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new KEF KC62 dual 6.5" subwoofer

Supalite SV

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I’m not sure what you’re trying to show me. I had no problem getting a wonderful Dirac measurement with this subwoofer. It produced an ideal sound for my apartment and fit perfectly into my decor.

My issues were: 1. Keeping the sub from going to sleep at low volumes, 2. A wicked turn on pop when coming out of standby, and 3. A hum which was intrusive enough to be heard. That’s why I had to unfortunately return it.
Well. After Dirac Sub "Activation" I had no issues with subwoofer ever after, no pops, auto sleep during low volumes or hums... My reply was to proof SubOut issue walk-around to Keep our M10/33 series useable the way we want. Thanks for your replies.
 

Willem

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If we compare 43 liters with 100 liters, why not to take Arendal 2V and finish the mockery?
I would prefer to compare the KF92 with the Arendal 2s because both are sealed designs, and both are about the same price. The Arendal 2v is ported, much bigger again, and also rather more expensive than the KF92.
 

fcracer

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Well. After Dirac Sub "Activation" I had no issues with subwoofer ever after, no pops, auto sleep during low volumes or hums... My reply was to proof SubOut issue walk-around to Keep our M10/33 series useable the way we want. Thanks for your replies.
I think I’m starting to understand the thread here, but I’m still unclear on what exactly you did to overcome the issues. If possible, please elaborate the steps you took. I know many M33 and M10 owners would appreciate knowing how to make low sensitivity subs work with the low voltage sub output. I think even NAD may appreciate hearing your solution, since their support made it clear that I’d need to choose another subwoofer with a variable input sensitivity.
 

Chrispy

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I think I’m starting to understand the thread here, but I’m still unclear on what exactly you did to overcome the issues. If possible, please elaborate the steps you took. I know many M33 and M10 owners would appreciate knowing how to make low sensitivity subs work with the low voltage sub output. I think even NAD may appreciate hearing your solution, since their support made it clear that I’d need to choose another subwoofer with a variable input sensitivity.

Just how low is the sub pre-out level on the Nads? What subs arent of sufficient sensitivity? The plate amp subs I have don't need much....my pro amp driven diy subs need a bit more but still are happy with all my avrs' pre-outs....
 

fcracer

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Just how low is the sub pre-out level on the Nads? What subs arent of sufficient sensitivity? The plate amp subs I have don't need much....my pro amp driven diy subs need a bit more but still are happy with all my avrs' pre-outs....
The M33 sub out is maximum 1.1V. The pre-out is maximum 3.9V for comparison. KEF does not provide any information on what input voltage it requires to reach full output.
 

Chrispy

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The M33 sub out is maximum 1.1V. The pre-out is maximum 3.9V for comparison. KEF does not provide any information on what input voltage it requires to reach full output.
Yeah many subs don't share the spec. Was that the spec provided by Nad or a bench test bear it out or ? I'd think 1.1V would work with all my plate amps, tho; my pro amps are 1.4V so would fall a tad short. Curious what subs have been tried....
 

fcracer

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Yeah many subs don't share the spec. Was that the spec provided by Nad or a bench test bear it out or ? I'd think 1.1V would work with all my plate amps, tho; my pro amps are 1.4V so would fall a tad short. Curious what subs have been tried....
This is from NAD’s spec. The only reason I looked up the spec is because it wasn’t sufficient to wake the sub at reasonable volume levels. I assume the KEF needs 2V to work correctly, but that’s purely my speculation.
 

sigbergaudio

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As a small subwoofer manufacturer I can attest to the fact that it's hard to make this work perfectly across any number of sources or preamps apparently without any shared standards.

We have customers who struggle with the subwoofer not turning on at very low levels, and others where the subwoofer won't even turn off due to some kind of constant signal from the source.

Luckily the sensitivity is adjustable, but to get this perfect for every setup out of the box is probably impossible.
 

Dennis_FL

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At only 3 months old, mine went dead. Probably a circuit board/power supply. The LED lights are out and no sound.

So I sent it back under warranty using the original box and packaging (over $70 insured) and UPS was kind enough to poke something through the box and damage one of the two speaker surfaces.

If I had it again, I'd have double boxed it. It is pretty heavy at 32 pounds, and the box is really small and no handles. Insurance claims take weeks.

I filed the claim at UPS and I swear, they lady at the UPS store was prepping me for the inevitable. "You know, it needs to be packed well, and because of the value, we'll need pictures, and .... " she went on with no trace of it being UPS's fault....it had to be me.

So, it turns out I had pictures of all sides before shipping and KEF sent me the arrival pics. Nothing much you can do when they pierce it with something and also it was dropped on a corner.
 

73hadd

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Regarding the high pass implementation, I am under the impression that it goes through adc/dsp/dac?

I really like the size of this sub but without specific measurements of the crossover feature I am not sure what to do.

Question for the contributors here, what is more accurate of these statements, "the KC62 crossover feature is:
a. probably better than other subwoofer included high pass feature
b. probably the same as other subwoofer included high pass
c. superior to minidsp as a crossover
d. superior to an outboard analog high pass
e. without measurements, what is the point in guessing?

If the goal is only to avoid "bit loss", does anyone recommend an outboard analog high pass? Yes, we lose the benefit of DSP (which is notable) but have tampered with the signal less? This is more important if you do not plan to do any DSP to the mains. I would not hesitate to do additional DSP to the subs.
 

jasoncd

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Hi all, new here, I've had the KC62 for a week now and would like to know roughly where everyone is setting the gain dial? My setup is pretty basic - a Bluesound Powernode powering two bookshelves, with the KC62 connected to the subwoofer out on the Bluesound. The Bluesound has the subwoofer crossover enabled so it's LPF/HPF to the sub and my speakers. Crossover is set at 100hz (my speakers have very little low end).

Having the gain dial set at the 9 o'clock position and the KC62 is really loud. If I go down one click, it's a little too quiet, and if I go down just a few more clicks it's off. I feel like I'm missing something stupid here. I've had other subs connected in the same setup, and they don't seem to have that issue, ie I'm usually in the middle of the gain dial and going up or down gives more fine control. If I get near 10 or 11 o'clock on the KEF it feels like MAX gain with the KEF near the limit.

There's no gain control in the Bluesound app. Tried changing the RCA cable. Tried plugging into the the other (not labled LFE) input on the KEF. Tried Manual/LFE settings on the back of the KEF.

Feel like this is the opposite of the 'won't wake from standby' problem, as if the KEF is getting a very high voltage signal. But I thought my Powernode was like the NAD's sending only 1.1v.

Any ideas?
 

KMO

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I've got the KF92, which is similar, and the gain adjustment is quite fine. It's a pretty precise 0.5dB on each click, with 5 clicks between each "dot" on the dial. I understand the KC62 may be slightly less fine, but should be similar. I've got my KF92 set to 10 o'clock, for what that's worth, but totally different system. Given that the KC62 is like 3dB less output, your 9 o'clock does suggest a quite high input level.

One thought on level here is that the Bluesound is a stereo source system that doesn't have to deal with LFE signals. It's quite possible that their bass-managed subwoofer output is 10dB higher than that from a receiver because they're not reserving headroom for the LFE. It's pretty conventional for a bass-managed analogue sub interconnect to be -15dB relative to the main channels. 10dB for the LFE and 5dB to give some headroom for bass management summing. They may be at only -5dB, leading to your low sub gain.

The LPF knob on mine (and I've seen another report here) has some slightly funny behaviour at extremes - the last couple of notches aren't distinct, it kind of snaps to the end. So it jumps from 46Hz to 40Hz, between 7 and 8-o'clock. I've not done the same test on gain, but can imagine it's the same.

I get the impression that the knobs are analogue potentiometers with physical clicks, rather than digital selectors, and it's not always getting a precise measurement of position, particularly at the extremes.

So what you're seeing may be a manifestation of the knob sensing problems but higher up the dial? You may actually find sweeping the knob down and back up to a position gives different behaviour.

(I've got the luxury of an AVR where I can make 0.5dB gain adjustments externally, so I can just choose a rough position like 10-o'clock and fine-tune elsewhere).

To add to the confusion, the KEFs have a "Smart connect" feature that applies a gain if it detects only one input signal (not sure if this has to be to the LFE). This takes a few seconds to kick in, which is something to be aware of when doing automatic calibration. Although it's not much more of a problem than having to get the auto-wake-up to respond.
 

jasoncd

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One thought on level here is that the Bluesound is a stereo source system that doesn't have to deal with LFE signals. It's quite possible that their bass-managed subwoofer output is 10dB higher than that from a receiver because they're not reserving headroom for the LFE.

Appreciate the thoughts KMO!. Above is the only thing that makes sense to me. But at the same time, 0db or 'middle of the gain selection' on another B&W subwoofer I'm demoing versus the KC62 is equivalent to 9 o'clock on the KEF.

The thoughts about the behavior of the LPF knobs is interesting, I'm going to do some up and down sweeps and maybe come at the gain from the other direction.

My unit does wake up consistently and quickly, even with just turning on the TV which the Bluesound is also connected to.

I googled KEF's SmartConnect, and found:
KEF’s SmartConnect technology determines if you are using a mono input or a stereo input and adjusts the gain to ensure you are getting the proper input level.

I'm not sure which would have higher gain applied, the mono or the stereo signal. The Bluesound only has a single RCA Sub Out, and I'm not sure if connecting a Y cable to give me two RCA's on the KEF's end would actually trick the KC62 or not. Worth a shot I guess.

My room is 15 x 13 x 8 feet. Not a big room, but not small enough that the KC62 should be overpowering it. Down the road, I'd like to replace the Bluesound with something that has room correction. But I can't do a full size AVR, and the smaller options at the moment are pretty pricey (NAG, Lyngdorf, etc). I have no experience with room correction, but I'd think they may have more options for things like subwoofer gain.

I did get a microphone today, and played around with REW testing various settings. The graphs looks strange to me, but it might all be my room and not the sub. But hopefully it will be at least some data points when testing.
 

sigbergaudio

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It's important to understand that the gain setting on the back of subwoofers is just that, a gain setting. It's not a volume knob. The point is to match the gain with your power amplifier / speakers. So even though you have to set it to 9 o'clock, that doesn't imply anything about whether you're close the the maximum capacity of the subwoofer, it just implies a gain mismatch (which you are fixing by setting the gain).

So the B&W isn't necessarily "better" or have more capacity because the gain can be at 0dB, it just means the internal gain structure/value in the two subwoofers are different.
 

jasoncd

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It's important to understand that the gain setting on the back of subwoofers is just that, a gain setting. It's not a volume knob. The point is to match the gain with your power amplifier / speakers.

This makes sense, thank you.

With more consideration of the knobs from KMO, I did some more deliberate testing. Starting with the gain knob all the way down, there's no sound from the subwoofer. Going up one click, also no sound. Same for two, three and four clicks up. At five clicks up, the woofers start to move but the volume level is very low. At six clicks up, the sub is mildly too loud. And I am not bass shy!

So maybe this is just a bad pairing with the Powernode, and somewhere between them gain/volume are lining up in a way that does not give any fine adjustments.
 

KMO

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At five clicks up, the woofers start to move but the volume level is very low. At six clicks up, the sub is mildly too loud.

How profoundly irritating. It looks like that resembles what I saw at the upper end of my LPF knob. First 4 clicks down did nothing, LPF remained at 140Hz, rather than stepping down through 136/132/128/124Hz. Then 5th click gave 120Hz as expected, then smoothly down at 4Hz per click.

But it appears your fifth click is still somewhere lower than it should be, then your sixth click is probably correct.

So you've got this dodgy KEF knob input which is only dodgy at its extremes (maybe they thought they'd get away with it), but that then collides with what seems to be an unusually loud output from the PowerNode. Either one would be okay on its own, but together :facepalm:

Sticking a 9-10dB RCA audio attentuator in your link might solve your problems. (Although you might then enter the world of reluctant wake-up). I guess just 3dB would do - you only need to get past that 5th/6th click. But complain to the Powernode people. It's pretty poor to make a device with no output level control for the sub, and if they're not going to have a control it really shouldn't be outputting at the equivalent of a receiver at "+10dB" trim.

Oh, and complain to KEF too. Their knobs should work. (Are they really analogue pots? Are they that much cheaper than a nice digital encoded knob?)
 

jasoncd

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How profoundly irritating. It looks like that resembles what I saw at the upper end of my LPF knob. First 4 clicks down did nothing, LPF remained at 140Hz, rather than stepping down through 136/132/128/124Hz. Then 5th click gave 120Hz as expected, then smoothly down at 4Hz per click.

But it appears your fifth click is still somewhere lower than it should be, then your sixth click is probably correct.

So you've got this dodgy KEF knob input which is only dodgy at its extremes (maybe they thought they'd get away with it), but that then collides with what seems to be an unusually loud output from the PowerNode. Either one would be okay on its own, but together :facepalm:

Sticking a 9-10dB RCA audio attentuator in your link might solve your problems. (Although you might then enter the world of reluctant wake-up). I guess just 3dB would do - you only need to get past that 5th/6th click. But complain to the Powernode people. It's pretty poor to make a device with no output level control for the sub, and if they're not going to have a control it really shouldn't be outputting at the equivalent of a receiver at "+10dB" trim.

Oh, and complain to KEF too. Their knobs should work. (Are they really analogue pots? Are they that much cheaper than a nice digital encoded knob?)

Profoundly infuriating is right! I think you nailed the knob behavior, and that is certainly not helping, but I agree Bluesound is likely the main culprit here. Seems like both companies could have been more thoughtful in some of these details. I don't get how there appear to be some app control for the sub IF you have the LS50 Wireless, but nothing if you don't. Seems like they could have added Bluetooth to the KC62 and had some app control without much extra effort.

I just recalled Darko has a Youtube video of the Powernode and the KC62. He didn't mention anything similar to this, although he did cross his LS50 Meta much lower than my setup.

I did google the problem from the Bluesound end, but only found support threads related to subwoofer output too LOW with the Bluesound Node and Powernode. These were older posts, so maybe somewhere Bluesound decided hey let's just bump up that sub out.

I've never needed an attenuator, and wasn't really aware of them, but that sounds like just the thing. Worth the small cost to give it a shot anyway, so I'm ordering a few, thank you!
 

sigbergaudio

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With more consideration of the knobs from KMO, I did some more deliberate testing. Starting with the gain knob all the way down, there's no sound from the subwoofer. Going up one click, also no sound. Same for two, three and four clicks up. At five clicks up, the woofers start to move but the volume level is very low. At six clicks up, the sub is mildly too loud. And I am not bass shy!

Sounds strange. I would consider reporting this behaviour to Kef to check if that's working as intended, or is actually a malfunction.
 

nothingman

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See this thread and post for a lot of relevant information:


From the bottom until 10 o clock, the jumps are big, then from 10 o clock to 3 o clock, it should be linear and about 4db per click marked dot.

So you’re firmly in the “big jumps between clicks“ zone, but that doesn’t explain the “no sound the first three clicks” problem you’re having.

I don't get how there appear to be some app control for the sub IF you have the LS50 Wireless, but nothing if you don't. Seems like they could have added Bluetooth to the KC62 and had some app control without much extra effort.

Not really. There is no sub control via the app if you have the WII, there is only control over aspect of the signal that the WII sends. Its the sort of controls you wish your Node had: gain control on your sub out. You can’t really blame them for not packaging in a bluetooth app on top of this. It’s an insanely small cabinet with novel mechanical engineering and two 500W amplifiers crammed inside. Woulda been great to have app control, but it’s not crazy that they didn’t include it on the first go.

Hi all, new here, I've had the KC62 for a week now and would like to know roughly where everyone is setting the gain dial? My setup is pretty basic - a Bluesound Powernode powering two bookshelves, with the KC62 connected to the subwoofer out on the Bluesound. The Bluesound has the subwoofer crossover enabled so it's LPF/HPF to the sub and my speakers. Crossover is set at 100hz (my speakers have very little low end).

Have you tried lowering the LPF out of the Node to see if your problem really just is too much room gain at the upper end of the KC62’s range? Maybe you can leave the KC62 at “six clicks” but lower the LPF to somewhere in the 45-70hz range like KEF recommends for the LS50 (not much low end there either) and then you’ll find that the KC62 isn’t too loud where the KC62 is playing. Just an idea.

For example, I run my HPF at 95hz on my LS50 which only robs them of bass further, and even then my LPF out is set to 60hz because of all the gain between 70 and 95hz in my room. That setting creates a bump that needs to be ironed flat by Dirac/DSP still. You may just be playing the KC62 at too high of a frequency and it’s messing with your perception of the volume setting. Just a thought.
 
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sigbergaudio

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Sounds weird. 4dB is a lot, how can you possibly get the right level with that implementation?

Is it made for systems with subwoofer level support only?
 
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