Improving sound from loudspeakers in a room is a big issue as we are facing a rather complicated but serious problem, especially at low frequencies, where we can experience very big variations in sound pressure level - up to 30 dB - in a room. Listening rooms are often rectangular rooms, and the parallel walls will give a big number of audible resonance and anti-resonance frequencies in the room and at low frequencies a booming bass. Traditional equalizing of loudspeakers systems and room-correction systems does not face the real problem - the reflections from the room. A new an untraditional way of looking at the problem in the time-domain has lead to a novel solution also working in the time-domain called Controlled Acoustically Bass System (CABS) which include additional canceling loudspeakers at the back wall in order to remove the back wall reflection. CABS is able to give a homogeneous sound pressure level in the whole room at low frequencies and is based on a special developed DSP system which also can do automatic calibration of the system.