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:
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:
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:
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:
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:
Combined we have a very good predicted in-room response:
The best news is dispersion. Check out the beam width in horizontal axis:
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:
Being coaxial, the vertical contour looks almost as good:
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:
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.
------------
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/
In every way KEF could nail the look and feel of the speaker, it has done so:
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:
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:
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:
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:
Combined we have a very good predicted in-room response:
The best news is dispersion. Check out the beam width in horizontal axis:
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:
Being coaxial, the vertical contour looks almost as good:
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:
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.
------------
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/