Perhaps look at this from a musical standpoint rather than just a chart. A tiny effort will show that many ordinary (A=440) musical instruments readily produce tones to 32 Hz. This includes the string bass, the piano, many synthesizers, most bass electric guitars, a contra-bassoon, etc. Tones (to the octave 1 of the musical scale) are in the range of 32 to 65 Hz.
Some pipe organs have 32' stops which produce tones down to 16 Hz (C-0). Most humans cannot hear much below 20 Hz, but the rest of that octave can be gently felt. It is why the builders of these spend huge sums to make those sounds.
Even if you don't listen to such music, consider movie LFEs. Frequencies in the lowest range of hearing may be heard as adding gravitas to a soundtrack. Their use is common.
I provide this, not to argue with you, but to emphasize that what we are doing here is investigating real music, not just tones, sweeps, graphs, and charts. So, for typical music, I argue that research down to 32 Hz is needed, and down to 16 Hz is desirable and not inappropriate. But if your goal is just to reproduce the 'sound' of a pop concert sound system, (arguably) 40-50 Hz is probably all you're going to find there.
Not just -one man's view.
I’ll give you the fundamental, but I am not going to buy a bookshelf to do what a floor stander is needed for.
And 2/3rds to 3/4s of the towers still would like a subwoofer.
To think that a bookshelf should get to 32Hz is starting to border on optimism, and 2 Hz seems like it is around 4 octaves below that!
And also somewhat below the canonical 20Hz.
So to even show an impedance down to 2 Hz is bordering on intentional dishonesty for almost anything but perhaps a rotary subwoofer…
And one risks loosing credibility when they do so.
I would argue it is deviating a ways from science when a bookshelf speaker is tested to 20Hz, much less 3+ octaves below 20 Hz.
It reflects poorly on the tester, and for people to defend it, it can also be postulated as they’re having lost their sense of critical reasoning skills.
Hence I brought it up as Amir specifically said, at the end of post #1, “that recommendations and comments were welcome.”
I assume I am in the minority here, as that plot is being defended.
Here it’s is for review:
…
Oh boy! What the heck is going on here? We have rising chewed up high frequency response. Response is much smoother down low but sensitivity drops like a rock to …
Impedance dips very low at high frequencies:
View attachment 216249
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As always, questions, comments, recommendations, etc. are welcome.
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I do not know how much more helpful I can be?
I assume that “we” want to be taken as serious adults.