Audio Research 610T Monoblock Power Amplifier

Masterpiece!

It won’t do this consistently, of course— most of the time you’ll have to settle for a superb approximation of the real thing rather than a facsimile—but the fact that it can do it at all is amazing.

Fourth, transient attack has also received a new jolt of speed, particularly in the midband. When I reported on how realistically the Kuzma and Walker turntables (with Air Tight PC-1 cartridge) reproduced the thunderous initial G minor chord of Andrej Gavrillov’s piano and the answering shrieks, plucks, and groans of Gidon Kremer’s violin that begin Schnittke’s witty dialogue between tonality and atonality, Quasi una sonata [EMI], I was also reporting on the 610T. Though a great solid-state amp like the MBL 9011 or the GamuT DI 150 still holds a transient-speed edge on the 610T, this is one very fast tube amp that can hold its own on everything from string pizzicatos to that lightning timp strike near the close of The Firebird. Moreover, the 610T maintains the tube’s superiority on stopping transients, reproducing decay and ambience as realistically as any amp I’ve heard.

Fifth, there is the unusually lifelike way that the 610T delivers power. It is a bromide to say that a tube amplifier clips “softly,” rounding off transient peaks when it runs short on steam rather than shearing them off the way a solid-state amp does (with subsequent audible distortion). However, it is one thing to clip softly; it is another not to clip at all. We are talking here about a monoblock amplifier that is capable of 630 watts of pentode power into any load. Unless you’ve heard a tube amp that is this seemingly unrestricted in power, you may have trouble understanding how smooth and unstrained—how non-hi-fi—the 610T sounds. Gone is not only any clipping distortion but the very sense of a dynamic ceiling hanging above the music. I think the best way to conceptualize this, at least for those of you who know your recordings, is to think of an album in which dynamic limiting has been deliberately applied— such as an old RCA Dynagroove—and then think of an album in which no limiting has been used—like a Sheffield direct-todisc. The 610T consistently sounds like the Sheffield, and makes most other amps sound like the Dynagroove.

Getting rid of any of the usual chokes on power delivery has a wonderful liberating effect on music of every kind. It is not that music will play “louder” with the ARC 610T, although it will; it is the way it gets loud that is so uncannily lifelike.

Take a tenor voice, such as Mario Lanza’s on “Il lamento di Federico” from Cilea’s L’Arlesiana (Mario Lanza Live in London [RCA]) for example. Part of the reason why a tenor voice is no snap for an amplifier to reproduce (and why it can cut through dense instrumental textures and seemingly soar ahead of and above an entire orchestra) is the tremendous amount of acoustical power it has in the 2–3kHz range (the “formant” range for higher-pitched male singing voices), for which see the chart to the right, reprinted from the late John Eargle’s superb text Music, Sound, and Technology (Van Nostrand Reinhold, 1995].

A powerful tenor can reach astonishing dynamic peaks on fortissimos. Indeed, this Lanza recording has undone many an amplifier at CES and in my home. At lifelike levels, during the searing climax of the Cilea aria, most amps simply hit the wall—making Lanza’s gorgeous voice sound progressively rougher, shriller, flatter, “beamier,” as he nears the crescendo’s peak, before shattering at the peak itself as if from mike overload.

Rather than roughening and flattening Lanza’s voice during the crescendo of this aria and then clipping at its climax, the Audio Research 610T has the power reserves and the natural delivery to project it, making it sound bigger rather than beamier, fuller rather than flatter, stronger rather than shriller, more forward rather than more recessed as he builds to the crescendo and then to simply sail through the peaks without any loss of composure or impact. I’ve called this ability to realistically reproduce the way imaging changes with changes in dynamics “action” or bloom, and the 610T simply handles vocal and instrumental action better than any amplifier I’ve yet heard (and, in so doing, makes instrumental dynamics more lifelike than any other amplifier I’ve yet heard).

Finally, soundstaging, always an ARC strength, is here taken to a new level. On a great orchestral recording like Lutoslawski conducting the Nationales Symphonie- Orchester des Polnishcen Rundfunks in a bracing performance of his own Concerto for Orchestra [EMI]—one of the truly great pieces of music of the second half of the twentieth century—the 610T fills the back third of my room with a virtual orchestra, Lanza’s voice as he himself was projecting wall-to-wall, wall-to-floor, floor-to-ceiling. Even on smaller-scale music, like Joan Baez and the Greenbriar Boys singing “Banks of the Ohio” [Joan Baez, Vol. 2, Vanguard], the 610T will fill the space between speakers and boundaries with near-life-sized images of Joanie, her backup singers, their instruments, and the ambience of the recording venue. (There are reasons why manufacturers of big speakers, like Dave Wilson, often prefer the 610T—they will drive any speaker and fill any space, no matter how small or large, with music.)