KEF/Coaxial 2 Ways vs 3 way point source qualities

[aarons915]

I wanted to bring something up that most people never talk about and that is the point source qualities of 2 way KEF speakers like the LS50 and then the 3 ways that are generally crossed over around 400-500Hz to the UniQ. The pros of the 3 ways are obvious, more extended bass and the ability to play louder with less distortion but what I've noticed when comparing them directly is the point source quality is a bit degraded, male vocals are the most obvious and it just sounds a bit disjointed to my ears and not coming from only 1 point. The easiest comparison is to A/B an LS50 or Q1/3 to a Q11 or R11 since they have multiple woofers flanking the UniQ driver. Do any other KEF people notice this? I really never see people talking about this.

I've had the LS50 then the R3 back to the LS50 and just recently tried the Q6 and noticed it with both 3 ways although the woofers flanking the UniQ seems to be a bit better. At this point it seems to me that the best of both worlds is just to use an LS50 and cross them over higher, since there are very few directional cues under 200Hz, I can go up to 150Hz on a 2nd order high pass and don't notice any localization. I just think it's maybe not the best idea to split vocals between multiple drivers if you're going for a point source design, or an alternative would be to use a beefier UniQ in the 3 ways, something closer to the LS50 UniQ driver and cross them over somewhere in the 150-200Hz range so that the woofers range has very little directional information. Anyway, just wondering people's thoughts on this.

 

[RobL]

I think this is one reason why Genelec places two woofers, one on top and bottom of the coaxial unit, in order to extend the “apparent point source” a little lower in frequency.

 

[Putter]

FWIW I replaced my LS50 Meta in the desktop system with modded d'Appolito design Pioneer SP-C22 speakers for the greater 'height' of the stereo image. The Meta's went into the home theater system downstairs. It looks like I want to look into the Genelec's if upgrading.

 

[Matt_Holland]

I haven’t done the comparison with their 2-ways, but I didn’t think either R5 or Q7 sounded disjointed at all. In fact they posses a quality very rare in any speaker in terms of imaging consistency and naturalness that makes listening very low fatigue (or requiring no concentration).

You may have a point though when undertaking critical comparisons. However I would counter that from an engineering perspective by proposing that by having the region below 400Hz emanating from separate drivers that are closer to the floor you reduce or even negate floor bounce cancellation which often affects stand-mounted 2-ways and reduces the natural body and warmth of male voices and certain instruments like cellos.

I would take a 3-way KEF over a 2-way all day long.

Edit to add: the floor bounce cancellation benefit assumes a floor standing model in most cases.

 

[Digital_Thor]

I would take a 3-way KEF over a 2-way all day long.

Absolutely.
A 3-way has always been my favorite too. When I heard the R3 in comparison with the LS50 - bingo - straight to the 3-way. A dedicated midrange makes so much sense in every way

 

[Heinrich]

I wanted to bring something up that most people never talk about …

Don‘t want to sound rude, only for brevity. You report is on a personal, subjective, sighted, somehow weak impression, that others don‘t talk about. More so, the effect you are insinuating would be way more prominent with less cautious designs, non-coaxial, but seemingly isn‘t observed. Not the least, the KEF are in some specimen symmetrical, but you don‘t differentiate. As a last point, what does it mean, ‚point source‘? There was a debate recently, that at least told me, coax wasn‘t worth it, but point source is (whatever that means).

sorry, what I mean is, the KEFs are pretty much o/k. I‘ve got my own extended experience, I‘m still flashed by the performance. Don‘t doubt your stereo too much, see my signature. Enjoy!

 

[jonfitch]

Isn't the polar maps nearly omnidirectional up to 500hz? I would think it would be really hard to tell where the woofer is coming from. I suppose they could try pushing the x-over even lower if they thought it was worth it, like the Elac Adante. But I never felt like the Adante imaged necessarily any better than the Kef R3 personally, or felt any more coherent.

 

[aarons915]

Don‘t want to sound rude, only for brevity. You report is on a personal, subjective, sighted, somehow weak impression, that others don‘t talk about. More so, the effect you are insinuating would be way more prominent with less cautious designs, non-coaxial, but seemingly isn‘t observed. Not the least, the KEF are in some specimen symmetrical, but you don‘t differentiate. As a last point, what does it mean, ‚point source‘? There was a debate recently, that at least told me, coax wasn‘t worth it, but point source is (whatever that means).

sorry, what I mean is, the KEFs are pretty much o/k. I‘ve got my own extended experience, I‘m still flashed by the performance. Don‘t doubt your stereo too much, see my signature. Enjoy!

No offense taken but I've noticed this when comparing speakers blind also and note that it's not something you really notice unless you're directly comparing 2 speakers, I had my R3 for a year and didn't have any complaints until I bought the Neumann KH120 to compare. Oddly those are non coax and a typical 2 way and it was really surprising to my ears they pulled off the point source sound better, my theory is since nearly all of the fundamental frequencies and vocals are coming from the midwoofer in that design that the highs coming from the tweeter don't really take away from the effect much. Point source simply means the sound emanates from one point like in a Coax or full range driver.

Isn't the polar maps nearly omnidirectional up to 500hz? I would think it would be really hard to tell where the woofer is coming from. I suppose they could try pushing the x-over even lower if they thought it was worth it, like the Elac Adante. But I never felt like the Adante imaged necessarily any better than the Kef R3 personally, or felt any more coherent.

Yes I'm not implying any flaws in the design, they are very well integrated. The non meta reference series did appear to have a lower crossover point to the woofer and they were much better in this regard when I listened to them, I only notice this with the 3 ways crossed around 500Hz. I don't think imaging would be affected, it's more of a psychoacoustics issue of what sounds the most natural, and with vocals at least, it seems we would want them to come entirely from one source. I know most people don't seem bothered by it but if it wasn't a beneficial design goal I can't imagine why they would go through the trouble of designing the woofer system to create the "apparent point source" in the Blades.

 

[aarons915]

Absolutely.
A 3-way has always been my favorite too. When I heard the R3 in comparison with the LS50 - bingo - straight to the 3-way. A dedicated midrange makes so much sense in every way

The main thing that bothers me about the LS50 is the fact that they have higher distortion in the bass and cone movement causes IMD distortion, the 3 ways obviously don't have that problem and can handle an 80Hz crossover with no problem. With the LS50 I have to go higher in the 120-150Hz range but overall this is preferable to me since you retain the point source down to the bass frequencies that aren't localizable.

 

[phoenixdogfan]

The main thing that bothers me about the LS50 is the fact that they have higher distortion in the bass and cone movement causes IMD distortion, the 3 ways obviously don't have that problem and can handle an 80Hz crossover with no problem. With the LS50 I have to go higher in the 120-150Hz range but overall this is preferable to me since you retain the point source down to the bass frequencies that aren't localizable.

If you have REW and a Umik-1. it might be nice for you to take a measurement of how the LS 50's + sub crossed over at 150 HZ look, particularly with regard to distortion at 85 and 96 db. Don;t think anyone has ever done that measure on that particular set up here.

 

[Heinrich]

No offense taken ...

Thanks!

... I bought the Neumann KH120 to compare. ... Point source simply means the sound emanates from one point like in a Coax or full range driver.

That's really odd, but the vast number of additional parameters in the description of a speaker comes to the rescue. A full range, as an extreme example, will always show chaotic directivity, very high distorsion and what not. The comparison is never fair to the point you point to. Namely an x/over somewhere else, the third way. When it comes to 'point source' the common terminology is a bit sloppy, to say the least. And it is not on focus with the x/over either.

Yes I'm not implying any flaws in the design, they are very well integrated. The non meta reference series did appear to have a lower crossover point to the woofer and they were much better in this regard when I listened to them, I only notice this with the 3 ways crossed around 500Hz. I don't think imaging would be affected, it's more of a psychoacoustics issue of what sounds the most natural, ...

Hope you allow me another time to put it quite directly, with no offense intended. You simply cannot 'compare blindfolded' an LS50 with an R3, because due to very obvious limitations of the former you always know what you are listening to, and then impose 'the problem' on the latter.

When I had the LS50 (plain) I was shocked how bad it was bordering unusable. Not playing loud or so it was still a major disapointment. I didn't even bother to add a sub which only would have needed to just switch the amp on, go figure! I measured it, no defect, but back to sender immediately. Comparison: big DIY, cinema style stuff.

If there's a valid theory on how bad it is to have three-way, the LS50 should decidedly not be the corner stone in it.

 

[aarons915]

Thanks!

That's really odd, but the vast number of additional parameters in the description of a speaker comes to the rescue. A full range, as an extreme example, will always show chaotic directivity, very high distorsion and what not. The comparison is never fair to the point you point to. Namely an x/over somewhere else, the third way. When it comes to 'point source' the common terminology is a bit sloppy, to say the least. And it is not on focus with the x/over either.


Hope you allow me another time to put it quite directly, with no offense intended. You simply cannot 'compare blindfolded' an LS50 with an R3, because due to very obvious limitations of the former you always know what you are listening to, and then impose 'the problem' on the latter.

When I had the LS50 (plain) I was shocked how bad it was bordering unusable. Not playing loud or so it was still a major disapointment. I didn't even bother to add a sub which only would have needed to just switch the amp on, go figure! I measured it, no defect, but back to sender immediately. Comparison: big DIY, cinema style stuff.

If there's a valid theory on how bad it is to have three-way, the LS50 should decidedly not be the corner stone in it.

I'm not really sure what point you're trying to make about point source but it quite literally means the sound is coming from 1 point, something like a line source has audio coming from a line array, the naming convention isn't some trick.

You can compare any speakers, of course you don't want to play beyond the limits of the smaller speaker but the LS50 plays plenty loud for a comparison, there's a reason why you level match speakers and I also high pass so bass differences aren't as pronounced. It sounds like you care more about SPL than sound quality which is fine but the LS50 can play loud enough to do permanent hearing damage, not sure who would need to go louder than that... I'm not really sure what you're arguing but the original post is simply about point source characteristics, not really what speakers you like or dislike...

 

[Heinrich]

I'm not really sure what point you're trying to make about point source but it quite literally means the sound is coming from 1 point, something like a line source has audio coming from a line array, the naming convention isn't some trick.

You can compare any speakers, of course you don't want to play beyond the limits of the smaller speaker but the LS50 plays plenty loud for a comparison, there's a reason why you level match speakers and I also high pass so bass differences aren't as pronounced. It sounds like you care more about SPL than sound quality which is fine but the LS50 can play loud enough to do permanent hearing damage, not sure who would need to go louder than that... I'm not really sure what you're arguing but the original post is simply about point source characteristics, not really what speakers you like or dislike...

‘Point source’ has a specific meaning in serious literature. It has been lost in hifi jargon. The term is used, not to its advantage, in all kinds of twisted ways. The avoidance of lobing, the real purpose of ‘point source’, was recently labelled completely irrelevant on this board in a specific thread. Nothing to worry about, just the usual craziness.

You write that the center-center distance of around 17cm between the drivers is relevant for an R3 to produce an audible effect. There is no theory as to how this might come about, unless the statement ‘it is not a point source’ is now to be regarded as a theory.

I am not going to argue against this by presenting rough calculations or even making a simulation. I just doubt that the hearing (sorry: listening!) test has any relevance. The supposed effect was not isolated from the other differences between the loudspeaker models. I suspect that the effect is simply an unquestionable preference for the LS50 under given, unknown circumstances. All's well then!

 

[Goldhamster916]

I get what you mean and it also is a concern of mine. i have compared the reference 1 meta with the reference 3 metas and expected the reference 3 meta to subjectively have the image of the sound source to be more locked to the Uniq due to having woofers below and above. I was suprised that i couldnt really detect a difference in this regard. Howver it was a short listen and i will have a longer demo at the end of the month.

 

[Heinrich]

... compared the reference 1 meta with the reference 3 metas and expected the reference 3 meta to subjectively have the image of the sound source to be more locked to the Uniq due to having woofers below and above. I was suprised that i couldnt really detect ...

It is always a suprise when a sighted audition confirms the expectation. I never got around that strange phenomenon ;-)

 

[thewas]

It is always a suprise when a sighted audition confirms the expectation.

But in that case the opposite happened?

 

[Arindal]

The easiest comparison is to A/B an LS50 or Q1/3 to a Q11 or R11 since they have multiple woofers flanking the UniQ driver.

Woofers flanking the coaxial driver in some sort of d´Apollito arrangement, reproducing the bands below the UniQ´s frequency range, should in theory not be leading to vertical localization errors, as the phantom sum of the woofers´ localization is in fact the central axis where the coaxial resides. Other companies call this virtual coax. If your theory would be applicable, one should expect the speaker concepts with just three drivers, like the 3-way bookshelf designs, to show this flaw the most, not the floor standers.

I am anyways a bit reserved regarding clearly detectable localization error, as the frequency range in which the woofers are dominating, is pretty low, reducing the risk of vertical localization contradicting with the coaxial´s.

What might contribute to imaging effects is the differences in directivity. Rather compact 2-way coaxials tend to have a pretty broad radiation pattern below 500Hz, so the narrowing down in directivity towards higher frequencies becomes more audible, but is on the other hand pretty uniformly distributed over different frequencies and angles. With a 3-way design and fairly high x-over freq between woofer and midrange (and everything like 300Hz or more is high), you can expect to have significant effects of interference, lobing or cancellation under vertical angles in the transitional band.

There are indications that our brain can perceive this as the resulting room reflections, particularly ceiling and floor reflections, as they also reflect these tonal issues.

I was suprised that i couldnt really detect a difference in this regard.

I would take that as a hint that the vertical localization issue might be close to negligible.

If the ceiling/floor reflections make a difference or not, is also a matter of the room and listening distance.

 

[thewas]

The curved baffle and not separated woofer of the LS50 offers an advantage in radiation continuity which the flat surfaced R series tries to compensate with the shadow flare but still doesn't fully reach, this can be seen by comparing the early and full directivity indexes of the LS50 Meta (continuous lines): vs R3 Meta (dashed lines):

 

[Arindal]

this can be seen by comparing the early and full directivity indexes of the LS50 Meta (continuous lines): vs R3 Meta (dashed lines)

The inconsistency in radiation angle, particularly steeply, continuously increasing directivity index between 1.5K and 5K, is much more pronounced with the LS50Meta. It will most likely influence the tonal balance of the reverb to midrange-heavy as well as imaging/perceived proximity in almost any room, as it is lacking a lot of off-axis energy in the 3-5K band and above that compared to lower bands.

A 2-way conventional coaxial driver is always a compromise. You need sufficient diaphragm area and excursion to produce bass, but you do not want midwoofer diaphragm displacement to negatively influence treble dispersion.

In a 3-way floorstander, apart from keeping midrange excursion low and midrange diaphragm smaller/flatter, the baffle and woofer<>midrange transition can partly be used to compensate for the problems just described, resulting in a somewhat higher directivity index in the 400-800Hz band (which is fundamental for reverb tonality) and 1-2K (which prevents proximity and reverb localization errors when sufficiently attenuated). It is not perfect in this example, though, as everything above 3K is still underrepresented off-axis with a significant step up in directivity index.

 

[thewas]

The inconsistency in radiation angle, particularly steeply, continuously increasing directivity index between 1.5K and 5K, is much more pronounced with the LS50Meta. It will most likely influence the tonal balance of the reverb to midrange-heavy as well as imaging/perceived proximity in almost any room, as it is lacking a lot of off-axis energy in the 3-5K band and above that compared to lower bands.

I don't agree there as its more continuous than the R3 in that region and better than most conventional similar sized ones.

A 2-way conventional coaxial driver is always a compromise. You need sufficient diaphragm area and excursion to produce bass, but you do not want midwoofer diaphragm displacement to negatively influence treble dispersion.

I agree there, for mid to higher listening levels or distances you definitely need a subwoofer, in this case I personally prefer it to the R3 and there are few others who have had similar experiences.