Speakers are one of the few audio components that have made little advancement over the past decade. Until recently, that is. Power handling was not a prevailing issue for speaker manufacturers five years ago, but with the advancements in amplifier design, big power is cheap! This is forcing today's speaker manufacturers to come up with new solutions to build high power subwoofers that actually perform. The result has created a new movement with a massive onset of high excursion, high power handling subwoofers hitting the market - and the competition is getting fierce.
So in what way is the evolution of speaker technology advancing? Simply put, just about every component of the subwoofer has been improved. We're talking sophisticated new cones, baskets, surrounds, and temperature management systems. The purpose of this article is to break down the subwoofer, part by part, to show the functions of each, and how they have changed for the better (or simply changed). For historical perspective Mike Klasco gives us a brief overview of the making of the modern long throw subwoofer.
Anyone vaguely familiar with the car audio market knows how important it is to have great bass in a vehicle. Now with the proliferation of home theater setups we are seeing the rising prominence of compact high output subwoofers. I'm an "old timer," so naturally lot of people have asked me who cooked up this technology. The easy answer is that the "micro" subwoofer is the evolutionary product of numerous innovative and creative people. The first application was autosound. The car interior is relatively small, especially if space is to be left over for passengers and bags; but as the appetite for intense bass is large in that arena it made sense that it should happen there first.
While I cannot take credit for these subwoofer contributions, I was at the scene of a number of these breakthroughs. So here is an abbreviated history of deep bass, woofers and subwoofers that delivered more wallop in less space than their less capable competition.
To begin with, anyone can jam a large woofer into a small box. Reproducing satisfactory deep bass from that enclosure is another story. As a woofer moves inwards the air in the enclosure compresses, acting like a spring. This stiff spring shifts the in-box fundamental resonance upward and rolls off the bass. The compressed air wants to escape and looks for some form of pressure release. Without any release, you can have buckling of the cone and surround.
Over the last 50 years various researchers have looked for ways to get more bang for their buck out of the small woofer box, using unique speakers, bass reflex venting and other box-tuning techniques, trick amplifier servo feedback circuits, and signal processing.
In 1954, Acoustic Research (AR) introduced the AR-1W, which packed a long throw (high excursion) woofer into a relatively compact sealed enclosure. Bass extended down to almost 20 Hz without any equalization. A few years later AR introduced a full range home stereo speaker (AR-3) based on this design. More recently AR went retro and reintroduced a modern day version, the AR303. Stereo phonograph records followed by multiplex stereo FM radio became a reality during the late 1950s and audio turned from a do-it-yourself construction hobby to commercially available way to play back music. This success was dependent on finding a way to unobtrusively place not a single but a pair of speakers into the living room without divorce. Amplifier power was scarce in the 1950's and gigantic highly efficient JBL and Altec speaker systems derived from movie theaters sound systems had been the solution. Amplifier power, like the Dynaco's 60 watter and the McIntosh MC275 (dual 75 watt) were the big guns at the time.