KEF LS50 disappointment :(

[shkumar4963]

Don't forget that not all music has much going on under 50Hz - 70s rock for example, may sound clean and clear (sometimes) but bass is usually pretty scarce in general. A track like No Doubt's Hella Good shows what sort of kick ass bass the LS50s do have, and if you want notes you just won't be able to hear, try Modeselektor's Evil Twin. For sub 50Hz, there's a fair amount of electronica out there that will fit the bill to allow you to test with/without a sub. I hear various tracks where there's little bass where I know there should be a nice deep note, but there's no way on earth a speaker the size of an LS50 is going to be able to reproduce it.

I hear you and agree that many tracks don't have much below 50 hz. What I was surprised about was that with tracks that do have good bass, i did not hear that much difference between with sub and without. Remember, that using REW, I could see that with a sub, I had better covergae below 50 hz than without but just could not hear that difference in sound quality. See the REW plots here. <img> http://imgur.com/x53Kit9 In these plots, xover was 90hz and LS50s was not getting the low freq. when Sub was active.

It seems that my (or our) hearing is not that susceptible to freq. response below 50 hz. as long as there is good amount of output in that octave.

Another surprise for me. There were room modes at 150-200 hz (much above xover freq. of 90 with 24db/octave) when sub was active that were not there when only LS50 were playing. By the way, the measurements were very repeatable so it is not probably a measurement error. Anyone has any explanation for that? Could be because of single sub vs dual ls50, or interaction between sub and ls50. But the room mode freq. is above one octave from the xover freq. and so the sub should essentially be 24 db down.

 

[shkumar4963]

Now that I have played around with and decided on the use of sub with LS50S, I would like to start a discussion if getting rid of room modes by a DRC will help the sound quality and by how much.

Specifically I would like to get your opinion if IIR or FIR is the best way to suppress room modes.

What is the difference between the two and practically what makes most significant improvement in perceived sound quality. I have REW and have recently downloaded Mathaudio.

I am also open to buying additional hardware and software to try out different tools and see what produces the most improvement.

Do we have anyone here who has good knowledge of DRC, specially about difference between IIR and FIR filters, how they work and what may provide the better sound quality improvement.

 

[Frank Harvey]

I hear you and agree that many tracks don't have much below 50 hz. What I was surprised about was that with tracks that do have good bass, i did not hear that much difference between with sub and without.

Define "good bass". Is that under 50Hz or above 50Hz? Or is it just quantity? As I say, try the No Doubt track and you'll hear how impressive it sounds on small, supposedly bass limited speakers like LS50s, and you'll hear just how meaty the bass actually sounds. I played this track on my previous Ken Kreisel speakers, which are properly bass limited (satellites), on their own without a sub, and it made me realise that despite me thinking there was plenty of low bass in the track, it wasn't as deep as I had thought, and it is surprising just how deep the 50-100Hz actually sounds.

 

[shkumar4963]

and care is taken during setup, they should blend extremely well, and you'll be hard pushed to hear wither you're listening to a floorstander or sub/bookshelf speaker set up.

Thanks David. Can you elaborate what you mean by "blend extremely well"? Look at the REW frequency response plots here: http://imgur.com/x53Kit9 and let me know what I should look for in the amplitude or phase matching that shows that the SUB and LS50s are blended well.

Thanks

Everyone else, I am open to all suggestions..

 

[Frank Harvey]

I just meant that you shouldn't be able to detect the crossover point (despite what any readings may say), and what you're listening to should sound more like a full range speaker than a pair of speakers and a subwoofer.

 

[jiggyjoe]

Looking at your REW plots the kefs are doing well down to 50hz or so, so I think your point of crossover is way to high. Your sub is playing to much into the upper bass which is spoiling the the nice flat response of the kefs on ther own. I would set your crossover point around 40hz and take another measurement.

 

[Frank Harvey]

The LS50's -3dB point is 79Hz (officially), but the room will help lower this point. In AV systems, I usually set 80-100Hz as a crossover point for them, but as has been mentioned, they seem to have a decent amount low down - in my room I'm guessing between the 60-80Hz region, although I do have a huge dip around 50Hz. A higher crossover point will ease the load on the relatively small driver, which should make them sound a little cleaner, and depending on the sub being used, may/should have more output around the LS50s lower region.

 

[shkumar4963]

Looking at your REW plots the kefs are doing well down to 50hz or so,  so I think your point of crossover is way to high.   Your sub is playing to much into the upper bass which is spoiling the the nice flat response of the kefs on ther own.   I would set your crossover point around 40hz and take another measurement.   

Agree with you about coverage till about 50 hz. But I was concerned about the elevated volume between 50 and 100 hz with ls50 alone. I was hoping that a cross over at 90 will flatten that region as the sub is very flat. But then I get numerous room modes even as high as 150 hz when a Sub is present.

Do you agree? Also I am really surprised about these dips in fr. I am calling them room modes but they may be something else.

 

[matt49]

Agree with you about coverage till about 50 hz. But I was concerned about the elevated volume between 50 and 100 hz with ls50 alone. I was hoping that a cross over at 90 will flatten that region as the sub is very flat. But then I get numerous room modes even as high as 150 hz when a Sub is present.

Do you agree? Also I am really surprised about these dips in fr. I am calling them room modes but they may be something else.

I think you're quite right. The sub is exciting the room modes, and the result will be (broadly) symmetrical dips and peaks.

There are two (practical) answers to this: get rid of the sub or get some DSP that will cut off the peaks, though it won't do much about the dips.

You can also try moving the sub around, which might make things a bit better.

 

[jiggyjoe]

Again looking at the plot, I would be very pleased with the response you have obtained with the ls50 on their own. Although you could argue it is a few db too strong 60-150hz, it is very flat and even bar a slight rise at 65hz.

Too most people a slight rise in output towards the bass end is the prefered balance anyway, as a totally flat response can sound very lean and thin.

when you are using the subwoofer at a high point of crossover as you say you're exciting all of the room modes and creating a very uneven response.

Again I would be looking to dial that subwoofer in only by filling in the low bass and leaving the kefs to handle the fine job their doing on their own!

 

[shkumar4963]

Again looking at the plot, I would be very pleased with the response you have obtained with the ls50 on their own. Although you could argue it is a few db too strong 60-150hz, it is very flat and even bar a slight rise at 65hz.

Too most people a slight rise in output towards the bass end is the prefered balance anyway, as a totally flat response can sound very lean and thin.

when you are using the subwoofer at a high point of crossover as you say you're exciting all of the room modes and creating a very uneven response.

Again I would be looking to dial that subwoofer in only by filling in the low bass and leaving the kefs to handle the fine job their doing on their own!

I agree and am enjoying the system now. One thing I realized is that at freq. lower than 100 hz, it is more important to have the enrgy there, flatness of the curve is not that important at least as far as I can HEAR it.

One conceptual question though: How does a sub operating at 90 Hz and below excite a room mode at close to 200 Hz. Remember these plots were made using a sweep sine wave. So the response is for the sine wave at that frrequency. And if there is some output from the sub at 200 Hz. then why that room mode is not excited when LS50s are playing on their own. Clearly LS50s have a lot more energy at that frreq. than a sub set at 90 hz with 24db/.octave slope.

Am I thinking about this the right way?

 

[jiggyjoe]

Do you have the subwoofer positioned right in the corner of the room? This is usually the recomended place because it is where you get maximum room gain. If you have placed your kefs well away from corners and the back wall you will get minimal room gain (so not exciting those room modes as much).

You have to remember that corner positioning can add up to 15db of gain so even tho you have a 24db/octave rolloff at 90hz you may well still only be down 8 or 9 db @180hz, and it could still be playing at full level around 130-140hz.

Its good that you are using REW as you can play around with sub settings and get a measurement, this way you can integrate the subwoofer properly. Much better than doing it by ear.

 

[shkumar4963]

That makes sense. It is surprising that some modes are being excited at upto 200 hz that is more than one octave away. But then it may not take that much to excite a room mode.

 

[shkumar4963]

That makes sense. It is surprising that some modes are being excited at upto 200 hz that is more than one octave away. But then it may not take that much to excite a room mode.

 

[ellisdj]

What freq range did you measure?

You have about 20db gain of bass over mids by that graph? I like a house curve but that's a crazy big one.

You need to look at the waterfall to see why there is so much gain at certain freq

My guess will be a long time decay in the bass hence it's elevated freq response. Long decay means looser much less defined bass easily fixed with absorption.

 

[shkumar4963]

What freq range did you measure?

You have about 20db gain of bass over mids by that graph? I like a house curve but that's a crazy big one.

You need to look at the waterfall to see why there is so much gain at certain freq

My guess will be a long time decay in the bass hence it's elevated freq response. Long decay means looser much less defined bass easily fixed with absorption.

Thanks what did you mean by "Long decay means much less defined bass ????? Easily fixed with absorption"

 

[techboy]

OP, I have experienced similar problems with speakers that are out of phase.

I'm 99% sure your speakers are out of phase. Perhaps your tweeters are out of phase with respect to your woofers. Go to a shop and get this checked. You'll thank me later.

Your room, sub or whatever is NOT the problem.

 

[stereoman]

Hi all,

I'm new to the forum (and to hifi) and wondered if someone can help me out....

I recently took a chance and bought a set of KEF LS50's on a friends recommendation and after reading rave reviews (inc What Hifi)

Having wired them up to my amp (Yamaha DSP A3090) and played around with the settings, words cannot express my disappointment

Everyone who listens to them sits there with confused faces and remarks that while the clarity excellent, they lack 'something'.

For me the bass, although there to some extent, sounds clinical and doesnt engage or excite me - everyone who hears them just sighs and says they expected better. A friend told me yesterday he gets more bass in his ford fiesta.

Theres no shortage of power and they go loud, but as you turn them up are so bright that they hurt the ears.

I bought these speakers as a returned item and im wondering if there may be something wrong with them. Some people have suggested it could be my amp, others have said its because the woofers are at the back?

A friend has some KEF Q1's and his speakers sound WAY better than mine. Dynamic punchy bass and crystal clear sound. He's using a vintage stereo amp which i think is a pioneer. His woofers are at the front.

We're both playing music through spotify at the moment and im using my apple tv which is connected to the amp by optical cable. I know the quality will be impaired by that to some extent but the friend with the Q1's does a similar thing and his sound is crushingly better than mine

If anyone has any ideas please let me know,

Mark Jones

Unfortunately speaker purchase is always a hit & miss. they sound a bit different at home , a bit different in shops etc. When you do not like it from the first listen then fat chance you're gonna keep them. You need to search for those who will immediately strike your taste. There are plenty of those but you need to simply discover the right ones for you.

 

[thewinelake.]

An ancient thread again...

Would someone who's read the whole story let us know what happened? ;-)

 

[floyd droid62]

As a previous owner of these speakers, they are definitely not bass light ,that is the only reason I sent them back ,to much bass in my small room!

 

[floyd droid62]

As a previous owner of these speakers, they are definitely not bass light ,that is the only reason I sent them back ,to much bass in my small room!

 

[Native_bon]

As a previous owner of these speakers, they are definitely not bass light ,that is the only reason I sent them back ,to much bass in my small room!

What may be bass heavy for you may be bass light for another. Will also depend on music type.

 

[lpv]

bass or boom?

 

[floyd droid62]

As a previous owner of these speakers, they are definitely not bass light ,that is the only reason I sent them back ,to much bass in my small room!

What may be bass heavy for you may be bass light for another. Will also depend on music type.

they was only bass heavy as my room is small, 14ft x 11ft, But compared to my old floorstanders they was bass, light,it is a matter of perspective.but I will say I found the kefs a excellent speaker,I would have kept them,but I never liked them fully bunged,as I had to do, being so close to wall.but I did find in my room,the bass was over emphasized.

 

[avole]

can boom in the wrong position. Kefs are rear ported, which means they should really be located some distance from a wall.

Infinite baffle speakers are better in this regard, hence the BBC monitors and others based on this model sound a lot tighter. However, they don't go down as low, which the porting tricks your ears that they can.