KEF LSX Review (Wireless Speaker)

[Colonel7]

I mean the app and connectivity are terrible.

 

[brandall10]

I mean the app and connectivity are terrible.

I had some issues during initial setup but it's been rock solid since. Certainly nothing like the first couple years with the first LS50s. FWIW, my router is 20 feet through one set of doors around a bend.

 

[BrokenEnglishGuy]

More KEFs are here to be tested.

Please the KEF R7, wonderful towers, i love them!

 

[xarkkon]

Note: Rating is for far-field listening.

Preference Rating
SCORE: 4.6
SCORE w/ sub: 6.8

Frequency response: +/- 3.8dB 54Hz-20kHz

View attachment 139701View attachment 139702View attachment 139703View attachment 139706View attachment 139707View attachment 139708​

Link to all graphs/data

Interesting review and outcome! I'm assuming the preference rating is what it is because of the dip post 8k? Does that dip impact the listening experience subjectively?
I do agree that apart from the 3 flaws (port resonance, post 8k dip, and farfield listening), the measurements look attractive. Just wondering if the 2 frequency response issues had any bearing on the listening experience.

 

[vkvedam]

Good to see that KEFs are at least decently performing and consistent unlike the other British heavyweights . Would be interesting to see the Metas assessments . I still love my LS50s, still going strong after 7 years.

 

[Maiky76]

This is a review and detailed measurements of the KEF LSX "Wireless" speaker. It is on kind loan from a member and costs US $1,250 from Amazon including Prime shipping.

In every way KEF could nail the look and feel of the speaker, it has done so:

View attachment 139680

Not only is the iconic coaxial driver there, the whole speaker is now wrapped in nice fabric which you can see better in this picture:

View attachment 139682

Check out the accent color even on the port which normally would not be seen! Absolutely great.

What is not so great is if you get the speaker without the hard remote and you want to use the Aux in analog input. Upon power up, it would not play anything from that input. A dancing sequence of colors were going on in the front which would require the German Enigma machine to decode. I figured the easiest thing is to plug an Ethernet cable into it so I didn't have to mess with configuring WiFi. Searched for KEF and the KEF Connect app came up. Strangely it said it was from "GP Acoustics." Had to do some searching to see that is the entity that owns KEF now. But why reduce consumer trust by using that name instead of KEF???

Anyway, I start the app and it says to register. I register and then it comes up asking me if I want it to search for speakers. I say yes and the app simply hangs forever. I try it and try it again to no avail. I see a reset button on the back. I push that it and nothing resets either. What the heck? Sometime later I discover that the hole below Reset market is an LED! The switch is below it. What is remarkable is that you need to reset the speaker if you want to go from Bluetooth to Wifi mode. So why, oh why, is it not a real switch? And why require a reboot for heaven's sake to switch between those two protocols?

Back to trying to figure out why I can't connect, the app says to open "Google Home" if it can't find the speaker. Google Home? I knew there was such a thing on iOS but not on Android. I find and start it. An app opens up that seems to have been written by an intern developer. On top it says something about "IOT" (Internet of Things) exception that it has printf formatting characters in it with back slashes and such. Desperate, I tell it to search for them. To my pleasant surprise it says it found the device and gives me some cryptic designation for it. I say fine.

To test, I bring up Google Music (or whatever it is called) and start to play a track. I hear music! Yeah.... But wait, why is the volume so low? I crank it up and mostly I hear bass. It was just then that I realized the sound was NOT coming out of KEF LSX but elsewhere in the house!!! I immediately hit pause go to the living room. I see my wife in near tears as the Pioneer AVR that we use for TV sound had switched to be a remote device for Google Home and started to play the bloody music at full volume! Had to spend 10 minutes calming my wife's nerves. Shut the whole thing down and left it there for a couple of days.

I came back to it and searched and searched and nothing online would talk about this problem. By accident I watch a KEF configuration video and it shows a different app than the one I used. It is called KEF Control, not Connect! I boot that up and it immediately makes progress past where I was stuck with the other app. Sadly it configures itself using ad-hoc WiFi access point in the speaker. So you need to connect to its network first, give it your real WiFi credentials and then it connects. It should do this with Bluetooth in this day and age. Anyway, once there, I managed to select Aux In and could test the speaker.

Online reports are full complaints about the App with the most serious one being that it doesn't remember its settings. Horrible job here by KEF.

Measurements that you are about to see were performed using the Klippel Near-field Scanner (NFS). This is a robotic measurement system that analyzes the speaker all around and is able (using advanced mathematics and dual scan) to subtract room reflections (so where I measure it doesn't matter). It also measures the speaker at close distance ("near-field") which sharply reduces the impact of room noise. Both of these factors enable testing in ordinary rooms yet results that can be more accurate than an anechoic chamber. In a nutshell, the measurements show the actual sound coming out of the speaker independent of the room.

I performed over 1000 measurement which resulted in error rate of 1 to 2%.

Reference axis was the tweeter center.

KEF LSX Measurements
Acoustic measurements can be grouped in a way that can be perceptually analyzed to determine how good a speaker is and how it can be used in a room. This so called spinorama shows us just about everything we need to know about the speaker with respect to tonality and some flaws:

View attachment 139685

Ignoring a few kinks, this is a very reasonable on-axis frequency response. There is a strange drop post 8 kHz and a glitch around 800 Hz. We can see the cause of both in our near-field measurements:

View attachment 139687

We see that a resonant tone is coming out of the port around 800 Hz and interfering with the woofer response. We also see quite an uneven response from the tweeter. it is worse than our spin graph though so this may be partially due to artifacts of measuring the tweeter at very close distance (comb filtering from the face of the microphone and woofer).

Directivity is very good which is why the early window response is reasonable:
View attachment 139688

Combined we have a very good predicted in-room response:

View attachment 139689

The best news is dispersion. Check out the beam width in horizontal axis:

View attachment 139691

I think the last time we saw something this good was on a Genelec with coaxial driver. Very nice.

This is reflected just the same in our contour plot:

View attachment 139693

Being coaxial, the vertical contour looks almost as good:

View attachment 139694

What this means is that the speaker tonality will not change much if you sit above or below tweeter axis. Or slide to left or right. It will also be room friendly as reflections have similar tonality to on-axis response.

Distortion at 86 dBSPL is reasonable. Not so at 96 dBSPL:

View attachment 139695

View attachment 139698

I could hear massive distortion in low frequencies as the sweep was running in the lab. This is typical of many small powered speakers as I think the amp is running out of power, not the driver.

KEF LSX Listening Tests
I chose to test these speakers in near-field since many will buy them to use on their computer desk and such. It took just a few seconds to realize the tonality was correct. Listening spot was wide and I could detect very little change as I moved left and right, and sat taller and lower. Track after track sounded excellent, obviating the need for any equalization in my setup (for the speaker that is, the room you still need to EQ).

Throwing sub-bass heavy tracks to LSX created no drama. It simply attenuated them heavily and went about its business. I much rather have this that a driver bottoming out and cracking as many speakers do.

Conclusions
The KEF LSX is not quite technically perfect but comes pretty close. It is wrapped in super attractive packaging making for a very nice combination. It is expensive for the fidelity you get but studio monitors that do as well are very ugly and industrial compared to LSX.

I am happy to put the KEF LSX on my recommended list. I hope they improve their App and documentation though. I hate them for that.

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As always, questions, comments, recommendations, etc. are welcome.

Appreciate any donations using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

Hi,

Here is my take on the EQ.

These EQ are anechoic EQ to get the speaker right before room integration. If you able to implement these EQs you must add EQ at LF for room integration, that usually not optional… see hints there: https://www.audiosciencereview.com/...helf-speaker-review.11144/page-26#post-800725


The raw data with corrected ER and PIR:

Score no EQ: 4.5
With Sub: 6.8

Spinorama with no EQ:

• Port/internal resonance?
• Nice directivity
• Not that flat

Directivity:
0 to 20deg in any direction looks fine

EQ design:

I have generated two EQs. The APO config files are attached.

• A light version
• A Full version but that needs to be tested as compensating the deep might not be ideal

Score EQ Light: 4.8
with sub: 7.1

Score EQ Full Score: 5.2
with sub: 7.5

Kef LSX APO EQ Score Light 96000Hz
July082021-102510

Preamp: -4.4 dB

Filter 1: ON HPQ Fc 56.17,    0.00,    1.25
Filter 2: ON PK Fc 1345.71,    1.98,    1.49
Filter 3: ON PK Fc 17553.29,    4.31,    1.01

Kef LSX APO EQ Score Full 96000Hz
July082021-101751

Preamp: -4.3 dB

Filter 1: ON HPQ Fc 56.17,    0.00,    1.25
Filter 2: ON PK Fc 1353.96,    2.33,    2.90
Filter 3: ON PK Fc 5313.02,    2.50,    8.40
Filter 4: ON PK Fc 4525.61,    -0.91,    4.83
Filter 5: ON PK Fc 7382.90,    -0.68,    3.84
Filter 6: ON PK Fc 18596.95,    4.25,    0.83

Spinorama EQ Light

Spinorama EQ Full Score

Zoom PIR-LW-ON

Regression - Tonal

Radar no EQ vs EQ score
Minor improvements

The rest of the plots is attached.

 

[Kachda]

FWIW, the LSX II is rumored to drop sometime this summer... would def wait if you want a deal on this version or the latest and greatest.

yeah I was thinking about that, given that it is a smaller version of the LS50W. So a meta treatment should be in the works ?

 

[Zensō]

This is a review and detailed measurements of the KEF LSX "Wireless" speaker. It is on kind loan from a member and costs US $1,250 from Amazon including Prime shipping.

Just to clarify in case it wasn’t clear, these are $1,250 per pair.

 

[Kachda]

Only if they plan to use this wireless speaker non-wirelessly. Can they do that?

what do you mean ? this speaker does not even need a wire between them to connect, they talk wirelessly (though at 48khz, connecting via Ethernet cable gets you up to 96khz).

edit: just saw your comment regarding the app. I have no idea about that.

 

[Zensō]

I mean the app and connectivity are terrible.

Agreed. Sonos is far ahead of KEF in that regard.

 

[brandall10]

So a meta treatment should be in the works ?

Yep!

 

[brandall10]

Agreed. Sonos is far ahead of KEF in that regard.

If you have Roon you get around this for day to day usage. The initial setup is frustrating through.

 

[amirm]

BTW, the volume control in their app is atrocious. It is very hard to adjust and takes good 2 to 3 seconds to take effect. Touch it the wrong way and you are at 100% volume for another 3 seconds before you turn it back down!

 

[Alice of Old Vincennes]

I simply cannot fathom purchasing this overpriced computer monitor speaker with clunky absymal software. I would rather dig out a radio shack speaker from my attic, or open my window and Bluetooth to my caddie ct4 with Bose. I'll bet warranty claims present a schizophrenic delight.

 

[brandall10]

BTW, the volume control in their app is atrocious. It is very hard to adjust and takes good 2 to 3 seconds to take effect. Touch it the wrong way and you are at 100% volume for another 3 seconds before you turn it back down!

Again, instantaneous in Roon.

I personally don't understand why someone would use the provided apps for stream control to any of these types of systems, they're invariably bad.

Roon all the way for both these and my Buchardts. And if/when they support Tidal/Spotify Connect/etc, that's the way to go if you don't want to pay for a license for secondary software.

 

[Zensō]

Again, instantaneous in Roon.

I personally don't understand why someone would use the provided apps for stream control to any of these types of systems, they're invariably bad.

Roon all the way for both these and my Buchardts. And if/when they support Tidal/Spotify Connect/etc, that's the way to go if you don't want to pay for a license for secondary software.

My perspective is that an important part of what you’re paying for with this type of “wireless system” speaker is the quality of the app and ease of use. If the native app is poorly designed and the system is difficult or unreliable, I’d rather just use a wired studio monitor that provides higher performance at a lower price.

 

[restorer-john]

The red accent on the back port is one of those wow touches on a premium product. I absolutely love it.

Funny, to me it looks really cheap. Like they ran out of the right colour in the parts bin.

 

[brandall10]

My perspective is that an important part of what you’re paying for with this type of “wireless system” speaker is the quality of the app and ease of use. If the native app is poorly designed and the system is difficult or unreliable, I’d rather just use a wired studio monitor that provides higher performance at a lower price.

I wouldn't. I've been massively happy with my wireless systems and blissfully unaware of the sucky apps over the entirety of their ownership.

The streaming aspect works great, no need to throw the baby out with the bathwater. Just think of the apps as a means to set up the speakers and you'll be fine.

 

[Zensō]

I wouldn't. I've been massively happy with my wireless systems and blissfully unaware of the sucky apps over the entirety of their ownership.

The streaming aspect works great, no need to throw the baby out with the bathwater. Just think of the apps as a means to set up the speakers and you'll be fine.

My point is why pay so much to buy into a system then not use it? The Adam T5V competes well with this speaker at less than a third of the price. https://www.audiosciencereview.com/forum/index.php?threads/adam-t5v-review-studio-monitor.18122/

 

[brandall10]

My point is why pay so much to buy into a system then not use it? The Adam T5V competes well with this speaker at less than a third of the price.

Can an Adam T5V install like this and summon sound within seconds from my phone or laptop? I assure you the "wireless" aspect is used in full force in my household.