Distracting buzzing detracting from overall quality of BeoLab setup

7 replies
M(
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makeITfunctional (archived)
Bronze
Posted June 17, 2011 at 00:45 GMT
#1689917

Hi, BeoWorld!

I am having an annoying issue with my sound system setup and wondered if anyone could help troubleshoot this from a distance.  The problem is fairly simple, but I wanted to fully detail all of the steps I've already taken and hopefully someone can isolate a commonality and resolve it for me.

Basic Configuration:

I have a pair of BeoLab 3's that originally used genuine B&O DIN connectors to RCA jacks.  In turn, I used a cable from Radio Shack to convert the two RCA channels (left and right) to a single male mini jack.  I could then plug this directly into my computer or iPhone/iPad and play music and control volume from my computer.

In the spirit of trying new configurations (and wanting to control this setup with my Beo4 remote), I plugged my iPhone into my BeoSound 1 AUX port and plugged the mini jack that connected to the BeoLab 3's into the headphone jack on the back of the BeoSound 1.  This way, the BeoSound gave me not only volume control but also a radio and CD player.

This setup in either configuration works flawlessly.

New Addition:

I then aquired a BeoLab 11 subwoofer to the configuration.  The BeoLab 11 is configured in the following manner: The PowerLink input socket is a DIN to mini jack connected to my computer or iPhone and the PowerLink outputs go to each  of the BeoLab 3's.  Everything sounds magnificent.

I can also connect my BeoSound 1 to the mix using the method described above without issue.

The Problem:

Everything works without issue until one thing is done: if I plug in my computer to the A/C adaptor and into the wall, the speakers emit a buzzing noise that goes away instantly if I unplug my computer from the wall and let it run on batteries.  Same thing with the iPhone/iPad (although the buzzing sound is admitedly less -- probably because my computer pulls more current than does my iPhone).

This buzzing noise only started occuring when I added the BeoLab 11.  I even reverted the changes to cut the BeoLab 11 out of the picture again and my computer can be plugged into the BeoLab 3's without a buzzing noise.

Things I've tried:

* Reverting the configuration back to the BeoLab 3's only -- the sound disappears meaning it's probably something with the BeoLab 11.

* Different iPhones, iPads, and laptops -- to rule out if it was just my devices or other peoples.

* Changing which wall sockets I power my laptop to -- no difference

 

Does anyone know how to resolve this buzzing noise?  Is there a switch on either/both the BeoLab 3's or the BeoLab 11 that I need to set?

Thanks for your help and please let me know if you have any questions.

--B.

E(
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elephant (archived)
Bronze
Posted June 18, 2011 at 04:19 GMT
#1689918

Welcome to BeoWorld

When I have encountered buzzing sounds like this it is either:

1/ incorrect powerlink cables -- there are at least 3 variations of these, called Mark I, II and III -- believe the difference tends to be the amount of shielding inside the powerlink cables

2/ the power being supplied to the different parts of the system is being sourced from different electrical circuits behind my walls -- I think this is sometimes called "an earth loop"

 

See here for a bit of discussion on the powerlink cables: 

mexking
Offline
mexking
Bronze
Posted June 18, 2011 at 09:44 GMT
#1689919

Had the same problem with my setup, it turned out to be powerlink cables crossing over or running close to power sources, separating power and speaker cables solved the problem, worst "hum" provider was a No-breake.

Location: Mexico city

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K(
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kirkus (archived)
Bronze
Posted July 9, 2011 at 18:13 GMT
#1689920

It sounds like you're using the same cable that you used to use for hooking your iPod to the BeoSound 1 as the cable to hook your computer to the PowerLink input on the BeoLab 11, and if so, this is where the problem resides.

The iPod input cables that are sold by most B&O stores tie signal ground (sleeve on the headphone plug) only to pin 2 on the DIN plug, and this works fine for an AUX input on a music system.  But recent PowerLink inputs (i.e. BL3, BL11) require pin 7 on the DIN plug to be tied to ground as well, or it will do exactly what you describe.

The iPod cable can be easily modified by replacing/reterminating the input (headphone) plug, and wiring as follows:

Yellow - unconnected and insulated

Brown - left signal (tip)

Green - right signal (ring)

Blue (pin 7 ground) and Brown/Green shield - signal ground (sleeve)

M(
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makeITfunctional (archived)
Bronze
Posted August 2, 2011 at 17:05 GMT
#1689921

Hi, kirkus,

You're absolutely spot-on.  I had a special cable made the way you specified and the hum is gone!  Perfect solution!

*Sorry for the delay in responding -- life has had me super busy!

 

Cheers!

X(
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xuandshoe (archived)
Bronze
Posted January 10, 2012 at 19:58 GMT
#1689922

hey i seem to have the same problems too, except I have Beolab 4. 

Can you help me? im not quite sure what cable u r talking about. 

My setup is a cable (7 pin DIN to 3.5mm) from BeoLab 11 to my computer. And then both my Lab 4s are connect to my 11. 

I don't know what that sleeve thingy is

Help me pleeease

thanks

M(
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makeITfunctional (archived)
Bronze
Posted January 10, 2012 at 22:01 GMT
#1689923

Hi, xaundshoe,

Thanks for your note.  Kirkus' solution (above) is the way to go, but I had it custom made for me at a B&O shop.  Try contacting John at the Gramophone Shop (an authorized B&O repair shop in my region) at 303.744.1284.  He made one for me and it was about $70.  I hope this helps.

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