How low can you go?

Time and again, readers of this column have asked us why our sound system has two subwoofers (stereo). Those who dropped by our exhibit room at the recent November Hi-Fi show also wanted to know. They are baffled because the size of our low frequency drivers already measure 15 inches each — huge by ordinary standards! With that size, the common belief is that the woofers can already produce the bass needed to give a system a much wider frequency band on the low end. Why bother setting up subwoofers then?

Our woofers — JBL D140 — seem large enough to reproduce the lowest frequency band, but the truth is they can only go as low as 35 Hz, not enough to cover the lower signals. Our goal is to have a system with the widest frequency range possible: one that can go as low as 10 Hz and as high as 35 KHz. It’s a rarity if you can find woofers with the same size going down to our desired level.

Getting our target high frequency range from a system is somewhat easy to achieve with vintage and even modern-day loudspeakers. The low (or the bottom octave) is the most troublesome and often the most complicated to achieve.

I often say that the presence of bass in an audio sytem is akin to the charisma of the color black in photography. Without it, a photograph looks dull and unappealing. Only a few speaker models — those with a heavy price tag at that — are reputed to reproduce sound frequencies in a broader spectrum.

Most of the speakers that are reasonably priced and which are common in various audio showrooms are of the monitor type; those that are usually designed to roll off at 70 or even at 50 Hz. This means that sound frequencies start being less audible at those levels. Other cleverly designed speaker systems, however, can give you an illusion of a broader frequency even if they roll off at 60 Hz. Sound purists will have none of these tweaks, however. They dislike being shortchanged.

Why is bass necessary in audio? Your perception of an orchestra playing on a stage in front of you is significantly enhanced. With it, the sense of the chamber’s volume is more fully conveyed. Recreating the circulation of the vast amounts of air being displaced by a full orchestra also adds magic to what you hear. Ergo, what full-range music brings is the perception of the real thing!

If you have monitor speakers and wish to add the bottom octave, you can try experimenting by hooking up subwoofers to your system.

For the past three stagings of the Hi-Fi Show, our team has relied on Rythmik (it’s the brand’s name. No wrong spelling here) Audio subs F12 to complement our horn set-up, and for good reason. It features a Direct Servo technology to ensure accuracy and definition.

You may have heard about other servo subwoofers which are generally well regarded for their accuracy. It is a well-established technology, most often based around an accelerometer which measures cone movement. But Rythmik’s Direct Servo technology has significant advantages over other servo technologies. It uses a sensing servo coil which acts like a microphone that compares the original signal to what the subwoofer is actually reproducing. The signal is then corrected instantly to compensate for any differences. Once you have understood the concept, you may wonder, just as we do, why anyone would make a subwoofer any other way.

My listening experience with the subs hooked up on my own system is more than gratifying. The 12-inch sized Rythmik cube subs can rock and literally shake the room. The ‘1812 Overtures,’ with its magnificent cannons, springs to life every time I play it. I could actually feel the bass rumble in Holst’s Suite No. 1 in E-Flat. 

Listening to Earl Klugh’s Late Night Guitar has never been more appealing. His superb plucking seems more commanding; the expression and lucidity of the bass are simply spectacular.

We equate the use of subs in home theater systems. But these low octave speakers can also do wonders in pure audio environment. Hear and feel your system as it takes you into the deepest lows!

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For comments or questions, please e-mail me at audioglow@yahoo.com. You can also visit www.wiredstate.com  for quick answers to your audio concerns.