High-Resolution Technologies Stage IV Speaker/Amplifier System

A Different Approach

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

This effect of literally suppressing one’s own room arises at bottom from the beaminess of the speaker. The twelve small mid/bass drivers in each speaker operate in effect as a unit so that with rising frequency one has what amounts to a driver that is large both horizontally and vertically compared to the wavelength of the sound. The four tweeter units (per side) form a vertical quasi-line source and have a lot of directivity vertically. Nothing much in the highs comes off floor or ceiling. I have written for years (as have other people) about the positive effects of beaming on image focus. Gradient, for example, has built its entire line of speakers around ideas of this sort. Acoustat, in the early days of TAS, used to argue compellingly for this in its “Manufacturer Comments,” for another example. The effects of various beamy patterns and minimization of floor reflections and so on is thus familiar in theory and in practice many times over the years. But the combined effect of the horizontal and vertical beaming in the Stage IV’s is very striking and will seize your imagination, I am confident.

Another aspect of using all those drivers is that no one of them is working very hard, resulting in low distortion. This is one clean-sounding speaker system, though some of that may come from minimization of early reflections. And the Stage IV’s will play loudly cleanly, too. The speakers sound really pure, quite startlingly so, even at high levels. The individual drivers were very carefully designed by Halverson, with a custom-designed cabinet and drivers from HRT—no off-the-shelf stuff here. Even one driver is low in distortion. Using so many that no single one is working hard pushes distortion down even further, down a long, long way to judge from listening. Really something.

The Limitations
In speaker design, no good deed goes unpunished, as it were. Almost all choices are compromises. In particular, directional behavior buys you differentiation against your own room, a desideratum for the reasons indicated, but it also puts upon you the need to sit in a particular spot. The Stage IV’s are sensitive to both the horizontal and the vertical position of the listener. I am undisturbed by such things, but you will want to experiment a bit to see if you are similarly complacent. This whole thing would probably work better in terms of consistency of pattern if the tweeter were in the center of symmetrically placed mid/bass drivers, as in the McIntosh XRT 28. On the other hand, putting the tweeter off to the side of a line source of mid/bass drivers seems to be common and commonly accepted—e.g., DALI Megalines, Scaenas—even though it creates a less than ideal horizontal pattern in principle. In practice, since I am inclined to listen without moving, having to sit where I belonged did not disturb me.

A second thing may seem a bit paradoxical. Although the speaker emphasizes direct arrival, which would suggest exceptional image focus, the Stages, in fact, make images a little unfocused, or if you prefer, larger than true point-source speakers when you get point-source speakers far from the walls. Again, Magneplanars, which are also physically wide in their bass and midrange drive units, exhibit to my ears a similar effect, though there are people who think of this as dimensionality rather than bloat. But a mono source ought to have a completely exact position on the vertical center line, and here, not quite.

None of this is devastating and all is easily forgiven in the context of the solution of the “second venue” problem. But there is one more difficulty, one that is somewhat serious to my mind, though negotiable. The Stage IV’s have a quite odd tonal character. The whole presence range is really shoved down, at least at the distance I was sitting. (The exact balance will be a function of distance because of the differing patterns of radiation at different frequencies.) This is not one of my OCD tonal tweaking items, calling up visions of my sitting up late at night frantically eq’ing to get pink noise to sound absolutely pink, as perhaps some readers imagine I do (and as I more or less do do sometimes). This is a quite big thing. The Stage IV’s sound a little muffled, actually. Further up in the treble, there is a partial return to level, so the muffled character is also very slightly edgy because the higher treble is up a bit compared to the lower treble.

Now this suppression of presence range energy is not exactly anti-musical, perhaps—and most surely not in the same way that a really exaggerated presence would be. But it is definitely there. Pleasant it can be—lots of recordings are over-present compared to concert sound. Indeed, most of them are. But not to this extent. Can you fix this with eq—so easy to do in the DSP world? Of course you can in principle—you can fix any response error as far as on-axis response is concerned—but because of the speaker’s complex pattern, it is not easy to know, even with measurements, what the eq is that will make the speaker sound tonally neutral in the sense of sounding like an ordinary speaker with flat response combined with power response that slopes smoothly down with frequency. I did get some balance eventually that made recordings sound tonally more or less as I was accustomed to. The final result was gratifying, with the balance essentially natural and the suppression of the room around you still startling good and the sense of being immersed in the original venue still superb. But the change from the un-eq’d balance was quite large.

To return to the purely positive, let me give a specific but typical example of the remarkable reproduction of recorded acoustics. Track 13 of Telarc’s Ravel-Borodin-Bizet CD (Kunzel conducting the Cincinnati Symphony Orchestra) begins with an off-stage trumpet call followed by an on-stage answering trumpet. One can hear the sound bouncing around the hall, not just general reverberation but specific wall reflections. The Stages reproduced this most convincingly. One really felt one was hearing the sound of the original venue in a detailed way. The effect was almost uncanny. Of course, to some extent one hears hall sound on any system. One can tell when sports announcing changes from the studio to the stadium on a mono table radio. Such things are, however, a matter of degree, and the Stages are top performers in the revelation of the acoustics of the original venue. You not only hear the stadium, as it were; you can count the seats (exaggeration for effect, of course, but one does get unusual insight).

I am not sure how the speakers (un-eq’d) balance was arrived at. I did not check an individual unit, but it is perhaps worth noting that stacking flat individual drivers is no guarantee of flat total response (the lower frequencies load adjacent drivers in a way that higher frequencies do not). The individual drivers are in separate enclosures, and the combined bass does not have the level one might otherwise expect. One needs a subwoofer. (HRT supplied a REL, which worked superbly, as RELs typically do in my experience.)