KEF Kube 10b, what is wrong with my measurement?

[HarmonicTHD]

Doesn't look much different than the measurements here though...


View attachment 258275

(maybe it describes something else,my German are poor)

Test Design-Subwoofer KEF Kube 8b, Kube 10b, Kube 12b - LowBeats

Bereits im November 2017 waren sie ja angekündigt. Nun stehen die neuen Subwoofer von KEF auch fläch

www.lowbeats.de

Good point and the 8b is a small sub afterall, although I would have expected at least a bit more when placed in-room especially in a corner. I might be wrong though.

At OP: where is the sub placed and where do you measure? To what position is the EQ switch in the back of the sub set to (should be on in-room)).

 

[Peerke007]

Doesn't look much different than the measurements here though...


View attachment 258275

(maybe it describes something else,my German are poor)

Test Design-Subwoofer KEF Kube 8b, Kube 10b, Kube 12b - LowBeats

Bereits im November 2017 waren sie ja angekündigt. Nun stehen die neuen Subwoofer von KEF auch fläch

www.lowbeats.de

Big difference. Mine runs from 70 Hz steep down from 75 dB to less than 40 dB at 40 Hz. But I will read this (I can read German) and if this is normal, the Kube will be send back. My little Sumiko S.5 (150 W 8") had more bass output than this 300 W 10" KEF. Sad it died.

I guess there is something wrong in the Xover in the KEF. Willem posted that his 8b gives plenty low up to 24 Hz.

 

[josefK666]

I have a Kube 10b and it goes plenty low. You say you have the gain at 9-10 o'clock. I have mine around 12-1 - I think that's what KEF recommend as a starting point. Secondly I remember when I began taking tests with REW for the first time I noticed that I didn't seem to have any sub response. I finally realised that by the time I'd got everything set up for my first measurements my sub had already gone into standby mode and I didn't see any response in REW. Seems obvious but might be worth checking.

 

[Peerke007]

Good point, although I would have expected at least a bit more when placed in-room especially in a corner. I might be wrong though.

At OP: where is the sub placed and where do you measure?

It is placed next to a wall and I measure at my listening position, as prescribed by doctor MiniDSP.

As mentioned, my little Sumiko gave more bass than this one. I assume it is not working correct. I connected it directly to the output of my preamp. So from laptop to input preamp to subwoofer. Same result. Made sure the settings of REW were correct.

 

[Peerke007]

I have a Kube 10b and it goes plenty low. You say you have the gain at 9-10 o'clock. I have mine around 12-1 - I think that's what KEF recommend as a starting point. Secondly I remember when I began taking tests with REW for the first time I noticed that I didn't seem to have any sub response. I finally realised that by the time I'd got everything set up for my first measurements my sub had already gone into standby mode and I didn't see any response in REW. Seems obvious but might be worth checking.

Oops, I did look upside down I guess. I have to put it at 3 to hear some bass.

When the sub is in standby, the LED on the back is coloured red. Mine is green during testing.

 

[Peerke007]

Just had contact with the seller. I will go there Saturday and they will have a look. They made a reservation for a replacement. Will let all you helpful people know what happened.

Thank you all.

 

[YSC]

Hope it work out. The odd thing is the apparent high pass filter in the sub, maybe the internal amp have something wired wrong

 

[JStewart]

What puzzels me is the result of the measurement I did with the REW software on the KEF Kube 10b. I read everywhere this sub can go very low. See attached file for my result. Target is set to 75 dB. Both front speakers and sub were "calibrated" at 75 dB.
Is my new sub broken, or is REW software to complicated for me (I guess the later). What do I do wrong?

This is a somewhat common occurrence with Windows.
Check mic properties

(photos shamelessly copied from a Dirac document)

Dirac Live Quick Start Guide - Dirac Live Support - Confluence

confluence.dirac.services

 

[Peerke007]

I'm going slightly mad, but the more the better. I don't know what happened, but suddenly the bass is there. Even with the volume at 12 there is plenty. Just before I had to turn it at least to 75% to hear a bit of bass. Now it is fine.

I have no idea what caused this, but that does not matter anymore. I hope it stays like this. Perhaps this weekend I will try to determine a PEQ setting for the KEF. The Veneres are already done. A shame I didn't do this years ago.

Thanks everybody for your help. Somehow it helped me . When I have the "new" curve, I will show it here.

 

[Peerke007]

This is a somewhat common occurrence with Windows.
Check mic properties

View attachment 258285

View attachment 258288

(photos shamelessly copied from a Dirac document)

Dirac Live Quick Start Guide - Dirac Live Support - Confluence

confluence.dirac.services

I will check this weekend your reply. Thanx.

 

[YSC]

I'm going slightly mad, but the more the better. I don't know what happened, but suddenly the bass is there. Even with the volume at 12 there is plenty. Just before I had to turn it at least to 75% to hear a bit of bass. Now it is fine.

I have no idea what caused this, but that does not matter anymore. I hope it stays like this. Perhaps this weekend I will try to determine a PEQ setting for the KEF. The Veneres are already done. A shame I didn't do this years ago.

Thanks everybody for your help. Somehow it helped me . When I have the "new" curve, I will show it here.

maybe you have our first proof of running in making a night and day difference

*I guess it could be some PEQ/highpass setting, or if it goes unstable could be some internal wiring getting loose?

 

[Peerke007]

maybe you have our first proof of running in making a night and day difference

*I guess it could be some PEQ/highpass setting, or if it goes unstable could be some internal wiring getting loose?

I've been listening for over an hour now. Wow, even with no PEQ on the sub it sounds great. The lows of "In the end" by Linkin Park are reproduced as good as I ever heard. I even have a CD with some church organ music (I bought that when I was visiting St James Basilica in Prague) and the KEF goes low.
"Diamonds on the sole of her shoe" from Paul Simon's Graceland proves that the sub is fast too.

I'm still confused what happened. I did what HarmonicTHD and Kervel suggested and connected the sub to the L+R output of the node 2i. Suddenly bass was there. Than I connected the node 2i to the input of the preamp and the subwoofer to the output, just like before and yes bas was still there. This weekend I will try some measurements again, but for now I will first enjoy.

 

[YSC]

I've been listening for over an hour now. Wow, even with no PEQ on the sub it sounds great. The lows of "In the end" by Linkin Park are reproduced as good as I ever heard. I even have a CD with some church organ music (I bought that when I was visiting St James Basilica in Prague) and the KEF goes low.
"Diamonds on the sole of her shoe" from Paul Simon's Graceland proves that the sub is fast too.

I'm still confused what happened. I did what HarmonicTHD suggested and connected the sub to the L+R output of the node 2i. Suddenly bass was there. Than I connected the node 2i to the input of the preamp and the subwoofer to the output, just like before and yes bas was still there. This weekend I will try some measurements again, but for now I will first enjoy.

if so likely the initial wiring or cabling is somewhat messed up, you know, sometimes you thought you plugged them in the same but in fact you didn't. nice to see your set worked out

 

[HarmonicTHD]

I've been listening for over an hour now. Wow, even with no PEQ on the sub it sounds great. The lows of "In the end" by Linkin Park are reproduced as good as I ever heard. I even have a CD with some church organ music (I bought that when I was visiting St James Basilica in Prague) and the KEF goes low.
"Diamonds on the sole of her shoe" from Paul Simon's Graceland proves that the sub is fast too.

I'm still confused what happened. I did what HarmonicTHD suggested and connected the sub to the L+R output of the node 2i. Suddenly bass was there. Then I connected the node 2i to the input of the preamp and the subwoofer to the output, just like before and yes bas was still there. This weekend I will try some measurements again, but for now I will first enjoy.

I now faintly remember that the KEF Kubes struggled with a finicky Standby circuit once. Maybe this one too. In addition I think the positioning of the gain/volume knob affects the circuit’s sensitivity. Check in the inter web and or manual.

 

[Peerke007]

Not making new measurements yet. I'm first reading and (trying to) learning on how to use REW and the Windows configuration for that. Just like buying new toys, I wanted to play immediate in stead of reading the manual first.

I possibly discovered my first faulty setting in Windows. I did not configure the Speaker output to Full Range. Would that mean that the (headphone) output of the laptop has a High Pass filter when the full range box is not ticked?

Anyway. I did made some RTA measurements with some Pink Noise to find if the low frequencies are indeed in the room. Did not use them to make PEQ settings in the MiniDSP.

Measurements I will do later, when the wife is out. She does not like me telling her to be quiet the whole time. I do believe I understand her . For now the reads on the internet are entertaining too.

 

[Peerke007]

Final update:

Still can't get a good sweep measurement of the KEF Kube 10b in REW. When I play music and do a RTA, the bass frequences can be seen, so I think it has to do with the signal form my lap top. I tried playing a sweep from a diffrent source, but the REW software can't work with that (most probably can, but I don't know how ).

So I set the cross over at 80 Hz and put some PEQ settings for the Veneres in the MiniDSP and adjusted the volume of the sub to a level I like. I reduced the volume of the left output channel of the MiniDSP a bit to compensate my hearing loss of my right ear and the not ideal position of my "listening seat".

I'm sure a professional can even improve the sound, but for me the result is very satisfying. I just start listening to music now, in stead of listening to my equipment, and I like it.

Thanks for all your replies, suggestions. I'm a happy man (for now ).

 

[jsilvela]

Final update:

Still can't get a good sweep measurement of the KEF Kube 10b in REW. When I play music and do a RTA, the bass frequences can be seen, so I think it has to do with the signal form my lap top. I tried playing a sweep from a diffrent source, but the REW software can't work with that (most probably can, but I don't know how ).

So I set the cross over at 80 Hz and put some PEQ settings for the Veneres in the MiniDSP and adjusted the volume of the sub to a level I like. I reduced the volume of the left output channel of the MiniDSP a bit to compensate my hearing loss of my right ear and the not ideal position of my "listening seat".

I'm sure a professional can even improve the sound, but for me the result is very satisfying. I just start listening to music now, in stead of listening to my equipment, and I like it.

Thanks for all your replies, suggestions. I'm a happy man (for now ).

I also bought a Kef 10b recently.

In your previous message you said:

I possibly discovered my first faulty setting in Windows. I did not configure the Speaker output to Full Range. Would that mean that the (headphone) output of the laptop has a High Pass filter when the full range box is not ticked?

Not sure I understand. Are you using the headphone out? Or how are you connecting the laptop to your amp?
If you are indeed using the headphone out 3.5mm jack: often the circuitry there is sub-par.
Then I would recommend you use the USB out if possible.

 

[Peerke007]

I also bought a Kef 10b recently.

In your previous message you said:



Not sure I understand. Are you using the headphone out? Or how are you connecting the laptop to your amp?
If you are indeed using the headphone out 3.5mm jack: often the circuitry there is sub-par.
Then I would recommend you use the USB out if possible.

Yes, 3.5 mm jack headphone out. I guess that is the problem indeed. I could use USB out with my old little DacMagic XS of course. Did not think of that before. Thanks.

 

[mike7877]

I have two Kube 10b subs.

On the website it says the subs use DSP to make the bass accurate.

It's not a bad thing - the design was purposeful - sealed design was chosen for more accurate bass (although 3dB less of it compared to a ported design). Small sealed boxes driven naturally (sans DSP) need very heavy cones and very very high high power amplifiers and handling. Or they need light cones and high-ish power.

Without DSP, for flat frequency response down to 24Hz in that box, the just the cone of the driver itself would probably need to weigh 5lbs, and you'd likely need a multi-thousand watt amp to drive it. But in this situation, the voice coil would overheat. No matter how good the speaker, thousands of watts pumped into one cubic foot = hot beyond belief in no time! So now we know that due to physics, a sealed speaker this size with a flat frequency response is an impossibility. Fortunately DSP is pretty awesome.


At this point, the "Q" of the speaker (speaker system - the speaker in the box as a unit) is on the high side. This means the spectrum around its resonance frequency has a peak in the frequency response - the middle is probably up 4-5dB, likely somewhere between 90 and 110Hz. The DSP is used to equalize this out. There's also some ringing at this peak - DSP fixes things again.

The mods to the audio signal are not perfect, but with DSP done really well, the result is sound that's almost as good as the box being 3ft x 4ft x 4ft (like it'd be naturally for your desired response), while the box is just 1ft x 1ft x 1ft !!!

There's one more caveat to small sealed box design.

But first: a benefit: your woofer gets to get less power around its resonance - DSP lowers the signal at and around the speaker's resonance frequency because it's not needed (the peak

The caveat: At really low frequencies (lower than resonance), when the driver is moving, in addition to the force placed on all woofers by the air they move to make sound, there's added resistance from the box (a lot of added resistance). The space behind the driver is very very small - just a cubic foot or so of air is there, and when that 10" subwoofer moves in and out 1" (which I believe is about its maximum excursion, maybe slightly less), you're needing to compress 1700 cubic inches of air by over 100 cubic inches! Then you need to stretch it by 100 cubic inches!
60Hz? You're doing that 60 times per second!

It ends up being a lot more work than if you just had the speaker in free air - this is why the subwoofer comes with a quality 300W RMS amplifier. If the speaker was just in open air, the pressure would equalize, eating all your bass , so good that the box is there. And good that the box isn't big enough to fit half a cow (that's probably how big it's have to be to extend to 24Hz -3dB naturally). Although the sound is good, the size of the box itself would likely ruin the aesthetic of the room and also probably affect the room's acoustics...


I don't think you're going to find a smaller more accurate sub than the Kef Kube 8/10/12b. Dual 10s was the lower limit for me because dual sealed 10s is like a single ported (you lose 3dB). I would've got dual 12b's, but there was a sale and the 12s were gone and the sale was really good and the only difference was +3dB and 3Hz lower extension that I'd be missing so I sprung for the 10s. They're good.

Yeah, basically I said this because all sealed subs smaller than a compact car have DSP to make the enclosure a manageable size. With powerful magnets/motors, Q of manageably sized sealed subs can be kept reasonably low so that DSP is able to effectively extend frequency response, attenuate peaks and minimize ringing to a level that's imperceptible

Good luck with your config

 

[Willem]

Yes, 3.5 mm jack headphone out. I guess that is the problem indeed. I could use USB out with my old little DacMagic XS of course. Did not think of that before. Thanks.

Did you ever manage to do some good measurements?