequency SPL with the same power.

BTW, having written this I still wonder how we should interpret the "6 dB" figure. In https://trueaudio.com/st_diff1.htm I read:

*Most loudspeaker modeling is performed based on the assumption of radiation into half space. A speaker radiating into half space plays 6 dB louder than the same speaker radiating into full space. This is the crux of the diffraction loss. A full range speaker finds itself radiating into half space at the upper frequencies but radiating into full space at lower frequencies. As a result, there is a gradual shift of -6dB from the highs to the lows. This is what is called the "6 dB baffle step" or the enclosure’s "diffraction loss".*

Here "

*6 dB louder*" sure kind of implies 6 dB SPL. However I understand that when the same power emitted into full space is directed into half space you'll experience twice as much power whenever you are located in that very half space. Assuming no directivity that means that the SPL will increase by 3 dB, and not 6 dB. I still agree that the sound POWER level (SWL) will increase by 6 dB (and 6 dB after all is a ratio of about 2) but not the sound PRESSURE level (SPL).

For instance, it's not the first time that I'm reading that adding a second subwoofer will increase the SPL by 6 dB. Wow, that would be wonderful indeed: if a speaker produces 100dB SPL with 1 watt, then add another one and you get 106 dB. Add another two speakers (4 watts in total) to get 112 dB. Eight watts yields 118 dB. And so on. Then a set of speakers good for 1024 watts would then produce a whopping 160 dB! Hmm.

Hence the baffle step would be 3 dB SPL, not 6.

Or did I miss something?

Andre