Written by 4:53 pm Subwoofers

Why I like Stereo (subwoofers)

Everyone knows for a proper system set-up, you need a subwoofer. But what about having more than one subwoofer? Is the old idea that more is better true when it comes to subwoofers?


AR-subs.jpgI’m a big fan of subwoofers. Whether it’s a surround or
stereo, subwoofers will get you the bottom two octaves of the music far more
cost-effectively and in a room-friendly way better than any “full-range” speaker I’ve ever
seen.

All my room-based systems use stereo right/left subwoofers. I’ll
put my pair of JL Audio F-112 subwoofers up against any single sub, regardless
of size of price. I even use stereo subs with my Dunlavy SC-VI speakers, which each
sport a pair of 15″ drivers.

The reason I use stereo subs is simple – they deliver more
convincing and directional bass. But bass isn’t directional below 80 Hz (the
THX standard crossover point). True, but since most subwoofers use a gradual
roll-off, be it 12, 18, or 24 dB per octave, it means that a subwoofer still
puts out some directional information.

Even two octaves up from 80 Hz with a 24 dB crossover slope (320
Hz) a subwoofer still has some midrange output. Sure it’s not much level (being
48 dB down), but it is enough to be audible in some setups and with some
sources. The leading edge of bass transient is the primary problem. This
leading edge contains upper harmonics that are will into the midrange. Mono
subs can “pull” a low frequency instrument’s image towards the center of the
soundstage because its leading edge is coming from a more centralized location
than it should because of the subwoofer. Stereo subs eliminate this problem.

Stereo subwoofers also “share the love” so that each one
only has to work half as hard to produce a given output level. Personally I’d
rather have two moderately priced subwoofers in a system than one that costs
three times as much. Not only will the two have lower distortion at higher SPLS
because each one will be operating in a more linear fashion, but with two subs
you can reduce room resonance peaks and place them in locations with less room
gain because you won’t need as much room gain. And although room gain is a
cheap way to get more output from a subwoofer, it is not without sonic
trade-offs. The principal trade-off is that room gain is not linear – it
amplifies only those frequencies that engage a room’s resonance nodes. The
result is often “lumpy bass” which while impressive, is not correct.

So the next time you begin to lust for those big full-range
speakers in your dealer’s showroom, perhaps trying a couple subwoofers with
more modestly sized speakers might be a more cost-effective way to get better
sound.

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