All of our Soundbars feature an Energy Saving Auto-Standby function. This feature is included in all our electronic products by law. This function is regulated by ErP (Energy Related Products), and has an official Directive number of 2009/125/EC.
After a period of time, units must go into a standby mode so that they are not left on for long periods of time. This features on other products you have such as a TV or set top box.
It is activated when volume that you are playing back is particularly quiet in relative terms and the soundbar is not detecting enough input volume, and therefore switches off after a period of time.
Increasing the source volume on your TV and decreasing the Soundbar volume will ensure that the soundbar recognises the input given to it.