Opening the LS50s

[killdozzer]

@killdozzer
I'm in the camp of "leave well enough alone". You will be completely miserable if you end up doing more harm than good on a repair attempt.

But, if it comes to it, at least A4L has singles available. Dunno about shipping though.
https://www.accessories4less.com/make-a-store/item/kefls50blkea/kef-ls50-5.25-2-way-mini-monitor-high-gloss-black-each-1/1.html

Doubt they'll ship to Croatia. Shipping alone could amount to another speaker. At this point in time leaving it alone doesn't seem at all plausible. FWIW I'm going very slowly about it, so if I reach that zen point of "meeh", I'll leave it. It just looks so "fixable". I think there's no way of doing more damage, at least the way I laid my steps in front of me.

I'll think about it, though!

maybe a good vacuum could pull it out? but would need to be super careful ive used the vacuum trick on a few speakers i bought where the cone was in,and supprisingly worked pretty good.

Thank you @xreaperx22 I think vacuum is a big no on this type of material. Don't know whether you've had any experience with these aluminium cones, they leave a feeling similar to thick foil used, for example, on top of some wines (more expensive ones). It is like a thicker aluminium foil. I guess magnesium is there for stiffness. Otherwise it would change shape just from being played (pushed in and out by the magnet).

Vacuum could easily make a hole if it ever got attached flat on the cone by suction. It would just rip through or make a huge bump on the cone. I could see myself trying this technique only with a straw and by the power of my lungs, nothing stronger.

I will try to set things right by slight tapping, first on the inside of the exact point where my finger first hit the cone. I expect everything to slowly come back after a series of tapping. If not, I'll tap separately where the indentation occurred and then where the bent appeared as the result of the stroke.

Tapping will be much lighter than the stroke that left the indentation. It has to go slowly and gradually, even if it takes a long time. Every now and then I'll be checking the progress. Nothing sudden, no high expectations.

 

[xreaperx22]

oh yeah that was my fault for not seeing the aluminum part,yeah i wouldnt attempt that then hehe,but i would be the same way if that happened to me i would have to fix it,or even as far as replace it entirely.

 

[snakeeyes]

oh yeah that was my fault for not seeing the aluminum part,yeah i wouldnt attempt that then hehe,but i would be the same way if that happened to me i would have to fix it,or even as far as replace it entirely.

I’m just imagining a torn off woofer clogging the vacuum.

 

[killdozzer]

A relatively high amount of 25$ for rubber covers. They are on the way. Once they arrive, the work commences. I'll keep you updated.

 

[killdozzer]

They have finally arrived. A set of four caps that cover the holes for the screws.

There's a drop of glue that holds the cap in position and when you try to remove the cap it tears.

Now all I need is a day off and I'll start. Before that I want to make a soft mat to put the speaker baffle on. I don't want for the membrane to touch the hard surface. The membrane will be suspended in air at all times.

 

[killdozzer]

As they say, trouble comes in pairs (or somethin' like that). My right speaker is buzzing. I switched them (left for right, detaching the cable, of course),but the buzzing stayed with the same box.

It is the same one I was meaning to open anyway. So, is there something you suspect as a culprit? It sounds mechanical, like having a light sheet of plastic on a poorly isolated speaker so when you turn the volume up it starts vibrating and creates sound of vibrating and flickering against the surface of the speaker.

Once again, I rule out the damage I did, because it is too small to be the cause.

On most LCD screens you will need to tilt your head to even notice the indent I caused. It is next to impossible for this to be the cause of the buzz.

The buzz can be heard when playing loud (the volume knob is at 11 o'clock with a bass heavy material that shows -10db in foobar player)
This is the song if it helps:

The intro is the worst for the buzzing. The buzzing can only be heard when you put your ear close to the side that is not visible in the picture (so it's the left lateral side). If you move your head away even slightly, let's say you put your head above the speaker with your beard almost touching the upper surface, you won't hear it any more.

First thing that came to my mind is the plate of the XO becoming loose and vibrating in its posts. The other is the wire (going from the XO to the driver binds) touching the inner side of the speaker box and vibrating against the surface.

Tell me if I'm wrong.

 

[PENG]

As they say, trouble comes in pairs (or somethin' like that). My right speaker is buzzing. I switched them (left for right, detaching the cable, of course),but the buzzing stayed with the same box.

It is the same one I was meaning to open anyway. So, is there something you suspect as a culprit? It sounds mechanical, like having a light sheet of plastic on a poorly isolated speaker so when you turn the volume up it starts vibrating and creates sound of vibrating and flickering against the surface of the speaker.

Once again, I rule out the damage I did, because it is too small to be the cause.
View attachment 26068
On most LCD screens you will need to tilt your head to even notice the indent I caused. It is next to impossible for this to be the cause of the buzz.

The buzz can be heard when playing loud (the volume knob is at 11 o'clock with a bass heavy material that shows -10db in foobar player)
This is the song if it helps:

The intro is the worst for the buzzing. The buzzing can only be heard when you put your ear close to the side that is not visible in the picture (so it's the left lateral side). If you move your head away even slightly, let's say you put your head above the speaker with your beard almost touching the upper surface, you won't hear it any more.

First thing that came to my mind is the plate of the XO becoming loose and vibrating in its posts. The other is the wire (going from the XO to the driver binds) touching the inner side of the speaker box and vibrating against the surface.

Tell me if I'm wrong.

Is it still under warranty?

 

[TLS Guy]

As they say, trouble comes in pairs (or somethin' like that). My right speaker is buzzing. I switched them (left for right, detaching the cable, of course),but the buzzing stayed with the same box.

It is the same one I was meaning to open anyway. So, is there something you suspect as a culprit? It sounds mechanical, like having a light sheet of plastic on a poorly isolated speaker so when you turn the volume up it starts vibrating and creates sound of vibrating and flickering against the surface of the speaker.

Once again, I rule out the damage I did, because it is too small to be the cause.
View attachment 26068
On most LCD screens you will need to tilt your head to even notice the indent I caused. It is next to impossible for this to be the cause of the buzz.

The buzz can be heard when playing loud (the volume knob is at 11 o'clock with a bass heavy material that shows -10db in foobar player)
This is the song if it helps:

The intro is the worst for the buzzing. The buzzing can only be heard when you put your ear close to the side that is not visible in the picture (so it's the left lateral side). If you move your head away even slightly, let's say you put your head above the speaker with your beard almost touching the upper surface, you won't hear it any more.

First thing that came to my mind is the plate of the XO becoming loose and vibrating in its posts. The other is the wire (going from the XO to the driver binds) touching the inner side of the speaker box and vibrating against the surface.

Tell me if I'm wrong.

Unfortunately I think you are wrong. Common things commonly happen.

I had a chance to listen and examine those speakers recently. They do sound very good, although the bass is miss tuned I think. They should have tuned it for a less prominent bloated bass. Apart from that the speaker sounded really good.

On close examination it is clear to me that the driver bears a very close resemblance to the old Jordan Watts driver. The designer was obviously clearly aware of that full range driver, as indeed almost all UK transducer speaker designers are.

I did a lot of work on that driver over many years, culminating in the MK 3

In my opinion it is by far the best full range driver to have ever appeared. As you can see the cone shape is very similar to the KEF. The JW is a very light tractrix cone just like the KEF.

Now my biggest challenge with this driver was adherence of VC and cone. Adhesives are better now, but I spent hours improving the reliability of this driver.

However I suspect that your driver is starting a problem with which I'm very familiar, and that is cone voice coil separation. What you are describing is exactly how the earliest symptom sounds. It usually progresses once it starts to complete separation.

So I suspect that driver needs replacement or rebuild.

 

[killdozzer]

@TLS Guy @PENG Thank you, guys. As far as warranty go I'll have to check with the store. Often promotional sales shorten the warranty period.

As far as the VC/cone separation goes, I doubt this is the case (for now). I would expect the sound to be louder in front of the speaker if it was VC/cone separation, but I can't hear anything in front of the speaker. Also, I would expect the sound to be at least equally heard on all sides of the box; up, down, left, right. And if not that, then at least on the right side as loud as on the left.

On the right side I can't hear a thing. Neither on any of the other including front and back.

This is what drew me towards my assumption that the left lateral side is making some sound and that this is the reason why it can't be heard nowhere else.

Well, not the side in itself, but some part of the set up.

If these additional info gives you another idea, please share.

For now I didn't get around to even open it as I have a lot of work at the moment and don't want to do it under stress or rush. So there's time.

Thank you again!

LATER EDIT: And another thing, not even for test have I ever pushed these beyond 92-93 db, let alone 106 of the factory upper limit. From all I've learned about KEF and this model in particular, no detaching should occur.

 

[TLS Guy]

@TLS Guy @PENG Thank you, guys. As far as warranty go I'll have to check with the store. Often promotional sales shorten the warranty period.

As far as the VC/cone separation goes, I doubt this is the case (for now). I would expect the sound to be louder in front of the speaker if it was VC/cone separation, but I can't hear anything in front of the speaker. Also, I would expect the sound to be at least equally heard on all sides of the box; up, down, left, right. And if not that, then at least on the right side as loud as on the left.

On the right side I can't hear a thing. Neither on any of the other including front and back.

This is what drew me towards my assumption that the left lateral side is making some sound and that this is the reason why it can't be heard nowhere else.

Well, not the side in itself, but some part of the set up.

If these additional info gives you another idea, please share.

For now I didn't get around to even open it as I have a lot of work at the moment and don't want to do it under stress or rush. So there's time.

Thank you again!

LATER EDIT: And another thing, not even for test have I ever pushed these beyond 92-93 db, let alone 106 of the factory upper limit. From all I've learned about KEF and this model in particular, no detaching should occur.

Its speculative what the problem is, but in my experience if a speaker starts to buzz, then the problem is usually with the driver.

Cone VC separation is quite a common mode of failure among failed drivers as a whole. It is not spl alone that leads to the trouble, but the music content more than anything else. The smaller the driver, then the more likely there will be failure, especially of there is music with significant bass content, especially sudden transients, like a big hit form a big bass drum, especially on classical recordings which have a high dynamic range.

For my designs with smaller drivers, I always use two for the bass/mid range and never one, unless it is for very small room or near field use.

 

[snakeeyes]

Think it is said that trouble comes in threes, actually. LOL

Hopefully you can get it repaired. Those are expensive speakers. Even the refurb ones at A4L are pricy.

 

[PENG]

I think you should try the warranty route first, by calling KEF directly if the dealer won't. If you are confident in opening it up yourself, may be you can get them to send you a driver. Worst case, try and convince the dealer or KEF to replace it at cost/reduced price. You only need one anyway.

 

[killdozzer]

All good advice!
@PENG yes, I'll contact the shop where I bought them. I doubt It'll do me any good, but I should try anyway.

@TLS Guy I agree. It's speculative. I didn't want to come off as being all wishful thinking, but it's not without any merit; if there's a sound emanating from the center of the speaker it should be equally or almost equally heard on all sides of the speaker. This is why my suspicion went the other way, towards the left side of the box being "involved" so to speak, in making this sound. This is what I'm thinking; if something is vibrating against the side of the speaker box, you can hear it when you bring your ear close by and there's a good chance the opposite side will not conduct/leak that same sound as it will get lost in the isolation and damped.

Here's a problem question for you TLS; if it's VC/cone do you think it is possible to hear the buzzing through the substantially thick side wall (LS has a "box-inside-a-box" built) and not through the front of the speaker, through the driver cone which is under 2mm thick at best?

Again, it's all speculation for now. I'll keep you posted and thank you all very much.

 

[PENG]

All good advice!
@PENG yes, I'll contact the shop where I bought them. I doubt It'll do me any good, but I should try anyway.

@TLS Guy I agree. It's speculative. I didn't want to come off as being all wishful thinking, but it's not without any merit; if there's a sound emanating from the center of the speaker it should be equally or almost equally heard on all sides of the speaker. This is why my suspicion went the other way, towards the left side of the box being "involved" so to speak, in making this sound. This is what I'm thinking; if something is vibrating against the side of the speaker box, you can hear it when you bring your ear close by and there's a good chance the opposite side will not conduct/leak that same sound as it will get lost in the isolation and damped.

Here's a problem question for you TLS; if it's VC/cone do you think it is possible to hear the buzzing through the substantially thick side wall (LS has a "box-inside-a-box" built) and not through the front of the speaker, through the driver cone which is under 2mm thick at best?

Again, it's all speculation for now. I'll keep you posted and thank you all very much.

@TLSGuy seems to have lots of experience with speakers and probably had built a few, so he may be right in his remote diagnostics, or he might have jump a little quickly to conclusion in this case. Is that noise loud and obvious enough that you can record it and post it?

 

[killdozzer]

@PENG

Great idea!!! I'll try.

I do trust TLS a lot. That's not a problem. First thing I doubt is that I managed to convey the info properly. Someone else's wording might lead to a totally different conclusion.

 

[Johnny2Bad]

I've seen vibration issues with conventional (not coax) speakers caused by a glue bond failure on the dust cap. So maybe not necessarily a voice coil issue per se.

 

[<eargiant]

As they say, trouble comes in pairs (or somethin' like that). My right speaker is buzzing. I switched them (left for right, detaching the cable, of course),but the buzzing stayed with the same box.

It is the same one I was meaning to open anyway. So, is there something you suspect as a culprit? It sounds mechanical, like having a light sheet of plastic on a poorly isolated speaker so when you turn the volume up it starts vibrating and creates sound of vibrating and flickering against the surface of the speaker.

Once again, I rule out the damage I did, because it is too small to be the cause.
View attachment 26068
On most LCD screens you will need to tilt your head to even notice the indent I caused. It is next to impossible for this to be the cause of the buzz.

The buzz can be heard when playing loud (the volume knob is at 11 o'clock with a bass heavy material that shows -10db in foobar player)
This is the song if it helps:

The intro is the worst for the buzzing. The buzzing can only be heard when you put your ear close to the side that is not visible in the picture (so it's the left lateral side). If you move your head away even slightly, let's say you put your head above the speaker with your beard almost touching the upper surface, you won't hear it any more.

First thing that came to my mind is the plate of the XO becoming loose and vibrating in its posts. The other is the wire (going from the XO to the driver binds) touching the inner side of the speaker box and vibrating against the surface.

Tell me if I'm wrong.

I hate to say it but you shouldn't have been so stubborn and listened to the advice I was trying to give you in the thread below (post #103). Instead you chose to be nasty and look what happened when you suited yourself.

https://forums.audioholics.com/forums/threads/kef-owners-thread.91389/page-6

As for the 106dB limit I call BS unless they are:

A) Measured in a shoebox
B) The spl mic is very close to the driver
C) The audio source being measured has zero low or midbass frequency content

Remember Occam's razor, look no further than the simplest answer. You overdrove them.

Next time, listen to advice from people (even if you don't like them) that have hands on ownership experience with the gear you are asking about.

 

[killdozzer]

Next time, listen to advice from people (even if you don't like them) that have hands on ownership experience with the gear you are asking about.

Never take advice from an idiot.

 

[killdozzer]

Being overworked for some time now, I took no further steps with the speakers. I need time to really go slowly and carefully.

One new info on the entire subject, I played the song in question at my workplace and got some trembling. Not quite the same, but trembling.

I don't know whether any of you tried playing the song I linked. I did try several different versions and it's always there, not on some other bass heavy songs, though. And now, new variable, it also makes my workplace system tremble (it is a basic Marantz stereo amp with two B&W built-in speakers, I don't use loudness on that system even when listening very quietly and the bass knob is at -2, so lows are attenuated, now, I know B&W makes for some sh... gear,, but since the trembling can also be heard on my KEF's, it can't be that).

I know it doesn't have to be every low freq. some will trigger it, some won't, but I can't help but find it odd that it would tremble/buzz on that particular freq and not some others that are very deep.

I really don't know when will I get to poke around this speaker. Best guess, after 1st of November. I'll keep you posted.

 

[killdozzer]

I've seen vibration issues with conventional (not coax) speakers caused by a glue bond failure on the dust cap. So maybe not necessarily a voice coil issue per se.

Thnaks @Johnny2Bad Perhaps I'm clinging onto something, but I can't find a reason a dust cap (or, in my case, a waveguide?? perhaps buzzing against the... dome of the tweeter? I really don't know),would only be heard when placing your head beside the speaker, at the same height as the speaker and only on that one side (to the left of the speaker as it is in the pic above).

This is the only reason I'm still suspicious about what @TLS Guy stated might be the problem. You can only hear it at that one spot and you have to be not further than 2 feet.

Come really close to the front baffle and you will not hear the buzz. Odd, I know.