The fundamental principle of bass management (also called LFE Crossover) in surround sound replay systems is that bass content in the incoming signal, irrespective of channel, should be directed only to loudspeakers capable of handling it, whether the latter are the main system loudspeakers or one or more special low-frequency speakers (subwoofers). There are notation differences between the pre-bass-managed signal and once it has passed through bass manager. For example, when using 5.1 surround sound:
As the table shows, the bass manager directs bass frequencies from all channels to one or more subwoofers, not just the content of the LFE channel. However, when there is no subwoofer, the bass manager would direct the LFE channel to the main speakers. This is the only time the LFE channel would not be sent to the subwoofer.
The key concept is that the LFE channel is not the "subwoofer channel".
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