Balanced Audio Technology Rex II Preamplifier and Rex II Monoblock Power Amplifiers

About a decade ago at the Hilton Hotel in Manhattan, Balanced Audio Technology demonstrated its electronics in a magnificent surround-sound configuration with Avantgarde Trio loudspeakers and Bass Horns subwoofers that were parked in each corner of the capacious room. A line formed outside to wait to hear it. One of the demo cuts featured the Catalan tenor Jose Carreras performing with a choir. You could almost pick out each voice in the chorus. Carreras’ voice sounded utterly ethereal. It was one of those audio experiences that you tuck away in your mental sonic album and return to with a sense of nostalgia. [The same system at a San Francisco show elicited a standing ovation with wild applause at the conclusion of Pink Floyd’s The Wall—the only instance of such a reaction to a show demo in memory. —RH]

Ever since that event I’ve followed the progress of BAT, as it is known, with more than casual interest. A few years ago I visited the factory in Delaware where the equipment is built, and became acquainted with the very intriguing and variegated trio—Victor Khomenko, Steve Bednarski, and Geoff Poor—that runs the company. All three are passionate music lovers and Khomenko’s design knowledge is not be trifled with. The guy, to put it bluntly, is brilliantly innovative. Consistent with Russian engineering, which makes the most out of basic parts (think AK-47), BAT equipment appears quite impregnable when it comes to reliability.

Since I saw the factory, however, BAT has undergone a change in ownership. The original team remains intact, but the company itself was purchased by Music Direct owner Jim Davis in 2013, who has provided it with vital financial backing.

When Khomenko, Bednarski, and Poor visited me to deliver the company’s new 160-watt Rex II monoblock amplifiers and preamplifier, I was thus curious to listen to the equipment for several reasons. For one thing, I wanted to see if the company had been able to build upon its new resources to improve its equipment. I was also simply avid to audition another tube amplifier, a pursuit that I’ve been following with some assiduity in the past year. Tube amplifiers that I’ve listened to at some length in recent months include the VTL Siegfried monoblocks, the Audio Research Reference 75 stereo amplifier, the Octave MRE 220 monoblocks, and the Doshi V 3.0 monoblocks. The Siegfried had a mesmerizing fullness of sound and stygian bass and the ARC a pellucid treble. The Octaves had a very transparent sound and the Doshis a winsome musicality. What would BAT bring to the table?

Quite a lot, as it turned out. Apart from superlative reliability, chief designer Khomenko focuses on a low noise floor, purity of power, and a mellifluous sound. He’s gone to heroic lengths in designing the Rex preamplifier, which boasts no fewer than 18 tubes. Upgrades from its first incarnation include replacing the Six-Pak of capacitors with amorphous-core output transformers. The Rex has only one gain stage for signal purity and uses no global feedback. Its ability to drive low-impedance loads is also superb, deploying for high-current delivery no fewer than eight 6H30 tubes, which hail from Russia. The outboard Power Module, housed in a full-sized chassis, contains what BAT terms a low-impedance local power supply. The Power Module is a true dual-mono design that eschews silicon diodes in favor of vacuum-tube rectifiers. The AC shunt regulators are also built from vacuum tubes, for a total of ten tubes in the Power Module.

Meanwhile, the Rex II amplifier is hardly less impressive: it features a fully symmetrical triode circuit, employs auto-bias, and is monitored by an electronic protection circuit. It looks almost impossible to damage these big boys, a big change from the days when turning a tube amp on and watching whether it would perform or emit a shower of sparks was a big question mark.

Perhaps most startling, BAT doesn’t rest content with the possibility of powering your speakers with just a pair of its monoblocks. Instead, there was literally a colossal amount of BAT amplification in my listening room—four power amplifiers to be precise. The way BAT has designed its amplifiers, which are each based around two pairs of the extremely robust 6C33C tube, it’s possible to daisy-chain them—pretty much infinitely, depending on your tolerance for heat and your willingness to countenance a whirling electric meter that might even take off like a flying saucer. Essentially, if I have it right, the second amp, which was tied to the first amp, functions as an extra source of reserve power. Specifically, adding the second amplifier in parallel doubles the voltage, doubles the current, halves the output impedance, and increases the signal-to-noise ratio by 6dB. The idea is that it will provide an increase in soundstage size and musical control.

This is the mode in which I first listened. As a result, the immense power and grip of the BAT amplifiers when coupled with the Rex II preamplifier instantly came to the fore. One of the things that most impressed me in listening to baroque and early classical music was the iron grip that the amps exercised on the bottom end. It wasn’t that the amps had the opportunity to deliver pounding bass. On the contrary, it was the way they brought out the hitherto barely audible and subtle details of the basso continuo, thereby perceptibly enhancing the sense of the room in which the recording originally took place.

As enjoyable as it was to listen to two pairs of tube amplifiers, I have to admit that I cracked pretty soon. The heat, even in my fairly large room, was simply too overwhelming. But I also couldn’t help wondering if the additional complexity of the quad-amplification system might also not carry some sonic penalties as well as assets. For example, I couldn’t avoid the sense that a very slight muddying of sound was taking place with extra sets of speaker cables and interconnects linking the amps. Thanks to the generosity of the Nordost Corporation, I had oodles of its superlative Valhalla II cabling on hand for the review. But perhaps four amps were too much of a good thing: with a single pair of monoblocks the musical presentation took another notch up in alacrity and spontaneity and coherence.

Which is a somewhat roundabout way of saying that the tandem of Rex II preamplifier and amplifiers sounded utterly beguiling. One of the most conspicuous strengths of this duo is the tautness of the bass. There was not a smidgen of the bloat that sometimes afflicts tube amplifiers. It doesn’t explore shifting tectonic plates the way Boulder amplifiers do. But this is no muffin-top amplifier. It’s lean and mean in the nether regions. The depth, explosiveness, and clarity were phenomenal. It’s not like you had to strain to hear it. Consider Leonard Cohen’s new album Popular Problems [Columbia Records]. On the cut “Almost Like the Blues,” the propulsive quality of the bass line comes through beautifully and makes for a riveting performance. It’s easy to scant the importance of bass, but make no mistake: There is no substitute for the stygian frequencies, once you’ve heard them authentically reproduced. True bass sets up so much of the ambience of a concert hall or recording studio. On the Cohen album, for instance, it not only endows all the instruments with remarkable weight and authority but also allows his gruff, hoarse voice to project from a black space. This sense of gravity extends to instruments such as the violin on the cut “Samson In New Orleans,” which sounded supple and plangent. Often instruments such as violin on pop recordings can sound thin and etched. Not with the Rex II gear. On a Teldec recording of Gidon Kremer performing the Schumann violin concerto, the very marrow of the violin emerged with great fidelity, producing a rich palette of overtones that lingered on long after the initial note had been sounded.

At the same time, the sheer scale of the soundstage was quite riveting as well. On a Telarc recording of the trumpet virtuoso Rolf Smedvig, the Rex provided a sumptuous and wide soundstage. It was possible to identify accurately, or about as accurately as it can get with excellent stereo, Smedvig’s position relative to the Scottish Chamber Orchestra. Seldom, if ever, have I heard so much of the acoustic envelope as the BAT supplied. But this is not to say that the BAT equipment poked into every nook and cranny of the orchestra. It didn’t. Rather, it gives you the whole gestalt, the sweep of an orchestra without getting lost in the details. Something occurred in listening to Pinchas Zukerman and Marc Neikrug performing Beethoven’s “Kreutzer” Sonata—the BAT superbly conveyed both their hair-raisingly audacious playing in the presto movement. It pretty much had me sitting on the edge of my chair. Here the Rex II winningly rendered the emotional energy that both Zukerman and Neikrug invested in the sonata—imaging was impeccable as were the uncompressed fortissimos. Accordingly, the dynamic impact was off the charts.

Overall, the Rex II amplifiers delivered, when appropriate, a tremendous wallop—not a sledgehammer assault but a true sense of the scale and sweep of the music. One track alone sufficed to demonstrate for all and sundry who were at my house for a party that the amplifiers can deliver a prodigious amount of current—on Monty Alexander’s mind-blowingly good performance of “Night Mist Blues” at the Montreux Festival, the palpability, speed, and body of the piano as he slams the keys were staggering, enough to bowl over even non-jazz aficionados. The piano seemed to resound in the very space in front of us.

Much of this can be ascribed to the Rex II’s ability to render realistic decays. I recall being instructed at the Oberlin Conservatory that music is all about death and decay: once a note been sounded it immediately begins to die. Sure, a piano pedal can allow it to resound longer but no matter the instrument, once a note has been produced it’s headed for the exits. The Rex duo excels at providing the full value of notes, allowing them to decay into the ether.

Part of its ability to accomplish this so persuasively is linked to its iron rhythmic precision. The preamp and amp never rush the notes, never overemphasize any part of the frequency spectrum. Instead, they have a kind of hypnotic ability to deliver a realistic sense of pacing, something that tube amplifiers can have difficulty accomplishing. No, the Rex is not quite as clean as the Boulder 2050 monoblocks that resided in my basement for a few months, but then again, I’m not sure anything can match that standard, at least for now. But there is a sense of ease—not, mind you, to be confused with complacency!—and steadiness that the BAT gear appears to offer.

If the BAT equipment has continued to make great strides toward what some more audacious than myself term the absolute, it also retained some of the qualities that have characterized its performance in previous generations. The timbral reproduction of both the preamplifier and amplifier, it must be said, continued to hew to the darker sound of the spectrum. This has both pluses and minuses. The upside is that the overall presentation is rich and organic without a trace of treble rebarbativeness. The downside is that the treble is not as extended as that of a variety of other amplifiers. A certain rounding of the treble means that even hand claps or whistles simply sound lower on the frequency spectrum than I have heard with other gear. There is absolutely no shrillness that can be associated with the Rex, but it’s also the case that the somewhat velvety treble impinges ever so slightly on the micro-dynamic performance of the Rex II.

Designing a preamp or amplifier consists of making choices, and as near I can tell, BAT has chosen to err on the side of a musical and seductive presentation. The great merit of the Rex twins is that they offer the sterling virtues of tube gear absent many of the shortcomings that have traditionally plagued the genre. The marvelous midrange and bass of BAT’s latest designs is almost impossible to listen to without wanting to listen to one recording after another, even as the glowing tubes exert an almost equally tantalizing visual appeal. Anyone seeking a tube amplifier with great clarity, indefatigable drive, and exquisite midrange magic need look no further than the BAT Rex II.

SPECS & PRICING

Rex II Preamp
Tube complement, control module: 8x 6H30
Tube complement, power module: 2x 5AR4, 4x 6C19, 2x 6H30, 2x 6C45
Frequency response: 2Hz–200kHz
Maximum gain: 18dB
Inputs: Five balanced on XLR jacks
Input impedance (minimum): 100k ohms
Outputs main: Two balanced on XLR jacks
Outputs tape: One balanced on XLR jacks
Output impedance: 200 ohms
Dimensions (each module): 19″ x 5.75″ x 15.5″
Weight: 76 lbs. (control and power module)
Price: $25,000            

Rex II Power Amplifier
Tube complement: 4x 6H30, 6x 6SN7, 2x 6V6, 4x 6C33C-B
Power output: 80W in 8 ohms or 4 ohms (3% THD)
Frequency response: 5Hz–200kHz
Input impedance: 108k ohms
Dimensions: 17″ x 9″ x 24″
Weight: 100 lbs. each
Price: $19,900 each

Associated Equipment
Continuum Caliburn Turntable with two Cobra tonearms, Lyra Atlas and Myajima mono Zero cartridges, dCS Vivaldi CD/SACD system, Wilson Audio XLF and Magenpan 3.7i loudspeakers and Wilson Hammer of Thor subwoofers, Nordost Valhalla II and Transparent Opus cabling, Stillpoints Ultra 5 and Ultra SS footers