April 2002 Reviewed by Roger Kanno	Bel Canto Design eVo6 Multichannel Amplifier

Description Model: eVo6 Price: $4900 USD Dimensions: 17.5"W x 14.5"D x 4.5"H Weight: 42 pounds Warranty: Five years parts and labor	Features Sculpted aluminum faceplate Bridgeable adjacent channels Configurable (3, 4, 5, or 6 channels) Differentially balanced topology (in bridged mode) Low energy consumption Cool-running operation Balanced XLR and single-ended RCA inputs Gold-plated binding posts Detachable IEC power cord

High-resolution movie soundtracks and multichannel sources such as SACD and DVD-A are testing the limitations of multichannel power amplifiers. Indeed, many of yesterday’s surround-oriented components lack the required fidelity in all channels to accurately reproduce truly high-resolution multichannel sound. But things are changing. Home Theater & Sound set out to determine just how the Bel Canto Design eVo6 would fare anchoring a home-theater system with high aspirations.

The Bel Canto Design eVo power amplifiers have been widely praised by the SoundStage! Network, including a very positive review on SoundStage! from editor-in-chief Marc Mickelson. They also won the Reviewers’ Choice Innovation in Design award for 2001

Bel Canto Design has fully embraced digital design. This direction is quite surprising considering that up until just a few years ago, they were known primarily for their single-ended triode (SET) tube preamplifiers and amplifiers. It should stand as evidence that they really believe in eVo.

eVo technology

The Bel Canto Design eVo6 amplifier is termed a "Class-T" digital amplifier. Class T refers to technology licensed from Santa Clara, California-based Tripath Technology Incorporated. Tripath’s Digital Power Processing (DPP) is incorporated into all eVo amplifiers, giving them several claimed advantages over other designs. For instance, eVo amplifiers are said to achieve extremely low levels of distortion and highly linear phase response across the entire frequency spectrum. And that’s just the start.

The eVo’s interface differs from that of true digital amplifiers, such as those from TacT or Sharp, which accept digital input signals. Instead, the eVos accept conventional analog signals. Digital, in this case, refers to a "digital switching" output stage that incorporates sophisticated digital signal processing (DSP) circuitry, which adds a small amount of "dither" to the signal to insure its linearity. This differs from long-established class D designs in regard to the "switching frequency." In class D, this frequency is fixed, whereas class T spreads this energy over a range of 200kHz to 1500kHz. Bel Canto Design reports that this minimizes noise bunching up at any given frequency. This, when coupled with an 80kHz filter to remove extremely high-frequency digital noise, produces a signal with excellent phase response and linearity.

The eVo6 is reported to produce 120Wpc into 8 ohms and 200Wpc into 4 ohms, with adjacent channels being bridgeable. In a bridged configuration, the eVo6 produces a whopping 350Wpc into 8 ohms to each of its then three channels. The class T-based design is very efficient with regard to heat dissipation and power conversion, with a claimed efficiency of over 90%, compared to 50% or less for a typical class A/B amp (and even lower for a class A amplifier). Because the eVo6 is so efficient, it runs relatively cool without the aid of external heatsinks. Its normal power requirements are said to be between 30W and 600W, which is uncharacteristically low for a six-channel amplifier.

Another unique design feature of the eVo amplifiers is their "dual-channel boards" which operate in "anti-phase" to reduce low-frequency power-supply modulation, in effect increasing the performance of the power supply. And when an eVo is operated in bridged-mono mode, it becomes a fully balanced differential amplifier. This further reduces low-frequency power-supply noise and increases common-mode rejection to improve the signal-to-noise ratio, meaning a quieter amplifier. In addition to these advantages, in bridged mode, output power almost triples, which would aid in driving less-efficient speakers.

The eVo6 weighs a chunky 42 pounds, in part due to its 1500VA power supply. It features a very attractive and substantial, curved aluminum faceplate. The power switch and the main power and protection mode indicator lights are located on the black front panel inset into the aluminum faceplate, giving the unit a clean, elegant appearance. On the back panel are six balanced XLR inputs and six single-ended RCA inputs, as well as five-way binding posts that will accommodate dual banana plugs. Balanced or single-ended input and bridged operation are selected by two switches provided for each of the three sets of dual-channel boards. A removable IEC power cord is provided.

eVo-lutionary or revolutionary sound?

Imagine very high-quality sound coming at you from all directions and that will give you a sense of what the eVo6 can do. I was floored by the level of transparency and detail that could be heard in movie soundtracks with the Bel Canto Design eVo6. The amplifier was incredibly neutral and did not draw undue attention to itself with unnatural detail or stark, overly precise imaging at the expense of fine resolution and subtlety.

For example, in chapter 35, "Fake War Casualties," of Romeo Must Die, the sound of automatic gunfire envelops the listener as the camera pans around the room. The explosive sound of this scene is extremely visceral, but can be jarring and even bright on some systems. With the eVo6, the sound was aggressive and still very involving, but the jarring effect was tamed considerably. Subtle directional cues such as the sound of ejected shell casings were enhanced to provide a great sense of depth. In fact, the unit's sound was so smooth and self-effacing that I quickly grew "accustomed" to it and almost started to take it for granted.

When I listened to exceptionally well-recorded soundtracks such as that of The Mummy, the eVo6’s attributes became even more apparent. In chapter 5, "The Magi Strike," the shaker imaged as precisely inside the left speaker as I have ever heard it and the bongos were placed well back in the soundstage with a wonderful sense of air and space around them. The DTS music score of The Mummy is one of the best-sounding of any film on the DVD format and the eVo6 made it sound more like an audiophile stereo recording than a movie soundtrack. It was that pure and precise.

DVDs such as Gladiator exhibited wonderful detail and subtlety during the opening credits. The rustling of the wheat fields and the fluttering of a bird’s wings as it takes flight were all rendered with exceptional fidelity and directionality. And when horses gallop across the screen, they imaged precisely as they moved from left to right and then into the rear speakers with the braying of individual horses being easily discernible.

Multichannel music CDs such as the DTS version of Lyle Lovett’s Joshua Judges Ruth [HDS 71021-54430-2-7] also sounded remarkably coherent and solid. Lovett’s vocals were incredibly smooth, but also had plenty of body and power behind them. The lower registers of the piano on "Church" were well defined, providing a great sense of the instrument as the strings and the piano itself resonated with its wonderfully rich deep notes.

The eVo6 acquitted itself equally well with two-channel music sources. There was a singular naturalness to the sound of the eVo6 that seemed unflappable no matter what I listened to, be it Wagner, Billy Idol, or anything in between. Vocals were clean and clear, imaging was exemplary with a good sense of depth and space, and every individual element in each recording was portrayed with great finesse.

But it was when I used the eVo6 in bridged-mono mode that it became obvious that this was no ordinary multichannel amplifier. It not only became more powerful, but the noise floor was lowered, imaging became even more precise, and just about every other performance parameter that I could think of went up at least a notch or two. The eVo6 is indeed a great amplifier when used in its standard configuration with six channels, but it becomes something very special when operated in bridged-mono mode. I could not stop listening to it in this way.

For instance, Eva Cassidy’s vocals on Live At Blues Alley [Blix Street G2-10046] were powerful yet silky smooth, at times nearly bringing tears to my eyes. In "Fields of Gold," the slight edge that is usually present when Cassidy reaches her peak was now gone, and her voice on the second-to-the-last chorus was airy and ethereal. The guitar of Ani DiFranco on "Garden of Simple" from Revelling: Reckoning [Righteous Babe RBR024-D] was acutely detailed with incredible delineation of the plucking of individual strings and the continued resonance of the body of the guitar. When you listen to the eVo6 in bridged-mono mode, you know that you are playing in the big leagues.

Caveats?

My only reservation with the eVo6 is that that in its standard configuration at 120Wpc it might not be powerful enough to drive difficult speaker loads or fill a large room with enough sound pressure to achieve that truly stunning home-theater experience. However, if your speakers are of adequate sensitivity or your room is of moderate proportions, the sound quality of the amplifier will almost surely win you over. And if more power is what you crave, then running the eVo6 in bridged-mono mode will not only provide a tremendous increase in power, but will also take this amplifier to an even higher level of performance.

Comparison

I have listened extensively to some excellent and reasonably priced multichannel amplifiers in the past few years. From the extremely affordable and brawny Anthem MCA 5 and Carver AV-705x to the more expensive Blue Circle BC32, Redgum RGH900, and most recently the Musical Fidelity HT600 (my current reference multichannel amp), all of these amps have impressed me in their own ways. The latter three, and the Redgum RGH900 especially, impressed me by coming very close in performance to my reference two-channel integrated amplifier, the venerable Krell KAV-300i.

However, it was the Bel Canto eVo6 that caught me off guard by surpassing the performance of the Krell with a sound quality that I did not think possible in a multichannel power amp. When mated to the excellent Sunfire Theater Grand II processor, the eVo6 provided a transparent yet wonderfully full-bodied sound that surpassed the Krell and was unlike anything that I have heard from my home-theater system. When listening to Eva Cassidy’s Live At Blues Alley through the Krell, there was always a slight graininess and glare to her vocals, whereas with the Bel Canto they sounded exceedingly smooth and composed. The soundstage of the Krell also seemed slightly constrained when compared to that of the Bel Canto, with individual elements in the music seeming to come from the space between the speakers rather than the entire area around and outside of them. In addition, with the Krell, the soundstage had less depth and a more limited sense of space.

Although the Krell did have a very finely detailed presentation, Eva Cassidy’s vocals were presented more bleakly, with sharper "edges" and less air around them, making them seem somehow disconnected from the rest of the acoustic space. The Bel Canto may have lacked some bass slam in its standard configuration when compared to the Krell or the Anthem, but when placed in bridged-mono mode, it could more than keep up with these amps in that regard, and the overall improvement in sound quality was stunning. Simply put, the eVo6 is my new reference amplifier for home theater, stereo, and everything in between.

Conclusion

The Bel Canto eVo6 may be expensive, but it is the finest power amplifier that I have used in my reference system. The added flexibility of being able to bridge adjacent channels for additional power and substantially improved sound quality provides a logical and cost-effective upgrade path for the eVo amplifiers. For instance, an eVo6 owner could later decide to have three bridged channels powering the front speakers and add an eVo2 to drive the surrounds, or use a bridged eVo4 to have perfectly matched power in five channels. The multitude of options possible for using both bridged and unbridged eVo amplifiers in a multichannel system make them a natural choice for use in systems with any number of channels.

While Bel Canto’s roots may be in tube-based amplifier designs, the eVo6’s superb sound transcends the traditional boundaries of amplifier technology, be it solid state, digital, or tubes, and makes it well suited for even the requirements of high-resolution multichannel audio formats such as DVD-A and SACD. The eVo6 should be at the top of your list for consideration in a top-flight home-theater system and will even do double duty as a reference-quality amplifier in a two-channel music system. 

Manufacturer contact information:

Bel Canto Design
212 3rd Avenue North, Suite 345
Minneapolis, MN 55401
Phone: (612) 317-4550
Fax: (612) 359-9358

E-mail: info@belcantodesign.com
Website: www.belcantodesign.com

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