It shouldn't damage them, but isn't desirable either...

I suppose that when the PC is off (is it a laptop or a desk machine?), the cable from the sound output picks up some noise or interference that the speakers consider to be audio, and turn on. I believe that might be remedied by a couple resistors connected from the L and R signal lines to ground - 4.7 kohms or so.

It could be a ground loop problem as well. Do you hear any hum from the speakers when they turn on with no input?

I think you're right, that's exactly what's happening.  It's a desktop PC and the B & O technician wired them up with a standard phono jack to RCA cable.  The line probably isn't very clean & so the speakers keep switching to active, expecting to get a signal.  I will ask the B & O guy to try that out.  Many thanks for the advice.

There is no hum or serious popping sound from the speakers at any time, only the constant switching from standby to active, which makes a mechanical click from the switch.  I don't think it is a ground loop problem.

Thank you so much!

Marius

The safest way would be a Beoport, but this wouldn't be an easy task to get one in Egypt I think.

Martin

Hi,

I understand, that they turn on, if there's no sound from the PC? I had the same problem.

Ok, do they turn on, if you reduce the output level of your soundcard to zero?

If yes, try a better soundcard with less noise.

If no, reduce the level of your soundcard and raise the input level of the BL4000... - ... Oh, sorry, the 4000 do not have an changeable input level.

Hm, I fear, then you need to use Beoport with Beoplayer software. That was my solution. I bought a used Beoport. 

JOV

I am guessing that your speakers are connected to some sort of line-level impedance output from your computer. I took a look at the manual of these beolab 4000 speakers: 

Connection panel: LINE–L–R switch - This switch has three settings. Set the switch to L or R when connecting the loudspeakers to a Bang & Olufsen system. Set the switch to LINE when connecting the loudspeakers to a non-Bang & Olufsen system.

Connection to non-Bang & Olufsen systems - Use a special adapter with an ordinary phono/RCA plug in one end, and a DIN-plug in the other (‘Cable for line signal’ – optional accessory, available from your Bang & Olufsen retailer). Set the switch to LINE.

I found it here http://www.bang-olufsen.com/~/media/Files/User%20Guides/BeoLab4000/beolab4000_userguide_english.pdf 

If I were you I would double check if your speakers are connected to a line-out/aux/etc. from your soundcard and run down the manual one more time. I highly suspect the L R switch not sitting in the line position. If they would only work with B&O I would say that's some insanely terrible design. According to this manual they should work with any line input anyway. If it is random noise from your soundcard causing the problem, I don't want to know the terrible state that thing is in and you should be able to hear it.

From what I understand about your cables: the whole thing is connected by a DIN->male jack->female jack->RCA right? I would always suggest not to use adapter cables for your signals, interference can leak in more easily. It shouldn't be hard to find DIN->RCA cables online as they don't have to B&O branded. Other tips I can give is to keep your audio cables away from video signal cables and power cables.

Can you tell us what kind of soundcard you have there and what connections it has? (and did anybody in this thread check the manual?)

Issue is that the Beolabs switch on when there's sound and switch off again when there's no sound. Had the same issue with my 4000's.

As a result of this, when your PC says beep, you hear your speakers clicking, but no sound, since the beep is gone before your speakers are properly switched on. Then after a few minutes, you hear another click, when your speaker switch off again. And this is repeating and annoying. When you play music, there's no issue because there's sound continuously. 

I'm sorry I don't have solution, I think only Beolab 4 pc is made to connect to a PC directly. I sold mine and bought a set of Bose PC speakers....

Joost

I have the same problem with a long RCA cable at my restaurant to a pair of Beolab 5000.

There's probably some sort of electricity spike buildup in the RCA cables from a mains cable running close by, and making the speakers wake up.

Best might be to put an on/off switch on the mains cable, or your RCA cable might be of poor quality and react to outside interference too easily.

Hi Marius,

you could buy a small USB-DAC - to improve the soundquality and to eliminate the interferences from the onboard soundcard?

Turn off all interieur sound in the audiopreferences of your Win/Mac.

I would suggest:

The Nuforce Icon-2

http://www.nuforce.com/index.php?option=com_k2&view=item&layout=item&id=8&Itemid=191/index.php]

Connect the BL's (set to line-in) to the analog-output of the dac, and control the volume with it.

The Nuforce-dac has a good headphoneamp included too.

Or the Dragonfly from Audioquest:

www.audioquest.com/usb_digital_analog_converter/dragonfly-dac

Might be possible to get these online even in Egypt [:S

Greetings Millemissen