KEF Unicore

[raistlin65]

92 dB at 30hz... even a Sonos Sub can do 99+ with higher WAF form factor

I think if this were a $700 to $800 sub, it would have more of a place as a price / performance value for those that absolutely wanted something this size and didn't need a lot of output.

But I'm sure they'll sell plenty to people who trust the KEF brand name about the specs, believe that a new technology is always better, and/or just want something to match their LS50 or LSX.

Many speaker brand manufacturers make subs that are way overpriced at full MSRP. Yet people buy them because they aesthetically match the main speakers.

 

[wgb113]

It's a shame they didn't build in preset cross-over & DSP setting for use with the LS50/LS50W/LSX, similar to what Dynaudio's done with their SUB6 and 18S.

 

[Shadaraman]

It's a shame they didn't build in preset cross-over & DSP setting for use with the LS50/LS50W/LSX, similar to what Dynaudio's done with their SUB6 and 18S.

For LS50 that would make sense, but LS50W and LSX have their own crossover settings, so the sub should be in LFE mode and bypass the crossover (there's actually a section in the KC62 manual specifically for those speakers).

 

[napilopez]

Just learned KEF published a white paper(PDF) for the KC62 on their website after all! A lot more information about the technology and useful measurements.

Curiously the sub-bass results look noticeably better than I was previously told. On the topic of output, this is the most relevant graph:

Here max output appears to be about 85dB at 20Hz and 81 dB at 10Hz, before room gain. Interesting to see room gain estimations as well, though I'm not sure how those values were determined.

The results here actually look significantly better than what I previously shared, so I'm not sure if someone had the wrong info or what. I guess we'll see once my review unit actually arrives!

Meanwhile, here's the THD graph on the improvement with their newfangled distortion reduction tech:

Tis' an interesting read as usual. Glad we got more details.

 

[voodooless]

Curiously the sub-bass results look noticeably better than I was previously told.

Here max output appears to be about 85dB at 20Hz and 81 dB at 10Hz, before room gain. Interesting to see room gain estimations as well, though I'm not sure how those values were determined.

Not really.. a proper guestemate was 90 dB at 20 Hz, it doesn’t even reach that.

Meanwhile, here's the THD graph on the improvement with their newfangled distortion reduction tech:

Not a bad improvement, about what is to be expected from this kind of tech. Respectable for a small sub.

 

[napilopez]

Not really.. a proper guestemate was 90 dB at 20 Hz, it doesn’t even reach that.

Not sure what you mean; earlier in the thread, I shared I'd been told by KEF the subwoofer could reach 80dB at 20Hz anechoic, and then I estimated about 90dB in-room based on past experience. This document suggests 85ish anechoic and 98ish in room. So the whitepaper shows better results than I'd been told. (Edit: what is "good enough" is another matter that's been discussed a lot already )

 

[NTK]

Compression starts kicking in at <50 Hz for the "moderate listening level", and <70 Hz at the "high listening level".

 

[Kachda]

Just learned KEF published a white paper(PDF) for the KC62 on their website after all! A lot more information about the technology and useful measurements.

Curiously the sub-bass results look noticeably better than I was previously told. On the topic of output, this is the most relevant graph:

View attachment 110197
Here max output appears to be about 85dB at 20Hz and 81 dB at 10Hz, before room gain. Interesting to see room gain estimations as well, though I'm not sure how those values were determined.

The results here actually look significantly better than what I previously shared, so I'm not sure if someone had the wrong info or what. I guess we'll see once my review unit actually arrives!

Meanwhile, here's the THD graph on the improvement with their newfangled distortion reduction tech:

View attachment 110205

Tis' an interesting read as usual. Glad we got more details.

Would be great it this is correct. Have you got a sample to do testing?

 

[napilopez]

Would be great it this is correct. Have you got a sample to do testing?

I should be getting one soon, though who knows when with this snowstorm...

 

[whazzup]

Compression starts kicking in at <50 Hz for the "moderate listening level", and <70 Hz at the "high listening level".

View attachment 110211

Curious, how does compression work from a physical perspective? Is the excursion reaching the max and hence the driver is mechanically/electronically limited to move beyond what's acceptable? Hence resulting in the performance we see above.

 

[voodooless]

Curious, how does compression work from a physical perspective? Is the excursion reaching the max and hence the driver is mechanically/electronically limited to move beyond what's acceptable? Hence resulting in the performance we see above.

It’s just a band limited dynamic limiter. Nothing fancy or special. The PA industry has been using these things for years.

 

[voodooless]

Not sure what you mean; earlier in the thread, I shared I'd been told by KEF the subwoofer could reach 80dB at 20Hz anechoic

Yes, that’s why I said “proper guestemate” That was based on what would be physically be possible given drivers and excursion. Since we are even below that, we can conclude that either Xmax is lower than expected and/or that the box is just to damn small. It’s probably the latter.

I’m also wondering what that wiggle at 25 Hz is about?

 

[raistlin65]

I’m also wondering what that wiggle at 25 Hz is about?

Maybe something going on at the tuning point?

 

[voodooless]

Maybe something going on at the tuning point?

What port?

 

[raistlin65]

What port?

Sealed subwoofers are tuned.

 

[voodooless]

Sealed subwoofers are tuned.

Yes, but they don’t exhibit any sudden change in response. Even a high-Q design can be transformed into a low-Q design using a transform function (Linkwitz Transform in this case). There should not be any strange wiggles. It might have something to do with the curious single magnet, double VC structure. Possibly the two woofers are not perfectly equal. Would make sense since the voice coils are not the same diameter.

In any case, it should be quite inconsequential for the sound. In room you will have far larger variations.

 

[BrokenEnglishGuy]

i have a question about volume, i downloaded a app in my smartphone that is saying im listening at 90-94dB with a fews 100dB peak, if the sub only can go up 90dB is not a lot? or im measure in the wrong way? 90 - 100dB at 1m is not a lot in my smartphone with my speakers 90db is moderate xD

at 90dB the woofers of my speakers barely move xD

 

[voodooless]

i have a question about volume, i downloaded a app in my smartphone that is saying im listening at 90-94dB with a fews 100dB peak, if the sub only can go up 90dB is not a lot? or im measure in the wrong way? 90 - 100dB at 1m is not a lot in my smartphone with my speakers 90db is moderate xD

Nobody said it could only do 90dB. It's just restricted on the low end. Above 55Hz it goes to 100dB already. Also note that we've been talking about the raw SPL without roomgain. With proper placement (corner or wall), you well get an additional 6dB of output on the low end. See pictures here.

 

[BrokenEnglishGuy]

Nobody said it could only do 90dB. It's just restricted on the low end. Above 55Hz it goes to 100dB already. Also note that we've been talking about the raw SPL without roomgain. With proper placement (corner or wall), you well get an additional 6dB of output on the low end. See pictures here.

I saw that, but for example now im listening at avg 86dB and max 95dB, that mark my smartphone.
But that is really moderate XD, when the speakers are silent i get 40dB of noise in my room, that said the speakers are at 95dB? i mean if that thing only produce 100dB at max volume is too low xD
I mean when the speakers are a a little loud they are at 100dB avg with 108dB peak

edit: my mom smartphone mark a stable 82dB avg and 84dB peak while my smartphone mark avg 87dB peak 92dB, i think my smartphone is just broken xD, my mom's smartphone mark the noise more stable too. My smortphone as i know measure really bad, but if this volume is 84dB
90dB-100dB is quite a lot.

 

[Willem]

These smartphone apps are mostly next to useless unless designed for the actual model of your phone.