This is a review and detailed measurements of the KEF Q100 bookshelf speaker. It is on kind loan from a member. The Q100 is discontinued but I think it cost US $550.I always say speaker business is 80% about marketing and KEF has mastered that art:The coaxial driver looks great and caters to audiophile intuition of "point source being good."Speaker is lighter than I imagined them being.Here is the back panel:I thought those two knobs were level controls which is surprising in a passive speaker. Turns out they are just shunting knobs that short the highs and lows together. Or disconnect them if you want to bi-wire wire/bi-amp them.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.In a nutshell, the measurements show the actual sound coming out of the speaker independent of the room.All measurements are reference to tweeter axis with the grill removed. Frequency resolution is 0.7 Hz (yes, less than 1 Hz) and plots are at 20 points/octave. Spatial 3-D resolution is 1 degree.Over 700 points around the speaker were measured (from 20 to 20 kHz) which resulted in well under 1% error in identification of the sound field up to 16.5 kHz. After that error climbs to 2% which should not be material. Final database of measurements and data is 1.2 Gigabytes in size.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:We have a broad lift from 700 to 1.5 kHz and another from 5 kHz to beyond 10 kHz. The actual variation is a few dB but because they are so wide, they will hit a lot more notes so colorations will be a lot more audible.There is a cancellation (notch) at 1.4 kHz which I will address later.Above graph is also our sensitivity. At mid-frequencies it is 85 dB but drops to 80 dB in bass frequencies. So you need to have good bit of power to drive it loud.In-room response is more or less what we have on-axis, tilted down:That's it for most major aspect of the speaker that sets listener preference in controlled testing.Impedance drops to below 4 ohm in bass frequency so you better have a good amplifier to drive it:Here is gated room measurement and distortion with floor of -50 dB:Zooming in we get:Waterfall display shows some of the resonances:One benefit of coaxial drivers is that their vertical dispersion is better than simple 2-way speakers:Using the power of 1 degree measurement in 3-D space, we can analyze what is going on with the speaker. To wit, let's see what happens at 1.4 kHz that we had a dip:The "nref" arrow is the center of the coaxial driver as you would look into it. We see that there is a strong sound source below it which has to be the port. Something coming out of that port is combing with the main driver and causing cancellation in the middle (to some extent). The frequency is 1.4 kHz. If we convert that to wavelength we get nearly 12 inches which happens to be the height of the cabinet. So it looks like it is a longitudinal mode of the internal cabinet coming out the port causing that partial cancellation.Note that the bandwidth ("ERB") of the notch is too small to be that audible. It is just an interesting thing to analyze nevertheless.I used the KEF Q100 in my main system, playing in mono (provides best discrimination). Experience was not that positive. Hardly any of my tracks sounded good. Bass loading was rather high and boomy. The location causes some of that but seems to be exaggerated here. There was a general lack of evenness response with some notes forward, some not. There was also some distortion which seemed to be constant throughout everything I played. A buzzing type of secondary tones.I believe a port plug comes with the speaker. For testing, I just stuck my hand in the port. That nicely lowered the bass boominess and seemed to reduce the distortion I was hearing. This was in near-field listening because obviously I could not reach with my hand 10 feet.I think the famous reputation Q100 has more to do with its great looks than sound. Measurements are not horrible but they lack the evenness that we need to see in on-axis measurements.Overall, I can't recommend the KEF Q100. Look forward to testing their current production models.------------As always, questions, comments, recommendations, etc. are welcome.Hate going to the local grocery store on Tuesdays. Why? Because they have a 10% discount for "seniors" and they always ask me if I am old enough to qualify. Makes me depressed that I must have lost by great and young looks! Anyway, I always walk away depressed. Please make me feel better bymoney using