I had basically written off the idea of buying old Reference series speakers based on the Blade / The Reference Meta whitepaper that showed a graph with the old Reference having slightly over twice the midrange distortion of the new one. Until I reread Amir's review of the non-Meta 4c that was amazingly low in midrange distortion:
www.audiosciencereview.com
I carefully reread the 2014 and 2022 whitepapers. My conclusion: The new Meta driver seems to be about the only change. The case with its constrained layer damping and the LF drivers appear to be unchanged. That leaves the MF/HF driver. It sports:
- the Meta absorber on the HF
- Neo magnets on both MF and HF (as opposed to ferrite magnets in both instances on the older UniQ)
- The split gap geometry with a heavy copper ring in the space between the two top plates and tiny aluminum rings above and below the top plates on the new MF vs a more conventional undercut design with heavy aluminum rings above and below the gap
- The decoupling between basked and magnet on the Meta UniQ
Let's have a look at the measurements:
So we the 2022 whitepaper says there was between 0.1 and 0.2% THD between 500 and 2000 Hz at 90 dB/1 m on the old design and the new one runs at about 40% of that. However, the old whitepaper shows between 0.07 and 0.04% distortion which would mean the old driver is in fact easily in the same leage as the now one and may even pull a little bit ahead.
Is there a good explanation why the Reference 1 MF should be so much worse in 2022 than the Reference 5 MF was in 2014? As far as I know, the UniQs are identical across Reference 1, 3, 5, 2c, and 4c, so the 1 and the 5 and 6c should have near identical midrange performance.
Speaking of which, Amir's measurement at 86 dB/1m is more like 0.04 to 0.02%. Ok, that was at lower level. How about 96 db/1m?
Well, there are a few tiny peaks approaching 0.2%, but mostly, it stays below 0.1% and even below 0.5% across wide bands. I'd say this is highly compatible with the plot from the 2014 whitepaper.
Next, inductance
The 2014 whitepaper gives us inductance only down to 500 Hz and at + and - 3 mm cone displacement. It is probably a safe bet that the rest position inductance is very close to these values, so about 0.17 mH at 500 Hz. The 2022 paper has a funny vertical axis but clearly it places the 500 Hz inductance of the older driver at or above 0.3 mH. Again, how can this be true?
Last example for today, the new spider is supposed to have done away with a 650 Hz kink of about 2 dB that is strangely shown in the 2022 graph of the 2014 driver but not in the original whitepaper (and the older graph looks less smoothed if anything, just look at 4 - 7 kHz):
Unsurprisingly, there is no hint of that 650 Hz kink in Amir's measurement:
Amir did find small blips in the impedance plot but they are at 500 and 920 Hz and not particularly evident in the FR plot either:
So what is going on here? Is there a good technical explanation or was this marketing getting ahead of engineering?

KEF Reference 4C Review (Center Speaker)
This is a review and detailed measurements of the KEF Reference 4C Center home theater speaker. It was kindly purchased new by a member and drop shipped to me. 4C costs US $7,500. Apology for using stock picture. Speaker weighs 100 pounds and I got interrupted mid-review with our home...

I carefully reread the 2014 and 2022 whitepapers. My conclusion: The new Meta driver seems to be about the only change. The case with its constrained layer damping and the LF drivers appear to be unchanged. That leaves the MF/HF driver. It sports:
- the Meta absorber on the HF
- Neo magnets on both MF and HF (as opposed to ferrite magnets in both instances on the older UniQ)
- The split gap geometry with a heavy copper ring in the space between the two top plates and tiny aluminum rings above and below the top plates on the new MF vs a more conventional undercut design with heavy aluminum rings above and below the gap
- The decoupling between basked and magnet on the Meta UniQ
Let's have a look at the measurements:
So we the 2022 whitepaper says there was between 0.1 and 0.2% THD between 500 and 2000 Hz at 90 dB/1 m on the old design and the new one runs at about 40% of that. However, the old whitepaper shows between 0.07 and 0.04% distortion which would mean the old driver is in fact easily in the same leage as the now one and may even pull a little bit ahead.
Is there a good explanation why the Reference 1 MF should be so much worse in 2022 than the Reference 5 MF was in 2014? As far as I know, the UniQs are identical across Reference 1, 3, 5, 2c, and 4c, so the 1 and the 5 and 6c should have near identical midrange performance.
Speaking of which, Amir's measurement at 86 dB/1m is more like 0.04 to 0.02%. Ok, that was at lower level. How about 96 db/1m?
Well, there are a few tiny peaks approaching 0.2%, but mostly, it stays below 0.1% and even below 0.5% across wide bands. I'd say this is highly compatible with the plot from the 2014 whitepaper.
Next, inductance
The 2014 whitepaper gives us inductance only down to 500 Hz and at + and - 3 mm cone displacement. It is probably a safe bet that the rest position inductance is very close to these values, so about 0.17 mH at 500 Hz. The 2022 paper has a funny vertical axis but clearly it places the 500 Hz inductance of the older driver at or above 0.3 mH. Again, how can this be true?
Last example for today, the new spider is supposed to have done away with a 650 Hz kink of about 2 dB that is strangely shown in the 2022 graph of the 2014 driver but not in the original whitepaper (and the older graph looks less smoothed if anything, just look at 4 - 7 kHz):
Unsurprisingly, there is no hint of that 650 Hz kink in Amir's measurement:
Amir did find small blips in the impedance plot but they are at 500 and 920 Hz and not particularly evident in the FR plot either:
So what is going on here? Is there a good technical explanation or was this marketing getting ahead of engineering?
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