KEF LS50 Bookshelf Speaker Review

[Frank Dernie]

Can it really be such a huge difference?

Yes, IME.
The position of speakers, room contents and carpets makes more difference to the sound than any of the equipment, but is less fun to mess about with...

 

[Steve Dallas]

I've experienced something similar the other day, I just wanted to ask you... I've read a lot about the importance of positioning and I understand the basics, but I've noticed I never managed to find a straightforward data on how big of a difference it can be. How much can you achieve, how audible it could be. And I somehow miss that info to fully grasp what we're dealing with.

Some very unpleasant harshness completely disappeared after moving speakers just 1 foot further appart.

IN DETAILS: I've changed some furniture in my listening room and chucked out the old huge TV stand for a smaller one, finally moved my bookshelves to stands and got a thick, fluffy carpet. Even though the current piece of furniture my system rests upon is smaller, I expected my system to play better bc of the stands and the carpet.

Yet, it didn't at first. Some horrible harshness came about. Even Bob Dylan's harmonica became razor sharp and unbearable (it played nice before).

I wrote it of as "less furniture - more harshness". But it got me thinking; the difference was not that big and there was an extra carpet... I've noticed that in the process, the equidistance was affected. My speakers were close to one another. Former TV stand was so huge that they were actually further appart in that setup than they were on the stands after that.

I wanted to move them further apart simply to respect the rule of thumb on the equilateral triangle. Not bc of the harsness, nor did I expect such a difference.

Ther result was, the harshness went away (????). I didn't do tests and honestly don't think it's necessary in this situation, it's night and day; from "for the love of god, don't play Bob Dylan" to "well this Bob Dylan guy has such a lovely and laid back harmonica solos". (same files, same system, same room... just a foot further appart)

Can it really be such a huge difference?

Yes, it can make a huge difference.

With regard to your furniture vs. stands, remember that the opposite ends of the frequency spectrum are reductive. If you increase bass, it has the effect of decreasing treble and vice versa. Speakers sitting on furniture tend to vibrate that furniture at its resonant frequency, which excites that FR and all its undertones and overtones. That could shift the tonality toward warmth, which reduces brightness. Moving the speakers to stands tightens the bass and removes that artificial warmth, which increases perceived brightness.

Moving the speakers relative the front and side walls changes boundary effects in all frequencies due to changing reflections. You can adjust the primary reflection point on the side wall by moving the speakers forward or rearward, for example. Bass quantity can be changed in the same way, thanks to boundary gain in low frequencies.

Changing the toe changes the listening axis. Less toe sounds warmer, more toe sounds brighter. I liked my LS50s with very little toe and equidistant to the MLP.

 

[killdozzer]

Yes, it can make a huge difference.

With regard to your furniture vs. stands, remember that the opposite ends of the frequency spectrum are reductive. If you increase bass, it has the effect of decreasing treble and vice versa. Speakers sitting on furniture tend to vibrate that furniture at its resonant frequency, which excites that FR and all its undertones and overtones. That could shift the tonality toward warmth, which reduces brightness. Moving the speakers to stands tightens the bass and removes that artificial warmth, which increases perceived brightness.

Moving the speakers relative the front and side walls changes boundary effects in all frequencies due to changing reflections. You can adjust the primary reflection point on the side wall by moving the speakers forward or rearward, for example. Bass quantity can be changed in the same way, thanks to boundary gain in low frequencies.

Changing the toe changes the listening axis. Less toe sounds warmer, more toe sounds brighter. I liked my LS50s with very little toe and equidistant to the MLP.

Great info!! Thanks a lot! Yes, equidistant and almost no toe for me too. In my case it was moving them further apart; left to the left, right to the right, which also might've acted like less toe in.

 

[thewas]

Similarly to my ex Kali IN-8, the Harman estimated in room response from the ASR NFS measurements (see post #1) matches my with MMM measured around my main listening position very well, especially above 600 Hz where its almost in a +-1 dB range:

 

[Nam]

After seeing review of Infinity Reference 253 https://www.audiosciencereview.com/.../infinity-reference-253-review-speaker.17923/
I am tempted to purchase the Infinity Reference 263.
I like my LS50 with PEQ. But i miss deep bass occasionally.
Please advice.
I listen to most kinds of music, except rap & electronic.
Thanks.

 

[peanuts]

well it shuts down his amp. until you have tried it in your system its impossible to know if the speaker will even work.

 

[thewas]

After seeing review of Infinity Reference 253 https://www.audiosciencereview.com/.../infinity-reference-253-review-speaker.17923/
I am tempted to purchase the Infinity Reference 263.
I like my LS50 with PEQ. But i miss deep bass occasionally.
Please advice.
I listen to most kinds of music, except rap & electronic.
Thanks.

I prefer the sound quality of my LS50 with EQ even to my Neumann KH120 so I doubt those Infinity would be a match, except of course that they go louder and deeper, I personally would rather consider 1-2 subwoofers.

 

[Steve Dallas]

After seeing review of Infinity Reference 253 https://www.audiosciencereview.com/.../infinity-reference-253-review-speaker.17923/
I am tempted to purchase the Infinity Reference 263.
I like my LS50 with PEQ. But i miss deep bass occasionally.
Please advice.
I listen to most kinds of music, except rap & electronic.
Thanks.

The LS50 is a very high quality speaker. It just needs a little EQ and some help with its limited bass. I doubt the budget Infinity is near the same class.

well it shuts down his amp. until you have tried it in your system its impossible to know if the speaker will even work.

This needs to be explored further. There is a good chance there is a problem with the test sample and not with the design.

I prefer the sound quality of my LS50 with EQ even to my Neumann KH120 so I doubt those Infinity would be a match, except of course that they go louder and deeper, I personally would rather consider 1-2 subwoofers.

^ This.

In my environment, it took Revel Performa series speakers to match or outclass my LS50s, and it was really only accomplished in the bass frequencies. Integrating LS50s with subs in my room was challenging, but ultimately rewarding. F206s increased the scale and allowed me to set the crossover lower, the results of which I like, but only barely. The other consideration is the wifey does not like the look of speaker stands, so I was pushed toward floorstanders anyway. I would have purchased KEF R7s had they been available at the time.

 

[phoenixdogfan]

I've use Maikey76's eq, added an SB2000, crossed over at 100hz with 24 db per octave L-R and did Dirac Live 3 with as close to a Harman curve as I could approximate, and the whole thing seems pretty good. Adding the Purifi amps which are now coming back repaired from Purifi and Hypex, and will add either an Octo 8+Ekio or a miniDSP Shd to replace the 2 x 4 HD.

That should hold me until I can put together the capital for D & D 8c's or, Revel 226Be's, or GGNTKT M1's, or Kef Reference One's. I think it would require that level of speaker to decisively better these, given all the tweaks and tunes.

 

[thewas]

Some comparison measurements and EQ to the new Meta generation
https://www.audiosciencereview.com/...ama-and-measurements.18353/page-3#post-603870

 

[Daprosy]

Sure, I had posted some there, but the one I am using currently is attached below.

Hi All, first post here (just registered), I have been reading a lot of your posts so thanks for sharing your findings. I just started using REW, UMIK-1 and APO after I purchased my LS50's a couple of weeks ago. Sorry for all the questions just a few things I'm not sure on currently

I tried this curve with my room response as attached. Do you think I should be turning the subwoofer up a little so the curve in 20Khz region follows the natural roll off more closely as I could then move the target curve higher up?

I turned down my sub levels when trying this curve, as I saw that you seemed to place your target curve much lower than I usually do (I just started out with this EQ and calibrated mic). Is your target curve placement mainly due to the high roll off after 10k, or so that the curve is placed below the nulls in the mid range section, so you can bring everything close to the curve? I find that if I place the target curve in line with the 20hkz roll off, that I am then unable to EQ down the 2khz bump etc. Perhaps I should set APO to not EQ above 5-7kHz perhaps if I use this curve.

I have a very small room (2.65x2.72m) and have a sub low pass crossed at 100hz or so as I have a room mode there. LS50's playing full range, I have a big bump at 60Hz so i didn't try your EQ/Maiky76 optimised one as that has a 3db gain at 65hz.

I also read on your other posts that it was not recommended to try and EQ the bass nulls, and also not to EQ above the low frequency range just following a target curve blindly as it could be room modes. I see from your graph that you do EQ that 100-150Hz null quite heavily, and also EQ the rest of the spectrum by a fair amount. I believe it was sharing quotes from a book where I read your post regarding this, do you think EQ'ing LS50 full range is OK then? I know some of the things I am EQ'ing up or down are indeed room modes, so is this not what I should be doing?

Still 50/50 if I should get some bass traps as I imagine I will need a ton of treatment to make a difference in this small room.

I uploaded my APO settings in the text file attached, compared with Maiky's and your EQ settings on page 22, very different when trying to match to this curve.

I have tried room placement and this is as good as it is going to get for me unless I try room treatment. Thanks again for all your posts I have found them most helpful while attempting to EQ my poor room acoustics.

 

[thewas]

First of all thank you for your kind words.

Your frequency responses look good to me, are you satisfied with the tonality and if not, what bothers you?

What you could try for example is use Maikys EQ to show you how the shape of target curve should be, especially above 500-1000 Hz.

If you want you could also make some REW MMM of L+sub and R+sub without any EQ and upload them here or send them to me per PM and I can make some EQ you could try, especially since your desktop LS50 setup doesn't look very different to mine.

 

[Daprosy]

First of all thank you for your kind words.

Your frequency responses look good to me, are you satisfied with the tonality and if not, what bothers you?
....

Yes I like the sound after EQ, I don't feel like too much changed, but the bass response especially is much better after EQ, the 60Hz bump really resonated in the room with no EQ, especially with a song like "Way down deep - Jennifer Warnes" that has a large 60Hz bass tone throughout.

I feel like I may end up turning the sub volume up slightly depending on the EQ settings I finalise on. But I am enjoying the more flat response overall.

I will sent the .mdat's for left + right REW responses, I cant upload here as file is too large. Thanks so much for helping, appreciate your time!

EDIT: I may as well post this here in case anyone else was interested, I also purchased Triangle Br03's as there were rave reviews on YouTube claiming they are the best speakers <$1000 and other review sites like soundstage and https://hifitrends.com/2020/01/05/p...iangle‌-borea-br03-bookshelf-speakers-review/ gave glowing reports. The triangles were sent back after A/B listening compared to LS50's. I much preferred the LS50's tonality as they sounded much more natural, the Triangles seemed artificially airy, especially with female vocals. They were nice speakers though, just not on par with LS50's.

 

[o2so]

I personally find the LS50 (I have the Metas) plus 2 subs, integrated with Minidsp and Dirac, to be the best system I have ever had in my room (3.7 x 5.5m). I previously had also the Revel M106s plus subs.
At the moment I cannot think of a better set up in small to medium rooms, regardless of the price. Maybe with the coaxial Genelecs but at what cost. The advantages of a coaxial system, if you cannot or prefer not to put a polar bear fur on the floor and/or if you listen while working on a desk, are significant in my opinion. That said I am tempted to try the M126 Be.
I am now crossing over at 120 Hz and this is what I get at the listening position. Aside from the distortion peak down low, which is my suspended floor/furniture/windows rattling a little, there is not much not to like, really. There is a bit of distortion peak at 180 Hz but that's dirac trying (too hard) to fill a bass null.

 

[o2so]

The LS50 is a very high quality speaker. It just needs a little EQ and some help with its limited bass. I doubt the budget Infinity is near the same class.



This needs to be explored further. There is a good chance there is a problem with the test sample and not with the design.



^ This.

In my environment, it took Revel Performa series speakers to match or outclass my LS50s, and it was really only accomplished in the bass frequencies. Integrating LS50s with subs in my room was challenging, but ultimately rewarding. F206s increased the scale and allowed me to set the crossover lower, the results of which I like, but only barely. The other consideration is the wifey does not like the look of speaker stands, so I was pushed toward floorstanders anyway. I would have purchased KEF R7s had they been available at the time.

Keen to hear more about the differences between the LS50s + subs vs Revel f206 + subs. Also how big is your room and what distance do you sit? Ta

 

[thewas]

I personally find the LS50 (I have the Metas) plus 2 subs, integrated with Minidsp and Dirac, to be the best system I have ever had in my room (3.7 x 5.5m). I previously had also the Revel M106s plus subs.
At the moment I cannot think of a better set up in small to medium rooms, regardless of the price. Maybe with the coaxial Genelecs but at what cost. The advantages of a coaxial system, if you cannot or prefer not to put a polar bear fur on the floor and/or if you listen while working on a desk, are significant in my opinion.

It is the same for me, which was the reason I even sold my Neumann KH120 from my desktop system and now use for both systems a pair of LS50 Anniversary and LS50 Meta. Also the three-dimensional imaging of my LS50 Meta setup at my hifi setup after some experimenting with placement is the best I ever had.

 

[Senior NEET Engineer]

LS50 vs. other speakers I've owned:

KEF Q150 < JBL LSR305 < KEF LS50 < Klipsch RP-600M < Emotiva B1 < Infinity P362 < 8030C = Shape 65 < 8341A

I should have just stuck with those $300/pair Infinity speakers...

 

[trivium]

Can someone help me out here, how hard are these really to drive? I’m not fully understanding why 84 db per 1 watt at 4 ohm is that bad. My marrantz pm6006 provides 60 watts at 4 ohms, what’s so bad about that? I mean if I only listen at 80DB from 6 ft away I should have more than enough power no? I currently have the Q150s that I have more than enough power unless I crank them to deafening levels, on paper the LS50s are only marginally harder to drive than the Q150. Of course it’s easier to look at easier to drive options but if one is mostly interested primarily in holographic/3D soundstage and imaging what other options are there under $1500?

 

[o2so]

I personally find the LS50 (I have the Metas) plus 2 subs, integrated with Minidsp and Dirac, to be the best system I have ever had in my room (3.7 x 5.5m). I previously had also the Revel M106s plus subs.
At the moment I cannot think of a better set up in small to medium rooms, regardless of the price. Maybe with the coaxial Genelecs but at what cost. The advantages of a coaxial system, if you cannot or prefer not to put a polar bear fur on the floor and/or if you listen while working on a desk, are significant in my opinion. That said I am tempted to try the M126 Be.
I am now crossing over at 120 Hz and this is what I get at the listening position. Aside from the distortion peak down low, which is my suspended floor/furniture/windows rattling a little, there is not much not to like, really. There is a bit of distortion peak at 180 Hz but that's dirac trying (too hard) to fill a bass null.



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Update: I was able to run an extended home test of a large pair of Dynaudios floorstanders, which I repeatedly compared (with no subs) to the LS50Meta+twosubs+MinidspSHD setup. To my surprise, I discovered that in my room I could only get the 2.2 system to match the (incredible) bass response of the Dynaudios with optimal placement of the two subs. This was with the two subs away from corners and walls, in front of me, in stereo mode (these are crossed over at 120Hz). Any other subwoofer placement in this room would result in suboptimal waterfall measurements, reflected in an audibly less fast bass.
So, in my experience an equalised 2.2 system with the LS50 can be as good as one can get, as long as you get the position right in your room.

 

[Frank Dernie]

Can someone help me out here, how hard are these really to drive? I’m not fully understanding why 84 db per 1 watt at 4 ohm is that bad. My marrantz pm6006 provides 60 watts at 4 ohms, what’s so bad about that? I mean if I only listen at 80DB from 6 ft away I should have more than enough power no? I currently have the Q150s that I have more than enough power unless I crank them to deafening levels, on paper the LS50s are only marginally harder to drive than the Q150. Of course it’s easier to look at easier to drive options but if one is mostly interested primarily in holographic/3D soundstage and imaging what other options are there under $1500?

84dB/watt is not "hard to drive", speakers which are hard to drive are those with low impedance and/or big phase shifts which demand a lot from an amplifier and some modest amps can not deliver the required current.
A low efficiency speaker with a benign impedance curve is not hard to drive it just needs more power for a given loudness and the small low impedance speakers tend to have a lower maximum loudness simply because the amount of power you can put into a small driver before damage is usually less too.

My LS50s are not hard to drive but they are small, they will go louder than the LS3/5a they replaced but nothing like bigger speakers.