KEF LS50 Bookshelf Speaker Review

[cleareyes]

I'd say that's a bit far, unless you really don't turn it up much... For me, more than maybe 6' doesn't work very well.

what would you recommend instead?

 

[AGLeS]

I have a pair of these. With a sub, they are awesome.

What sub did you pair with them? One sub or two? Trying to decide for my LS50s...

 

[bobbooo]

I did that for the JBL 305P a while back and difference was minimal there as well.

Good to know it's not a big difference. By the way, you might have already seen this, but I came across a whole list of clearly defined standards by the AES for audio electronics and acoustics measurements, experiments etc. on their site: http://www.aes.org/publications/standards/

As Sean Olive's AES profile says he's on the Standards Committee for Loudspeaker Modeling and Measurement, I think we can safely assume he used these standards when taking the measurements of speakers his preference formula is based on, and so following these same AES standards would produce measurements and so predicted preference scores from his formula that correlate most highly with actual preference. Here's that particular standards document: http://www.aes.org/tmpFiles/aessc/20200129/aes-05id-1997-s2019-i.pdf

I'm not an AES member, but if anyone who is wants to have a read of it, it may contain some useful information. These documents also might come in handy:
http://www.aes.org/tmpFiles/aessc/20200129/aes02-2012-i.pdf
http://www.aes.org/tmpFiles/aessc/20200129/aes56-2008-r2019-i.pdf
http://www.aes.org/tmpFiles/aessc/20200129/aes-01id-2012-r2017-i.pdf
(The last one probably isn't relevant as it seems to be about plane-wave tubes, but does mention mic placement in the contents so might have some useful nuggets of info.)

 

[MediumRare]

Thanks for this review. Coincidentally I just this week reviewed the LSX powered sister of this, expecting wonderful sound based on the reviews in other places. I was SO disappointed. In near field, especially a little below the driver plane, it was good. Anything more than 8 feet away the sound was muddled, muffled, and totally unsatisfying. I was so surprised I convinced the guy to take the speakers into the "good room" and compared them to some passive B&W 607s which cost 35% less. Tried in a pair and also mono. The difference was night and day. I was assuming all along that a sub would be required and of course adding one helped in general, but it couldn't help the mid and highs bemuddlement. *sigh* The search for powered wifi speakers continues.... All suggestions welcome.

 

[Crazy_Nate]

I'm waiting to give my LS50s the best chance that I can give them before I form a lasting opinion. Good power (AHB2 on the way once it gets built...), 'optimal' placement and probably a bit of time with REW integrating a Rythmik sub.

Currently, in a larger room (19' x 21'), the main listening position is about 13' from the speakers. I don't love them. But, if I sit about 6' from the speakers, it's substantially different. We'll see if I like them in a larger room with better conditions.

 

[Crazy_Nate]

Do you have boxless Rhytmik servo subs? Which model is that?

Likely a GR-research kit in something like a H frame (you can buy flat packs in the US for $6-800 per pair depending on which kit - duals or triples). I believe the amplifier kits are set up for open baffle, otherwise they're they A370 or HX300(or larger) from Rythmik. Danny's sub kits have a big "Rythmik Audio" silkscreened on the amplifier.

I've been eyeing building a pair of dual or triple 12s, but, alas, we have 3 cats. I will probably go with boxes.

 

[bigjacko]

Re: Bass

Care should be made to keep a coaxial's midrange/woofer portion movement minimal. After all, the driver is the waveguide for the tweeter and movement of said driver can result in pertebations high in frequency. Whether or not they are audible is a discussion to itself. But it's a measurable effect. You can see my results of the Q100 cone movement here:
https://web.archive.org/web/20180302013445/http://medleysmusings.com/kef-q100-drive-unit-testing/

Because driver will move in and out quite fast, would the sound in the end average out? But there is also the problem of how fast. If let's say the bass frequency is 35Hz, would the effect be audible? Is there anyone coming up any study on this?

 

[bigjacko]

Better for the money (for far-field and if you don't have hum issues).

But no, the LS50 scores slightly better.

What is that preference rating? How could someone get a preference rating? Is it based on some research?

 

[napilopez]

What is that preference rating? How could someone get a preference rating? Is it based on some research?

Yes it is. See this thread. It's based off of Sean Olive's generalized preference rating for speakers, which assessed 70 speakers of all shapes and sizes over multiple listening sessions based on the preferences of hundreds of listeners and was able to assess preferred speakers with 86 percent accuracy by using full anechoic data. So not perfect, but the best model we've got.

It's a follow-up to an earlier, smaller, more-controlled study that was able to predict preference for bookshelf speakers only with basically 100 percent accuracy.

 

[maty]

Thanks for this review. Coincidentally I just this week reviewed the LSX powered sister of this, expecting wonderful sound based on the review. I was SO disappointed. In near field it was good. Anything more than 8 feet away the sound was muddled, muffled, and totally unsatisfying. I was so surprised I convinced the guy to take the speakers into the "good room" and compared them to some passive B&W 607s which cost 35% less. Tried in a pair and also mono. The difference was night and day. I was assuming all along that a sub would be required and of course adding one helped in general, but it couldn't help the mid and highs bemuddlement. *sigh* The search for powered wifi speakers continues.... All suggestions welcome.

8 feet = 2.43 m

[PDF] https://us.kef.com/pub/media/documents/lsx/lsx-owners-manual.pdf

KEF LSX positioning, page 56

As I wrote, small loudspeakers have the better sound < 3 m. LSX has 4" woofer, is smaller than 5.25" -> << 3m.

 

[thewas]

Great review! I like the continued evolution of the measurements! The LS50 is a popular speaker and one I considered recently for a desktop setup given the price drop to $900/pair. Although generally very favourable, some reviews mention a hint a brightness, and the peak around 5khz supports those comments. Looks like the speaker would benefit from being placed near a wall and/or perhaps room correction/equalization.

Spot on, I do both and that's the reason I use them in last years for my PC/desktop setup.
When I used them for my classic Hifi setup I combined them with 2 subwoofers and did also some EQ.

 

[Dialectic]

I've retired my LS50s to TV sound duty, running them with a Devialet 120. With the Devialet's SAM feature, the KEFs were unlistenable on movies: the bass was simply overloading anything else the speakers could do.

To resolve the problem, I picked up a $399 SVS SB-12 NSD from Amazon. Because I've been too busy and too tired to do measurements in the family room, I quickly found a recommendation from KEF that subwoofers be crossed over to the LS50s at 79 Hz and followed it, setting a 4th-order crossover to the KEFs at 79 Hz in the Devialet.

The sound is now superb for TV use, and with most listeners off-axis anyway, I think the LS50s plus a subwoofer are more or less ideal for two-channel "home theater." I will test it with music in due course.

 

[Ron Texas]

What sub did you pair with them? One sub or two? Trying to decide for my LS50s...

I have a Martin Logan Dynamo W1000. They are discontinued. You should probably get a pair from Rythmic

 

[direstraitsfan98]

What sub did you pair with them? One sub or two? Trying to decide for my LS50s...

I would look into SVS. I see nothing wrong with them and they are quite cheap compared to other companies which are all using a plate amp sourced from China, and simply assembling the cabinet and driver in America. Measurements dont lie either, SVS subs measure extraordinary well. They have many options to suit all price points, though if your room is larger, you will have to spend more money on larger subs.

Be wary of people who say such and such manufacture is 'more musical' or is 'faster' such terms and words are used only for marketing purposes.

 

[audiophile]

Here’s the best placement for KEF LS50s which I discovered after trying everything possible over a period of several months: http://www.cardas.com/room_setup_near_field.php
Never place them close to the rear wall. Muddy bass and ruined soundstage guaranteed in this case. You’d hear only 10% of what these speakers can do. They need proper positioning on good stands with tweeter height slightly below ear level if you want to tame highs a bit.
A sub is a must, a pair of subs is better. A proper amp that can easily handle impedance drops to 3.8 ohm is a must.
Actually these speakers require so much work, commitment and additional investment to sound their absolute best, so I can’t easily recommend them to everyone.

 

[Dialectic]

I have a Martin Logan Dynamo W1000. They are discontinued. You should probably get a pair from Rythmic

Rythmiks are good, but at $399 on Amazon Prime, the SVS SB 12 NSD is hard to beat. You could get two for the price of one Rythmik or four for the price of two Rythmiks....

 

[Ares347]

I've retired my LS50s to TV sound duty, running them with a Devialet 120. With the Devialet's SAM feature, the KEFs were unlistenable on movies: the bass was simply overloading anything else the speakers could do.

To resolve the problem, I picked up a $399 SVS SB-12 NSD from Amazon. Because I've been too busy and too tired to do measurements in the family room, I quickly found a recommendation from KEF that subwoofers be crossed over to the LS50s at 79 Hz and followed it, setting a 4th-order crossover to the KEFs at 79 Hz in the Devialet.

The sound is now superb for TV use, and with most listeners off-axis anyway, I think the LS50s plus a subwoofer are more or less ideal for two-channel "home theater." I will test it with music in due course.

Same here have them on bedroom TV duty without a bass and I love them there. Now because of this measurements I know why, there are some exagerated frequencies that sound so different from everything else I own that feels refreshing. Probably the reason why reviewers like zeos and DSM like them so much mostly because they sound different not necesarily better but different.

 

[Ron Texas]

Rythmiks are good, but at $399 on Amazon Prime, the SVS SB 12 NSD is hard to beat. You could get two for the price of one Rythmik or four for the price of two Rythmiks....

I might need to look on Amazon. The least expensive Rythmik is $559. edit: The NSD on Amazon is sold by a third party. It might not have a warranty.

 

[jamestown]

I went from the Q150 to the LS50. My experience was that the LS50's cabinet is better built. Measurements suggest it is more innert as far as resonances go. That may or may not make it worth the doubling of price. As I understand it any ringing or resonances are a time domain problem and as a result cannot be effectively EQ'd out.

I certainly like the look of the blacked out LS50.

I was expecting more low frequency extension from the LS50 but that is not the case, they roll off very similarly and I was unsatisfied with the setup (given the cost) until I added a subwoofer (F12-300).

I read somewhere that the Q350 might be the better buy overall for more extension, and while I disregarded that advice initially they might have been on to something.

Would I have been satisfied with a lower extension bookshelf in general? Previously I owned and liked Paradigm Studio 20v2 which definitely play lower than the LS50/Q150, but that still doesn't really compare to the experience of having a well integrated subwoofer. Effortless base, something you can actually feel to some extent.

I think what is right for you would all come down to what you listen to. If any of it is electronic, dance, hip hop, rap, rock, metal etc not much can compare to adding a subwoofer. If you listen to acoustic guitar with singer recordings, or piano solos etc, the difference in what you hear is quite minor.

 

[Ron Texas]

The third party is an authorized SVS dealer.

Thanks, It says the warranty applies. There are two features I like, a relatively high cut off point and a pass through to connect a separate sub. Rythmik goes a little lower.