Samsung Soundbar woofer/bass drops out

Hi there, Only recently the bass has just started to drop out on my Samsung sound bar for about 4 seconds then comes back again! I have the sound bar connected by the optical cable. I'm guessing there is no problem with the cable, as if there were, there would be no sound at all! I've moved the woofer but still the same!!! Very frustrated!! (I did think it might be my Xbox One linect, but still the same with that turned on or off.