Kevin in Wappinger Falls New York (wherever that is) asked me an interesting question recently.
“Arnie Nudell popularized the line source loudspeaker design and many of his most revered Infinity speakers such as the Quantum Line Source, the IRS 1B, the IRS V, and the Genesis 1 (and apparently at least the two larger members of your forthcoming AN series loudspeakers) are all line source designs. Why don’t we see more line source loudspeaker designs? Is it strictly due to the cost because of the many more drivers, the larger cabinet, the increased manufacturing labor cost – or are there other attributes that have made them less popular?”
This is a really good question and one we don’t talk about much. Perhaps it’s a good idea to first get on the same page. The classic two-way or three-way loudspeaker has two or three drivers in a box. The multiplicity of drivers—tweeter, midrange, woofer—is needed to break apart the frequencies so each driver only has to handle a specific range: tweeters handle the higher frequencies about 2kHz and the woofer handles everything from that point down.
A line source handles the frequency divisions in exactly the same way—tweeters, midrange, and woofers—but instead of relying upon a single driver for each range multiple drivers are instead employed, typically with a line of many tweeters and sometimes many midranges. The advantages of multiple drivers in a line are manifold: each driver has fewer demands and the waveform comes out in a long, vertical, cylinder rather than a single driver’s ever-expanding circular wave.
The advantages of a line source vs. a point source can be summed up fairly easily. A point source sound radiates in all directions from the driver and quickly loses energy as it floods the room in a 180˚ plane. Worse, this expanded radiation pattern hits the ceiling, walls, and floor and reflects back into the room out of synch (time) with the initial launch. Only those listeners in a narrow sweet spot get to enjoy the best sound. A line source radiates a more focused pattern in the shape of a tall vertical cylinder that, above about 500Hz, has nearly no floor, ceiling, or sidewall reflections to dissipate energy and add to sonic confusion.
All that said, tomorrow we’ll look at some older Infinity designs.
Adding another way
When loudspeakers were first introduced they were essential 1-way designs: a single driver that carried the limited frequency range possible in those days. Soon we added a tweeter to augment the single driver’s high-frequency response in what became known as a 2-way and there the state of the art sat for many years.
Hardly satisfied with a woofer’s performance in the demanding midrange area a third way was later added in the form of a midrange driver that fit in between the woofer and tweeter and thus the 3-way was born.
It is certainly possible to add even more ways and speaker designers have by the addition of internal subwoofers for the lowest octaves and super tweeters for the ultra high harmonics.
What all these ways have in common is fundamental to their task of producing a full range musical performance. They divide up in ever smaller chunks the job of frequency reproduction. Regardless of the number of frequency divisions, not much has changed in the art of loudspeaker design for the last 50 years. That is until Infinity founder Arnie Nudell introduced the Variable Midbass Coupler.
Arnie always had a love of midbass (the range of frequencies between 100Hz and 600Hz) because this range is the basis of tonal balance. It’s fundamental to voices and many primary instruments and, coincidentally, where the loudest peaks of music happen. When we set up a pair of speakers it is this midbass region we struggle with most. When the left and right speakers are too far apart the midbass sounds thin and we think of it as strident or anemic. Too close together and it’s the opposite requiring a diet to remove unwanted fat. Yet, every time we move the speakers for best tonality we screw up the imaging. It is a never-ending battle.
Arnie’s invention of the VMC changed everything. By building 4-way speakers with an internally amplified subwoofer and VMC, the difficult setup process suddenly vanished. Now it was possible to place the speaker pair where it imaged best and adjust low bass with the subwoofer controls and tonality with a turn of the VMC control. More than that, by separately amplifying the VMC it would be possible to achieve stunning amplitude levels in the very area nearly every speaker on the planet cannot come close to reaching.
When we launch the line of AN speakers in 2019, you will have your first chance at experiencing for yourself the power of Arnie’s invention that we believe will fundamentally change our expectations of music reproduction in the home.