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KEF LS50 Meta with KC62

benzxc

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KEF LS50 Meta with KC62

I just recently got the LS50 Meta and the KC62. Sounds so good that I think it might be the one for the next few years at least.

HOWEVER...

There is this really weird issue with the KC62 that I haven't really seen discussed.

How I connect my system is preamp to amp & KC62 via separate RCA outputs on the preamp. When music is playing, the KC62 has absolutely no sound when the volume knob on the KC62 is at around 8:30 or lower. Once it gets to 8:30 or higher, there is immediately loud bass that corresponds to the level of music being played by the speakers (or even slightly louder).

Like, there isn't a gradual step up in volume before it gets to that level of loudness. And I basically get no use of the volume knob since any increase by a little bit will increase the volume but a lot, and as mentioned anything below 8:30 produces no volume at all.

Any suggestions? Is this a defective product?
 

AudioJester

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Maybe your preamp output does not have enough V to trigger the sub at lower volumes. Is the other output higher voltage xlr? If so maybe try and switch outputs to speakers and subs
 

Matias

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Maybe the sub is set to auto-on and on low levels it shut itself off? If so, keep it in manual mode.
 
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benzxc

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Maybe your preamp output does not have enough V to trigger the sub at lower volumes. Is the other output higher voltage xlr? If so maybe try and switch outputs to speakers and subs
Thank you. There is a third XLR output. I will try that.
 
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benzxc

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Maybe the sub is set to auto-on and on low levels it shut itself off? If so, keep it in manual mode.
Thank-you. The KC62 does not have auto on or other options. It is just on standby when it is powered on.
 
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benzxc

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I've decided to return the KC62. Seems like a serious defect to me... And shouldn't be present in a product at this price point. Which is a shame, because it is very good looking and sounds pretty good. If KEF comes out with a new version that addresses this issue I'd get it in a heartbeat.
 

AudioJester

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Have not heard of anyone having this issue before. Maybe your one is faulty.
What preamp?
 
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benzxc

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I've read some threads here and elsewhere that seems to show others have had problems with the KC62 shutting off at low volume. Sounds similar if not 100% identical to the issue that I am facing.
 

KMO

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There were quite a lot of early complaints about failure to come out of standby at low level, but that was based on input level on the signals.

You seem to be describing a potentially faulty gain knob - but if by 8:30 you mean a clock position, that seems quite low anyway. My KF92 is at 10:00.

(Unless you need to deliberately turn the volume down on the sub so you can turn it up on the source to overcome wakeup issues).

The gain and LPF knobs on the KC62/KF92 are a bit quirky - it seems to be an analogue potientiometer with click stops, and the software tries to convert the reading to digital values - 0.5dB steps for the gain - but it sometimes reads a bit inconsistently near the ends.

Maybe yours is especially quirky to the point of being faulty at the bottom. Can you just turn down the level on the source? (Ah, no) Or you could stick a 6dB attenuator in - would move you into the useful range.
 

Matias

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Have you tried contacting their customer service first? Maybe there is a setting or update to fix this. Or they can for sure say yes it's a defect that should not happen, return and get a new one which should not show such behavior.
 

KMO

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@jasoncd on that thread I linked above describes the same behaviour, I've just realised. That's why i was investigating the knobs.


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.
 
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benzxc

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@jasoncd on that thread I linked above describes the same behaviour, I've just realised. That's why i was investigating the knobs.

Yes that is the exact same thing I am facing. So glad to know I am not alone and/or not something I am doing wrong.
 

KMO

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I'd say the basic issue here, as discussed on that thread, is that when feeding a standard stereo signal, the level is FAR higher than if you're feeding a bass-managed subwoofer signal from a receiver. 15dB higher - the equivalent of 3¾ "hours" on the gain dial.

There is an auto-gain adjustment in the KC62 that detects the difference between 1 and 2 inputs connected that adjusts by 6dB (one-and-a-half-hours), to address the single-or-double input, but nothing to distinguish the "bass-management + LFE subwoofer levels" or "main channel levels".

So people using non-subwoofer-aware devices and feeding main channel RCAs will find they need the sub gain very low. The source is "too loud".

A perfectly good workaround is stick in attenuators to lower the level.

Some discussion here: https://www.audiosciencereview.com/...s-harrison-labs-attenuators-crossovers.16386/

I'd be inclined to go for 12dB, on reflection.

This is a design flaw, IME - the sub is supposed to work with stereo RCA main-channel input. I'm using a receiver on my KF92 and I'm only on 10-o'clock. I guess that's a louder sub, so maybe that's the equivalent of 11:30 on KC62. But still, it seems like nobody really needs much more than 12-o'clock. Seems like there's too much high-end gain possible and not enough low-end gain.
 
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benzxc

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I'm going to lower the output gain on my preamp (it has 4 different levels that I can select on the onboard DIP switch) to see if I can get more low end gain. Hopefully this can solve the issue as I really like the KC62.

Thanks! I'll be reporting back.
 

KMO

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I'm going to lower the output gain on my preamp (it has 4 different levels that I can select on the onboard DIP switch) to see if I can get more low end gain. Hopefully this can solve the issue as I really like the KC62.

Thanks! I'll be reporting back.
I don't think that will help on its own - you need to lower the signal to the subwoofer without lowering the signal to the speakers. Don't think you've got independent control of the two connectors on the pre-amp.

If you could also increase the gain on the power amplifier, that would help. Although that then means you'd be running the pre->power connection lower which might increase noise.
 
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benzxc

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Yes you are right, it didn't help. What helped was connecting from the speaker level / power amp side. The gain from the KC62 is much more tolerable now, however, the volume knob still does not work until nearly 9 o'clock.

Sadly, amp level connection doesn't work for me long term so I am going to have to return it or get a new preamp... The latter of which is not an option at the moment.

Hopefully there is a new updated version of the KC62 in the future which will work with my system.

Thanks again to all for the insight and help!
 
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benzxc

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I've decided to order a 12db RCA line level attenuator. Hope this helps
 
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benzxc

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So.... I've decided to return both the KEF LS50 Meta and KC62. Didn't want to deal with the hassle. I really liked how the LS50s sounded and looked, and it fit perfectly (a bit on the small side) in my room. I did speak to KEF on the phone and they concluded it was probably a system mismatch as they had never heard of any such issues before, and certainly had no reports on issues with the volume knob. I guess either I got a faulty one or my system just did not work with the KC62!
 

Fritzenheimer

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I've read some threads here and elsewhere that seems to show others have had problems with the KC62 shutting off at low volume. Sounds similar if not 100% identical to the issue that I am facing.
KEF fixed the problem of the unit falling asleep and not re-awakening.
 
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