Top sound - reach flop

I bought the speakers, so that I can listen to audiobooks while screws in the cellar or while cooking in the kitchen.
The sound is absolutely perfect for such a klwines thing!
But the reach leaves much to be desired.
When moving away from the source device, it starts over 5m to noise because threatens to end the connection.
Mind you, in free space! If there is a wall between them, is already at 2m Final!
With my Bluetooth headset I walk in all the house with no problems.
But the speaker is not at all times.
I have tested it with 4 different devices (Sony Xperia Z1 Compact, Google Nexus 7, Apple iPhone 4S, Samsung Galaxy Xcover 2), so it can not be due to the counter-devices!