Settings for Subwoofers
- The LFE, or low frequency effects, jack on the back of subwoofers is designed to allow the connected receiver or processor to perform crossover and phase adjustment for the sub. Receivers that perform automated setup routines evaluate the position and size of each speaker in the system, including the subwoofer. This allows better blending of the main speakers and subwoofer. Connecting the subwoofer's RCA cable from the receiver to the "LFE" input on the back of the sub bypasses the level and crossover control on the amplifier.
- Stereo receivers with subwoofer outputs must use the conventional left/right RCA inputs on the rear of the sub. The crossover, phase and volume settings are manually adjusted to achieve the proper blend of speakers and subwoofer. These inputs are full-range, relying on the user to adjust the subwoofer's built-in crossover to "tell" the woofer at what frequency to begin rolling off its output. This is done via a small knob on the rear, with crossover values indicated around the dial.
- Many home theater receivers and subwoofers purchased prior to the influx of automated setup routines -- such as Audyssey, Pioneer's MCACC and Yamaha's YPAO -- rely on a combination of bass management inside the receiver and manual settings on the back of the subwoofer. Normally, users of these receivers set all speakers to "Small" if a subwoofer is present. This sends bass from the smaller satellites to the more capable subwoofer. In this case, the proper setting for the crossover is all the way to the right, typically around 180 hertz. This effectively removes the woofer's crossover from the signal path.
- Other than critical crossover adjustments, subwoofer phase and volume are essential in proper bass reproduction. Volume on subwoofers connected to receivers not utilizing automated setup routines are calibrated using a sound pressure level, or SPL, meter. Using test tones provided by the receiver or from a setup disc, listeners calibrate the volume of each speaker and the subwoofer to the same level. Volume control on the rear of the subwoofer is usually set to its centered 12-o'clock position, allowing the trim settings in the receiver to fine-tune output.
- Phase describes the relationship between bass output of the subwoofer and the other speakers in the system. Subwoofers use a variable phase control knob, or a switch between 90 and 180 degrees. The best way to adjust this outside of automated setup is to have an assistant make small adjustments while you sit in the primary listening position. The proper phase setting is when the best blend of bass output between the primary speakers and the subwoofer is achieved.
