KEF LS50 disappointment :(

[shkumar4963]

THD+N @ 90dB, 50Hz - 10kHz (measured @ 2m)

Top curve: frequency response @ 90dB SPL

Bottom curve: THD+N @ 90dB (50Hz - 10kHz)

50 Hz: -10dB

100 Hz: -20dB

>200 Hz: -40 dB

Remember that these measurements ar about 90 dB at 2 meter. Not sure if LS50 were at the same loudness. But in any case the distortion at 50Hz seems to be worse

 

[Covenanter]

What Kef have done with the LS50s is cram a quart into a pint pot. When you do that there are compromises and it all comes down to whether you can live with the compromises or not. When I listened to them I first thought how brilliant they were but then little annoyances emerged and eventually I just thought they were tiring to listen to. (I only listened because the dealer suggested I should as they were his best selling speakers.)

To me they are a bit like fine Burgudy from a poor year. In a good year the wine maker has to do very little, there is so much fruit that getting the balance in the taste is easy. You open a bottle and can drink it right down to the end with pleasure. In a poor year a fine wine maker can create an impression of great wine, generally by increasing the alcohol content. The first glass is wonderful but by the end of the bottle it's getting very thin and disappointing (although you might be too drunk to notice

).

My problem with them is that I would always be listening to the speakers and not to the music. I think they are very clever but too artificial for my tastes. Tastes differ though ...

Chris

 

[lindsayt]

Just a polite question: how sensitive is the human ear to distortion at 50Hz?

Answer: almost totally insensitive.

http://www.axiomaudio.com/distortion

Let's be clear what that interesting test was measuring. It was measuring at what volume a sine wave produced by a third speaker could be heard when it was played at the same time as some compressed Phil Collins and Barenaked Ladies tracks.

That is not necessarily the same as playing a variety of music on different speakers such as Kef LS50's and Wilson Watt / Puppy 8's and deciding if we have a preference based on which sounds least distorted in the bass.

On the basis of that Axiom Audio test, I wouldn't conclude that the human ear is almost totally insensitive to distortion at 50hz.

 

[shkumar4963]

To be fair, nearly all reviews started by saying that these are great speakers for their size. But I wish they were more clearer. I wish they provided the measurements that show that while they are good for the size, they don't compare with larger size speakers if that is what they meant.

And then Stereophile magazine put them in Class A with limited bass category. This is the category for speakers that are perfect and can compare with any speaker at any price. I did not understand that.

Johan Coorg from Kef did mention in one of the magazine that R300 uniQ were better quality but did not say that R300 were better speakers than LS50.

Chis is right... it is like getting a better wine in a bad year.

 

[BigH]

Just a polite question: how sensitive is the human ear to distortion at 50Hz?

Answer: almost totally insensitive.

http://www.axiomaudio.com/distortion

I see what you mean. At 120 Hz iwe can detect -12 dB of distortion which is about 5.6% distortion. But at 1K we can detect -30 dB which is .1% of distortion. So at.4% that LS50 produces it is definitely detectable and may even be annoying.

May be that is what is observed when people say that at higher volumes, LS50 seems that it is straining. Now bettre amp can not remove this distortion as it is produced in the speaker and not in the amp.

It is clear that any distortion that amp produces is almost always much less than this and should not impact the sound quality at all.

Any thoughts? Are my calculations wrong?

Is not amp. distortion multiplied by the speakers?

 

[shkumar4963]

BigH: the distortion adds. So .4 percent of speaker will be added to .02 percent of many amps. But at low frequency the speaker distortion is much higer. So really amp distortion does not matter that much and I am not sure how people say they can hear it.

 

[matt49]

BigH: the distortion adds. So .4 percent of speaker will be added to .02 percent of many amps. But at low frequency the speaker distortion is much higer. So really amp distortion does not matter that much and I am not sure how people say they can hear it.

This assumes that an amp is running within its power envelope. I think what most people are hearing as distortion is the amp's clipping protection circuits, which can cause degradation of sound ranging from the subtle to the gross. And that's a kind of distortion, just not the e.g. 0.02% claimed by the manufacturer.

In other words, the distortion figures claimed by amp manufacturers are only one small (perhaps insignificant) source of real-world distortion. I do accept your point about the relative magnitude of claimed amp THD on the one hand and speaker distortion on the other. I'm just saying it's by no means the end of the story.

 

[BigH]

BigH: the distortion adds. So .4 percent of speaker will be added to .02 percent of many amps. But at low frequency the speaker distortion is much higer. So really amp distortion does not matter that much and I am not sure how people say they can hear it.

Not sure about that, I think most people don't realise they are hearing distortion, I remember the old amps that showed clipping. I think a lot of distortion comes from the crossovers in speakers.

 

[lindsayt]

It's a reasonable assumption to make that for most listeners, for most of the time, they are listening at levels well below the clipping point of their power amps.

However it is possible that many of us are listening to systems where the pre-amp section is overloaded by the source and is therefore clipping.

And THD+N is not the only type of distortion produced by amplifiers. It just happens to be one of the easier to measure ones (if you keep the output power levels above .01 watts) which is why you see it stated so often.

On the one hand: 2 wrongs don't make a right and you don't want amp distortion on top of speaker distortion.

On the other: at higher volumes, in the bass, any harmonic distortion from the amp will be swamped by distortion from the speakers.

 

[shkumar4963]

What Axiom paper measured was the a single frequency noise as it was not related to the music being played.

Some loudspeaker engineers feel that harmonic dustortion is even harder to detect and so can be totolerated at higher levels.

 

[shkumar4963]

We all know RMS power capacity, dynamic power capacity, frequency response, current capacity, output impedence and distortion are important measures.

What else is important in an amplifier. How can we tell an amplifier is of high quality based on hard engineering measurements.

I know that auditioning is needed to detect finer points of amplifier design. But here I am looking for things that can be objectively measured.

What can we measure in NAD and Parasound that is not available in Yamaha, Denon or Onkyo.

 

[iceman16]

BigH: the distortion adds. So .4 percent of speaker will be added to .02 percent of many amps. But at low frequency the speaker distortion is much higer. So really amp distortion does not matter that much and I am not sure how people say they can hear it.

[/quote

shkumar4963..

after all this bits n bobs which is absolutely nothing..can I ask you once..Do you like the LS50 or not?

 

[shkumar4963]

BigH: the distortion adds. So .4 percent of speaker will be added to .02 percent of many amps. But at low frequency the speaker distortion is much higer. So really amp distortion does not matter that much and I am not sure how people say they can hear it.

[/quote

shkumar4963..

after all this bits n bobs which is absolutely nothing..can I ask you once..Do you like the LS50 or not?

 

To tell you the truth LS50 are decent speakers. But I have not found them to be what stereophile raved about and what hifi also said they were.

In my quest to find out if these publications just outright lied to their customers I started learning about them. If you have something that can shed some light on this I will really appreciate.

It is possible that these speakers are just that good and I have not been able to get the best spund out of them. Or they are not that good but a hype has been created to push up sales which us neither wrong nor illegal. If I was head of marketing for KEF I would have done the same.

Through this I am learning a lot about speaker design and the compromises that have to be made to produce a small size speaker. Unfortunately I am also learning about hiding measurements and telling half truths.

 

[Frank Harvey]

*fool*

 

[CnoEvil]

*fool*

Don't you know that pontificating is much more important than actually listening!

 

[Vladimir]

This was my motivation for posting criticism in this thread. Not saying they are bad speakers, but that they are flawed equally as any other speaker of similar design and they do not imploy "revolutionary" engineering. It's all BBC, BBC, BBC, BBC, BBC... ad infinitum. The Far East loves the BBC story and apparently everyone else. It's all hype, meant to be from the day they sat in the board room and decided KEF deserves a piece of the BBC LS3/5A cake since they supplied the drivers to all iterations of the broadcasting van monitor. The LS50 is not a speaker that was made by an engineer and suddenly got all the hype accumulated because the people heard it and it was that good. Nope. It is a speaker born inside a marketing boardroom, not an engineering desk, just like everyone else.

If you want a speaker made by an engineer, a tinkerer, go to Richard Allen. If you want the BBC heritage that much, buy from Harbeth or an original from ebay. If you want something revolutionary, go to Vivid Audio, Cabasse, MBL etc. Every manufacturer has a forte. *wink*

 

[Vladimir]

Do I have to buy the golden calf so i can disenchant it?

 

[CnoEvil]

Do I have to buy the golden calf so i can disenchant it?

Apparently not.

 

[plastic penguin]

The Far East loves the BBC story and apparently everyone else.

Indeed that's true. From Southend-on-Sea up to Felixstowe are mad on the Beeb.

 

[BigH]

The Far East loves the BBC story and apparently everyone else.

Indeed that's true. From Southend-on-Sea up to Felixstowe are mad on the Beeb.

Hmmm, the far east is further north around Lowestoft, not sure they are mad on the Beeb there.

 

[Frank Harvey]

*fool*

Don't you know that pontificating is much more important than actually listening!

We should all bow down to Vladimir's superior intellect. He's telling it like it is, and all should listen, as he is the omnipotent one. Empires will crumble. Leaders will fall. Nothing will remain standing in his wake.

Then again, he could just be stating his opinion.

 

[Vladimir]

Just stating my opinion on a public forum. *unknw*

 

[Frank Harvey]

Just stating my opinion on a public forum. *unknw*

Then state "in my opinion", rather than presenting it as fact, unlike post #564.

 

[Vladimir]

Just stating my opinion on a public forum. *unknw*

Then state "in my opinion", rather than presenting it as fact, unlike post #564.

I trust everyone's intellectual capabilities here to discern opinion from stated facts.

 

[Frank Harvey]

I trust everyone's intellectual capabilities here to discern opinion from stated facts.

Oh yeah, the old switcheroony.

Not saying they are bad speakers, but that they are flawed equally as any other speaker of similar design and they do not imploy "revolutionary" engineering. It's all BBC, BBC, BBC, BBC, BBC... ad infinitum. The Far East loves the BBC story and apparently everyone else. It's all hype, meant to be from the day they sat in the board room and decided KEF deserves a piece of the BBC LS3/5A cake since they supplied the drivers to all iterations of the broadcasting van monitor. The LS50 is not a speaker that was made by an engineer and suddenly got all the hype accumulated because the people heard it and it was that good. Nope. It is a speaker born inside a marketing boardroom, not an engineering desk, just like everyone else.