I sometimes feel like a lonely preacher in my quest to get every audiophile invested in a subwoofer. The few who pay attention to my sermons write back with effusive praise and always there’s the accompanying exclamation, “I had no clue”.
Perhaps the most oft-quoted reason for not adding a subwoofer sounds something like, “I don’t need any more bass” or “my speakers already go low enough”. We should not forget the classic, “I don’t listen to music with subwoofer-deep bass”.
All these procrastinations are missing the point of what’s in it for them: an added realism that simply cannot exist without a full range speaker. And no, most passive speakers do not deliver subwoofer-low bass to listeners in the room.
It’s true most of our systems don’t need more bass. What they lack are the subtle cues we hear in real life like ventilation systems, footfalls, room modes, and environmental rumblings—and what they produce is the unnatural (and unintended) phase shift of their woofer’s high pass function.
All passive speakers have a high pass roll off at the point where the woofer is no longer is flat. This adds an unnatural phase shift to the music within our audible range. Adding a properly aligned and tuned subwoofer can correct this shift (as well as any crossover can) and take the sub’s high pass below the frequency recorded on the disc. Thus, we don’t hear the phase shift.
Powered subwoofers, whether built into a speaker or external to it, add life and realism to the music in not so obvious ways.
Is your system full range or missing the point?