BS9000/Lab 3's humming noise problem.

19 replies

Hello all.

I have a problem with the following set up and wondering if anyone can help.

BS9000 with a pair of beolab 3's running with B&O PL cable (not bosscom). 

 

When the power is switched on the system and the speakers there is an annoying high pitched humming noise that I can't resolve.  The noise is present all the time even when the music is playing (only heard at low volume and is drowned out at high volume).  I'm also getting a static charge onto the BS9000 floor stand to touch.  I have moved both items to another room where the same still happens but when I link the lab 3's with my BC2 the noise stops. 

Anyone had this problem before?

 

Thanks Ian

 

Sorry I forgot to sell hello (newbe) !!!!

There are others here better informed who will tell you exactly but I believe this issue has cropped up before (more than once) on this site. I seem to recall that there are different types of Powerlink cable and using the wrong type will lead to the problem you describe.

Oh and welcome to Beoworld - I hope you enjoy😁

Ian,

Welcome to Beoworld.

There are a very large number of reasons for the type of problem you have described, so we will need to narrow it down with a few questions as below:-

  1. Has the Beosound 9000 and Beolab 3 configuration previously worked without the problem ? In other words has the problem occurred since you purchased or changed the configuration ?
  2. What version powerlink cables are you using ? If they are standard B&O powerlink cables, if they are Mark III then there will be a small triangle on the plug next to the alienment key (dent in metal shield)
  3. How long are your Powerlink cables ? Are they routed with power or other signal cables ?

Given that you say that you have connected the Beolab 3's to a BeoCentre 2 and do not have the problem, I am assuming you used the same Powerlink cables, please confirm.

Location: Hampshire, England

Hi

The lab 3's are 2 years old and the BS9000 is a mk1 1998 (upgraded mk3 drive and chip-NUMUSIC etc) just had a full service by B&O.  The set up is new to me as the lab's were part of another system before which included the BC2 (rear speakers that weren't being used).

 I had Bosscom cables first of all but have now changed these for mk3 PL B&O cables (brand new).

 The PL cables are 10 meters long and are not yet chased into the wall (just hanging) but the power cables are not that far away.

 I also get the static in the stand when the BS9000 isn't pluged into the mains but just the lab3's are connected via PL and the lab3's  are powered up.

 ??????????

B&O are saying it could be an earthing problem....any idea how I earth a 9000???

Ian,

I agree, are you a technical person who has available a multi-meter ?

Location: Hampshire, England

Ian,

The Beosound 9000 does not actually have a mains earth, just a signal ground like most modern B&O products. One effect of this is if you have a mains ground to neutral potential greater than a couple of volts you can get problems. So my next question is:-

  1. Are you in an old or new house, in other words was the mains supply installed in the last 20 years ? The reason for asking is on modern homes the incoming neutral line is bonded to ground at your meter, older installations are not..So if you are in a newer home the problem is less likely to be a ground to neutral potential difference.

Location: Hampshire, England

Hi Keith...yes its a new house (3 years old)

Ian,

That's good, it takes several options off the table provided there is no wiring errors in any of your sockets for example neutral and earth reversed behind the socket. There is really two ways of proving the point:-

  1. Purchase a cheap (£5) mains tester from you local DIY store which you plug into your mains sockets and it tells you if it is wired correctly.
  2. Connect a wire from the screen of your FM aerial input on the Beosound 9000 to mains earth. If you are using standard 75 ohm aerial plug for your FM aerial input, then wind the stripped wire end around the metal of the plug, the other end of the wire connect to the earth pin of a mains plug. Make sure it is connected to the earth pin at the top ONLY and plug in BUT do not switch on at the socket.

If after making the connection in point 2 above the problem goes away, then you certainly do have an earthing issue.

Location: Hampshire, England

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