KEF Blade Meta One

3 hours ago, Axiom05 said:

Placement of the woofers within the room is something that has always concerned me with the Blades. In a narrow room, where one side of the speaker could be quite near the side wall, I suspect there could be some issues. Unfortunately, there is no way to know w/o actually trying them in one's own room. I know low frequencies are omnidirectional, but I would imagine that some unpredictable "loading" wrt the side wall could occur. My Studio2's are only around 14" from the side wall which seems a bit close for the side firing woofers and could also result in some lower midrange coloration.

I think it possibly depends on the proximity of the acoustic centres of motion of the bass drivers wrt energizing modal resonances. 14" from sidewall is likely an issue in most rooms irrespective of where the driver faces

4 hours ago, Axiom05 said:

Placement of the woofers within the room is something that has always concerned me with the Blades. In a narrow room, where one side of the speaker could be quite near the side wall, I suspect there could be some issues. Unfortunately, there is no way to know w/o actually trying them in one's own room. I know low frequencies are omnidirectional, but I would imagine that some unpredictable "loading" wrt the side wall could occur. My Studio2's are only around 14" from the side wall which seems a bit close for the side firing woofers and could also result in some lower midrange coloration.

Yeah.  KEF recommends:

A- Rear of speaker to front wall:  225mm (9")!!!

B- Side of speaker to side wall:  1m (36")

W- Distance between speakers:  2-3m (6-10 feet)

D- Centerline distance to MLP:  1-1.2 x W

The most curious item is how small A is but that may be due to the controlled directivity.  I am planning to experiment with that as I now have them about 36" from the front wall.

The others are not remarkable although Floyd Toole told me that he expected problems with "B."  Turns out that it was not a problem for me perhaps because my entire setup is off center in the room resulting in different measures for "B" on each side.

59 minutes ago, Kal Rubinson said:

Yeah.  KEF recommends:

A- Rear of speaker to front wall:  225mm (9")!!!

B- Side of speaker to side wall:  1m (36")

W- Distance between speakers:  2-3m (6-10 feet)

D- Centerline distance to MLP:  1-1.2 x W

The most curious item is how small A is but that may be due to the controlled directivity.  I am planning to experiment with that as I now have them about 36" from the front wall.

At 9" the lower freq modal resonances in corners and along the front wall would be exacerbated irrespective of higher frequency directivity, no? Did KEF give any explanation of "A- Rear of speaker to front wall:  225mm (9")!!!" Are they expecting bass reinforcement from room modes?

1 hour ago, Kal Rubinson said:

Floyd Toole told me that he expected problems with "B." Side of speaker to side wall:  1m (36")

Did he give any explanation?

1 hour ago, Audiophile Neuroscience said:

2 hours ago, Kal Rubinson said:

Floyd Toole told me that he expected problems with "B." Side of speaker to side wall:  1m (36")

Did he give any explanation?

Not with the 36" but with the much smaller distance I was initially using.

14 hours ago, Audiophile Neuroscience said:

I wouldn't have anticipated the Blades (which I have auditioned) to be particularly difficult to setup due to "directivity" issues. or to lend themselves to certain 'sounding rooms'.

Setup and placement should not be that difficult if there are none of the aforementioned  substantial problems with woofers and resonances.

I suspect difficulties in combining them with different rooms and getting pretty opposite tonal results can be merely prescribed to the directivity pattern over frequency. It ranges from 0 or even (theoretically) negative directivity index while woofers are still active to something close to omnidirectional in the (lower) midrange due to curved and narrow baffle to steadily decreasing off-axis energy the moment tweeter with waveguide comes into the equation. 

Means if any of the aforementioned problems with tonality occur you cannot do much with placement

8 hours ago, Arindal said:

I suspect difficulties in combining them with different rooms and getting pretty opposite tonal results can be merely prescribed to the directivity pattern over frequency. It ranges from 0 or even (theoretically) negative directivity index while woofers are still active to something close to omnidirectional in the (lower) midrange due to curved and narrow baffle to steadily decreasing off-axis energy the moment tweeter with waveguide comes into the equation.

Have you got a particular reference to the measured results of the Blades and where this is identified as an issue?

@Kal Rubinson mentioned reasons for careful placement in relation to bass room modes (which makes sense) but didn't echo ( <--poor attempt at pun) your other concerns. Kal did mention in room measurements were done and input from IIRC JA and Toole.

I would really appreciate someone that went from the blade to the blade meta describing the audible differences.

When I went from the salon to the salon 2 the step up in resolution was obvious making the investment a pleasant experience. When a reviewer claims the blade meta shows sibilance on nasal recordings I get nervous. 

8 hours ago, Audiophile Neuroscience said:

Have you got a particular reference to the measured results of the Blades a

I recommend to check the polar directivity plot and in-room made be Erin's Audio corner:

https://www.erinsaudiocorner.com/loudspeakers/kef_blade2_meta/

In this case it is important to focus on the angles way off-axis as the sweet-spot is pretty broad, i.e. the 100-180deg range which has a great impact on the calculated reflections and total energy of indirect sound in the room.

8 hours ago, Audiophile Neuroscience said:

where this is identified as an issue?

Please see post above:

On 8/6/2023 at 3:24 PM, krass said:

but I found the Blade 2s a bit disappointing (flat, dull, ‘closed’ midrange)

That is exactly the phenomenon I tried to explain knowing that it will very much depend on the room if you get such a result or not.

14 hours ago, Audiophile Neuroscience said:

Kal did mention in room measurements were done and input from IIRC JA and Toole.

I did not mention JA in this context and my interaction with Floyd on this was casual (although I always appreciate their comments).

9 hours ago, Kal Rubinson said:

I did not mention JA in this context and my interaction with Floyd on this was casual (although I always appreciate their comments).

I was really just searching for further comment on the measurement profile of the Blades in relation to supposed difficulties matching them to certain rooms.

the https://www.erinsaudiocorner.com/loudspeakers/kef_blade2_meta/erinsaudiocorner review measurements were offered (not by you) to support this difficulty

The review concluded:

• Exceptional sound quality and objective measurements
• Incredible on-axis linearity and off-axis is top notch not just horizontally but vertically as well

There was no discussion or interpretation regarding directivity or dispersion patterns in relation to any special difficulties.

One thing I learned from JA over the years of reading his measurement and listening reviews was to be very careful interpreting any one speaker measurement to predict how it will sound .This includes polar dispersion plots and in room "balance" or voicing of that speaker. He did talk about difficulty predicting effects of discontinuous or uneven radiation patterns especially at crossover regions where driver size and wavelength size may not be optimal. Even more difficult when considering on axis vs off axis voicing of perceived in-room response.

I am not saying that the frequency balance contained in reflected sound is not important or that speakers will have a perfectly uniform on and off axis dispersion, smoothly increasing directivity with increasing frequency.

So what do you make of the dispersion plots for the Blades when matched to your room and listening experience? Are they well "voiced" to match most rooms or difficult?

OTOH do they measure extremely well and, as with any other well designed speaker, room interactions must be controlled and individually tailored?

I found this old measurement with Omnimic from one speaker on HF axis at 1m (not from listening position) and prior to the apartment renovations.  I cannot recall exactly where it was situated and I do not have the info on the averaging or smoothing in effect.   The trough in the 100-200Hz range is now corrected with DL.

If/when there is time and inclination, I would like to do more.

20 hours ago, Audiophile Neuroscience said:

One thing I learned from JA over the years of reading his measurement and listening reviews was to be very careful interpreting any one speaker measurement to predict how it will sound

That is absolutely matching my experience. Measurements are very useful to understand how a speaker works and give a good idea if it would be acoustically compatible with a given environment. The moment anyone would be trying to extrapolate how it will actually sound solely based on measurements, this will inevitably fail. In the real world the result is in most cases far from the prediction.

20 hours ago, Audiophile Neuroscience said:

He did talk about difficulty predicting effects of discontinuous or uneven radiation patterns especially at crossover regions where driver size and wavelength size may not be optimal.

That is accurate as well if it is about predicting sound characteristics. If you just want to know if a speaker is a match for the given room or which major flaws are to expected in case of a clear incompatibility, the directivity plot is very useful and pretty reliable. That is particularly true to the most common incompatibilities like overly broad dispersion (low directive index) either full range or in some frequency bands (typically lowest octave of a tweeter or a midrange) or continuously increasing directivity index i.e. dispersion pattern narrowing down towards higher frequencies.

The latter might work perfectly in some rooms, like those showing signs of overdamping in the bass and lowers mids or overly huge ´open spaces´ with almost no reflective side walls. In smaller rooms like a typical living room with reflective walls on the sides and decreasing RT60 towards higher frequency, you will almost certainly get a lower-midrage-heavy, dull and softened tonality resulting from the indirect sound. There is not much that can be done against it, particularly speaker positioning or DSP equalization cannot provide any solution.

4 hours ago, Arindal said:

 

That is absolutely matching my experience. Measurements are very useful to understand how a speaker works and give a good idea if it would be acoustically compatible with a given environment. The moment anyone would be trying to extrapolate how it will actually sound solely based on measurements, this will inevitably fail. In the real world the result is in most cases far from the prediction.

 

 

That is accurate as well if it is about predicting sound characteristics. If you just want to know if a speaker is a match for the given room or which major flaws are to expected in case of a clear incompatibility, the directivity plot is very useful and pretty reliable. That is particularly true to the most common incompatibilities like overly broad dispersion (low directive index) either full range or in some frequency bands (typically lowest octave of a tweeter or a midrange) or continuously increasing directivity index i.e. dispersion pattern narrowing down towards higher frequencies.

 

The latter might work perfectly in some rooms, like those showing signs of overdamping in the bass and lowers mids or overly huge ´open spaces´ with almost no reflective side walls. In smaller rooms like a typical living room with reflective walls on the sides and decreasing RT60 towards higher frequency, you will almost certainly get a lower-midrage-heavy, dull and softened tonality resulting from the indirect sound. There is not much that can be done against it, particularly speaker positioning or DSP equalization cannot provide any solution.

There are some concerns for me here, for example on one hand you say you cannot extrapolate from measurements how it will actually sound and will inevitably fail in the real world, but on the other hand it seems you can extrapolate from measurements how it will actually sound in real rooms in the real world. I am struggling a little with the compatibility of those statements. Sorry, if I have misunderstood.

I do (hopefully) understand a little bit about the reasoning behind dispersion patterns and interaction with room acoustics. That is a matter of science. I am still wary of looking at one measurement, like polar plot of dispersion/radiation and confidently predicting how it will sound in any given room or type of room. I am of course interested if there is an uneven and discontinuous pattern which might make the reflected sound voiced very differently to the direct sound.

Now, what about the speaker deemed to have great on axis as well as off axis response - lets call that (perhaps) a dispersion pattern wide in lower frequencies and smoothly "narrowing down towards higher frequencies.". I am not at all sure that is "best" but prima facie, I would say okay lets run with that, given wavelengths and driver sizes and practical limitations, laws of physics etc

I now have concerns about your conclusions that:

4 hours ago, Arindal said:

The latter might work perfectly in some rooms, like those showing signs of overdamping in the bass and lowers mids or overly huge ´open spaces´ with almost no reflective side walls. In smaller rooms like a typical living room with reflective walls on the sides and decreasing RT60 towards higher frequency, you will almost certainly get a lower-midrage-heavy, dull and softened tonality resulting from the indirect sound. There is not much that can be done against it, particularly speaker positioning or DSP equalization cannot provide any solution.

There are issues talking about RT60's in small spaces. lets move past that for now. Lets leave DSP out for now....

The characteristics of the speaker also aside for now, the room will need acoustic treatment for any speaker you put in it. You can measure the room but you already know (in some cases where the geometry is more predictable) where the room resonant modes are going to be. You know where the higher frequency first reflections will be. You treat accordingly and as much as needed (for me, by listening). You know where diffraction/diffusers might help. You know if you stuff the room full of a thousand pillows, it will suck up high frequencies etc etc. You know that placing the speaker in a corner will likely not be a good position and there will be other more suitable positions to try. same goes for listening position.

So now you take your speaker with a supposedly "great" measured on axis and off axis response which is predictable and you place it into your room. As said, you know where the room will likely need acoustic treatment. That treatment may be different for some speakers. Different but not difficult more or less. If the room is "showing signs of overdamping in the bass and lowers mids", fix the room. If you can't fix the room, and many cannot for obvious reasons, I predict it won't matter what speaker you place in it - you will hear the room to more or less extent. Enter the DSP discussion (but its not my thing)

5 hours ago, Audiophile Neuroscience said:

I am struggling a little with the compatibility of those statements.

Maybe I have not made myself clear and will try to explain.

The attempt to predict solely based on measurements whether a speaker will sound neutral, dull, bright, present, bass-heavy or alike, requiring equalization or not, how loud it will go, how will be its staging, localization and other factors, is impossible according to my experience. I might want to add that there is a certain correlation when it comes to the question how low the bass will reach to the lower cutoff frequency but this will also not allow a prediction what will happen with the bass in the room and how it will be perceived.

On the other hand measurements like the directivity plot allow a pretty good estimation whether a combination of a loudspeaker, room and desired loudspeaker placement will lead to acoustical mismatches which cannot be equalized later or not. This is particularly the case with expected dominating indirect sound at a given listener´s position or tonally imbalanced indirect sound (which we are discussing here as the KEF Blade is a textbook example of a speaker showing continously increasing directivity index towards higher frequencies). 

Please note that the latter is not a precise prediction how it will sound. It is just a strong hint that certain mismatches will most probably occur, which is particularly useful for making an informed choice as the resulting acoustical problems in most of cases cannot be cured by equalization, reasonable amount of room treatment and speaker placement within a reasonable range (true nearfield placement is an exception here as well as building a matching room from the scratch). 

5 hours ago, Audiophile Neuroscience said:

I am not at all sure that is "best" but prima facie, I would say okay lets run with that, given wavelengths and driver sizes and practical limitations, laws of physics etc

I know that this concept of continuously increasing directivity index is pretty popular and in some applications (like nearfield listening, midrange-overdamped rooms, open spaces with no reflective side or back walls in proximity or alike), it is proven to work without major flaws. 

That said, we should not forget that in many cases it will not work but lead to the dull tonality described by another poster. 

5 hours ago, Audiophile Neuroscience said:

The characteristics of the speaker also aside for now, the room will need acoustic treatment for any speaker you put in it.

Not necessarily. Depends on the speaker, the room and how things will be placed.

5 hours ago, Audiophile Neuroscience said:

You can measure the room but you already know (in some cases where the geometry is more predictable) where the room resonant modes are going to be.

Unfortunately such models are only reliable in rectangularly-shaped rooms with all 6 sides solid concrete/stone/brickwall behavior, no overly huge windows. That is not the norm anymore, as light and resonant walls are pretty popular nowadays, or always have been like in the US or Canada.

5 hours ago, Audiophile Neuroscience said:

If the room is "showing signs of overdamping in the bass and lowers mids", fix the room.

That would not be necessary as overdamping in bass and (lower) midrange is on purpose, like in a studio room, and the aforementioned increasing directivity index of the speaker will acoustically cure this "problem". 

In untreated living rooms this behavior is basically non-existent. In most cases you find a rather high amount of bass and lower midrange energy while having more or less well-damped treble which contributes to the described problem of a ´dull-sounding´ speaker due to its increasing DI towards higher frequencies. Please note that these two problems add up so I call it an incurable incompatibility.

5 hours ago, Audiophile Neuroscience said:

If you can't fix the room, and many cannot for obvious reasons, I predict it won't matter what speaker you place in it - you will hear the room to more or less extent.

This is absolutely not matching my experience. If you have an untreated room with usual acoustical problems, a speaker with low or very uneven directivity index over frequency will most likely highlight all the problems making listening to music on a certain level or reproduction quality impossible. The longer the distance between listener and speakers, the more. Nearfield listening might help in these cases.

If you, on the other hand, take a speaker which was designed as a higher DI and/or constant DI model for such rooms, you can avoid most of the problems originating from reflections as the directivity pattern is to a certain extent simply ´fading out the room´ or making a majority of the reflective walls ´acoustically invisible´ to the sound originating from the speaker, if that makes sense. Which dispersion pattern is best and how much room treatment job might be left to do in order to achieve perfection, is a matter of listening distance and how the room actually behaves in terms of early reflections.

Most of loudspeakers getting this constant directivity requirement right are limiting it to the midrange and treble. Some specialized models exist, though, with offer a directional bass as well, mostly dipoles and cardioids. There are also speakers which, in contrary, tend to emphasize bass resonances and most likely cause booming but you would not find any hint in the measurements.

I might want to add that sound reinforcement systems particularly in acoustically problematic environments work like this for a long time already. And there is also a long history of dedicated hi-fi speakers relying on a narrow directivity pattern such as electrostatic panel speaker, line arrays, broadband-horns, dipoles and many others. In the past these have been very popular but far from flawless but since we have DSP technology in active speakers it is astonishing what can be achieved.

6 hours ago, Audiophile Neuroscience said:

Enter the DSP discussion (but its not my thing)

I do not think this would be the right place to start such a discussion as the phenomena related to the particular series of KEF speakers are not those which you are capable of countering with digital equalization. You cannot equalize a frequency-dependant mismatch between direct and indirect sound and that is in my understanding the main reason why reports on the Blade´s sound characteristics are widely incompatible with each other.

43 minutes ago, Arindal said:

 

Maybe I have not made myself clear and will try to explain.

 

The attempt to predict solely based on measurements whether a speaker will sound neutral, dull, bright, present, bass-heavy or alike, requiring equalization or not, how loud it will go, how will be its staging, localization and other factors, is impossible according to my experience. I might want to add that there is a certain correlation when it comes to the question how low the bass will reach to the lower cutoff frequency but this will also not allow a prediction what will happen with the bass in the room and how it will be perceived.

 

On the other hand measurements like the directivity plot allow a pretty good estimation whether a combination of a loudspeaker, room and desired loudspeaker placement will lead to acoustical mismatches which cannot be equalized later or not. This is particularly the case with expected dominating indirect sound at a given listener´s position or tonally imbalanced indirect sound (which we are discussing here as the KEF Blade is a textbook example of a speaker showing continously increasing directivity index towards higher frequencies). 

 

Please note that the latter is not a precise prediction how it will sound. It is just a strong hint that certain mismatches will most probably occur, which is particularly useful for making an informed choice as the resulting acoustical problems in most of cases cannot be cured by equalization, reasonable amount of room treatment and speaker placement within a reasonable range (true nearfield placement is an exception here as well as building a matching room from the scratch). 

 

 

I know that this concept of continuously increasing directivity index is pretty popular and in some applications (like nearfield listening, midrange-overdamped rooms, open spaces with no reflective side or back walls in proximity or alike), it is proven to work without major flaws. 

 

That said, we should not forget that in many cases it will not work but lead to the dull tonality described by another poster. 

 

 

Not necessarily. Depends on the speaker, the room and how things will be placed.

 

 

Unfortunately such models are only reliable in rectangularly-shaped rooms with all 6 sides solid concrete/stone/brickwall behavior, no overly huge windows. That is not the norm anymore, as light and resonant walls are pretty popular nowadays, or always have been like in the US or Canada.

 

 

That would not be necessary as overdamping in bass and (lower) midrange is on purpose, like in a studio room, and the aforementioned increasing directivity index of the speaker will acoustically cure this "problem". 

 

In untreated living rooms this behavior is basically non-existent. In most cases you find a rather high amount of bass and lower midrange energy while having more or less well-damped treble which contributes to the described problem of a ´dull-sounding´ speaker due to its increasing DI towards higher frequencies. Please note that these two problems add up so I call it an incurable incompatibility.

 

 

This is absolutely not matching my experience. If you have an untreated room with usual acoustical problems, a speaker with low or very uneven directivity index over frequency will most likely highlight all the problems making listening to music on a certain level or reproduction quality impossible. The longer the distance between listener and speakers, the more. Nearfield listening might help in these cases.

 

If you, on the other hand, take a speaker which was designed as a higher DI and/or constant DI model for such rooms, you can avoid most of the problems originating from reflections as the directivity pattern is to a certain extent simply ´fading out the room´ or making a majority of the reflective walls ´acoustically invisible´ to the sound originating from the speaker, if that makes sense. Which dispersion pattern is best and how much room treatment job might be left to do in order to achieve perfection, is a matter of listening distance and how the room actually behaves in terms of early reflections.

 

Most of loudspeakers getting this constant directivity requirement right are limiting it to the midrange and treble. Some specialized models exist, though, with offer a directional bass as well, mostly dipoles and cardioids. There are also speakers which, in contrary, tend to emphasize bass resonances and most likely cause booming but you would not find any hint in the measurements.

 

I might want to add that sound reinforcement systems particularly in acoustically problematic environments work like this for a long time already. And there is also a long history of dedicated hi-fi speakers relying on a narrow directivity pattern such as electrostatic panel speaker, line arrays, broadband-horns, dipoles and many others. In the past these have been very popular but far from flawless but since we have DSP technology in active speakers it is astonishing what can be achieved.

 

 

I do not think this would be the right place to start such a discussion as the phenomena related to the particular series of KEF speakers are not those which you are capable of countering with digital equalization. You cannot equalize a frequency-dependant mismatch between direct and indirect sound and that is in my understanding the main reason why reports on the Blade´s sound characteristics are widely incompatible with each other.

May I ask do you have any references/articles/sources that deal with the specific issues you have raised that speakers matching the blades directivity plots are dull sounding in typical living rooms? I note you referenced erinsaudiocorner but that guy raved about the measurements, "Incredible on-axis linearity and off-axis is top notch not just horizontally but vertically as well" and he also raved about the sound quality. Kal also raved about the speakers in Stereophile and JA also gave high praise for the measurements for directivity, "The contour lines in this graph are commendably even up to 80° off-axis". A quick google search hit on ASR and even they seem impressed with the (reported) measurements and rave about the sound (possibly because the measurements are so good?).

3 hours ago, Audiophile Neuroscience said:

I note you referenced erinsaudiocorner but that guy raved about the measurements, "Incredible on-axis linearity and off-axis is top notch not just horizontally but vertically as well" and he also raved about the sound quality.

Take a look at his measurements, particularly the behavior far off-axis (100+ deg) and the calculated in-room frequency response (which is seemingly calculated with unrealistically small listening distance and should not be taken as a precise prediction how subjective tonality will be, but it is, as mentioned, giving a first hint if there are incompatibilities with room response and directivity). 

And yes the comments on the measurements are surprisingly not addressing this important aspect. Subjective sound quality assessment I would put aside as it is possible that they were made under conditions in which the aforementioned incompatibilities are not relevant. I have already explained why and under which conditions this is the case.

To be clear here: I do not mean to doubt the measurements which look plausible and just judging from the on-axis graph there is little to critize. But if you have listened to the speakers in different rooms under different conditions, you would know that the on-axis FR does not tell the whole story. 

I am absolutely not surprised by other people reporting the speakers in their environment sounding dull, distant, overly soft in the treble region, lacking presence and dynamics or anything alike. I tried to explain where such contradictive reports most probably result from. You can accept this explanation or not. 

On 9/22/2024 at 11:57 AM, Audiophile Neuroscience said:

 

May I ask do you have any references/articles/sources that deal with the specific issues you have raised that speakers matching the blades directivity plots are dull sounding in typical living rooms? I note you referenced erinsaudiocorner but that guy raved about the measurements, "Incredible on-axis linearity and off-axis is top notch not just horizontally but vertically as well" and he also raved about the sound quality. Kal also raved about the speakers in Stereophile and JA also gave high praise for the measurements for directivity, "The contour lines in this graph are commendably even up to 80° off-axis". A quick google search hit on ASR and even they seem impressed with the (reported) measurements and rave about the sound (possibly because the measurements are so good?).

Kef speakers have narrowing directivity which makes them sound comparatively (to typical speakers) dull because of the in-room treble roll-off. (objectively speaking)

The Blades are the exception, producing a relatively constant directivity above 300Hz.

KEF Reference 5, lateral response family at 50", normalized to response on tweeter axis

KEF Blade Two, lateral response family at 50", normalized to response on tweeter axis

KEF Reference 5, spatially averaged, 1/6-octave response in JA's listening room (red); and of KEF Blade Two (blue)

Stereophile - Kef Reference 5 measurements

Stereophile - Kef Blade 2 measurements

On 9/22/2024 at 4:00 PM, Arindal said:

 

Take a look at his measurements, particularly the behavior far off-axis (100+ deg) and the calculated in-room frequency response (which is seemingly calculated with unrealistically small listening distance and should not be taken as a precise prediction how subjective tonality will be, but it is, as mentioned, giving a first hint if there are incompatibilities with room response and directivity). 

 

And yes the comments on the measurements are surprisingly not addressing this important aspect. Subjective sound quality assessment I would put aside as it is possible that they were made under conditions in which the aforementioned incompatibilities are not relevant. I have already explained why and under which conditions this is the case.

 

To be clear here: I do not mean to doubt the measurements which look plausible and just judging from the on-axis graph there is little to critize. But if you have listened to the speakers in different rooms under different conditions, you would know that the on-axis FR does not tell the whole story. 

 

I am absolutely not surprised by other people reporting the speakers in their environment sounding dull, distant, overly soft in the treble region, lacking presence and dynamics or anything alike. I tried to explain where such contradictive reports most probably result from. You can accept this explanation or not. 

 

As you can see in the in-room response plot above the Blade 2 produces hardly any treble roll-off in the room. But the treble is effortless and there isn't the off axis flare in the presence region typical of many speakers.

I suspect that the Blade 2s sound dull to some people because of the sound (deviations) that they're used to hearing, and perhaps enjoy.

The Reference and R series do sound a bit dark/dull, perhaps more than that if people are used to bright-sounding speakers.

6 hours ago, semente said:

 

As you can see in the in-room response plot above the Blade 2 produces hardly any treble roll-off in the room. But the treble is effortless and there isn't the off axis flare in the presence region typical of many speakers.

I suspect that the Blade 2s sound dull to some people because of the sound (deviations) that they're used to hearing, and perhaps enjoy.

The Reference and R series do sound a bit dark/dull, perhaps more than that if people are used to bright-sounding speakers.

I think that KEF attempts to add nothing to the process is the reason so many find them dull. When I bought my R105/3's my buddies gave me grief because they all owned Klipsch and loved the boom and tizz. Personally I couldn't care what somebody spends their own money on, and I appreciate being afforded the same courtesy.

4 hours ago, steve59 said:

I think that KEF attempts to add nothing to the process is the reason so many find them dull.

Sounds like a contradiction to me as ´sounding dull´ is usually a result of something either added (boosted level or added indirect energy in the bass/midrange region) or selectively taken away (brilliance or treble energy). 

Music (reproduction) under technically neutral condition sounds surprisingly ´thin´ and presence/brillance-rich, subjectively lacking bass/midrange, to most of ears, may it be under free-field conditions or in neutrally overdamped rooms. Anyone who has ever listened to hi-fi loudspeakers outside of rooms or an open-air concert involving human voices might confirm this.

I am not doubting some people are used to treble- or brilliance-rich hi-fi sound resulting from their tweeter´s overly broad dispersion pattern compared to their midranges. But I fail to see the difference to a boost in bass and lower midrange leading to a dull and overly ´fat´ perception for people who are used to linear reproduction.

11 hours ago, semente said:

The Blades are the exception, producing a relatively constant directivity above 300Hz.

Cannot confirm this. The increase in directivity index towards higher frequencies is for sure not as significant and continuous as with the R5, but it is definitely there. You hardly see it in JA´s polar plot as this one is covering only a 90deg window. Look at what is happening at 100deg and more, particularly between 1K and 5K.

11 hours ago, semente said:

As you can see in the in-room response plot above the Blade 2 produces hardly any treble roll-off in the room.

I am not saying the treble roll-off is equally significant (and visible in an in-room frequency response graph) in every room as it seems to mostly originate from the speaker´s behavior far off-axis  - that was exactly my initial point. The more uneven the tonal balance of the RT60 in a given room and the early/discrete reflections are audible at the listening position, the higher the risk it will actually sound dull, boring, lacking transparency, details, dynamic and alike.

3 hours ago, Arindal said:

You hardly see it in JA´s polar plot as this one is covering only a 90deg window. Look at what is happening at 100deg

IIRC JA makes the point that beyond 90 deg the (his) measurement method is inherently unreliable for off axis FR, which is why he doesn't offer it. Perhaps something to do with the acoustic center of the driver not matching the center of mass...I would have to search for it....

Regarding treble roll off, if it does exist in the far off axis response in the upper treble region, in this region mostly the direct sound on axis response dominates room curves anyway, at least as measured by Toole. The tweeter is directional and treble indirect imperfections off axis maximally and easily absorbed.

On 9/19/2024 at 1:16 AM, Kal Rubinson said:

Yeah.  KEF recommends:

A- Rear of speaker to front wall:  225mm (9")!!!

B- Side of speaker to side wall:  1m (36")

W- Distance between speakers:  2-3m (6-10 feet)

D- Centerline distance to MLP:  1-1.2 x W

The most curious item is how small A is but that may be due to the controlled directivity.  I am planning to experiment with that as I now have them about 36" from the front wall.

The others are not remarkable although Floyd Toole told me that he expected problems with "B."  Turns out that it was not a problem for me perhaps because my entire setup is off center in the room resulting in different measures for "B" on each side.

I recall experimenting with the positioning of my Blades. (Original Blade) Measuring with REW it was clear that I had a modest "null" at about 120Hz. Moving the speakers nearer to the front wall seemed to have little influence on the overall frequency response, but it did fill this null a little.

So I thought to myself, OK - as an experiment, why not try going right back to the 225mm minimum specified by KEF? Yes, it did help with the null, according to the measurements at least, but some things started to sound a little odd, this I could not live with. It was not long before the speakers were moved much further into the room. So 225mm / 9" did not work for me in my room, what was interesting though is that I could move the Blades only a little further into the room, the "odd sound" disappeared and things started to sound pretty decent again. Obviously this is all very room dependant, but I think for some you could get reasonable results much closer to the front wall than you might expect.

3 hours ago, Audiophile Neuroscience said:

JA makes the point that beyond 90 deg the (his) measurement method is inherently unreliable for off axis FR, which is why he doesn't offer it.

Could be plausible for various reasons but does not change the fact that the angles behind the loudspeaker can make a significant difference.

3 hours ago, Audiophile Neuroscience said:

Regarding treble roll off, if it does exist in the far off axis response in the upper treble region, in this region mostly the direct sound on axis response dominates room curves anyway,

According to Erin´s isobaric plots you have the maximum of roll-off from 400 Hz (close to perfect 4pi radiator with almost no attenuation anywhere and directivity index close to 0 at this point) all the way to 7K where the plot is showing attenuation of approx,. -15dB at 90deg and almost nothing beyond that. 

That's actually the frequency range in which our ear is the most sensitive in general and the most capable of distinguishing between direct and indirect sound. If such a roll-off is audible at the listening possible solely in the indirect sound, you can be sure it leads to a coloration of the reverb and changing other aspects of reproduction as well.

3 hours ago, Audiophile Neuroscience said:

The tweeter is directional and treble indirect imperfections off axis maximally and easily absorbed.

The problem is not the tweeter which shows indeed a pretty controlled directivity thanks to the inner waveguide construction. The problem is the transition from on almost omnidirectional pattern in the midrange to high directivity index pattern within like 3 octaves. This is clearly audible in the indirect sound field and depending on the room´s properties could easily lead to dull impression.

52 minutes ago, Confused said:

The most curious item is how small A is but that may be due to the controlled directivity. 

That's a pretty confusing recommendation as positioning a speaker very close to the front wall is mainly a matter of bass boost and to which extent room resonances are excited. That is very much depending on the room and totally independent from the directivity pattern as the latter is anyways omnidirectional in this particularly frequency band.

For clarity, per the KEF manual, 9” / 275mm is the minimum distance, not a recommended distance.