KEF Q350 Speaker Review

[QMuse]

Yes, but if we assume that:

• Harman's top models beat KEF's top models in their blind tests, and
• KEF speakers' performance is superior according to Olive's preference system (which it almost certainly is)

then the following must be true:

• Olive's preference system is invalid (or insufficient) in respect of these speakers.

Moreover, at least one of the following must be true:

• Something other than off-axis performance is decisive in respect of these speakers.
• Olive's system is false in respect of off-axis performance.

Yes, you summarized the implications well. I wouldn't say Olive's preference system is invalid but I would say it needs refinement/revision.

• Something other than off-axis performance is decisive in respect of these speakers.

This is a tough one as it is hard to imagine what would that be, but it certainly has to be considered as a possiblity.

 

[andreasmaaan]

It's mentioned here:
https://www.avsforum.com/forum/89-speakers/710918-revel-owners-thread-399.html#post56105466

I assume it originally came from Toole.

Ok, my evidentiary bar is a little higher when it comes to hearsay like this But ok, it does seem to be a possible/plausible explanation.

 

[QMuse]

It's mentioned here:
https://www.avsforum.com/forum/89-speakers/710918-revel-owners-thread-399.html#post56105466

I assume it originally came from Toole.

Are we to conclude from this post that KEF was beaten by Harman in spite of superior spinorama and better preference score because of high IMD in the bass region?

 

[QMuse]

Ok, my evidentiary bar is a little higher when it comes to hearsay like this

"evidentiary bar".. "hearsay".. You are either a lawyer or you really like watching series like "The Good Fight".

 

[andreasmaaan]

"evidentiary bar".. "hearsay".. You are either a lawyer or you really like watching series like "The Good Fight".

Haha. It's the former

 

[andreasmaaan]

Are we to conclude from this post that KEF was beaten by Harman in spite of superior spinorama and better preference score because of high IMD in the bass region?

Although IMD is caused by displacement and this is caused by bass frequencies, the distortion manifests across the whole frequency range of the driver so, in terms of midwoofers, it's actually in the midrange that it tends to be most audible.

 

[Beave]

Kef has more downward tilting ER slopes than Harman, so why doesn't it sound better? Harman claim they speaker must beat all competitive spekers on the market before going into production, so their speakers must have beaten KEF's in their internal blind tests.

Not exactly. They claim to beat all the competitive speakers they are put up against. They certainly don't - and reasonably can't - test against ALL competing speakers. So they select (cherry pick?) a few competitors in the price range, and compete against them.

Some might argue that their selection is biased in that they pick speakers they know will lose to their own, and neglect in their comparisons speakers that might beat their own.

 

[QMuse]

Although IMD is caused by displacement and this is caused by bass frequencies, the distortion manifests across the whole frequency range of the driver so, in terms of midwoofers, it's actually in the midrange that it tends to be most audible.

Sure. It certainly isn't the LF where it makes audible issues. So, is this post implying it is the IMMD that is a missing link in Olive's scoring system?

 

[QMuse]

Not exactly. They claim to beat all the competitive speakers they are put up against. They certainly don't - and reasonably can't - test against ALL competing speakers. So they select (cherry pick?) a few competitors in the price range, and compete against them.

Some might argue that their selection is biased in that they pick speakers they know will lose to their own, and neglect in their comparisons speakers that might beat their own.

Harman's reputation would be seriously impacted in my eyes if we learn that KEF, whcih is one of their most respected competitors, is not included in their tests.

 

[Beave]

Harman found out that while the Kef Referece scored higher than Revel, the Revel was still prefered by listeners. When they investigated this further, they came to the conclusion that is was because the Kef had a fairly high amount of audible intermodulation distortion.

Are you sure that was the KEF Reference? I thought they were referring to the KEF LS50, which does have an issue with the woofer being the waveguide. The three-way KEFs, such as those found in their Reference Series, don't have the problem of excessive movement of the midrange.

 

[andreasmaaan]

Sure. It certainly isn't the LF where it makes audible issues. So, is this post implying it is the IMMD that is a missing link in Olive's scoring system?

If we take the hearsay () attributed to that Harman person (Toole??) in the AVS thread at face value, you'd have to say yes I think.

I wouldn't be betting my life on that post's accuracy/authenticity, though

 

[Beave]

Harman's reputation would be seriously impacted in my eyes if we learn that KEF, whcih is one of their most respected competitors, is not included in their tests.

They included the LS50 in a test against the Revel M105 (or M106?), and it lost. Note that they did *not* include the KEF R300, which is similarly priced to the M106 in the U.S. The R300 wouldn't have suffered from the same issues that the LS50 has (when running full range, as it is in the Revel comparisions).

 

[QMuse]

Are you sure that was the KEF Reference? I thought they were referring to the KEF LS50, which does have an issue with the woofer being the waveguide. The three-way KEFs, such as those found in their Reference Series, don't have the problem of excessive movement of the midrange.

It seems it was a 2-way system as he says "this effect will probably be mitigated in a 3-way system ", so it may as well be a LS50.

 

[QMuse]

I wouldn't be betting my life on that post's accuracy/authenticity, though

Of course you wouldn't, as a lawyer you are supposed to question everything and everybody.

 

[andreasmaaan]

It seems it was a 2-way system as he says "this effect will probably be mitigated in a 3-way system ", so it may as well be a LS50.

This is also how I interpreted the post. Whatever KEF speaker it is referring to, it appears that it is a 2-way, ie an LS50 or a Q series speaker.

 

[QMuse]

.. ie an LS50 or a Q series speaker.

Or Reference 1.

 

[andreasmaaan]

Or Reference 1.

It's a 3-way.

 

[hyperplanar]

It's mentioned here:
https://www.avsforum.com/forum/89-speakers/710918-revel-owners-thread-399.html#post56105466

I assume it originally came from Toole.

Wow, thanks for the link. This quote was very interesting:

That 80% correlation between measurements and subjective data is not perfect. Yup. However, as I point out in my books, and have stated in these forums, that number is for 70 loudspeakers of all prices and sizes - inexpensive bookshelf units to monster high-end floor standers. As Olive showed, about 30% of our subjective ratings is attributable to bass performance. That means that a good speaker with bass beats an equally good speaker with less bass. So, in a very uneven playing field, it is indeed remarkable that a correlation coefficient of 0.8 was achieved. When the LF bandwidth factor was substantially removed by comparing only bookshelf speakers, in a separate well-controlled DB test, the correlation was 0.997. So, how much information is in a spinorama? A lot! In real circumstances, the performance at low frequencies includes the room, so no anechoic measurement will be totally predictive of results.

 

[thewas]

When I read that AVS post I also have a feeling that they refer to a KEF 2-way speaker since they mainly complain about IMD.
Well, we all here know that a KEF uses a 2-way speaker mainly in their entry series (except the LS50) so its not a real competitor to most Revels.
Also if the loudspeaker they used was a passive LS50, I can understand why it lost against the Revel, that is not only due to higher IMD, but also not great voicing with too much energy between 2-5Khz, I also don't like listening to my LS50 without EQ. Interestingly though John Atkinson sees the comparison more differentiated https://www.stereophile.com/content/tale-two-speakers
But as said using just 2-way KEFs is not a real comparison and if true, would give me a bitter aftertaste of "choosing their competitors cleverly".

 

[QMuse]

It's a 3-way.

Ah, obviously 1 coffee was not enough!