High-Resolution Technologies Stage IV Speaker/Amplifier System

A Different Approach

Equipment report
High-Resolution Technologies Stage IV Speaker/Amplifier System

The HRT Stage IV system arrived for review almost exactly, all but to the day, sixty years after the release of the first stereo LP. This coincidence could be thought of as deeply symbolic, because the Stage IV system constitutes an unusually effective way to present stereo information as it should be presented—at least in one theory. The explanation of this is going to involve a digression into the history and theory of stereo. But it will be, as I hope, well worth your while to follow this digression. How you decide to deal with the issues involved will determine how your system sounds far more than the choice of most equipment items.

Even before stereo began as a commercial reality, thoughtful people had realized that it would open up a new prospect for reproducing musical reality. Gone would be the interest in reproducing the sound of instruments and voices unto themselves, replaced by reproducing them within their natural acoustic context. This would be a fundamental improvement, because almost no music fits naturally into a domestic acoustic environment as such. One person singing quietly, an acoustic guitar played gently, a clavichord...one has almost exhausted the list. Even “chamber music”—string quartets, say—originally composed to be played in small rooms, has in modern times come to be performed primarily in concert halls, and its performance style has changed to accommodate the change of venue. And, of course, when one considers orchestras—in the words of At the Drop of a Hat [“A Song of Reproduction,” Flanders and Swann], “Personally I cannot think of anything I should like less than having an orchestra actually playing in my sitting room.” Stereo offered the chance to make reproduced music actually work in musical terms, by moving you, the listener, to the original venue, rather than pursuing the idea of bringing the performers to your domestic environment.

RCA, in particular, jumped on this prospect from the very start in its orchestral recording. In improvised but startlingly effective deployments of relatively few microphones, it produced a series of orchestral recordings in the late 1950s and early 1960s that captured not only the sound of the instruments and their positions but also the whole acoustic envelope of the real sound. The recordings, released as “Shaded Dogs” (for the design of the label on the records themselves), became legendary and remain high-water marks for recording of the real sound of orchestral music in a performance venue. Others pursued and reached the same goal later on, but RCA established once and, one supposed, for all that the thing could be done—that an orchestral recording could sound not like the painful and inappropriate idea of having the orchestral instruments in your own room, but rather like what you would have heard in the concert hall. It was a new era. And when high end and The Absolute Sound came along, Harry Pearson’s description of the idea—“the sound of real music in real space”—became the marching song, the veritable “Marseillaise,” of the stereo revolution.

What This All Has to Do With Playback
In one common view, audio recording and playback are treated separately. One sets up a “neutral” playback system and uses that to judge recordings, and “good” recordings are then supposed to sound good. But this picture is vastly oversimplified because what kind of playback will work ideally depends on how the recordings were made. Imagine recording one person singing. A close-up, quasi-anechoic mono recording played back on a single flat-response speaker with the same radiation pattern as the person singing would, in principle, sound like the person singing in your listening room—the person would be “there” for all audible intents and purposes. But, of course, nothing like this happens. Vocal recordings are often made in the way I’ve described, but when one plays them back on stereo speakers with radiation patterns that are not the same as a person singing, the whole attempt falls apart. The ear/brain is almost anxious to be fooled, to believe that what is being heard is real. And one can convince oneself that even such a recording is almost real. But, of course, it is, in fact, not the real sound at all. And even on the off-chance that the speaker’s radiation pattern worked out to get the over-all power response of a vocalist right, this would not be true for a musical instrument with a different radiation pattern than a vocalist—which is all of them. Instruments and voices into room is not only musically inappropriate in almost all cases, it is also bound to fail if one listens critically.

But what is possible, what does work, as Alan Blumlein pointed out in his original stereo patent in 1933[!], is to reproduce the whole sound of the original voice in the original venue, by recording the original soundfield in the original venue at a plausible listening position and reproducing this in the listening room by suppressing the acoustics of the listening room sufficiently. In effect, one can cut out a section of the listening room acoustics and replace it with the acoustics of the original venue. Actual realism becomes possible.

Enter the Stage IV
These ideas are far from new, and many speaker designs have pursued this general goal in various ways. And to some extent, speakers with wide uniform “dispersion” (a wide uniform radiation pattern) can synthesize an impression of large space using room reflections. The extreme form of this are omnis and the original Bose 901, which for all its controversial nature as a practical device, was based on a theory that made some sort of sense. Wide radiation pattern speakers can “sound good,” all right. I listen often to an (eq’d) pair of Acoustic Research 303s, which are wide in frontal pattern out to around 6kHz. The space heard may not be an exact replica of the original venue, but the tonal character is convincing on large orchestra works in particular. 

But some designers have tried to make the speakers work as well as possible in terms of suppressing the listening room and giving one access acoustically to the original venue in the most literal sense. Indeed, in the early days of high end, this was a common goal. But in the contemporary world, this has become less common. Still, this quest continues on occasion. And Kevin Halverson’s HRT Stage IV’s do this exceptionally well. The base system comes with one amplifier and one pair of speakers, with each speaker containing three woofers and a tweeter. The speakers can be stacked horizontally atop one another on HRT-supplied stands to realize the four-speaker array (the "Stage IV") reviewed here. Even if you are accustomed to speakers with some directional behavior by design, you will find it startling to walk up to the Stage IV’s from behind, and then sit down in a chair in front of them. The sense of walking into a sound world detached from the room around you is really surprising, almost uncanny. And, of course, on a well-made recording, this new sound world is the sound world of the venue where the recording was made.

This phenomenon is immediately and permanently entrancing. When Scot Markwell of Elite A/V Distribution, HRT’s U.S. distributor, mentioned to me that many of the customers for HRT speakers were replacing far more expensive designs, I could surely understand why. Indeed, upon my first listen, it crossed my mind that maybe this was a speaker which would justify getting rid of all fourteen pairs of large or medium-sized speakers I had accumulated over the years. (Later on, certain reservations occurred to me—more on those in a bit.)