New Kef Kube 2 Humming

GrotShot

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Bought a set of Kef 2005.3 speakers yesterday and connected them to my Denon 500SD all in one system. This is temporary until I can find a Denon 1909 in stock and at a decent price! I've had the Denon 500sd for 4 years with no problems but want to upgrade having just bought a new TV and BluRay.

I've connected all of the satellite speakers, removed the speaker wire from the amps sub speaker terminal (old sub was passive) and used a single RCA from the amps sub pre out to the Kef Kube 2 left input. I set the sub volume to full and crossover to max as recommended in the Kef paperwork.

When I powered up the system and did a signal test it took a fair volume to get the sub to power from Red (standby?) to Green (active?) and once it was on I noticed a quite nasty hum!!

With the amp off and the sub still on green the hum is still present. I've tried powering the sub from the same block as the amp/tv/sky+/bluray and also from a separate socket but with no change. With it powered from another socket I can get rid of the hum by powering off the amp/tv/sky+/bluray socket but that's not exactly going to help!!

Has anybody else got this setup or experienced hum with the Kef 2005.3 speakers? Any thoughts would be appreciated.
 
Hi there,

Sorry to hear your having trouble with your sub :(

I doubt this will be the case but I thought I might put it forward anyways. The only time I've experienced a hum from the Kube 2 is when it's been moved or knocked. Each time I discovered that the coaxial cable was causing it - simply fiddling with the connection resolved the issue.

Anyways I hope you get it sorted, it's a shame to have trouble with such a great set of speakers. Good luck!
 
It's OK, I've fixed it!! :thumbsup:

Having done a bit more searching within the forum, I discovered several threads relating to earthing issues and this appears to be exactly what the problem was.

The Denon 500sd only has a 2 core power cable meaning no earth connection. The KEF sub has a 3 core power cable and is therefore earthed to the house electrical system.

I got a piece of wire, bared both ends and connected one end to the amp by unscrewing one of the casing screws and connected the other end to one of the screws holding the power socket face plate to the wall. Hey presto, no hum or noise whatsoever :clap: !

Hope this helps others.
 
HI Grot Shot,

Even i am having the same humming noise with me new KUBE 2 subwoofer. I have paired KEF 2005.3 + KUBE 2 with DENON 1909. Can you please let me know whether the same earthing issue could be the cause?

Regards
Lucky
 
I guess it could be. Still waiting for the Denon 1909 to come back into stock at Richer Sounds so hope to see soon.
 
Hi Grot Shot

I have a 1909 (has no earth) with Kef 2005.3 and have a really bad humming from the KUBE 2 sub. I think it's an earthing problem because I plugged the sub power cable into a short extension with the earth wire removed and the hum went away totally. I don't fancy permanently removing the earth because i don't think the sub is double insulated. Before I try your fix can I just check exactly what you did, am I right in thinking that you connected a wire between the case of your amp to one of the fixing screws that holds your 240V 3 pin wall socket in place?

Cheers.
 
Terrytibbs,

That's exactly what I did. When I eventually get the new amp I will look at a slightly neater method where I will put a removable 3 pin plug on the amp. This will enable a wire from the earth pin of the plug to be wrapped around the power cable to the amp and earthed on the casing.

This at least will make it self contained and not leave wires dangling around the living room! I find it bizzare that we are left in this position of DIY electrics by two major Hi-Fi companies ! :mad:
 
Thanks for that, I've been pulling my hair out, I tried a direction sub cable with no effect and a ground loop isolator that reduces the hum but I needed to turn the sub volume down to about 25%.

I tried it last night with some speaker wire and it worked a treat. I think I will fit a 3 pin plug and wrap the earth around the cable as suggested.

Thanks again
 
Terrytibbs,

Managed to buy a Denon 1909 today although in Silver. Just finished my first attempt at setup and with the supplied power cable I had hum on the Kef sub!! Made up a cable with Live & Neutral going to the IEC power connector and the earth as a flying lead which I connected to the casing using the screw on the left, back. Switched on and no hum :thumbsup:.

All I've got to do now is spend 3 days setting up the amp ! :rolleyes:
 
Hi Guys,

I had the same issue with humming noise in my KUBE2 subs- looked at couple of websites & then bought a subwoofer cable with earth lead (for ÂŁ23) & worked a treat.

Its very simple - cable comes with earth leads on both the ends & its directional. Plug one end in the amp & other in subwoofer, & connect each of the earth lead to chasis of the amp & subs.

there you go,,, switch on & no humming noise at all.

you can buy the cable from
The Multi-Room Company - Dealer area

call them & enquiry about sub A cables.

Hope it helps

Regards
Lucky
 
Any of you fellas upgraded from a 2005.2 sub to the new Kube, is it as good as the 3005 sub as I'm a little disappointed with the the original 2005 one.
 
Bringing this back to the top. The earthing solution saved me. Many thanks
 
Hi Guys,

I had the same issue with humming noise in my KUBE2 subs- looked at couple of websites & then bought a subwoofer cable with earth lead (for ÂŁ23) & worked a treat.

Its very simple - cable comes with earth leads on both the ends & its directional. Plug one end in the amp & other in subwoofer, & connect each of the earth lead to chasis of the amp & subs.

there you go,,, switch on & no humming noise at all.

you can buy the cable from
The Multi-Room Company - Dealer area

I have this problem but only when I have Sky on, unplug sat leads from wall hum goes away, Id like to try one of these leads, Is there a link to the product Itself ?
Cheers
 
Just wanted to add this as I had the same problem however my sub wire runs over a 15M cable buried in walls and ceilings so replacing the cable wasn't an option.

Search ebay for "ground loop isolator"
ÂŁ3.95 -

Perfect and back to normal
 
created account to post, (sorry for necro) might help someone

kube 2 hum-

disconected everything apart from power cable- turn on - hum
volume/freq= doesnt make a diffrence ie doesnt get louder/quieter.

Solution i got-
only plugged in 1 RCA input rather than both.

0 hum.

seems to be earthing via RCA on my amp.
will be buying new RCA conects for it asap.
 
Sorry for bumping a very old thread!

I have a similar system (Onkyo TX-SR508 w/ Kef Cube I) and I'm also experiencing the "hum" noise.

If I understood correctly, what the OP said is that he connected a wire from his Denon chassis to the earth prong on the power socket. My subwoofer has 3 core power cable but the AV receiver only has a 2 core power cable. In my case, connecting the subwoofer to the power outlet without the earth connection, stops the "hum". So, doing what OP mentioned might solve the issue for me. Is this safe and valid way of fixing the issue?
 
I had the hum and did the wire thing which fixed it. Tried everything to resolve the issue beforehand and this was a last resort as is doesn't seem the safest but I've had no problems for two years.

Eventually I'm just going to buy a soundbar and do away with the sub and av I think.
 
I have the humming issue with a new (2019) KEF Kube 10b. I didn't at first, but then it started. By reading comments made here, I decided to determine whether the power amp feeding the speaker-level inputs was somehow causing the hum (Rotel 100W RB-870BX, from early 90s). Sure enough, when I saw that both the pre- and the power amp that sent a signal to the KEF (through the speaker outputs of the power amp) had 2-prong power cords, I believed I had found the problem. To verify, I tested the KEF with a different power amp that has a 3-prong plug, and the hum was gone. So, I plugged my Rotel power amp cord into a heavy-duty three-prong extension cord, and plugged that into my power strip/surge protector. The hum disappeared. Then, of course, it came back. Then I discovered that the CD player I was using had gone into standby mode. When I turned it back on, the hum disappeared.

Summary: In my experience, the amp providing the signal to the KEF Kube 10b needs to have a 3-prong plug, AND the signal source must be on, but not necessarily making any sound.
 

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