No Subwoofer Output in 2-Channel Mode

Lately I have been receiving numerous emails from fellow Audioholics regarding subwoofer operation problems with their DD/DTS AVR Receivers. One of the most common scenarios is where the user has a 5.1 speaker system, but the AVR Receiver does not allow subwoofer output in 2-channel. Another is when the user has large bass capable main speakers but they experience no bass output, in 2-channel mode, to the subwoofer if the main speakers are configured large.

The Solution:

For the 1st scenario, no subwoofer output in 2 channel, regardless of speaker settings, I recommend the following if you have bass capable main, center and rear speakers:

1. Set all speakers to "large". This bypasses all of the High Pass Filters (HPF) built into the receiver. Usually these Receivers with poor bass management set the cut off frequency too high (between 80-100Hz) with a gradual roll off of 6-12dB/octave and thus they are not worth using in my opinion.
2. Set the subwoofer setting to "none".
3. If the Receiver has preamp outputs for the main channels, then connect the left and right main preamp outputs of the Receiver to the inputs of the subwoofer, just like you would hook up any other component such as a DVD or CD player.
   
   Note: Make sure you connect both left and right channels into the sub, otherwise you will loose significant bass information and amplitude being sent to the subwoofer. This will ensure all of the left and right channel bass information is being routed to the subwoofer.
   
4. If you do not have preamp outputs on the main channels, you must connect the subwoofer via speaker level to the main speakers.
   
   Note: Make sure when you connect the sub to the main channel speaker level that the connection is in parallel. If you use the speaker "B" outputs to connect your sub, press it 1st to verify that the connection is in parallel. If you can still hear sound out of the mains, then the connection is in parallel. If not, than you will have to connect the sub and the mains through speaker "A".
   
5. Adjust the subwoofer cross-over setting between 50-60Hz.
6. Adjust master volume of Receiver to a typical listening level.
7. Adjust subwoofer volume on subwoofer to a level that sounds appropriate.

For the 2nd scenario where you have bass capable main speakers, but small, bass shy center and rear speakers, repeat the above steps with the following exceptions:

1. Set the center and rear speakers to "small"

2. Adjust the subwoofer cross-over to around 80-90Hz. This will ensure optimal blend with the internal HPF's cut-off frequencies for the center and rear channels of the Receiver.