How Do I Connect a Subwoofer for Music Listening?

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Q What’s the best way to connect a subwoofer used mainly for music listening? I’ve been trying both the stereo RCA and mono LFE input connections on my Klipsch R 120SW subwoofer, but am not sure which works best, and also where I should set the low-pass/LFE filter on my Onkyo TX-NR717 receiver. My front speakers are Klipsch R-28F towers. I would appreciate any recommendations on crossover settings for the receiver and the subwoofer itself. —Ken Zarubi, via email

A The decision on which subwoofer input connection to use — stereo RCA or mono LFE — will depend on whether you plan to use the AVR or the subwoofer’s built-in low-pass filter settings. When using the sub’s LFE input, the AVR’s electronic crossover provides low-pass filtering of bass information. If the source material is a movie soundtrack with an LFE (.1) channel, that signal is combined with the bass information from the main channels and routed to the subwoofer.

Using the stereo RCA inputs on a subwoofer is a less-common scenario where you would connect it from the preamp outputs on an AVR or integrated amp. In this case, you would set the main left/right speaker outputs in the AVR’s setup menu as Large. The signals being sent to the subwoofer will then be full range, and you’ll use its crossover dial control to set the low-pass filter — the upper frequency limit of sound that the sub will reproduce (80Hz, for example).

If you’re mainly using your speakers for music-listening, you can choose either connection type, though the AVR’s electronic crossover should allow for greater flexibility when experimenting with setup options. When listening with a tower speaker with 8-inch woofers like the Klipsch R-28F, you may find that a setting lower than the standard 80Hz “THX” crossover works better. Since your Onkyo receiver allows for variable crossover settings, I would try a different point — 60 Hz or even lower — to see if it results in a better sounding blend between the main speakers and subwoofer. In this case, you should set the subwoofer’s crossover dial to its maximum frequency to avoid “overlap” with the receiver’s crossover filter. Also, since you’re mainly listening to stereo music, the receiver’s low-pass filter for LFE setting won’t be crucial and can be left at its 120Hz default.

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