Question Bang and Olufsen Beolab 6000 NAD 7155 Buzz


Novice Member
I have a NAD 7155 Stereo receiver and have acquired a pair of B&O Beolab 6000 active speakers. I was advised I could use both together successfully.

I was advised that I could use the Beolab speakers with the NAD amp and all the normal functions of the amp (eg. volume, tone, balance, etc) would be available. I was to remove the two metal U-links from the pre-out sockets on the rear of the amp and save these for future use. Then, select 'LINE' on both speakers and connect them using an RCA cable to the NAD's preamp sockets, L and R.

I have two speaker cables behind the skirting boards with out connectors on the end, so I have spliced some RCAs onto the end of them in a DIY kind of way! The RCA Insulated wire connected to the striped part of the speaker cable, and uninsulated RCA wire to unstriped speaker cable - at both ends (of course).

I've attached both speakers to each other using a power link cable, and then each speaker individually into the NAD preamp sockets, one cable into the Left and the other into the Right. When the NAD is off, the two speakers buzz incredibly loudly if they are both on at the wall. When the NAD is on, the buzz lowers, but is still significant. I can hear the TV audio very clearly, but this drone over the top and when on mute is too much.

Has anyone any bright ideas as to what the problem is? Are the speakers themselves faulty, have I wired them incorrectly?

Any help and advice would be gratefully received.

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Novice Member
Update - I've bought new phono plugs and wired them straight to the existing speaker cables. Still loud buzz when just connected to phono. Lots of activity on the board, no one has any insight?


Distinguished Member
If it's a buzz, the speakers are broken and need servicing. OTOH, it's odd that both speakers should have the same defect.

If it's a hum, it's most probably a ground loop. Start off by plugging all devices (NAD, speakers and anything connected to the NAD) into the same wall socket. If that doesn't work, disconnect every cable from the NAD except the speakers and power, and post back. What we need to do is figure out where the ground loop is so we can resolve it. The most common cause is bad cable / satellite TV grounding, but that's easy to find.


Active Member
I'd like to add two comments to those of Mark above.
First your connection between the NAD preamp outputs and the B&O active speakers should be made with a screened cable all the way ie you need an RCA to RCA stereo screened cable of the full correct length but for test purposes place the speakers next to the NAD and use a shorter length stereo RCA to RCA screened cable. Having a section of unscreened cable interspersed could be precisely what is causing your problem.

Second you should be able to switch the power on to the B&Os with their audio inputs disconnected and here no nasty noises. You might hear some feint hiss or hum if you put your ear right up against the speaker grilles but from a distance they should be quiet.

Hope that helps,

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