To me that is not correct. We can' t just look at the breakup to judge if it's not audible when above 20kHz. How about medium and woofer breakups then? Here on the R3 I guess they'd respectively appear at 9kHz / 6kHz.Again, "hard metallic cone" is just a subjective perception people I did describe above came up. One of the measurable factors that describe this is when the dome breaks up near 20kHz or below so it becomes audible.
Stiff cones tend to have 3 issues:
1) Elevated peak of energy due to breakup
2) Stored energy at breakup making CSD look bad
3) Breakup creates peaks in THD, which in turn re-stimulates the breakup and issue 1) and 2) become problematic again even if crossed over took care to attenuate breakup.
The Kef R3' s CSD is not exactly clean, so maybe there are issues related to breakup/stored energy.
Its THD looks suspiciously clean to me, especially considering the 105dB SPL..
I'm not a big fan of having THD shown in %..
I did some listening tests and indeed found 3rd and 5th harmonic (7th being even worse). already objectionable at low levels (from -50dB 3rd is clearly audible) while testing on sines. So just looking at the highest peaks of THD is not a good indication of perceived distortion.
Anyway, here's an example of a metal cone, SEAS M15CH (pretty bad for the sake of the example)
The breakup peak of that woofer is some 15dB (!) above its SPL in usable range:
And what you see in the THD measurement is that this peak gets replicated in low frequencies:
Then in the CSD we can see that it' s ringing like a bell at breakup frequency:
https://hificompass.com/en/speakers/measurements/sbacoustics/sb-acoustics-sb17nbac35-8
cone is bigger, breakup a bit lower, but lightly damped, and THD is much cleaner.
To me that's quite the opposite: If I look for reviews online, I'll always see plenty positive reviews. I even see reviewers that do not give any bad review, everything is great for them. How is that meaningful?I would take any day 1 positive review/opinion from someone with credentials than 100 bad reviews
To me, only the negative reviews (or at least some cons) might warn you about issues that would be too late to notice once you bought the stuff.
Granted, one should always question reviews and spot BS.
I think they only do that for active speakers. For passive, you'd have to respect both excursion and thermal limits and see how far you could push the speaker. I guess driver specs and cross over transfer function should lead you a good educated guess if you can' t measure. That' s some work..I'm interested in finding out the max SPL for the KEF R3 or R5 or R7 along the frequency response, similar to this Neuman graph. Is there such a thing?
In my view, the most important part of that curve should be below 200Hz where excursion limitation is most likely to occur, which can typically be obtained from woofer box simulation software too.