Lyngdorf Power amp earth hum

DeadEye

Active Member
Hi All

I added a Lyngdorf SAD-2400 to my Arcam AVR390 as my new DIY speakers need a good kicking and boy does the Lyngdorf do that!

I was, until adding the Lyngdorf, using my old Pioneer receiver as a power amp with no problems at all, in fact, it worked surprisingly well.

However, I now have an earth-loop hum coming from the Lyngdorf. Only thing I've tried so far is changing from phono-phono to phono to XLR but no difference.

I suspect the problem comes from the lyngdorf having 3 pins connected (as in it's earthed via the mains lead) and the Arcam and Pioneer only have two pins connected. I don't really understand why they are not earthed, I'm sure there's good reason?

What do I do here? Do I make a power cable without the earth for the Lyngdorf or do I somehow connect the chassis of the Arcam to the chassis of the Lyngdorf?
 

Zurv

Standard Member
Hi DeadEye,

Are you sure it is because caused by the addition of the new amp? It could be that it was always there and your old amp did a good job of filter it out.
I had the same issue with my tube amps and audio from my gaming PC. When the PC is fully rocking (also over clocked and mod'd) it created noise (EMI? coil whine?) that flowed thru the HDMI to the TV to the AVR, etc.
using my NAD amp i couldn't hear it (it filtered it out), using my tube amp i could still hear it. ie, it wasn't the tube amp that was adding the noise.

It might be ground problems but it might not be. (i spent a few $k running all new power lines to my HT area to fix my hum and that wasn't the problem. (the video card was in my case.)

Is the hum there when sources are playing, but muted? (that helps troubleshooting) If so, maybe start disconnecting sources and see if you can narrow there it comes from.

(or it could be ground... so get a UPS or filter or something. But my gut tells me it is something upstream from the amp.)
 

DeadEye

Active Member
Thanks I’ll do some investigation. It’s gone from absolute silence to fairly audible 5 meters away.
 

DeadEye

Active Member
So after investigation it’s the HDMI cable going to the TV that causes the hum.

The 10m HDMI cable which is very buried in the wall and ceiling.

Turning the tv of at the mains makes no difference.

So, should I try and earth the power and and receiver? Or try one of those plugs that removes the earth?
 

Zurv

Standard Member
What happens if you directly run an HDMI from the TV to the AVR? Does that fix the issue?
Is you TV doing eARC? It could be another device connected to to the TV that is causing the problem. (get something long on amazon and return it... or keep it if that fixes the issue and use it as a new run.)
(That was/is my issue. video card caused the issue. passed it to the TV, which passed it to the AVR, which then passed it to the AMP and speakers.)
 

DeadEye

Active Member
I'll try a another cable but replacing the current one is not an option sadly.

I'll also butcher a power cord with the earth chopped as an experiment.

All my kit is being the lounge in a cupboard and all the cables where put in before the house was plastered. I noticed that even with everything turned off apart from the power amp, there was still some very feint noise from the speakers. The TV was probably still on but on standby. The projector which is also in the cupboard didn't have an effect. My PC is also in the cupboard.

The only things connected to the TV is the HDMI from the Arcam, Ethernet and power.
 

rccarguy2

Well-known Member
What if you just have power cable to the anp, no audio cables from arcam to lyndorf?
 

DeadEye

Active Member
What if you just have power cable to the anp, no audio cables from arcam to lyndorf?
That's how I started, then added the phono cables, then powered on the Arcam then added Sky Q via HDMI (also in cupboard), then powered on Sky Q etc.

Only when adding the TV HDMI does the noise come. And it's only the front L/R via the Lyngdorf.
 

DeadEye

Active Member
So….

Different HDMI cable helped but butchering a power cable (cutting the earth) fixed the problem.
 

rccarguy2

Well-known Member
So….

Different HDMI cable helped but butchering a power cable (cutting the earth) fixed the problem.

I think that's called lifting the earth which is dangerous thing to do?
 

DeadEye

Active Member
I think that's called lifting the earth which is dangerous thing to do?
I don’t know for certain but it must be earthed for a reason. However, not many power amps have an earth pin.
 

DeadEye

Active Member
Maybe earthing the receiver is the better thing to do.
 

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