This is a review and detailed measurements of the KEF Q350 Bookshelf/stand-mount speaker. It was purchased new by a member and kindly drop shipped to me for testing. The Q350 costs US $700 on Amazon including prime shipping.
As with other KEF coaxial speakers, the look is unique and quite attractive:
Gone are the curves of the LS50 but replaced with a rectangular box with larger woofer which should spell better bass output.
There is a port in the back and a foam plug is provided with an insert to play with level of exhaust there:
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.
Spinorama Audio Measurements
Acoustic measurements can be grouped in a way that can be perceptually analyzed to determine how good a speaker can be used. This so called spinorama shows us just about everything we need to know about the speaker with respect to tonality and some flaws:
Overall on-axis is reasonably flat which is what we like to see. Bass response is stepped though, being much higher above 100 Hz. There are two problematic resonances at 700 and 1.2 kHz as noted. Maybe we can see those in the waterfall plot:
A kink in the impedance flat around 650 Hz confirms the issue there:
On the good news front, directivity (now good on and off-axis response are) is quite good resulting in reflections that more or less mirror on-axis response:
Putting all of this together, this is our predicted response in a typical room:
Directivity plots in both horizontal and vertical are rather pretty, courtesy of that coaxial driver:
Notice however that horizontal directivity is narrow in the low to me frequencies.
Here is our distortion and in-room response with or without plug:
I tried stuffing the plug half way and then all the way but it made next to no difference. The plug is pretty porous and I could tell it reducing the port action but definitely doesn't plug it fully.
Above was at 86 dB. Boosting to 96 dB creates tons more distortion:
Subjective Speaker Listening Tests
My first impression was "blah" with sound that was rudder muddy and coming from smack center of the speaker. I first turned off my room mode EQ to give some help to 100 Hz. That helped a bit but there were still problems.
Next I attacked the two resonances with two quick filters and results were positive:
That upper bass slight tubbiness required more work than I was willing to put in it. And at any rate, would require in-situ (in-room) measurements to proper correct.
With the two quick filters in place, the sound became pleasant but I could not get past the point focus of it. The optical bias is strong here so may be in a blind test it won't stand out as much. But I think narrow directivity from 500 to 1000 Hz may be at fault here. For new readers, my testing is in mono (one speaker to the left).
Conclusions
There is clear engineering effort here to produce a speaker with good objective metrics. Alas, the upper bass boost may not work for everyone and lack of control of the two resonances has a high impact on clarity and detail. Directivity control due to coaxial driver seems to create a much more of a point source which many people think they like, but was not my cup of tea.
So, reasonably good objective measurements but doesn't do it for me. I can't recommend the KEF Q350 despite its positive attributes.
-----------
As always, questions, comments, recommendations, etc. are welcome.
Going to run off to dig more ditches for tomato plants. I think I am up to 60 plants! I don't do anything half-way.
When I come back with another back pain, I hope there is more money in my pocket form you all's donations : https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
As with other KEF coaxial speakers, the look is unique and quite attractive:
Gone are the curves of the LS50 but replaced with a rectangular box with larger woofer which should spell better bass output.
There is a port in the back and a foam plug is provided with an insert to play with level of exhaust there:
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.
Spinorama Audio Measurements
Acoustic measurements can be grouped in a way that can be perceptually analyzed to determine how good a speaker can be used. This so called spinorama shows us just about everything we need to know about the speaker with respect to tonality and some flaws:
Overall on-axis is reasonably flat which is what we like to see. Bass response is stepped though, being much higher above 100 Hz. There are two problematic resonances at 700 and 1.2 kHz as noted. Maybe we can see those in the waterfall plot:
A kink in the impedance flat around 650 Hz confirms the issue there:
On the good news front, directivity (now good on and off-axis response are) is quite good resulting in reflections that more or less mirror on-axis response:
Putting all of this together, this is our predicted response in a typical room:
Directivity plots in both horizontal and vertical are rather pretty, courtesy of that coaxial driver:
Notice however that horizontal directivity is narrow in the low to me frequencies.
Here is our distortion and in-room response with or without plug:
I tried stuffing the plug half way and then all the way but it made next to no difference. The plug is pretty porous and I could tell it reducing the port action but definitely doesn't plug it fully.
Above was at 86 dB. Boosting to 96 dB creates tons more distortion:
Subjective Speaker Listening Tests
My first impression was "blah" with sound that was rudder muddy and coming from smack center of the speaker. I first turned off my room mode EQ to give some help to 100 Hz. That helped a bit but there were still problems.
Next I attacked the two resonances with two quick filters and results were positive:
That upper bass slight tubbiness required more work than I was willing to put in it. And at any rate, would require in-situ (in-room) measurements to proper correct.
With the two quick filters in place, the sound became pleasant but I could not get past the point focus of it. The optical bias is strong here so may be in a blind test it won't stand out as much. But I think narrow directivity from 500 to 1000 Hz may be at fault here. For new readers, my testing is in mono (one speaker to the left).
Conclusions
There is clear engineering effort here to produce a speaker with good objective metrics. Alas, the upper bass boost may not work for everyone and lack of control of the two resonances has a high impact on clarity and detail. Directivity control due to coaxial driver seems to create a much more of a point source which many people think they like, but was not my cup of tea.
So, reasonably good objective measurements but doesn't do it for me. I can't recommend the KEF Q350 despite its positive attributes.
-----------
As always, questions, comments, recommendations, etc. are welcome.
Going to run off to dig more ditches for tomato plants. I think I am up to 60 plants! I don't do anything half-way.
When I come back with another back pain, I hope there is more money in my pocket form you all's donations : https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
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