KEF LS50 thoughts

[ematthews]

Have you tried swapping rooms between the Sierra's and the RBH's?
It'd be interesting to see if that would address any of your complaints.

I have. These are two completely different sounding speakers. I am only using the RBH in my HT set up since they didn't do music so well. Bass is much better on the RBH, but a little muddy. They would be perfect with a RAAL ribbon and tighten up the bass a little.

 

[TheWarrior]

Are you having fun putting words in my mouth? I said that compared to the LS50, the R100's on axis response was smoother around the XO point, and consequently, there is no large peak off axis in that range as seen with the LS50.



I don't know what you're looking at, but I see nothing on the R100's 0-30 degree charts suggesting a significant problem with resonance.

View attachment 23506

My apologies, I see where I took your words out of context.

What I am looking at with the R100 is at 1.5 and 2.2 kHz, where the off axis measurements are blurring together - while I don't have Floyd here to say that is a resonance too, it is safe to say that also will cause coloration of sounds.

 

[TheWarrior]

The issue I have right now. I am going to sell off a lot of what I own except the Ascends and look for a tower to rule them all and be done. RBH Sound are also in the mix since I own the SX-6300R and my only complaint was a little muddy on the low end and thought they needed a little more detail in the upper range. Well the new ones have addressed both. Lot's of options out there and I am going to be patient.

Well, I can definitely vouch for the bass of the Phil 3's. The highs of the ribbon are superb, and offer the most realistic reproduction of stringed instruments I have ever heard, including on beryllium, which is just barely ousted.

My only complaint of the ribbons is that I feel they audibly compress the sound of complex movie soundtracks, where beryllium really shines. My perception was that there was just too much being asked of the ribbon to reproduce, particularly for center channel duties.

 

[TheWarrior]

I have. These are two completely different sounding speakers. I am only using the RBH in my HT set up since they didn't do music so well. Bass is much better on the RBH, but a little muddy. They would be perfect with a RAAL ribbon and tighten up the bass a little.

Was the RBH bass muddy in both rooms? That could be a placement issue and might be worth experimenting with the distance to the wall behind them, if possible.

 

[Steve81]

My apologies, I see where I took your words out of context.

Thanks

What I am looking at with the R100 is at 1.5 and 2.2 kHz, where the off axis measurements are blurring together - while I don't have Floyd here to say that is a resonance too, it is safe to say that also will cause coloration of sounds.

I'd suspect diffraction effects rather than resonance. Given that the "fuzz" doesn't get particularly notable until about 60 degrees off axis, it's not something I'd consider a serious coloration in the grand scheme of things. That said, I've heard that some of the engineers at KEF consider the dedicated midrange/tweeter UniQ array to be a better than the midwoofer/tweeter arrays, and that looks like one potential reason why (Ref 1 as an example).

 

[shadyJ]

I honestly don't know how this conversation about the LS50s is still going. The LS50s have an overall superb measurement set. Anyone listening to them would have to be super picky to be bothered by any of the mild resonances that exist in the available measurements. Room Acoustics are much more likely going to be more damaging to the end response than the speaker itself. Yeah, its not as frequency response flat as the JBL M2 monitors, but how many speakers are? And even if they were, how many people have the acoustic environment to take full advantage of that kind of response? And even then, the slight imperfections it has are the kind that could be EQ'd, for those who are such perfectionists that they would have a problem with the LS50's native response. It's crazy that anyone would argue that the LS50s are anything less than an extremely well-designed speaker.

 

[shkumar4963]

It's an anechoic measurement - not an ink blot!

??

Sent from my SAMSUNG-SM-G930A using Tapatalk

 

[KEW]

I honestly don't know how this conversation about the LS50s is still going.

As someone who has bought and returned this speaker twice, this thread has been very educational and useful. While they are not my "perfect sound", I certainly recognize that they are well designed speakers and can understand why PENG and others swear by them.
However, earlier this morning I was thinking about what a great thread this is from the standpoint of assisting someone considering this speaker. Given the info here, if someone takes the time to read through it, they will have a great perspective from which to audition it in a showroom and if they bring it home, more readily determine if the aspects questioned here are an issue or not for their preferences.
It is also one of the better real world example/discussions on how to interpret measurements.
This thread is about the subtle hues of gray, not over-simplification to black or white.

 

[shkumar4963]

I'm not sure its a problem with directivity or resonance based on the whole set of NRC measurements.

Consider a cleaner view of the on axis FR from the distortion graph:
View attachment 23502
It seems to me the tweeter is clearly tipping things up between 2kHz and 5kHz relative to the mid/woofer level. It also seems to me that off axis, those relative proportions are maintained pretty well.
View attachment 23503
Drop the tweeter level 4dB or so, and all you'd really see is that off axis dip around 4kHz, and the rise afterwards as a result of the tangerine phase plug.

Distortion curve shows a peak at 4k while the directivity curves show a trough at 4k. Not sure why.

Sent from my SAMSUNG-SM-G930A using Tapatalk

 

[Beave]

It's an anechoic measurement - not an ink blot!

So is this a resonance as well?

 

[Beave]

Correct, this is not an ink blot. If the only rebuttal's at this point are to say, "well if you ignore the measurement" then this thread is truly finished.

You're good at misrepresenting what people write. I didn't say 'ignore the measurement.' I said ignore a small part of the measurement that may be a diffraction effect that makes the nearby peak appear to be something it isn't.

What's more, the point of my post was to get differing perspectives on the measurements. In that sense I think I succeeded.

 

[Beave]

I'm not sure its a problem with directivity or resonance based on the whole set of NRC measurements.

Consider a cleaner view of the on axis FR from the distortion graph:
View attachment 23502
It seems to me the tweeter is clearly tipping things up between 2kHz and 5kHz relative to the mid/woofer level. It also seems to me that off axis, those relative proportions are maintained pretty well.
View attachment 23503
Drop the tweeter level 4dB or so, and all you'd really see is that off axis dip around 4kHz, and the rise afterwards as a result of the tangerine phase plug.

You may very well be right. I know that medley's measurements of the raw drivers show that the tweeter output peaks right around 2kHz, with a sharp dropoff below that, and a broad hump for an octave or so above it.

 

[Beave]

Beave said it directly, and I felt you alluded to it in the sentence I quoted.

We've already confirmed that we have incomplete data to really narrow down the cause. So floating ideas on what could be done differently with incomplete data is really beating this thread into a pulp.

BTW the 'tangerine phase plug' is the tweeter which, given the very respectable high frequency extension, does seem to minimize propagation loss in the upper octave with it's waveguide.

As I stated earlier, given that this is a nearly symmetric coax design, we have enough data. There's no need for vertical data when it will mirror the horizontal data - unlike dome over cone speakers that will have large suckouts in the vertical plane due to driver interference near the crossover.

 

[Beave]

Smooth is usually described with a speaker's ability to maintain a +/-3dB variation across it's operating range. Neither of these speakers offer that.

They don't?

I see a low of about 81 or 82dB, and a high of about 86dB. That's a total variation of about 4-5dB, which means it easily fits in the +/3dB variation if you consider the mean to be about 83-84dB.

 

[TheWarrior]

So is this a resonance as well?

Possibly, but this is insufficient data. That call was made on the LS50 after seeing all of the Soundstage measurements.

You're good at misrepresenting what people write. I didn't say 'ignore the measurement.' I said ignore a small part of the measurement that may be a diffraction effect that makes the nearby peak appear to be something it isn't.

What's more, the point of my post was to get differing perspectives on the measurements. In that sense I think I succeeded.

Ignoring any part of the measurement to suit ones own purposes(bias) is misleading and wrong. You wanted to ignore the part of the measurement that I was claiming is a resonance.

But you also commented about Floyd verifying this on another forum. So no, I did not misinterpret you.

As I stated earlier, given that this is a nearly symmetric coax design, we have enough data. There's no need for vertical data when it will mirror the horizontal data - unlike dome over cone speakers that will have large suckouts in the vertical plane due to driver interference near the crossover.

A cone or dome or coax does not radiate equally in all directions. Combine that with floor and ceiling reflections that will influence the listener's impression, you absolutely need to know what the speaker sent out.

They don't?

I see a low of about 81 or 82dB, and a high of about 86dB. That's a total variation of about 4-5dB, which means it easily fits in the +/3dB variation if you consider the mean to be about 83-84dB.

I agree this one is smoother than the LS50, but I counted from below 80 hz.

 

[TheWarrior]

Thanks



I'd suspect diffraction effects rather than resonance. Given that the "fuzz" doesn't get particularly notable until about 60 degrees off axis, it's not something I'd consider a serious coloration in the grand scheme of things. That said, I've heard that some of the engineers at KEF consider the dedicated midrange/tweeter UniQ array to be a better than the midwoofer/tweeter arrays, and that looks like one potential reason why (Ref 1 as an example).

Any idea why these few particular KEF's have lower than average sensitivity? I don't ask to criticize, it just is a pattern I am noticing.

 

[Steve81]

Any idea why these few particular KEF's have lower than average sensitivity? I don't ask to criticize, it just is a pattern I am noticing.

WRT the LS50 and R100, mostly just the nature of the beast I suppose, i.e. compact speakers trying to offer some semblance of bass extension. For the LS50 driver itself (and presumably that in the R100), compared to something like the SEAS ER15 driver in the Salk SongTowers, the KEF midwoofer is short on Sd and high on Mms, which tends to work against high sensitivity. OTOH, the R100's rated sensitivity at SS is practically identical to that of the beefier Revel M106, so KEF doesn't need to feel too bad about it

 

[Beave]

Ignoring any part of the measurement to suit ones own purposes(bias) is misleading and wrong. You wanted to ignore the part of the measurement that I was claiming is a resonance.

No, I wanted to ignore the part of the measurement just above the part that you claim is a resonance, the part where it dips, not peaks. Doing so makes the peak look more like a consistent rise in treble/tweeter response, which is consistent with Steve's observations.

A cone or dome or coax does not radiate equally in all directions. Combine that with floor and ceiling reflections that will influence the listener's impression, you absolutely need to know what the speaker sent out.

A coax in a symmetric cabinet radiates the same vertically as horizontally. In this case I think the cabinet isn't quite symmetric, but it's close enough to say that the vertical responses will be very similar to the horizontal responses. So we have a very good idea what the vertical response is for this speaker. If there's any doubt, look at JA's vertical plots for frequency response differential. It's nearly identical to the equivalent angles for the horizontal response. There are no huge dropouts in the crossover region.

You can't say that at all about dome-over-cone speakers.

I agree this one is smoother than the LS50, but I counted from below 80 hz.

Huh? This was the plots for the LS50. It's flat within +/-3dB on axis, and at 15 and 30 degrees off axis. Its listening window is as well. Same goes for the R100.

Surely you're not saying speakers need to be within +/-3dB at 45, 60, and 75 degrees off axis?

Counting from below 80Hz, well, show me any speaker - especially a small monitor - that's flat within +/-3dB below 80Hz. You've moved the goalposts substantially.

 

[PENG]

I honestly don't know how this conversation about the LS50s is still going. The LS50s have an overall superb measurement set. Anyone listening to them would have to be super picky to be bothered by any of the mild resonances that exist in the available measurements. Room Acoustics are much more likely going to be more damaging to the end response than the speaker itself. Yeah, its not as frequency response flat as the JBL M2 monitors, but how many speakers are? And even if they were, how many people have the acoustic environment to take full advantage of that kind of response? And even then, the slight imperfections it has are the kind that could be EQ'd, for those who are such perfectionists that they would have a problem with the LS50's native response. It's crazy that anyone would argue that the LS50s are anything less than an extremely well-designed speaker.

Been waiting for you to show up, what took you so long? I doubt you can convince TheWarrior though.

 

[PENG]

about the subtle hues of gray, not over-simplification to black or white.

+∞