Joseph Audio RM22si Signature loudspeaker
Which brings me to Jeff Joseph of Joseph Audio, a veteran of the retail wars and a fixture at recent shows, as much for his bowls of M&Ms as for his musically stimulating auditions. Jeff's insistence that a system be at the service of music (and not the other way around) is always a welcome contrast to the bombastic cornpone many manufacturers trot out to flaunt their low-end extension. "We try to make speakers for real people," is how Joseph sums up his no-nonsense approach, as symbolized by his company's evolving line of cost-effective, high-performance speakers. Their most recent addition is a sweet, clear, articulate floorstanding design, the two-way RM22si Signature Reference Standard.
When I first encountered the RM22si at the 1998 CES, I was immediately captivated by its big sound and modest physical dimensions. Over time I came to appreciate the sound musical thinking behind Joseph Audio's novel mix of components and design refinements, centered around the Infinite Slope® crossover technology of chief designer Richard Modafferi. Modafferi was a senior engineer at McIntosh in the 1970s, working primarily on the company's renowned line of tuners. (He tweaked the last of their great tube models, the MR-71, and designed the MR-77 and MR-78.) After leaving McIntosh, Modafferi began exploring speaker designs, and discovered that no matter the quality of individual drive-units, once you combined them in a system, they began interacting with one another to create all kinds of problems. Modafferi reasoned that if he could minimize these interactions he'd arrive at a better-sounding speaker system. After several years of experiments he hit on a unique passive crossover circuit, and subsequently applied for and received a patent.
"It differs from traditional crossovers in that it accomplishes this very sharp rolloff with a relatively low number of components and an astonishingly simple circuit," Jeff Joseph explains. "The trick has to do with a pair of inductors and having them interact with each other—it's called mutual inductance. By coupling these inductors, Richard has invented what is called a bandpass transformer.
"You see, all speaker crossovers are filters. The difference is that our filter has this added kind of element to it that lets it roll off the sound very, very quickly, so that we're silencing the woofer before it can start to ring and interact with the tweeter; and we're silencing the tweeter before there's any bass energy that can go into it and cause it to overload. To really explain it, you have to go into pole-zero theory—this is the mathematical analogy of a filter—and the trip is really not worth it because ultimately so many things are responsible for the sound of a speaker, not just a crossover. It's how the cabinet is made, what the drivers are made of, how they're balanced relative to one another. Has the designer really optimized it for a wide range of areas, or has he nailed one thing and let everything else fall by the wayside? The crossover is really of interest only in what it allows us to accomplish, which is to take two drivers featuring dissimilar materials and fuse them together into a coherent whole."
The RM22si's drivers are from SEAS of Norway: a 6.5" aluminum-cone woofer with a central stationary phase plug rather than a dustcap and a 1" silk-dome tweeter. The theory behind the RM22si is to combine the snap and focus of an aluminum cone with the smooth, airy response of a silk dome. Having heard some speakers featuring exotic drivers, I was a little wary about such an approach at first; and, given the nature of metal-cone drivers, one might be forgiven for having visions of renegade xylophone bands marauding about the soundstage. According to Joseph, however, with the crossover's 120dB/octave slope the woofer actually begins its descent in the 1750-1800Hz range and drops off completely above 2000Hz, so that the ringing one might expect from such a driver is nonexistent.