KEF LS50 Wireless II - subwoofer advice

2xcess

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Mar 7, 2011
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Hi,

I'm looking for a little advice on adding a subwoofer or subwoofers to my LS50 W2s. The low-end presence of the LS50 W2s is actually quite good but I feel it could be better and clearly there will be frequencies below where the KEFs roll-off that they simply can't produce. What I'm looking to achieve is to pick up those low frequencies south of 45 to 50Hz (anyone know exactly where the LS50 W2s roll-off?) and perhaps help the KEFs out with the lowest frequencies in their range (below 80Hz?).

I've settled on 2 options (but am open to other suggestions):
1. Two x REL Tzero M3s used in stereo
2. Single REL T5i (with the idea that I might buy a second at a later date if it seems necessary).

So the main question is; would option 1 be better than option 2 in this use case? I'm leaning towards Option 2 which I think will allow the sub to go to lower frequencies with the option to add a second later. This may be due to not having heard the effect of stereo subwoofers on a system.

BTW does it matter which of the LS50 W2 speaker's sub outs I chose to use in the single subwoofer case? I can't see this mentioned by KEF anywhere. The secondary speaker (left) is in a more convenient location to allow placement of the single subwoofer so I'd prefer to connect the sub to that.

Any thoughts welcome.

Steve.
 

12th Monkey

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Aug 31, 2015
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If I read your post elsewhere correctly, you've only had these for ten days. If so, maybe you'd be best off returning them and opting for something that does the job you require, possibly floorstanders? You are finding fault within that short a time, during what should perhaps be the honeymoon period, I wonder whether that bodes ill for the long term?
 
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2xcess

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Mar 7, 2011
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If I read your post elsewhere correctly, you've only had these for ten days. If so, maybe you'd be best off returning them and opting for something that does the job you require, possibly floorstanders? You are finding fault within that short a time, during what should perhaps be the honeymoon period, I wonder whether that bodes ill for the long term?
I completely get what you are saying here and appreciate the caution and advice, it is something I am considering (esp given the dropouts). However, I did enter into the LS50 W2 purchase with the expectation that I would add a subwoofer to provide the lower bass frequencies that the LS50 W2s cannot provide. The sound stage and detail are exactly what I hoped for and the bass, for such compact speakers, is actually better than I'd anticipated; a sub isn't as clearly required as I expected. I don't think I need to help the LS50s out with the bass frequencies they are capable of producing, just where they roll-off. What I'm looking to achieve with the subwoofer is the retain the sound stage etc of the LS50 W2s while adding those lower frequencies around and below where the LS50s roll-off.

So I know what I want to achieve but I have little experience with Hi-Fi subwoofers, so if my thinking here is floored then please let me know. This setup is replacing my Dali Ikon 6 floorstanders which have provided good service for many years.

My main issue with the LS50 W2s is the occasional dropouts and glitches, that issue might send them back. On the plus side, it means I won't pull the trigger on the subwoofer until I'm happy that it is an issue that can be resolved with either changes to my wifi setup or a firmware upgrade. It gives me time to properly consider if the KEFs will fit my needs, with or without a subwoofer - as you point out I have not had them long.

Steve.
 

2xcess

Well-known member
Mar 7, 2011
22
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18,525
My main issue with the LS50 W2s is the occasional dropouts and glitches, that issue might send them back. On the plus side, it means I won't pull the trigger on the subwoofer until I'm happy that it is an issue that can be resolved with either changes to my wifi setup or a firmware upgrade. It gives me time to properly consider if the KEFs will fit my needs, with or without a subwoofer - as you point out I have not had them long.

Steve.
A quick update - the issue above has been resolved, the problem was not the LS50 W2s but lay in my Mesh Wi-Fi setup. See this post for more information on the problem, solution and the Wi-Fi setup.

Steve
 

hsaam

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Jan 7, 2021
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@2xcess wondering if you ever managed to add a subwoofer to LS50W2? I am working to make my set up with LS50W2 + Polk Audio sub work but so far no luck. It seems I need to enable the sub out signal but KEF Connect app does not allow this (yet)?

Henry
 

Deliriumbassist

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Apr 27, 2011
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@2xcess wondering if you ever managed to add a subwoofer to LS50W2? I am working to make my set up with LS50W2 + Polk Audio sub work but so far no luck. It seems I need to enable the sub out signal but KEF Connect app does not allow this (yet)?

Henry
The sub output is always on with LS50W2 - never had to switch anything in the app in order to get something playing through the sub (on either speaker). Tweak around a bit with the filter settings to integrate it, sure, but nothing needed to actually enable it.

Maybe it isn't triggering the wake up on your Polk? Maybe try boosting the subwoofer output gain in the app, and turn the volume control on the sub itself to compensate?
 

2xcess

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Mar 7, 2011
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@2xcess wondering if you ever managed to add a subwoofer to LS50W2? I am working to make my set up with LS50W2 + Polk Audio sub work but so far no luck. It seems I need to enable the sub out signal but KEF Connect app does not allow this (yet)?

Henry
@hsaam as @Deliriumbassist says the sub out signal is always on with the LS50 W2s.

I've ended up going with a single REL T5i, I'm still playing with setting it up and getting the 'blending' of the sub and the LS50 W2s right. Part of the complication (for me at least) is having the settings both in the KEF Connect app and physical crossover/gain on the REL. As far as your subwoofer not seeing the LS50 W2s my only suggestion is to set the Polk Audio subs crossover as high as it will go - and to set both the high-pass frequency and the sub out low-pass frequency as high as they'll go in the KEF Connect app. This should at least ensure that the sub is seeing a signal it can work with and you'll know where the sound is coming from. The high-pass will set the value above which frequencies will be handled by the LS50 W2s while the sub low-pass out will determine those frequencies sent to the sub. How best to overlap these settings to seamlessly blend with the REL and it's crossover settings is where I am at the moment. A second sub would make positioning etc easier, but I'm not sure that my wife is going to want a second sub in the living room just yet..

On KEFs website they have an LS50 W2 manual and a whitepaper, both briefly discuss the use of a sub but are actually a little inconsistent, at least that is my interpretation. Both are worth downloading if you haven't already.

BTW if you make any progress with the setup let me know as I may still be figuring things out myself.

Steve.
 

hsaam

Member
Jan 7, 2021
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Thanks for the advice @2xcess and for the detailed info @Deliriumbassist. I was finally able to get some faint response after max'ing out the high/low pass frequencies, the sub gain (on KEF Connect) and the volume on my subwoofer. Now I need to figure out why the KEF output is so weak... I am getting a relatively normal response when connecting to Bluesound sub output but it's definitely considerably weaker on KEF.

I will follow up with any progress.

Henry
 

Deliriumbassist

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Apr 27, 2011
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Don't max out the high pass on the app - that's going to create a big hole, as that reduces the low end being played by the LS50WII driver, it has zero to do with the subwoofer output.

Does your sub have a dedicated LFE mode? Try engaging that.
 

2xcess

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Mar 7, 2011
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I'm not sure what the high-pass filter is doing in the KEF app. to be honest. Leaving my low-pass at 90Hz, and only changing the high-pass from 70Hz to 120Hz (max) or switching it off provided a big boost in bass. Setting the REL up has been easier with it off and out of the way, as it's not doing what I expected - you'd expect with the original overlap (low-pass 90Hz, high-pass at 70Hz) that turning it off or maxing it out would not provide a big boost in low bass? REL crossover is at about 70 to 75Hz. For now I'm happy with high-pass toggled off.
 

Deliriumbassist

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Apr 27, 2011
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The high pass is there so you can almost turn the LS50W into a three way speaker. You would actually set it at a higher frequency than the low-pass.

The way a crossover works is by using two filters - so you have one for the lower driver that starts to roll off at the top end (low pass filter - the frequencies below the chosen one are unaffected, the ones above start dropping in volume - low frequency drivers can distort pretty badly when given high frequencies), and one for the higher driver (high-pass filter - the frequencies below the chosen frequency are attenuated, the ones above are unchanged, because you don't want the higher frequency driver to get bass signal as it could get damaged due to overexcursion)

When you see a speaker specification that gives you a crossover value - that's just telling you at what point those two falling slopes literally cross over (hence the name), so for a region of sound, you actually have two drivers playing the same frequencies - just a lot quieter individually. But as they add together, you get them at higher volume. The trick is to set those two frequencies so that, when the two signals are added together, you get a nice straight line - smooth integration.

So if you set the HP filter for the speaker at a lower frequency than the LP filter for the sub, then you'll get a boost in the area between and around the crossover point. If you have them too far apart, you'll have a dip in that area.

The 'crossover' control on a subwoofer is actually just a low pass filter on its own.
 
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2xcess

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@Deliriumbassist Thanks, the description of the low-frequency/bass boost you describe makes sense (dohh). I've been exchanging emails with REL and they are trying to get hold of a set of LS50 W2s so that they can test them and, more importantly, the new app out to see if they can come up with some rough settings as a starting point. Where I get confused is the fact that both the REL and the KEF app have low pass filters. Do you have examples of the roll-off rate? Is there a standard filter that manufactures apply? This would help me get the high-pass and low-pass 'gap' roughly right in the KEF app so that I have a near level additive crossover to start with before using my ears to fine-tune. Currently, I've gone back to 70Hz and 90Hz for low and high. What happens when that gets passed to the REL, and what gets passed, is another layer of complexity - REL has suggested that to benefit from their circuitry that I will be better passing the full frequency range to the REL and only use the low-pass/crossover there.

In the KEF app, the only thing that can be toggled off is the high-pass filter. It makes more sense to me to be able to toggle the low-pass filter off and then use the REL to adjust the crossover/low-pass? Then adjust the KEF app high-pass to get that level output across the frequency range between low and high-pass? Am I missing something that KEF intend here? Basically, I'm struggling to understand why the KEF app doesn't allow you to toggle off the low-pass when using a subwoofer with its own low-pass/'crossover'.
 

Deliriumbassist

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Apr 27, 2011
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I'd imagine the Rel has the ability to bypass the its onboard LPF - might be called LFE mode. LFE mode is mainly used for home theatre because, whilst you might set a crossover for routing the bass of the main channels to the sub, you also have the .1 bit, which is it's own separate channel - you don't want that to be filtered, but if you set the crossover on the sub, then that's what you would be doing.

According to the KEF white paper, the crossover is a 4th order Linkwitz-Riley, so that's a 24dB/octave slope. 80Hz is where you start to localise the sub, so I would start with the LPF lower than this, and then adjust the HPF until it sounds right - room placement, sub efficiency etc plays a part here (and does in every other sub/speaker interaction, not just in this case).

On my LS50W2, I use the LPF on the app after using the LFE mode on my sub, so that I could just adjust the LPF from my listening position instead of getting up, changing it, going back, testing again etc. I don't particularly see the benefit of using the crossover on the Rel.
 

sansui au719

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Jan 23, 2014
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Hi

I use a Rel T5i to extend the bass of my KEF LS50s - which are driven by a vintage Sansui AU-719 in a medium to large room. The combination works very well (and IMO looks good in matching piano black).

This is more a vote of confidence in the combination. I can't really advise with setting up the Rel for LS50 Wireless II
 
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2xcess

Well-known member
Mar 7, 2011
22
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I'd imagine the Rel has the ability to bypass the its onboard LPF - might be called LFE mode. LFE mode is mainly used for home theatre because, whilst you might set a crossover for routing the bass of the main channels to the sub, you also have the .1 bit, which is it's own separate channel - you don't want that to be filtered, but if you set the crossover on the sub, then that's what you would be doing.

According to the KEF white paper, the crossover is a 4th order Linkwitz-Riley, so that's a 24dB/octave slope. 80Hz is where you start to localise the sub, so I would start with the LPF lower than this, and then adjust the HPF until it sounds right - room placement, sub efficiency etc plays a part here (and does in every other sub/speaker interaction, not just in this case).

On my LS50W2, I use the LPF on the app after using the LFE mode on my sub, so that I could just adjust the LPF from my listening position instead of getting up, changing it, going back, testing again etc. I don't particularly see the benefit of using the crossover on the Rel.
Yes there is a .1/LFE input, which I can try. As an alternative would the same result be achieved by setting the REL low-pass/crossover to its highest setting (120Hz) to place the REL full range then using the KEF app to set the low-pass frequency? As long as the low-pass value in the KEF app is well below the REL crossover I'm effectively taking control away from the REL?
 

Deliriumbassist

Well-known member
Apr 27, 2011
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Yes there is a .1/LFE input, which I can try. As an alternative would the same result be achieved by setting the REL low-pass/crossover to its highest setting (120Hz) to place the REL full range then using the KEF app to set the low-pass frequency? As long as the low-pass value in the KEF app is well below the REL crossover I'm effectively taking control away from the REL?
In theory yes, but then you're putting an analogue signal through superfluous circuitry (I'd imagine, being unsure about the actual guts of the Rel), and if it's just a case of flipping a switch or plugging from one RCA input to another, then there is very little point in keeping it in the current setting.
 

Terence J

Member
Jan 20, 2021
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I completely get what you are saying here and appreciate the caution and advice, it is something I am considering (esp given the dropouts). However, I did enter into the LS50 W2 purchase with the expectation that I would add a subwoofer to provide the lower bass frequencies that the LS50 W2s cannot provide. The sound stage and detail are exactly what I hoped for and the bass, for such compact speakers, is actually better than I'd anticipated; a sub isn't as clearly required as I expected. I don't think I need to help the LS50s out with the bass frequencies they are capable of producing, just where they roll-off. What I'm looking to achieve with the subwoofer is the retain the sound stage etc of the LS50 W2s while adding those lower frequencies around and below where the LS50s roll-off.

So I know what I want to achieve but I have little experience with Hi-Fi subwoofers, so if my thinking here is floored then please let me know. This setup is replacing my Dali Ikon 6 floorstanders which have provided good service for many years.

My main issue with the LS50 W2s is the occasional dropouts and glitches, that issue might send them back. On the plus side, it means I won't pull the trigger on the subwoofer until I'm happy that it is an issue that can be resolved with either changes to my wifi setup or a firmware upgrade. It gives me time to properly consider if the KEFs will fit my needs, with or without a subwoofer - as you point out I have not had them long.

Steve.
Good afternoon Steve, we have had our LS50 2s since November of last year.....over 2weeks working with KEF Supportat the beginning to finally get hooked up so that they wouldn't cut out on us ; tried hard wiring a SUB into the Principle Speaker - never worked; our TV ONLY connects via Optical - there is no recognition for HDMI ( ARC ) and or Bluetooth - simply do not connect - Samsung Q7 75" - no resolution from KEF. I would recommend that you spec out whatever it is that you are looking at to determine if it will work ( connect ) ? It has been, and continues to be very frustrating to have invested in the system to have so many connectivity issues ( maybe they weren't ready or maybe we got a lemon ? ). We are considering to add a SUB as well , but quite frankly dont know if they will work?!
 

2xcess

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Mar 7, 2011
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Good afternoon Steve, we have had our LS50 2s since November of last year.....over 2weeks working with KEF Supportat the beginning to finally get hooked up so that they wouldn't cut out on us ; tried hard wiring a SUB into the Principle Speaker - never worked; our TV ONLY connects via Optical - there is no recognition for HDMI ( ARC ) and or Bluetooth - simply do not connect - Samsung Q7 75" - no resolution from KEF. I would recommend that you spec out whatever it is that you are looking at to determine if it will work ( connect ) ? It has been, and continues to be very frustrating to have invested in the system to have so many connectivity issues ( maybe they weren't ready or maybe we got a lemon ? ). We are considering to add a SUB as well , but quite frankly dont know if they will work?!
Well, your experience is a little concerning. At present, I intend to only use the LS50 W2s for music so I have not tried the other inputs. Perhaps I should do that at some point, I don't want to find out at a later date if I repurpose the speakers.

To your questions though:
Connectivity; I'm exchanging emails with KEF currently, a new forced firmware version rolled out Tuesday, ver 1.3. It got stuck, hosing the speakers, so it resulted in me contacting KEF. I tried a number of times but it got stuck at varying percentages each time when upgrading the primary speaker. What fixed that in the end was connecting the primary speaker to my network via ethernet cable, it might be due to the fact that connecting wirelessly after powering on takes longer?? I have now removed that ethernet cable and the speakers continue to have a solid wireless connection to the network. No drops. What still doesn't work, and is the reason for continued contact with KEF, is the connection between the speakers, the secondary continuously drops. I don't mind having the speakers connected by ethernet cable but I would like the option of connecting them wirelessly.... So I still have some connectivity issues although it is not preventing me enjoying the speakers.
Subwoofer; this works fine. REL are trying to obtain a set of LS50 W2s to test and will get back to me with their results for setup (at least a rough guide given each room will be different). Currently, I have the T5i is set to full range (crossover/low-pass at 120Hz) and the gain to ~11 o'clock. This leaves me +/-10dB gain adjustment in the app. At the KEF app end, I am at 75Hz high-pass and 65Hz low-pass. As @Deliriumbassist posted above it is a 24dB slope, so quite steep. I'm still messing around with the final settings but somewhere between 10 and 15Hz gap seems best. I expect REL might suggest for me to shift the low-pass in the app to 250Hz (max) and then to control the crossover on the REL, but that is just a guess, we'll see what they come back with. I should say that REL have been incredibly helpful and responsive.
 

Terence J

Member
Jan 20, 2021
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Well, your experience is a little concerning. At present, I intend to only use the LS50 W2s for music so I have not tried the other inputs. Perhaps I should do that at some point, I don't want to find out at a later date if I repurpose the speakers.

To your questions though:
Connectivity; I'm exchanging emails with KEF currently, a new forced firmware version rolled out Tuesday, ver 1.3. It got stuck, hosing the speakers, so it resulted in me contacting KEF. I tried a number of times but it got stuck at varying percentages each time when upgrading the primary speaker. What fixed that in the end was connecting the primary speaker to my network via ethernet cable, it might be due to the fact that connecting wirelessly after powering on takes longer?? I have now removed that ethernet cable and the speakers continue to have a solid wireless connection to the network. No drops. What still doesn't work, and is the reason for continued contact with KEF, is the connection between the speakers, the secondary continuously drops. I don't mind having the speakers connected by ethernet cable but I would like the option of connecting them wirelessly.... So I still have some connectivity issues although it is not preventing me enjoying the speakers.
Subwoofer; this works fine. REL are trying to obtain a set of LS50 W2s to test and will get back to me with their results for setup (at least a rough guide given each room will be different). Currently, I have the T5i is set to full range (crossover/low-pass at 120Hz) and the gain to ~11 o'clock. This leaves me +/-10dB gain adjustment in the app. At the KEF app end, I am at 75Hz high-pass and 65Hz low-pass. As @Deliriumbassist posted above it is a 24dB slope, so quite steep. I'm still messing around with the final settings but somewhere between 10 and 15Hz gap seems best. I expect REL might suggest for me to shift the low-pass in the app to 250Hz (max) and then to control the crossover on the REL, but that is just a guess, we'll see what they come back with. I should say that REL have been incredibly helpful and responsive.
I agree that the sound quality is excellent and we thoroughly enjoy the look. I still believe the issue is simply that although there have been "back and forth" with their support there is no solution to the other inputs - as a customer for a premium product we shouldn't have to perform work arounds to get their functionality to work.
Of their inputs so far, after we got passed wifi connectivity in the first two weeks, we have unresolved issues with Bluetooth, HDMI, and Auxiliary.
The speakers are also not registered with Roon as of yet either.
A simple equipment disclaimer from KEF on incompatibility would have directed the decision elsewhere.
Btw - I am on Version 1.3 - wasn't aware that there was an update this week? Think the 1.3 has been there for a while.
It is interesting to note that I received a notification on a New Subwoofer that KEF has launched ( the size is perfect ! ) however I cant trust that it will actually connect?!
I have sent several KEF Support emails since I have entered the WhatHIFI forum - but no response to date - I really don't think they know what to do?
Good luck.
 

2xcess

Well-known member
Mar 7, 2011
22
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18,525
I agree that the sound quality is excellent and we thoroughly enjoy the look. I still believe the issue is simply that although there have been "back and forth" with their support there is no solution to the other inputs - as a customer for a premium product we shouldn't have to perform work arounds to get their functionality to work.
Of their inputs so far, after we got passed wifi connectivity in the first two weeks, we have unresolved issues with Bluetooth, HDMI, and Auxiliary.
The speakers are also not registered with Roon as of yet either.
A simple equipment disclaimer from KEF on incompatibility would have directed the decision elsewhere.
Btw - I am on Version 1.3 - wasn't aware that there was an update this week? Think the 1.3 has been there for a while.
It is interesting to note that I received a notification on a New Subwoofer that KEF has launched ( the size is perfect ! ) however I cant trust that it will actually connect?!
I have sent several KEF Support emails since I have entered the WhatHIFI forum - but no response to date - I really don't think they know what to do?
Good luck.
FW version 1.3 was released on 19th Jan according to KEFs support site. It mentions "Improved HDMI ARC compatibility for LG, Sony and Panasonic TVs" would be interested to know if it solves any of your connectivity problems.

Yes I spotted that KEF announcement too, the REL sounds good and I'm still to fine tune it (still no sign of LS50 stands.. sigh) so will stick with it for now at least. If I'd not already committed the new KEF would definitely have been something I'd have looked at, although at that price I'd want to see a few reviews and audition it first.
 

Terence J

Member
Jan 20, 2021
8
0
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FW version 1.3 was released on 19th Jan according to KEFs support site. It mentions "Improved HDMI ARC compatibility for LG, Sony and Panasonic TVs" would be interested to know if it solves any of your connectivity problems.

Yes I spotted that KEF announcement too, the REL sounds good and I'm still to fine tune it (still no sign of LS50 stands.. sigh) so will stick with it for now at least. If I'd not already committed the new KEF would definitely have been something I'd have looked at, although at that price I'd want to see a few reviews and audition it first.
Good afternoon 2xcess, hope things are well, Interesting on the Version 1.3 ( Jan 19th ); tried the HDMI again yesterday with the update to no avail......the issue we have is with a Samsung, maybe they haven't figured that one out ?
Getting a little concerned that their support has not reached back to "try something".
 

AndyCC72

Well-known member
Jan 13, 2021
92
67
120
Hi

I use a Rel T5i to extend the bass of my KEF LS50s - which are driven by a vintage Sansui AU-719 in a medium to large room. The combination works very well (and IMO looks good in matching piano black).

This is more a vote of confidence in the combination. I can't really advise with setting up the Rel for LS50 Wireless II
Out of interest what do you have the crossover set at ?

I have the LS50’s and 2 x T5i’s and have the crossover on each at 55hz and volume at 9 o’clock

The reason I’m asking is that I’m reading on lots of forums of people having their crossovers set as high 120hz because the LS50 drops off at around 75hz. So having them set at 55hz and I missing the bit between that and 75hz??

Just interested as even though I’m really happy with the sub set up (after much tinkling) I can’t help thinking it could be better and I’m might be missing a trick
 
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