Tip # 28: Subwoofers – The Missing Link!

TIP #28:

Things around the shop have been interesting as usual. The current lively debate has been about the use of subwoofers in an audiophile system. After all, isn’t a sub for powerful bass extension? And isn’t the best place for a sub in a home theatre system? A great place no doubt, but the only one? We say no! The biggest benefit in using a sub to enhance the joy of stereo listening, is not just the extra bass it produces (which may not be noticeably lacking anyway) but rather the recovery of the recording’s original ambiance.

Through our ears we perceive the nature of the space around us, from the many thousands of differently timed sonic reflections that a particular space creates. If we close our eyes and speak aloud, our ears can accurately reveal the size and makeup of the room we are in, by interpreting the feedback from the sound of our voice reflecting and resonating with all the objects in the room. Referred to as “phase” or “ambiance”, it adds texture to music. Low frequency information is the most omni-directional frequency of the audio spectrum, and can be perceived as emanating from almost anywhere in the room. Thus, the best frequency range with potential for ambiance enhancement when listening on our stereo system, is in the lower registers, the realm of the almighty subwoofer. If we add a single, powered subwoofer to a hi-fi system, the sense of size and authority increases significantly. By no means does this single subwoofer have to sound like it belongs in the back of a 78 Ford Pinto. If properly set up, there is no need for a fat, blooming, chesty sort of sound, but rather a greater sense of authority. Not much new here you say? But wait! To get a directional fix on a sound, we have been given two ears. Through triangulation, our perception of the originating source of sound is determined from sound waves arriving at our ear drums at minutely differing time intervals. We assess the phase of a sound to fix where it’s coming from – or, allow ourselves to be fooled, by electronically produced sound, into thinking we have a fix on the source (the basis for all 2 channel stereo systems). So why should bass be any different? With this question in mind we recently set up two pairs of stereo subwoofers, each pair with a different set of main satellite loudspeakers. One pair of subwoofers was set up with an inexpensive pair of satellite speakers, the other with an exotic pair (each system containing the identical model sub on both right and left channels). The extra texture produced by these systems is wonderful, regardless of the quality of the main speakers. Don’t get me wrong, there is no doubt that better main speakers increase image, clarity and believability. However, the addition of a pair of stereo subs to each of these systems increased the performance of the inexpensive speaker system almost to the point of eliminating the difference between the two sets of main speakers when compared in a stand alone listening test (with no subs present). The addition of subs to a stereo system enhances the sense of the room in which the original recording was made, and the interaction between the instruments. Image is no longer only in front, but wraps around the listener completely. Stereo subwoofers are great, regardless of system complement, and that is the great debate. Some people, even those in our industry, feel that putting two subs in the listening room is akin to wearing your baseball cap backwards, and is a sort of subtle swipe at audiophile dogma. We say poppycock! (among other phrases), and the proof is in the listening.

We are currently experimenting with four subwoofers in one room, and the results are even better. With careful setup and placement in the room, the system will image behind you with only two main speakers and no recording enhancements. Cool, eh? Obviously this can also dramatically improve the home theatre experience as well. As a matter of fact, the new AC3 surround format can be run with as many as six separate subwoofers, each sub dedicated to a separate full bandwidth channel. This illustrates that the designers of the new Dolby theatre standard knew what they were doing, when they used multiple subs in a high end stereo system. Their purpose was not to emulate the sound of a bass heavy movie system. As audio reproduction technology advances it must also adapt to the demands of the people buying it.

The demand for systems that integrate easily with one’s decor and lifestyle have lead to the mini revolution in smaller loudspeakers which are capable of increasingly impressive sound reproduction. The only thing smaller speakers can’t reproduce as well as larger ones ( without a large monetary penalty) is deep bass. However, with quality powered subs that drawback is eliminated, and with stereo subwoofers perhaps many of the good larger speakers are eclipsed in performance. Smaller main speakers have advantages other than size. In fact, all other parameters being equal, a smaller speaker should image better and be more focused than a larger set of similar value. Being smaller, allows the sound to envelope the speaker enclosure more quickly, thus increasing the size of the “sweet spot” in which the listener’s can sit. As well, the smaller drivers can be controlled to a greater degree than drivers of heavier mass. So if you need to free up some space in the listening room, or if you want a great sense of image and impact from your dual use audio/video system, the addition of stereo subwoofers can do the trick.

If you already have one and would like to hear the difference, we offer weekend loaners to allow you to get a taste and make your own assessment. Give it a try, you may not want to go back.