KEF LS50 Bookshelf Speaker Review

[laudio]

The LS50s were probably the ultimate fanboy speaker on audio sites the last several years, they have a serious following. Just looking at them however you can tell (without any measurements at all) they aren't going to satisfy by themselves without a sub helping out. I like the measurements but at the end of the day the listening impressions are what matters.

 

[Blumlein 88]

This narrowly beats the JBL 305P in preference rating which matches my experience with the two speakers.

I have heard both and prefer the 305 until you add a sub to the 50. With a sub on both the ls50 is still a touch bright. A little eq with both and the LS50 is a step up in real sound quality vs the 305.

And yes the LS50 can use some power.

 

[JohnBooty]

So, I have these and a Rhythmic sub. And I am getting the minidsp balanced (waiting for it to arrive). Where should I put the crossover for the sub - in the 100-150 hz range based on the above?

Usually a tad above the -3dB point, which is around ~55hz for these. I'd experiment in the 60-80hz range.

No, you have to measure because your room heavily changes the response there. In general, it is best to set the crossover at 80 Hz so that the sub can't be located (by ear). Then measure and correct the overall response.

Nah, anything >60Hz would be fine, the -6dB point is ~45Hz, so accounting for compression and roll-off slope, >60Hz would be fine; though the best for your room would need experimenting.

I vote lower than 80hz whenever possible.

In my experience a 60hz crossover always sounds better than 80hz assuming one's main speakers can play strong at 60hz and from measurements it looks like that should work with the LS50.

It's true that 80hz isn't very localizable, but:

80hz crossover and 12 dB/octave slope means sound will only be down -10dB at 160hz, which is audible and localizable and now there may be extra bonus phase issues in that crucial region.

One can use a steeper crossover slope like 24dB/octave or even 48dB/octave (MiniDSP will allow this) but now the subwoofer(s) may not blend as smoothly with the mains.

The lower the crossover point, the more these problems disappear. Assuming we stay within the capabilities of your main speakers' bass output. That's why speakers with the ability to play some decent bass are always a good investment, even if one is planning on using a subwoofer.

 

[BYRTT]

So, I have these and a Rhythmic sub. And I am getting the minidsp balanced (waiting for it to arrive). Where should I put the crossover for the sub - in the 100-150 hz range based on the above?

On their own below two high shelves should bring them in area of M30 which amirm seems like at this link: https://www.audiosciencereview.com/...r-30-speaker-review.11108/page-15#post-315521

 

[TimW]

I have heard both and prefer the 305 until you add a sub to the 50. With a sub on both the ls50 is still a touch bright. A little eq with both and the LS50 is a step up in real sound quality vs the 305.

This is exactly what I do with my pair of LS50s. When I auditioned them I kept in mind I would be using subs. Playing with toe in I found they sounded best pointed almost straight forward. Then I played with EQ based on measurements to fix that brightness in the 2-5 KHz region. It probably helps to have a high power amplifier too.

 

[laudio]

Whatever happened to 2 good speakers that don't need EQ and don't need a sub?

 

[TimW]

Whatever happened to 2 good speakers that don't need EQ and don't need a sub?

They exist. Usually cost more then monitors that require subs to have good bass extension.

 

[mitchco]

80 Hz maybe, but the dang LS50's can't even make it there, lol - see post 58.

Pro tip, use a room modelling tool like https://amcoustics.com/tools/amroc and pick your mains to sub XO point between room modes. Your ears will thank me later

 

[Sancus]

Whatever happened to 2 good speakers that don't need EQ and don't need a sub?

I mean to genuinely get speakers that can play without a sub is either more expensive, or the speakers are huge and 80lb+ each, or both. If you're fine with something like a Revel F208, then sure, but many people aren't due to budget or room restrictions.

 

[laudio]

I mean to genuinely get speakers that can play without a sub is either more expensive, or the speakers are huge and 80lb+ each, or both. If you're fine with something like a Revel F208, then sure, but many people aren't due to budget or room restrictions.

Ummm.... there are bookshelves that get down into the low 40's without any help. Will need to wait out on the reviews here to find out.

 

[stereo coffee]

Whatever happened to 2 good speakers that don't need EQ and don't need a sub?

AR ceased production of the Classic AR range in 1974 ... might be the answer. The very smallest the AR7 has/ had useful output to 40hz
https://www.americanradiohistory.com/Archive-High-Fidelity/70s/High-Fidelity-1973-08.pdf#page=41

 

[laudio]

AR ceased production of the Classic AR range in 1974 ... might be the answer.

Ha ha. Could also get a 10 band equalizer then that does pretty much the same as DSP does now. Preparing for flames.

 

[Sancus]

Ummm.... there are bookshelves that get down into the low 40's without any help. Will need to wait out on the reviews here to find out.

I guess it depends on your standards then, "getting down to 40s" isn't good enough to me to count as playing without subs. Flat 40hz on up would be the bare minimum, and most bookshelves that claim to get down that low are doing it at -6 to -10db if you're lucky and believe the manufacturer.

 

[Tks]

Whatever happened to 2 good speakers that don't need EQ and don't need a sub?

Do these count?

 

[laudio]

I guess it depends on your standards then, "getting down to 40s" isn't good enough to me to count as playing without subs. Flat 40hz on up would be the bare minimum, and most bookshelves that claim to get down that low are doing it at -6 to -10db if you're lucky and believe the manufacturer.

Small room 40 is fine with proper speaker placement (very key point) for good music enjoyment. Have many speakers that get below 30 - just don't see the point in rating a speaker that can't get anywhere close without help unless you also review the sub.

 

[Sancus]

Small room 40 is fine with proper speaker placement (very key point) for good music enjoyment. Have many speakers that get below 30 - just don't see the point in rating a speaker that can't get anywhere close without help unless you also review the sub.

Well, I wouldn't really consider running without subs just because with room EQ, they substantially smooth out bass, so I consider "used with subs" to be the default if you're really trying to achieve the best sound with no compromises. This is a pretty common attitude, there's a million examples that show how much 2 and even 4 subs improve bass quality. You just can't achieve the same thing with full range speakers.

A lot of people feel the same way, which is why there are separate preference ratings including and excluding LFX. Of course, everyone's budget and room is different and if full range speakers are your thing, that's also fine, and those will be reviewed in the future as well, I'm sure. But it's obviously easier to buy, ship, and get small monitors on the measuring platform so they're getting measured first because they're the most practical.

E: Added link to March Audio's excellent post on multiple subs + DSP.

 

[Blumlein 88]

Small room 40 is fine with proper speaker placement (very key point) for good music enjoyment. Have many speakers that get below 30 - just don't see the point in rating a speaker that can't get anywhere close without help unless you also review the sub.

Well lots more people these days get stand mounts or monitors and use subs. So worth a review for sure. Since first hearing the LS50 I didn't consider it a complete speaker even as a monitor really. One could get relatively modest subs to handle 40-125 hz that it can't do and have a really good sounding speaker however.

These days with the DSP we have then using multiple subs can get better low ends than is likely with any size floor stander due to placement issues. I think even for an ambitious system floor standers are good if they make 40 hz. That lets them move plenty of air 80-200 hz, and have depth to crossover nicely down to 40 hz, with multi-subs handling the 25 or 30 to 80 hz range.

 

[laudio]

Well, I wouldn't really consider running without subs just because with room EQ, they substantially smooth out bass, so I consider "used with subs" to be the default if you're really trying to achieve the best sound with no compromises. This is a pretty common attitude, there's a million examples that show how much 2 and even 4 subs improve bass quality. You just can't achieve the same thing with full range speakers.

A lot of people feel the same way, which is why there are separate preference ratings including and excluding LFX. Of course, everyone's budget and room is different and if full range speakers are your thing, that's also fine, and those will be reviewed in the future as well, I'm sure. But it's obviously easier to buy, ship, and get small monitors on the measuring platform so they're getting measured first because they're the most practical.

No disagreements. I've eq'ed my HT with REW years back with subs with nice results too I'm not ignorant of how it's done, it's fun and also a PITA, you end up spending more time looking for the right curve than enjoying the sound. Not everyone has the patience or wants to be an acoustic DIY sound engineer. I see perfectly flat curves posted here who will tweak until it looks right.

All I am saying is give me 2 good bookshelves that are no fuss no muss and just... sound good flat. Some reviews around here are like "well... if you do this or that" then you have a great sounding speaker even though it costs $1k. Just tell me which one out of the box delivers as is. Think amir summed it up, the LS50 didn't. So on to more reviews, until we see on that does!

 

[DeeJay]

SoundStage/NRC did a linearity measurement (76dB to 96dB @1m anechoic):

I hope Amir will do proper linearity measurements in the future (eg. at 1W, 2W, 4W, 8W,...).

 

[Thomas_A]

Looks like a forward and hard sounding speaker. The Harbeth is Dr Jekyll and the LS50 is mr Hyde.