I have had a pair of BeoLab 4000s for about 8 or 9 years now.

They are fed from a Technics amplifier via B&O attenuators, so they are activated by the audio input.

One has always been quicker to shut down than the other, but it now seems to power off during quiet passages of music.

Is the threshold/delay tweakable internally? is there a component failure that could cause this? is it possible to disable the auto feature completely? (I'd be quite happy to switch them on and off manually)

Any suggestions gratefully received.

Peter 

Bang & Olufsen attenuators? What are they for?

Can't you just connect the pre-out from the amp directly to the line in on the speaker, and put the switch to "Line" as stated in the manual? 

There isn't a pre-out - the speaker output is attenuated to line level (the purists wouldn't like this, but it works)

The point is that when it's not connected via  Beolink system (which signals the speakers to turn on and off) it powers on and off according to the presence or absence of audio, and one speaker is powering off when it shouldn't

A thought I've had is that possibly one attenuator is reducing the signal too much. I'll try swapping them over and see if that makes any difference. 

Ah, I see. Just like speakerlink to the beolab penta 1. Have never used something like that. According to the user manual your speakers shouldn't turn off for several minutes after the signal is gone. How did swapping the attenuators work out?

To bypass the auto-on you could use rca->powerlink cables. You would have to supply a voltage >2.5v to the Speaker ON-pin to turn on the speakers, and to turn them off, you could have a switch setting it to 0v.