KEF LS50 disappointment :(

[Freddy58]

We tend to do the majority of our testing on large amps that we know well. We do this so that we focus on maximising the speaker performance in an absolute sense. The danger of using a lower performance amp is that you start to tune the speaker to compensate for the character of the amp. We generally always will then do some final testing on typical partnering equipment to check there are no nasty suprises.

Kind regards, Jack.

Thanks Jack. What "typical parterning equipment" have you used to test LS50. I know that you may not want to reccomend an amplifier. So, I am just asking for names of amplifiers that you have used in the past that were OK with LS50. I am assuming that these typical partnering amplifiers are in the range of US$500 to US$1000. Any lower priced amp that sounded OK?

Yeah, and whilst we're at it, do cables make a difference? *biggrin*

 

[shkumar4963]

We tend to do the majority of our testing on large amps that we know well. We do this so that we focus on maximising the speaker performance in an absolute sense. The danger of using a lower performance amp is that you start to tune the speaker to compensate for the character of the amp. We generally always will then do some final testing on typical partnering equipment to check there are no nasty suprises.

Kind regards, Jack.

?

Thanks Jack.  What "typical parterning equipment" have you used to test LS50.   I know that you may not want to reccomend an amplifier.  So, I am just asking for names of amplifiers that you have used in the past that were OK with LS50.  I am assuming that these typical partnering amplifiers are in the range of US$500 to US$1000.  Any lower priced amp that sounded OK?

Yeah, and whilst we're at it, do cables make a difference? *biggrin*

Don't joke unless you are willing to take the time to understand and explain to people like me. Or at least share some technical articles that can explain the topic.

 

[chebby]

We tend to do the majority of our testing on large amps that we know well. We do this so that we focus on maximising the speaker performance in an absolute sense. The danger of using a lower performance amp is that you start to tune the speaker to compensate for the character of the amp. We generally always will then do some final testing on typical partnering equipment to check there are no nasty suprises.

Kind regards, Jack.

Thanks Jack. What "typical parterning equipment" have you used to test LS50. I know that you may not want to reccomend an amplifier. So, I am just asking for names of amplifiers that you have used in the past that were OK with LS50. I am assuming that these typical partnering amplifiers are in the range of US$500 to US$1000. Any lower priced amp that sounded OK?

You are asking him to walk through a minefield. If he started naming brands then that could be construed as 'recommendation' or 'endorsement'.

 

[Freddy58]

We tend to do the majority of our testing on large amps that we know well. We do this so that we focus on maximising the speaker performance in an absolute sense. The danger of using a lower performance amp is that you start to tune the speaker to compensate for the character of the amp. We generally always will then do some final testing on typical partnering equipment to check there are no nasty suprises.

Kind regards, Jack.

Thanks Jack. What "typical parterning equipment" have you used to test LS50. I know that you may not want to reccomend an amplifier. So, I am just asking for names of amplifiers that you have used in the past that were OK with LS50. I am assuming that these typical partnering amplifiers are in the range of US$500 to US$1000. Any lower priced amp that sounded OK?

You are asking him to walk through a minefield. If he started naming brands then that could be construed as 'recommendation' or 'endorsement'.

Exactly, hence my "joke"

 

[Vladimir]

Don't joke unless you are willing to take the time to understand and explain to people like me. Or at least share some technical articles that can explain the topic.

Nice reading material that saves us a lot of typing.

 

[Freddy58]

We tend to do the majority of our testing on large amps that we know well. We do this so that we focus on maximising the speaker performance in an absolute sense. The danger of using a lower performance amp is that you start to tune the speaker to compensate for the character of the amp. We generally always will then do some final testing on typical partnering equipment to check there are no nasty suprises.

Kind regards, Jack.

Thanks Jack. What "typical parterning equipment" have you used to test LS50. I know that you may not want to reccomend an amplifier. So, I am just asking for names of amplifiers that you have used in the past that were OK with LS50. I am assuming that these typical partnering amplifiers are in the range of US$500 to US$1000. Any lower priced amp that sounded OK?

You are asking him to walk through a minefield. If he started naming brands then that could be construed as 'recommendation' or 'endorsement'.

Exactly, hence my "joke"

Sorry I didn't read that until just now after you pointed it out.

I tend to click on "view n new' (where n = number of updates since lasted viewed) and start with the oldest 'new' updates. Frequently I don't even get to the last ones (like your joke).

I just clicked 'quote' on post #744 from yesterday and wrote my response then moved on to something else. I rarely read everything in a thread.

No worries Chebby, my comment wasn't aimed at you anyway

 

[chebby]

We tend to do the majority of our testing on large amps that we know well. We do this so that we focus on maximising the speaker performance in an absolute sense. The danger of using a lower performance amp is that you start to tune the speaker to compensate for the character of the amp. We generally always will then do some final testing on typical partnering equipment to check there are no nasty suprises.

Kind regards, Jack.

Thanks Jack. What "typical parterning equipment" have you used to test LS50. I know that you may not want to reccomend an amplifier. So, I am just asking for names of amplifiers that you have used in the past that were OK with LS50. I am assuming that these typical partnering amplifiers are in the range of US$500 to US$1000. Any lower priced amp that sounded OK?

You are asking him to walk through a minefield. If he started naming brands then that could be construed as 'recommendation' or 'endorsement'.

Exactly, hence my "joke"

Sorry I didn't read that until just now after you pointed it out.

I tend to click on "view n new' (where n = number of updates since last viewed) and start with the oldest 'new' updates. Frequently I don't even get to the last ones (like your joke).

I just clicked 'quote' on post #744 from yesterday and wrote my response then moved on to something else. I rarely read everything in a thread.

 

[Native_bon]

Don't joke unless you are willing to take the time to understand and explain to people like me. Or at least share some technical articles that can explain the topic.

Nice reading material that saves us a lot of typing.

Even though its true try getting people to believe it. Marketing & popularity of a product is what people believe more.

 

[shkumar4963]

I have read many Audio Critic issues. Too bad it had to close shop.

I have also read research from Audio Engineering Society as well as from Boston Acoustic Society (or is it Boston Audio Society? Any way the one that is headed by DRMORAN). They all say that it is impossible to tell any difference in ABX testing between two properly designed amplifiers as long as they are below clipping volume.

But then I also respect Jack's opinions and am open to learning new concepts and ideas. That is why I was most interested in getting Jack's thoughts on this. It has been some time since Audio Critic magazine stopped publishing and there may be new developments in amplifier technology that Jack may be aware of. Besides he tests speakers everyday and will be best to comment on what he hears when he pairs his LS50 with various amplifiers.

Jack: Is it true that you can not hear any difference in sound quality between two amplifiers as long as they are both below clipping? In your last answer you gave several reasins why a more expensive amplifier could sound better. I just assumed that you can actually hear the difference in sound quality.

(Please excuse my typos)

 

[shkumar4963]

I used to think that 0 db level in my amplifier is the level where clipping will start. So never played my LS50 Even close to that level.

Yesterday I read this from THX website.

"On every THX Certified AV Receiver the “0” on the volume dial represents THX Reference Level, a setting designed to mirror the exact volume level used by moviemakers and sound artists in the studio.
When you are watching a movie with the playback volume set to “0” on a THX Certified Receiver, you experience every sound element exactly like it was produced by the filmmaker—with the same fidelity, detail and clarity."

That means it is ok to play at 0 db level. Later in the article it also says that THX certified amplifiers have 20 db head room when played at 0 db volume. So no need to worry about clipping.

Does anyone know if LS50 will survive this 0 db THX reference volume.

May be Jack can comment on that as well... . Thanks Jack in advance.

 

[shkumar4963]

We tend to do the majority of our testing on large amps that we know well. We do this so that we focus on maximising the speaker performance in an absolute sense. The danger of using a lower performance amp is that you start to tune the speaker to compensate for the character of the amp. We generally always will then do some final testing on typical partnering equipment to check there are no nasty suprises.

Kind regards, Jack.

Thanks Jack.  What "typical parterning equipment" have you used to test LS50.   I know that you may not want to reccomend an amplifier.  So, I am just asking for names of amplifiers that you have used in the past that were OK with LS50.  I am assuming that these typical partnering amplifiers are in the range of US$500 to US$1000.  Any lower priced amp that sounded OK?

You are asking him to walk through a minefield.  If he started naming brands then that could be construed as 'recommendation' or 'endorsement'.

Exactly, hence my "joke"

Sorry I was slow...

On a serious note, do send material and technical articles that illustrate the concepts behind our understanding of audio and how different components affect it.

 

[Frank Harvey]

Does anyone know if LS50 will survive this 0 db THX reference volume.

Most good quality speakers should handle Reference Level as long as they have been set up properly (within the context of an AV system). As long as they're set to small and a suitable crossover point is chosen to ease the load on the mi/bass driver, they should be fine.

 

[Vladimir]

But then I also respect Jack's opinions and am open to learning new concepts and ideas. That is why I was most interested in getting Jack's thoughts on this.

+1

As well as I.

I posted the Audio Critic article to clear off cables from the discussion swiftly and mercilessly. *biggrin*

 

[hg]

Does anyone know if LS50 will survive this 0 db THX reference volume.

No. They are essentially desktop speakers and will provide THX referencel levels (85dB + 20dB headroom) at 1 m. They cannot provide this level at 3m in a room for which you would need larger speakers designed for this purpose.

 

[shkumar4963]

Does anyone know if LS50 will survive this 0 db THX reference volume.

No. They are essentially desktop speakers and will provide THX referencel levels (85dB + 20dB headroom) at 1 m. They cannot provide this level at 3m in a room for which you would need larger speakers designed for this purpose.

0 dB in my amplifier is probably a lot louder than 85dB. The sound at 2 meters from this amplifier at -25 dB with LS 50 is similar to a lawn mower operating at 1 ft and for a 6 ft. man about 6 ft from his ears.

So either the amplifier's 0dB is wrong or THX reference is louder than 85dB. What is the speaker sensitivity assumed for THX certification? THX certified amplifier is probably assuming that speaker sensitivity.

The point from David regarding use of 5 channels and subwoofer may have an effect. Though I am not sure how?

1. Subwoofer will take some load of the amplifier. Not sure if it will take any load off the speakers above 80 hz. frequency. I am not using a sub right now.

2. 3 additional speakers will take power from the amplifier transformer that also supplies power to the the two front channels. But assuming that the transformer has been designed correctly and with sufficient capacity, it should not have any impact on sound levels.

3. Use of THX encoded signal may adjust preamp output thus making 0dB sound much softer than the signal from CD without THX. I will check if volume levels at 0dB goes down with THX encoded DVD.

4. It is also possble that the Yanaha AVR is not properly caliberated and does not show THX reference volume at 0dB. There may also be a option somewhere in the amp that has not been set correctly. I do see that increasing the volume past 0dB (without any input signal) does not show any positive dB numbers. If it was a THX reference level, should I not be able to increase the volume beyond reference volume level?

Does anyone know what does 0dB in an AVR volume truly mean?

 

[BigH]

Does anyone know if LS50 will survive this 0 db THX reference volume.

No. They are essentially desktop speakers and will provide THX referencel levels (85dB + 20dB headroom) at 1 m. They cannot provide this level at 3m in a room for which you would need larger speakers designed for this purpose.

Why do you say they are desktop speakers?

 

[BigH]

I have read many Audio Critic issues. Too bad it had to close shop.

I have also read research from Audio Engineering Society as well as from Boston Acoustic Society (or is it Boston Audio Society? Any way the one that is headed by DRMORAN). They all say that it is impossible to tell any difference in ABX testing between two properly designed amplifiers as long as they are below clipping volume.

But then I also respect Jack's opinions and am open to learning new concepts and ideas. That is why I was most interested in getting Jack's thoughts on this. It has been some time since Audio Critic magazine stopped publishing and there may be new developments in amplifier technology that Jack may be aware of. Besides he tests speakers everyday and will be best to comment on what he hears when he pairs his LS50 with various amplifiers.

Jack: Is it true that you can not hear any difference in sound quality between two amplifiers as long as they are both below clipping? In your last answer you gave several reasins why a more expensive amplifier could sound better. I just assumed that you can actually hear the difference in sound quality.

(Please excuse my typos)

I guess the key words are properly designed amps? Also don't manufacturers tweek the sound so they sound different? Also are you saying class A sounds the same as class D?

More reading: http://en.wikipedia.org/wiki/Bob_Carver

Can be made to sound the same using distortion pots, so they don't all sound the same?

 

[Vladimir]

An amplifier has no way of knowing how much actual real dB of SPL the speakers are producing at 1m for its setting of 0dB.

0dB in an amplifier means the variable resistor (potentiometer, aka volume pot) has the signal coming from the preamp fully untapped on its way to the power amp section. When you start turning the volume pot from fully on and backwards, you start reducing the amplification by -XdB (by increasing resistance). When you reach at the lowest setting, there is no signal passing from the preamp to the poweramp and consequently to the speakers.

Source » Preamp » Volume pot » Power amp » Speakers

Passive attenuation that you find in almost every amplifier on the market is like a valve. Just like your faucet in the kitchen, the default setting for your amplifier attenuation is at fully shut.

 

[hg]

So either the amplifier's 0dB is wrong or THX reference is louder than 85dB. What is the speaker sensitivity assumed for THX certification? THX certified amplifier is probably assuming that speaker sensitivity.

The reference level of 85dB average and 105dB peak is at the listening position. This is why the LS50 can produce standard cinema levels at a 1m listening distance when used as desk speaker but not when used as main speakers in a room. Even at 1m the LS50 is unlikely to produce a low distortion 105dB below 200 Hz or so at a guess.

To set 0dB on the receiver you would use a microphone and/or sound level meter and to play whatever signal the THX standard specifies as the signal for calibration. You would need to look up the details. The sensitivity of the speakers will not matter directly but the combination of amplifer, speakers and room will need to be able to reach 105dB at the listening position/s.

 

[Frank Harvey]

No. They are essentially desktop speakers...

Desktop speakers? Standmount or bookshelf speakers, I believe the description would be. Desktop speakers are the type designed for PCs and laptops.

 

[hg]

Why do you say they are desktop speakers?

Because they are sized to be used at a 1m listening distance. They are unable to play loudly enough cleanly to function as main speakers.

 

[Frank Harvey]

The point from David regarding use of 5 channels and subwoofer may have an effect. Though I am not sure how?

Yes, the subwoofer eases the load on the amplifier. Quite significantly in some cases. It will also ease the load on the speakers in many ways. Firstly, it will remove the need for the speaker to have to reproduce large excursion frequencies, which allows them to play louder. Secondly, the lower the excursion of the mid/bass driver, the less distortion that driver will be producing. And thirdly, it will allow the frequencies that it is producing to be reproduced more accurately.

The crossover point needn't be 80hz - it could be 100Hz, 150Hz, even 200Hz or even more depending on the subwoofers used.

 

[Frank Harvey]

Because they are sized to be used at a 1m listening distance.

That would be one useless pair of speakers.

 

[BigH]

Why do you say they are desktop speakers?

Because they are sized to be used at a 1m listening distance. They are unable to play loudly enough cleanly to function as main speakers.

That sounds like rubbish to me, how do you know the distant is anyway? So at 200W they would not be loud enough at 2m? In a 10m x 5m room at 5m distance I may agree but it also depends on the amp.? My speakers are about that size and at 2.5m listening distance in a larger than average UK room they can be far too loud if I turn the volume up.

those measurements 85db are at 1w, I think most amps can go louder than that. Most speakers are between 85-90 so in your view most speakers are desktop?

 

[hg]

That sounds like rubbish to me, how do you know the distant is anyway?

The reference level requires an average level of 85dB with peaks of 105dB. This is the level in a cinema, around the level for long term monitoring in a studio and around the level an enthusiast would listen to music in the home. The average level is rarely a problem but handling the peaks cleanly can be a problem if the speakers are inadequately sized.

On the KEF spec sheet the maximum SPL is given as 106dB but without specifying the conditions which is perhaps wise because they will almost certainly not produce this SPL cleanly in the low frequency range. Alternatively one could look at the sensitivity of 85dB and the maximum power of 100W to get a maximum SPL around 105dB.

So at 200W they would not be loud enough at 2m?

The LS50s cannot take 200W. The SPL falls by 6dB with a doubling of distance (some caveats) and so at 2m the LS50 would need to accept 400W but the real problem would be the very large linear deflection of the cones.

In a 10m x 5m room at 5m distance I may agree but it also depends on the amp.? My speakers are about that size and at 2.5m listening distance in a larger than average UK room they can be far too loud if I turn the volume up.

A speaker that is starting to distort the peaks in the music will usually be perceived as louder than one that is handling the peaks cleanly. Might this be what is happening with your speakers? The average level is not the problem, the problem is handling the peaks cleanly.

those measurements 85db are at 1w, I think most amps can go louder than that. Most speakers are between 85-90 so in your view most speakers are desktop?

It is not the senstivity but the size of the low frequency driver that primarily determines the SPL capabilities of a speaker. The LS50 has an effective surface area approaching that of a 4" driver due to the lost area to the tweeter and to make matters worse the cone cannot deflect too much without the movement knackering the output from the tweeter.