LS-50 Speakers (Passive)

No matter where I and a friend reads, most people are raving about the Kef LS-50’s (passive version).   However, sadly, neither one of us have heard them with no local dealer.  The best would be to evaluate them in our respective rooms as the room accounts for about 1/3 of the sound.

Moreover, I recently heard that the new LS-50’s ((passive) are not the same as the originals as Kef tried to save some money.  Is there any truth to this rumor?  I certainly hope not so I thought I throw it out there and see the response I get.

Thanks for your input....
I don't think the LS50s have changed.  KEF tries to save money like every other manufacturers: by achieving economies of scale.
What I believe is that the new Q150s are very close to the LS50s.  So the initial LS50 development investment will continue to pay off for years to come.
By the way, the LS 50s are outstanding in the midrange and up - outstanding soundstage and imaging - a great speaker, unique.
I have the ELAC UB5s now, replacing the LS50s.  The Elacs are somewhat a me too product, outstanding for the money, very close to the LS50s, but not as refined imho.  However, the bass (quality, evenness) on the ELAC is absolutely way better than on the LS50s...
So take your pick... a matter of taste.
You don't have to "take your pick" if you use the LS50s with a pair of subs.  I highly recommend something like the Velodyne SMS-1 bass manager that provides acoustic room correction for subs and is helpful for integrating the LS50s with the subs.

db, you may be right, but with bass management as you say.  I personally like to let the main speakers play what it was designed to play.  In other words, I crossover to my sub naturally at the point where the mains can't no longer output, and keep the use of the sub to a minimum.
ELAC UB5s are 1/3 the price of the LS50s. If you think they are equivalent, that makes the ELACs the bargain of the century.

I have a pair of UB5s, as well as a pair of ~1978 Chartwell LS3/5As. I should compare them some time.
I have both the Elac UB5 and LS50s.  I also have a pair of Totem Hawk as reference.   In my room and with my modest marantz integrated, The UB5s are coming really close to the LS50s in terms of imaging/soundstage, clarity, details.  The LS50s develop more the midrange without being forward, while the UB5s are little less refined and more forward.
The UB5s bass -without the use of equalization or crossovers at mid-bass frequency- are more even and refined.
That's just my take on things!
crutchfield sells the LS50's with a 45 day return option...only costs about $10 to give them a try
I'm pretty sure the passive LS50s were the original version, and the wireless came afterwards.  The wireless are supposed to be better, which makes sense as the designers could incorporate DSP and match amplifiers to the drivers.

I've only demoed the passive ones, and I thought they sounded nice.  I own the Elac UB5s as well, and to my ears they're incredibly close.  The LS50s have a nicer construction and nicer finish, and I think they're a bit darker than the Elacs, but both are excellent speakers.  
The Elac UB5 is a very good speaker for the money, but it IMO it doesn't sound anything like the LS50 passive.  The imaging and dispersion pattern of the dual concentric UniQ driver on the LS50 in entirely different than the UB5, which sounds more "conventional" (not necessarily in a bad way).

While the LS50 is not my personal choice it is a superior and very distinctive speaker.  The UB5 is distinctive mainly for it's performance at it's price.  Again, IMO.

I would only get the LS50’s if you plan to also use a subwoofer (or two). They are great speakers, but they only get to 79Hz +/-3dB (ground plane, so some in room boost).

The Philharmonic “New Philharmonitor” would be my pick if you won’t be using a subwoofer. They are built to order though.

The UB5 (only addressing it as others are recommending it) has a midrange boost, and it’s imaging is pretty good, except in the 3kHz-7kHz region.

The HSU CCB-8 is very similar to the LS50, but a decent bit cheaper, and has a good amount of bass, so subwoofers aren’t a necessity.  
 The SVS Ultra bookshelves are also very good. However, I feel they are a bit overpriced. Via their outlet store, you can get the Piano Black finish, one being undamaged for $50 off and one with faint scratches for $100 off, they post pictures of the scratches, so that would be $850 total instead of $1000.
I have a pair of UB5s, as well as a pair of ~1978 Chartwell LS3/5As. I should compare them some time.
40 year old caps are probably suspect

crossover to my sub naturally at the point where the mains can't no longer output, and keep the use of the sub to a minimum.
crossing over an octave above the main 'lower' frequency @ 6db / octave with a passive XOver and setting sub[s] to 18db / octave and 180° with the sub[s] in the main plane yields better results than trying to get bottom out of a small driver / box. The phase is correct, the mains are not stressed and less power is required for the mains. Main and sub should be same type, i.e. sealed or vented.

C = 1 / ( 2 * π * f * R ) where f is desired frequency, R is amplifier input in Ω.
C is in farads, so multiply by 10^12 FOR pF

I have a pair of UB5s, as well as a pair of ~1978 Chartwell LS3/5As. I should compare them some time.
40 year old caps are probably suspect

Original LS3/5As can be worth $1,500 to $2,500 a pair. Modified ones ain’t worth sh*t :-)
The LS50s (recently manufactured examples) can compete with many ~$5K speakers IME. However, getting them to do that requires a high quality amp and source. If you pair them with a budget amp, say something in the <$1k range, as one likely would with $1500 speakers, you won’t realize their full potential, especially concerning their bass. This is why some find budget speakers like the Elacs to be nearly as good. It’s because they have system bottlenecks elsewhere.

It’s better to think of the passive LS50s as a $3500 speakers, because they simply require high quality gear. I run a pair with a budget amp in a third system. They sound ok for that application, but having had them paired with $2.5K amps in my other rooms, I know they’re capable of far greater performance. I wouldn’t read too much into comparisons with lower KEF models. Stereophile recently rated the Q350s as "class C" speakers while the LS50s remain "class A." I’ve owned and auditioned a fair number of their class C rated soeakers. The LS50s are in a whole different ballpark when properly powered. The wireless version is a better value proposition unless you already own a high performance amp.
Completely agree with Helomech above. I run my LS50’s with $3700 SimAudio amp and pre plus $2k DAC. BASS is clean, taught and well controlled. Room is 10’ x 14’ x 8.5’. Go for it!

As a Kef dealer agree with Helomech and Tom6897, we are also an Elac dealer, The Unifi do not have the resoloution of the KEFs, and are voiced to be a bit on the warm side. 

The Kef LS 50 are cleaner, with much  more sound stage focus. 

We just took on the Quad Line the S2 monitor at $1,000.00 a pair are scary good, and in some ways out performs the LS 50 while having much better low bass, and even greater treble clarity and a very wide soundstage. 

Please PM us if we can be of further assistance.

Dave and Troy
Audio Doctor NJ

Unfortunately, the quads have been on the market for 3 years now on no one cared for them in europe.
I own the LS50s for two years and it’s a very well balanced speaker. You won’t be able to hear anything bulging or missing unusually or unnaturally. Very well behaved speaker, I won’t repeat other users’ findings about soundstage coherence and imaging. Its hallmark is the midrange, but bass is quite satisfactory depending on the room size and placement. The highs are nice too, but I’ve heard more refined or maybe artificially more elevated twitters that add a sense of airiness, but at the account of being forward. LS50 is quite in the middle, neither forward not laid back. Pianos sound very natural on LS50 and that was my starting requirement.
Take my highs impression with a grain of salt as I’m using the LS50s with an amp of my make that is based on old school of high gain high feedback AB class.
KEFs so transparent, that I easily hear a difference when I roll opamps in my amp. Switching the amp altogether with my old Marantz is easily heard by anybody, not just by attentive ears.

On the negative sides, this is a tricky speaker to position and mate with the sub(s). It has a very strange bass dispersion pattern, where lateral or generally off-axis bass propagation is in my opinion quite stronger, so you end up with a very clean and lean bass in the listening plane and tons of bass in certain areas of the room, well off-axis. For my taste, I’m lacking the midbass hump for a better impression of size. Its lower bass, is actually quite heavy and gives nice slam impression.
Also, LS50 do have the tendency to sound better on higher volume.

With the end net sound being very dependent on the amp, I wanted to shortcut the amp matching game, sell them and buy the new wireless version, which I listened positively  at "High-end" in Munich last year.
I had a chance to hear a pair of out of the box LS50w last week and they completely put me off of my previous decision. They were nowhere near the mids and highs perfomance of the passives. I guess they really need a long break-in period to start working, but I didn’t want to risk with that.

So, to sum up, if you have a small to medium size room, you will be hard pressed to find anything to complain about the LS50. In larger rooms, the midbass energy drops quite a bit and you will need a solution for that. I haven’t found it yet because it’s not the low bass or sub bass that is missing but the midbass. My sub helps add weight but not in the upper bass and I cross the sub quite high at about 100Hz. Then again, the placement of my LS50s and the sub is far from ideal.
Maybe someone will help with an idea of a sub or bass that covers not only the sub range and has a very good managment of the bass.
^There’s a good chance your LS50s are placed on a room mode. If your speakers are somewhere between 2 and 3 feet from the forward wall, this is likely the case. These distances typically result in an upper bass null. It’s unfortunate because that distance allows decent soundstaging while remaining aesthetically acceptible. You might try moving the speakers to less than 20" from the forward wall (of course this will cause imaging to suffer) or try moving them 5 to 6 feet from the wall (measured to the centerline of the speaker cabinet).
I just don’t get why anyone would buy a speaker with a 6.5” woofer in a <1 cu.ft. box and expect it to move the earth. Nor do I understand why you would then try to marry it to one or more subwoofers and expect no ill effects on the sound quality. If you’re after full range sound, buy a full range speaker with a big woofer in a big box. There’s a reason that there were very few subwoofers before the advent of “home theater”. That’s where they belong.
@helomech: thanks for the advices. Actually I am keeping them closer to wall with exactly the effect that you describe. But anyway, wherever I tried in my irregularly shaped medim soze room, I still develop some string modes. This is not exclusive to LS50, I tryed other seakers.

@ripkeith: two reasons. The first is price and the second is the fact that I’m living in an appartment with weak acoustic isolation. My idea was to use the speakers w/o the sub in the quiet hours and with the subs in more noise tolerant hours. Let alone space requirements of larger floorstanders.

btw, I don’t really listen to music that requires earth trembling bass. I use my sub very subtly to just add some foundation to the mains when there is such content in the music I listen.
Just put away the Totems this morning in order to listen to the Elac ub5, and wow am I impressed. Bass output is top notch, imaging and soundstaging are setting a really HIGH bar, not that much less than the LS50s.
Some have mentioned that the LS50s do show what they really are capable of with top notch amplification - no doubt. But that should go for the UB5s as well. The UB5s are a 3-way speaker. For the money, I repeat, the UB5s kill the LS50s in the bass/mid-bass department... and the rest of the frequency range is not too far off.
Obviously, the finish and front baffle of the LS50s outclass the cheap ELAC. But on sonics alone, not really.
I am saving money for the Adante AS-61.  Can't wait.
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Chris r your comment about the Quads are way off.

The S series and Z series have been quietly getting rave reviews all over the English press.

The S1 the smaller of the two bookshelves got a Hifi Choice 5 star review

The Z3 a $4,200 floor stander got the Editors Choice award 2016
in Hifi Choice

Quad Z 4 Editors Choice award Hifi News 2016

Quad Z1 Monitor Again Editors Choice

Stereopiile rave review of the Quad S2

We would say the biggest issue with the Quad speakers is that they are new to the US at this point.

The last distributor wasn’t very good, and other than the Electrostatic speakers which everyone knows about nobody even knew that Quad just came up with a fantastic line of dynamic loudspeakers.

Mofi distribution is now working with Quad to setup dealers and do shows to get this outstanding new line of speakers out there.

We have been working in high end audio for over 30 years, and I can count on one hand how many new and affordable loudspeakers really knocked our socks off, the Quads are really impressive and their clarity and soundstaging are just off the charts.

Dave and Troy
Audio Doctor NJ
Chris R we also have the Adantes, as well as the KEF and incomming are the Quad Z1, so if you have any specific questions please feel free to reach out to us, 

We also sell, Dali, PSB, ATC and a few others. 


Dave and Troy
Audio Doctor NJ
How would you describe the s series versus the z series?  I had the s series and agree, incredible speakers for the money.  I had them at the same time as a pair of P3esrs.  There was no comparison.  The s2 was a much more enjoyable speaker.
Malthuse, the Z series extends everything that is good about the S series. 

The sound is even more refined the soundstage is even bigger, greater clarity. 

Honestly the most impressive speakers for the money that we have ever heard.

We just demoed for a client the Naim Atom then the Uniti Nova with the Z2 and it sounded like a Radiho but without the hyper detailing presentation, very similar resolution and big open clean and fast reproduction,

The Quad ribbon tweeter is one of the finest high frequency drivers we have ever heard, the resolution is unbelievable but the speakers sound rich  
The Quad's damped ribbon is what makes the speakers so freaking good.

Please PM us if you have any further questions. 

Dave and Troy
Audio Doctor NJ
I have passive LS50 with a Vincent SP-331 (the lower end model around $1300), a Schiit Saga preamp, a Schiit Modi Multibit. The combo sounds very good but I don’t really want to spend thousands on better equipment to pair with the LS50. I was going to incorporate a 2x4 HD mini-DSP and sub but I wonder if I should just sell the passive LS50 and some of the gear and just buy the wireless LS50. Or is what I have equal to what I can get out of the wireless LS50? It’s for a small room 12 x 12.
I finally got around to comparing my passive KEF LS50’s ($1500) with the Audience ClairAudient 1+1 V2+ loudspeaker ($2345) using the same electronics (my office system).

Benchmark DAC3L + AHB2 amp + Audience AU24e interconnect and speaker wire + Sonnare microRendu + isoaccustic speaker stands on a big desktop

This is an extremely quiet system. Here is a review of the electronics.

As much as I like my KEF LS50’s I have to say the crossover less Audience speakers are better. The KEF’s are a little easier to position than the Audience. The KEF also have a little bit more bass however, when you listen to the Audience you get the sense that there is no speaker there. It is quite extraordinary how clear and deep I hear into the music. The KEF’s have more of a veil in the sound. I never really noticed it until I got the Audience. I love the LS50’s and will keep this one until it falls apart but for a little more dollars the Audience is a pretty special speaker that not many people are aware off.

The bass is clearly lacking with the Audience and you need to be careful about adding a sub because the sub must be fast to keep up (if interested discuss with Audience). I do not mind the missing bass because I use it during work hours in a small room and big bass would be distracting.

The Audience is also a bit more problematic in positioning and I had to move them 1 foot from the back wall to get the correct sound. The KEF could be placed about 6 inches closer to the back. In the future I will place the Audience on speaker stands and move them even further from the back wall (I will move soon). They are currently on isoaccustic stands on my office’s second uncluttered desk.

I am not a huge heavy metal rock fan but I find myself listening to lots of Iron Maiden, Judas Priest, Motorhead, etc.. through the Audience 1+1’s. This is some of the music of my youth but even back then I never listen that much to this type of music. It must be the speed of the speakers that is making this music so enjoyable. I listen to all types of music but the fast stuff is so addictive on the Audience.

BTW - I use the excellent PeachTree Nova 150 amp + DAC with the passive KEF LS50 in the bedroom. The office system cost me close to $9k and the bedroom one was $3k retail but I got it for $2500 used on A’gon. Now all I need to do is build out the big rig (with bass) for my living room.

Hi, I know this is an old thread from last year, but if you still get messages from Audiogon forums, I had a question or two for you in regards to your experiences with the  Audience 1+1's + AHB2's vs the KEF LS50 w/ Nova 150 amp.. If you'd be so kind as to help answer them for me, I'd greatly appreciate it:

1. Did you ever try the KEF LS50 w/ the AHB2's to compare apples to apples with the Audience 1+1's?  If so, how did the former fare?

2. Since the Nova 150 are like $1700 or so, and the AHB2's are nearly double the price, would you say there are diminished returns for the latter (i.e. they are not quite twice as good)?

I got a pair of LS50 (non-wirelss) for $900 and it seems the general rule is to spend the bulk of one's money on speakers and not amplification, so it seems that Nova 150 would be somewhat do-able but AHB2's would be significantly violating that "rule".

Thanks in advance for your reply.