It is a buffered, electronically balanced circuit that is parallel connected to the center channel input. 'Redirect' only works when the LFE channel bandwidth is set to 85 Hz and Redirect is turned ON. The purpose of redirect is to allow monitoring of the LFE channel without bandwidth limitation.
This may be of value when the mixer wants to be sure that no unwanted frequencies are being sent to the mix LFE channel.
Here are the various setting options of LFE Bandwidth and Redirection circuits.
- LFE input is full range (85 Hz LFE bandwidth ON with Re-direction set to ON): This means that all information present on the LFE channel will be reproduced through the monitoring system. Any information below 85 Hz is reproduced by the subwoofer and information above 85 Hz is redirected to the center channel loudspeaker. Any noise, distortion artifacts and other unwanted sounds on the LFE channel can be monitored in addition to the LFE signal itself.
- LFE input is band limited to 85 Hz (85 Hz bandwidth ON, Redirect OFF): Any information above 85 Hz present on the LFE channel will not be heard through the monitoring system. This setting is not recommend for everyday use as the LFE channel has a bandwidth up to 120 Hz on most surround sound formats and even higher on a few others. A good use for this setting is to simulate the effect of some consumer decoders that do not replay the information on the LFE channel that is above 80 Hz. Dolby and others recommend that, for DVD mixes for the home, the LFE channel is monitored as well as recorded onto mix with an 80 Hz low pass filter inserted in the console output buss. This setting is a quick and easy way to simulate the monitoring part of that recommendation.
- LFE input is band limited to 120 Hz (120 Hz bandwidth, Redirect OFF): This means that any information above 120 Hz on the LFE channel will not be heard through the monitoring system. This setting is used in the movie theater industry, as the LFE must be reproduced up to 120 Hz and usually with a separate subwoofer. This is the default from the factory.
Note: The DTS LFE channel is band limited to either 80 Hz or 120 Hz depending on the decoder setting. The Dolby Digital LFE channel is band limited to 120 Hz but is sometimes recorded with an 80 Hz LP filter in-line and other formats have a variety of other different bandwidths. In general, it is better to set the subwoofer to option 1 and do testing on the final mix with option 2 if necessary. Option 3 is for the movie industry only and should not be used by studios doing DVD mixes for the home