Subwoofer or receiver crossover?

Peter has written with the following question:

I bought a Yamaha RX-V450 receiver matched with Polk RM6000 speakers and Polk say to wire the speakers through the subwoofer and not use the subwoofer outlet from the receiver. Encel store say to use a subwoofer cable and set all speakers to small. What do you think?

This type of question comes up from time to time, and the answer is that it all depends on the receiver.

In general, it’s best to use the home theatre receiver’s crossover for bass, because this can operates at line level (and, in many cases, in the digital domain). Such crossovers are easier to implement, and are less like to audibly degrade the sound than a passive, speaker-level crossover in a subwoofer.

But there is a problem with subwoofer/satellite systems. Small satellites will often be pretty useless for producing sound below around 200 hertz. Home theatre receivers with fixed subwoofer crossovers use 80 hertz, which means that there will be low output in the octave between 100 and 200 hertz.

An increasing number of receivers allow the crossover frequency to be changed. If there’s a setting of 200 hertz, this should be selected and the speakers wired up conventionally. Otherwise, wire the front two satellites through the subwoofer. When setting up the receiver, tell it that the centre and surround speakers are ‘small’, the front stereo speakers are ‘large’, and that you don’t have a subwoofer.

Note, though, that even with this wiring scheme, any bass between 80 and 200 hertz that’s on the centre or surround channels will not be properly reproduced. Only Bose, I think, provides crossovers for all five or six channels in its subwoofers. So, really, the best solution is to choose a receiver with a flexible bass crossover in the first place.

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