KEF Q150 for $300 -, and

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KEF Q150 Bookshelf Speakers (Pair, Black)

Remember, the new Qx50 series are without the grill which can be purchased separately!

Model    Q150 Bookshelf Speaker
Design    Two-way bass reflex
Drive Units    Uni-Q driver array:
HF: 25mm (1in.) vented aluminium dome
LF/MF: 130mm (5.25in.) aluminium Uni-Q
Frequency Range Free Field (-6dB)    47Hz
Frequency Response (±3dB)    51Hz - 28kHz
Crossover Frequency    2.5kHz
Amplifier Requirements    10-100W [*]
Sensitivity (2.83V/1m)    86dB
Maximum Output    108dB
Nominal Impedance    8Ω (min.3.7Ω)
Weight    5,6kg (12.3 lbs)
Dimension (H X W X D)    303mm (11.92 inches) x 180mm (7.08 inches) x 278mm (10.944 inches)
Dimension (H X W X D) *with Rubber Feet    307mm (12.08 inches) x 180mm (7.08 inches) x 278mm (10.944 inches)

* Being the official sensitivity the same as the Q100, at least they will need 80 watts at 8 Ohms to show their full potential, I think. With good/very good recordings and high DR (dynamic range)!!!

I have not heard any speaker of the new series, with the rear bass-reflex. Maybe they do not require a burn-out as long as the previous one, maybe.

The old KEF Q100 thread:

KEF Q100 for $300


Re: KEF Q150 for $300 - and
« Reply #1 on: 19 Dec 2018, 10:14 am »
At Cruchfield the same price, $299.99 pair

Europe and World, they are too expensive for now  :?


Weight comparative.

* KEF Q100 (with grills)       5.9 kg (13 lbs)

* KEF Q150 (without grills)   5.6 kg (12.3 lbs)

* KEF LS50                          7.2 kg (15.8 lbs)

My tweaked and modded KEF Q100 sound much better after they have (after the summer) more mass over the furniture -> less vibrations -> sound more clear/detailed and 3-D. It was a substantial improvement.

Then, more mass will be beneficial in the new KEF Q150, I think.


For now there are not KEF Q150 measures, only the Q350.

The traces in figs.1 and 2 have a small wrinkle between 600 and 700Hz, suggesting the presence of a cabinet resonance in that region. However, when I investigated the vibrational behavior of the enclosure panels with an accelerometer, there was nothing untoward between 600 and 700Hz. However, there was a fairly strong mode at 309Hz on all surfaces (fig.3), and a slightly less strong one at 504Hz.

Fig.3 KEF Q350, cumulative spectral-decay plot calculated from output of accelerometer fastened to center of sidewall (MLS driving voltage to speaker, 7.55V; measurement bandwidth, 2kHz).

The small blip at 39kHz in the magnitude trace in fig.1 indicates that the tweeter's fundamental dome resonance lies at this very high frequency, but the traces in this graph are otherwise free from the small lower-frequency discontinuities that would suggest the presence of cabinet resonances of some kind. Cumulative spectral-decay plots of the cabinet walls' vibrational behavior, calculated from the output of a plastic-tape accelerometer, didn't uncover any midrange resonances on any of the surfaces, though the sidewalls flexed a little at the frequency of the port tuning frequency (fig.2).

Fig.2 KEF LS50, cumulative spectral-decay plot calculated from output of accelerometer fastened to center of side panel (MLS driving voltage to speaker, 7.55V; measurement bandwidth, 2kHz).


Dan S. Higgins

The Q350's Take Time to Break In

I've been listening to the Q350's for about five weeks and the woofers are still not broken in; that warm speaker feel and sound hasn't come to fruition yet. I'm confident with more time they'll loosen up, and warm with time.

I use an iPad Mini 4 as the sound source and have found the "rock" setting in the equalizer sounds best overall. The integrated amp I use is the Yamaha AS-801 and I need to turn the bass knob to about "two o'clock" to get the warmth I like to hear. The only track I've seen to actually work and move the woofers is Rocket Empire's 'Cruising the Galaxy', loud.

Presumably the Q150 will have the same problem, as happened with the previous series. My Q100 needed about 200 hours! New they had a bright sound, without bass.


About the YAMAHA A-S801 integrated amplifier:


to English:

I do not like:

I like:


    Rated power (1% THD + N, 1 kHz) [W] 8 Ω, 2x 130
    Rated power (1% THD + N, 1 kHz) [W] 4 Ω, 2x 132
    Sensitivity (for maximum power) [V] 1x 0.22
    Signal / noise ratio (A-weighted filter, with reference to 1W) [dB] 83
    Dynamics [dB] 104
    Damping factor (relative to 4 Ω) 94

Rated power in SS must be measured at 0.1% THD + N.


To compare.

My second system: PC -> ODAC -> AV Marantz SR4500 + KEF Q100, all tweaked and modded by me.

Win 10 Pro 1709 64 bits, very very very optimized to play multimedia. Before summer only very very optimized.

This graph shows that the SR4500's left channel, from CD input to speaker output with two channels driving 8-ohm loads, reaches 0.1% distortion at 100.4 watts and 1% distortion at 114.6 watts. Into 4 ohms, the amplifier reaches 0.1% distortion at 128.2 watts and 1% distortion at 158.8 watts.

Response from the multichannel input to the speaker output measures –0.43 dB at 10 Hz, –0.13 dB at 20 Hz, –0.11 dB at 20 kHz, and –0.67 dB at 50 kHz. THD+N from the amplifier was less than 0.015% at 1 kHz when driving 2.83 volts into an 8-ohm load. Crosstalk at 1 kHz driving 2.83 volts into an 8-ohm load was –79.69 dB left to right and –80.28 dB right to left. The signal-to-noise ratio with 2.83 volts driving an 8-ohm load from 10 Hz to 24 kHz with "A" weighting was –100.92 dBrA.

2.83 volts into an 8-ohm load = 1 watt/8 Ohms. Now you can look at the THD+N graphs.

Now it has lowest noise -> higher S/N (A). And higher bias and...

Modern AVR have worse measures, much worse. You can verify it:


Very good with films (sound has low/very low DR) but not music with good/very good recordings with high DR (dynamic range).

With modern commercial/popular music, very badly recorded and low/very low DR, nothing to object.
« Last Edit: 29 Jan 2020, 03:17 pm by maty »


And you must add grills so that wife does not shout at you 8)


Wonderful Speakers
By Mike Anderson December 22, 2018

These speakers sound fantastic, look wonderful, and shine at reproducing guitar. The bass is significantly more than I was expecting and on par, but much cleaner, than my old Spica TC-50's. As stated by everyone else the imaging is ridiculously good and really fun to play with. I tried out one of the main competitors (rhymes with "dorfdale") and found these more suited to my musical taste which is along the lines of Jack Johnson, Rush, and movies. Of course considered the UB5 [maty: ELAC] but settled on these. Only thing to note is that the tweeters took about an hour to warm up so dont freak out when you first set them up.

The problem is not the tweeter is the coaxial speakers suspension. New is very rigid -> they sound bright because the bass are small not because the tweeter is cold.

It seems that it is confirmed that they suffer from the same as the previous Qx00 series:

* furniture vibrations (thin DM walls), like a lot of spekers to spend money: in wood and, above all, in logistics.

* very rigid speaker suspension, they need a long burn-out.

The 5.25" Uni-Q coaxial speaker is very good but expensive too.

Knowing the weaknesses, with patience first and spending a little money on refining the first order filters and adding mass we will have excellent speakers. And on some supports, filled with cheap sand (not from the beach, because salt corrodes), better than on a shelf. Cheap construction sand -like mines- or silica for pets.

Of course, having rear bass-reflex will need space. How much? I do not know.

KEF LS50 passive need about 90 cm / 30-35" of distance from the three walls, that is why many sound bad in their homes, because they have not bothered to inform themselves properly! Well, and only 79 Hz at -3 dB. To have more bass, they approach to walls and lose their magic. They need a subwoofer to play all kind of music.

KEF LS50 wireless/active have a DSP which seems to improve the sound on a shelf and the few bass. Btw: tweeter with class AB and woofer with class D.

frequency response

(±3dB) Measured at 85dB/1m
45Hz – 28kHz (More bass extension)
50Hz – 28kHz (Standard)
61Hz – 28kHz (Less bass extension)
Depending on speaker settings <- DSP


Left Speaker 10.0kg (22.0lbs.)
Right Speaker 10.2kg (22.5lbs.)


by Darren, December 28, 2018

...Sound quality: Wow. It's really hard to describe how these sound because it's almost like the sound isn't coming from the speakers at all. What I can detail is how clear and crisp everything is. The highs are crisp and crystal clear. The mids are clear and warm. Then there's the bass. Do not believe in the frequency range numbers. These definitely go down beyond the claimed 51Hz. I was worried about having to get a subwoofer, coming from RP-500m's, but these produce an astonishing amount of bass for the size. Provided in the box are two bass port plugs with 2 stages: both foam pieces together or you can remove the inner foam piece for just a foam ring. My advice: put them in with just the outer foam because it tightens up the bass and makes it less boomy. All in all, these sound great. I like electronic music mostly and these are perfect for EDM or house music. Deadmau5 sounds amazing on these. Likewise, these will sound great with pretty much any genre of music.

I'm powering them with a Nobsound TPA3116 100W mini amplifier and it's plenty of power. I did recently purchase an Audioengine N22 amplifier and while it sounded great with the KEFS, it unfortunately had unbalanced channels. So I'm sticking with the Nobsound for now. I'm sure these would sound much better with a high end amplifier, but it shows how forgiving these are of the power source.

In conclusion, these are great for near field listening: punchy bass, warm mids, and crystal clear highs. These definitely need to be broken in because they will sound harsh during the first couple of hours. After that, they become mellow and warm sounding. It's easy to listen to and pretty to look at. Can't wait to see what KEF does in the future!


Max power must be at 0.1% THD in a SS.

These definitely go down beyond the claimed 51Hz

If they are too close to the walls there will be a forced enhancement of the bass. If it is electronic music, nothing to object, but with more refined ones, better keep the distances, I say.


Excellent execution by KEF

by Shane from Clay, MI on 12/27/2018

These are excellent. After a Christmas shoot out with another pair of speakers that we're getting rave reviews, these beat them out immediately. They're going in my office with my Elac Unifi UB5's. That's who they compete with. Bass great. Treble is a little crisper than the Elacs which is nice. It's not overwhelming though. Soundstage is apparent right out of the box. Digital Trends got the analogy correct. If the Elac Unifi UB5 is a Chardonnay, then the KEF q150 is a smoky Pinot Noir. Right on. The Elac mids stand out a little more. The KEF's are the more laid back Brit sound. I absolutely love them. Highly recommended. Powered by an old Onkyo 809 receiver and Oppo bdp 93

Pros: Great bass. Crisp highs but not etchy at all..just enough. Great soundstage

Cons: Not as much attack as say a horn speaker but it's really not a con. It's preference. I could listen to these for hours without fatigue.

Front L/R   135 W + 135 W (8 ohms, 20 Hz-20 kHz, 0.08%, 2 channels driven, FTC)
160 W + 160 W (6 ohms, 1 kHz, 0.1%, 2 channels driven, FTC)

Note: if an AVR does not say power at 4 Ohms (usually modern AVR) -> it must be hot/very hot at medium power (speakers "4 Ohms"). This is a known problem in modern Marantz/Denon and others.



About the KEF Q150 bass

I get very loud deep bass, they sound quite bloated and they lack definition / punchiness. I don't feel the bass when in certain sound I know I should feel it. They're currently powered by a Marantz M-CR511 (40w in 8ohms), could the problem be there?

To be more specific, they're in a 20 square meters room, both on 60mm stands, 30cm from the wall...

Without graphs we can not know if KEF has enhanced the bass in the Q150.


Maybe Q150, with rear bass-reflex, is like LS50, which need about 90 cm from the three walls.

Small room and rear bass-reflex. Rear is more neat but can be more problematic, depending on the design.

If reader who has it could provide light on this, it would be appreciated.


KEF Q100 graphs:

The black line is the front bass-reflex frequency graph:

Maybe the Q150 rear bass-reflex has a big first peak.

Impedance and phase too:

But it is not a small room!

To be more specific, they're in a 20 square meters room, both on 60mm stands, 30cm from the wall...


Ok so I spent hours listening to different musics that I know and placing the speakers at different positions in my room. I finally found something that sounded good! Without any ajustement on my receiver I finally was able to detach the voice of Jack Johnson from the bass in "Middle Man".

The only problem is that it was almost in the middle of my room and facing a corridor so I could not let them there but what's sound the closest at the moment is when I place them in their original place and change the output frequency characteristics to cut the low frequencies of 60 Hz or under by –12dB/oct.

Still not perfect I guess because I feel like I'm loosing some bass...but I'll try to buy another amp later if I can to see if it improves. Something like a Marantz PM6006, I heard that it might have better control than my AVR. I won't be able to try the Q350 as it's a bit over my budget at the moment and I thought that for the size of my listening room the Q150 would suffice.


Something like my EQ with my 120 Ohms, 105dB and 53mm cheap open dynamic headphones Takstar ts671 (tweaked, modded and recabled) when I connected them to my tweaked and modded AV Marantz SR4500 (330 Ohms at output headphones). But HPF at 60 Hz.

* The optim fr to cut is 210 Hz. Before tweak and mod: 178 Hz, years ago, with the AV without mods.

** Tweak, mod and recable optimized to listen to them with my class A iFi iCAN head amp. The problem is now, AV tweaked and modded, the sound is much better with the class AB Marantz!

******* ******* ********

Off topic

The files of KEF LS50 sound test from here:



KEF LS50 wireless has inside two amps: woofer with 200 watts class D and tweeter with 30 watts class AB.

KEF LS50, passive, has a true sensitivity of only 83 dB/W/m.

KEF Q100, has a true sensitivity of 85 dB/W/m.

I suppose that KEF Q150 has the same true sensitivity of Q100, 85 dB/W/m.

What power do I need to match the same SPL? At max power.

KEF LS50 wireless, 200 watts and 3m

KEF Q100 or Q150, 126 watts and 3m

KEF LS50 wireless at 200 watts has the same SPL than KEF Q100 and Q150 with 126 watts.

Well, the more important thing is that KEF thinks that these 5.25" coaxial speakers like amplifiers with a lot of watts, which is what I have been affirming for a long time.

At least, 80 watts at 8 Ohms with THD 0.1% the Q100. Then the same the Q150.

PS: very good recordings with high/very high DR. With modern commercial music, with DR << 10 dB we need less power.