Kef Q150 Bookshelf Speaker (review by Erin)

[warthor]

Thanks to Erin for his work here.

Q150: 4.8 preference score
Q350: 5.7 preference score

Would this Q150 (or Q350) speaker make a good center channel? For $300 it is hard to beat if so. It seems to me that both have good horizontal directivity and would be comparable to any of the nice center channels in this price range.

 

[Toblerone]

Erin replied to my comment on his YouTube channel regarding the resonance issue and said he couldn't reproduce it with his speakers. So that's good. I dissembled mine and didn't see anything wrong and put them back together and still had the same issue. So definitely returning them.


One positive note is after taking apart the q150s I decided to check out the trim on the metas and sure enough had the shadow flare issue. Pushed the trim in so they are recessed and the difference is amazing. Like almost as dramatic as the terrible resonance on the q150 but in a positive direction. They went from bright/fatiguing to perfect. Kef's quality control???!

 

[abdo123]

Thanks to Erin for his work here.

Q150: 4.8 preference score
Q350: 5.7 preference score

Would this Q150 (or Q350) speaker make a good center channel? For $300 it is hard to beat if so. It seems to me that both have good horizontal directivity and would be comparable to any of the nice center channels in this price range.

If room EQ is available then the Q350 should be great as it does not have a directivity mismatch.

 

[ernestcarl]

Erin replied to my comment on his YouTube channel regarding the resonance issue and said he couldn't reproduce it with his speakers. So that's good. I dissembled mine and didn't see anything wrong and put them back together and still had the same issue. So definitely returning them.


One positive note is after taking apart the q150s I decided to check out the trim on the metas and sure enough had the shadow flare issue. Pushed the trim in so they are recessed and the difference is amazing. Like almost as dramatic as the terrible resonance on the q150 but in a positive direction. They went from bright/fatiguing to perfect. Kef's quality control???!

The distorting sound from your video seemed much worse than what I would expect just from the resonance seen in the spin.

 

[dc655321]

FYI: @Toblerone I subjected my pair of q150s to that YouTube track and was not able to replicate the problem.

By chance does your listening room have a slap-echo?

 

[Ayebee]

This is not a DIY-thread, but I can't help but wonder how many of the objective weaknesses could be mitigated by a slightly more ambitious crossover. Might be wrong, but as it is I think there's just a coil and a cap (and possibly a damping resistor)? I suppose it's in KEF's interests to both keep the costs (way) down, and also keep some space between the Q- and the more expensive series. But from a consumer perspective, $50 in passive parts could make a big difference. The question is of course - which parts?

 

[raindance]

Crossover changes could help with directivity issues, which already aren't awful for the price. A steeper crossover on the tweeter might help improve power handling. But the elephant in the room is the very lightweight cabinets that could do with bracing and damping. It would be interesting to see a better cabinet built, with the same dimensions, and the drivers and crossover simply installed in it.

 

[abdo123]

Crossover changes could help with directivity issues, which already aren't awful for the price. A steeper crossover on the tweeter might help improve power handling. But the elephant in the room is the very lightweight cabinets that could do with bracing and damping. It would be interesting to see a better cabinet built, with the same dimensions, and the drivers and crossover simply installed in it.

You’re better off buying the LS50 Meta if you’re going to invest that much money and effort.

 

[Ayebee]

Crossover changes could help with directivity issues, which already aren't awful for the price. A steeper crossover on the tweeter might help improve power handling. But the elephant in the room is the very lightweight cabinets that could do with bracing and damping. It would be interesting to see a better cabinet built, with the same dimensions, and the drivers and crossover simply installed in it.

I have a pair of Q150's in storage, that's why I'm extra curious. As you say, the cabinet is cheap and flimsy. I wonder if it would be possible to actually put some extra bracing in the original boxes? Of course - as abdo123 points out - you now really need to consider the law of diminishing returns... But if you're a DIY:er at heart?

 

[raindance]

I have a pair of Q150's in storage, that's why I'm extra curious. As you say, the cabinet is cheap and flimsy. I wonder if it would be possible to actually put some extra bracing in the original boxes? Of course - as abdo123 points out - you now really need to consider the law of diminishing returns... But if you're a DIY:er at heart?

My thoughts about the original boxers were to build a box around the box on the outside (top/sides/bottom) using glue so the wood is bonded. Add heavy adhesive damping material to the inside of the front and rear panel. I would be cautious about changing enclosure volume by adding inside bracing as it will change the tuning frequency. I would also improve the mounting method for the drive units. Of course this idea would look pretty awful . I thought about doing this with my IQ3's, but they had curved cabinets so I just sold them instead.

 

[dc655321]

It would be interesting to see a better cabinet built, with the same dimensions, and the drivers and crossover simply installed in it.

Yes, interesting from an academic perspective, but not from a practical one.

I bought q150s for their drivers, not the ****** little box they came in.
They will make great components in a more capable 3 way system.

 

[Actungz]

I wonder if rotating the q150s on to their sides and putting weights on top would help with the resonance issues. I love mine but the cabinets feel cheaper than the Klipsch rp500m’s that I used to have as well

 

[raindance]

I wonder if rotating the q150s on to their sides and putting weights on top would help with the resonance issues. I love mine but the cabinets feel cheaper than the Klipsch rp500m’s that I used to have as well

Maybe a butchers block with a weight on it on top of the speaker. But it really doesn't address the issue very well.

 

[Actungz]

Maybe a butchers block with a weight on it on top of the speaker. But it really doesn't address the issue very well.

Yeah I thought so too. Fortunately I don’t hear the resonance in that frozen clip and in general really. Just something in the back of head

 

[amirm]

I didn't realise that Klippel sweeps were that short. 2S for ten octaves is a pretty fast sweep.

Klippel puts no restriction on frequency sweep. You can make it minutes long if you like. The problem is that a typical speaker measurement involves 1000+ measurements. So if you add 2 seconds to each sweep, the total measurement time now increases by 2000 seconds. That's 33 minutes! You are doing one measurement so you can run longer sweeps.

I also use averaging which multiplies the above yet again. I experimented with averaging and after three cycles, you have gotten most of the gain. That is in my rather quiet room though. You may need more. But 16 times averaging is just not in the cards.

 

[sarumbear]

Klippel puts no restriction on frequency sweep. You can make it minutes long if you like. The problem is that a typical speaker measurement involves 1000+ measurements. So if you add 2 seconds to each sweep, the total measurement time now increases by 2000 seconds. That's 33 minutes! You are doing one measurement so you can run longer sweeps.

I also use averaging which multiplies the above yet again. I experimented with averaging and after three cycles, you have gotten most of the gain. That is in my rather quiet room though. You may need more. But 16 times averaging is just not in the cards.

Thank you for the explanation. Once again, I learned something. However, I want to repeat what I said earlier. I was not commenting on the measurements. What you do is perfectly OK and reasonable beyond doubt.

I was simply talking about the diagnostic procedure that is used once the resonance is heard during listening tests. I was simply suggesting that once an issue is reported/heard it is easier to understand the cause and severity by using a slow sweep instead of repeatedly listening a certain section of a track.

 

[hardisj]

I was simply talking about the diagnostic procedure that is used once the resonance is heard during listening tests. I was simply suggesting that once an issue is reported/heard it is easier to understand the cause and severity by using a slow sweep instead of repeatedly listening a certain section of a track.

I replied to @Toblerone in my YT video comment section. But I'll reply here as well.

I did, in fact, do what you're talking about. At least to some degree. I have a signal generator app on my iPhone (link) that I use for things like this as well as finding room modes and identifying trouble areas in my listening tests. It's much easier to pick a frequency on the app than run a sweep over and over again, hoping to identify the frequency. I use the app to manually sweep and then when I hear something that sounds off (or what I am listening for) then I'll slow down and go back over those frequencies until I nail down a specific frequency or range.

With that said: In my testing for this issue, using the signal generator at varying volume, I didn't find any such resonance. I suggested he look into the speaker's mechanical parts to make sure nothing was out of sorts. Which he said he did, to no avail. I find that these issues can often be caused by a) debris falling into the VC/magnet gap or b) asymmetry of suspension (but usually only at extreme excursion).

Again, no issues on mine. No one replying to the video has mentioned this issue. I bought mine from Amazon and they came BNIB. I didn't see anything about it on the Googles-web, either. From what I can tell, @Toblerone has a faulty unit. Hopefully he can send it back for replacement.

 

[sarakyel]

I wonder if rotating the q150s on to their sides and putting weights on top would help with the resonance issues. I love mine but the cabinets feel cheaper than the Klipsch rp500m’s that I used to have as well

In my (admittedly limited) experience, the weights might help. I use a couple of Q150 paired with a JBL LSR310S subwoofer as studio monitors. When I first installed them in my (moderately treated) room, the resonances were audible on sweeps - even though much less offensive than the broad dips in the response of the LS50/LS50 Meta.
My full studio rig also includes a pair of "mixcubes" (small single-driver active speakers weighing around 3 kg each) that I put on top of the Kefs. After I was done setting up the whole space, the Q150 resonances were inaudible to me, and the REW measurements confirmed that both spikes in frequency response and harmonic distortion were lower than without the mixcubes. I can post raw REW data if you're interested.

Oh and btw, thanks a lot @hardisj for the measurements. I have to admit, I expected them to perform better than that: in my room they were the second best speakers I measured after the Neumann KH120, head and shoulders above monitors from Dynaudio, JBL or Amphion.

 

[More Dynamics Please]

Andrew Jones suggested in the Elac Uni-Fi 2.0 Review some simple external speaker points to check when a resonance is heard that could potentially be a mechanical issue:

There are cabinet vibrations in this frequency range. There are in any speaker at this price point. My speculation is something that is mechanically coupled is vibrating. I took a sample from my lab and did a slow sweep with a good old fashioned analog oscillator, so I could sweep slowly back and forth around 600Hz. Yes, the cabinet is lively in that range, and what I first heard was rattling of the binding posts on the terminal panel (I was using banana plugs to connect to the speaker). Once I tightened them the problem went away. The interesting thing is, that result of the rattle could be heard on every panel of the speaker when I put my ear close. I've had this happen before, once on a TAD speaker where I traced it to the speaker cable plug cover, and another time to a loose spiked foot on the speaker stand.

 

[Astrozombie]

Wowza, I'm sure the 100 is similar, wouldn't think I would want that kind of brightness but I haven't minded it in my case.