April 2010

Bel Canto Design e.One REF500M Mono Amplifiers

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Thinking of a 500W amplifier conjures visions of a behemoth squatting between the speakers, its weight and bulk requiring a pair of weightlifters to muscle it out of its shipping carton. And when that monster is only half of a pair of monoblocks, the imagination drifts to forklifts maneuvering them into place. But with the Bel Canto Design e.One REF500M monoblock ($3990 USD per pair), such nightmares are replaced by a more benign reality. This amplifier measures only 8.5"W by 3.5"H by 12"D -- and at 15 pounds, it qualifies as a featherweight in the world of high-end brawn. Add to the virtue of small size its svelte appearance and excellent sound, and you have to wonder how Bel Canto has defied expectations that every high-end product must be an outsized example of "bigger is better."

John Stronczer was a research scientist working on advanced integrated-circuit technologies. More relevant to audiophiles, he was one of us: a tube enthusiast whose passion for music led him, some 15 years ago, to found Bel Canto Design, of which he’s still the CEO. Since then, the company’s award-winning products have won a following among discerning audio buffs.

I came late to the game; the first Bel Canto products in my system were the e.One CD2 player and DAC3 digital-to-analog converter, both of which I reviewed favorably in the August 1, 2009 issue of Ultra Audio. The e.One models, Bel Canto’s line of premium electronics, emphasizes the company’s cutting-edge technologies and their environment-friendly production and use -- two REF500Ms, coupled to the company’s CD2/DAC3 source, use less power than a 40W light bulb.

About the e.One REF500M

When the REF500Ms arrived, I had some misgivings. The REF500M is what’s popularly labeled a class-D amplifier, and while I had no prior experience of the breed, I’d read and heard enough negative comments about class-D amps to arouse my suspicions. Those initial uneasy feelings soon gave way to the realization that such labels matter far less than the way designers use the class-D architecture to maximize its strengths (speed, power efficiency, size) and minimize its weaknesses (noise, audible artifacts, dynamic compression) -- something that holds true for other classes of amplifiers, including the highly vaunted, current-gobbling, hot-running class-A amps I’m used to.

Bel Canto eschews the term class-D, preferring the more descriptive switching power amplifier. Class-D amps switch their output devices on or off at very high speed, thus converting over 90% of the input current to output power. But what counts is how Stronczer has implemented the concept.

Like its sibling monoblock, the REF1000M, the REF500M uses the newest version of Bang & Olufsen’s ICEpower module, which contains its own switching power supply, but Bel Canto cascades its proprietary 300V DC power supply ahead of the ICEpower module. This is claimed to cut noise, store more energy, and produce a cleaner, weightier sound. Another factor in Bel Canto’s version of class-D amplification is its custom input stage, which uses premium parts -- Caddock resisters, low-ESR decoupling capacitors, low-noise regulated power supplies -- to reduce the REF500M’s sensitivity to power-line effects and to achieve lower noise, better power delivery, and increased dynamic capability. The result is a small footprint, and an amplifier claimed to put out 500W into 4 ohms or 250W into 8 ohms, with a damping factor of over 1000 and a measured dynamic range of 121dB.

As observed above, the REF500M has Bel Canto’s minimalist house look: a rectangular silver box with a black oblong window centered on its faceplate. When it’s switched on with a rear-panel toggle, a small blue LED lights up dead center in the window. The rear panel is similarly simple: the power switch above the AC socket, a pair of binding posts for the speaker-cable connections, and a clearly marked section for XLR and RCA inputs.


I installed the REF500Ms in my reference system, alongside a Cary 306 SACD Pro player, a Reimyo CAT-777 line-stage preamplifier, modified Jadis JA80 monoblocks, Von Schweikert VR-4 Gen.III HSE speakers, and a compatible mix of wires that included Nordost Quattro Fil interconnects as well as Siltech G3 AC cords, interconnects, and speaker cables. My listening room is about 21’L x 18’W by 8.5’H, with the speakers about 8’ apart and 3.5’ from the front (shorter) wall. My listening position varied; much of the time I sat in the sweet spot, about 9’ from the speakers, but sometimes moved forward for nearfield listening, and sometimes back against the bookcase-lined rear wall.


Even during an extended run-in period of more or less casual or background listening, it became apparent that questions about the efficacy or quality of class-D amplification would not arise. The REF500M’s sound was free of edginess, glare, noise, and other gremlins I feared might raise their ugly heads. When it was time for critical listening, I turned to a new recording of Verdi’s Requiem, with Antonio Pappano conducting the crack Santa Cecilia Academy Rome Orchestra and Chorus and an all-star quartet of soloists (CD, EMI 98936). I’d listened to it often through my Jadis amplifiers before the Bel Cantos arrived, and since this is far and away my favorite choral work, as well as being a killer challenge for audio systems, I wanted to hear whether the REF500Ms, with about eight times the claimed power output of the tubed Jadises, would deliver more punch and sheer thrills.

Well, they did and they didn’t. The Bel Cantos supplied marginally more incisive transients -- the leading edge of soprano Anja Harteros’s voice was slightly more coherent, and the tremendous bass-drum thwacks in the Dies Irae may have been ever so slightly more impactful -- but such marginal differences were below my expectations. This could be explained by two things: First, that a 60W tube amp actually can hold its own in the thrills department even when up against a vastly more powerful solid-state amp; as the saying goes, most music is in that first watt. And second, when I focused on the music rather than on thrills, I heard that the REF500Ms were handling this awesomely powerful music with aplomb. The massive climaxes in this work weren’t only forceful, they were transparent (a credit to EMI’s engineering), with the words in the descending choral opening of the Dies Irae section clearly audible -- a rarity in recordings of the Requiem. The REF500M also had delicacy; the extraordinarily beautiful Recordare duet for soprano and mezzo-soprano gave full due to Harteros’s and Sonia Ganassi’s respective timbres, the differentiation allowing me to note each singer’s nuances of phrasing and coloration. Against such musicality of reproduction, the possibility of being figuratively knocked through the back wall by waves of bass-drum heroics faded into unimportance.

A byproduct of the Verdi experience was that it led me to listen more closely to the REF500M’s mid- and low bass in large-scale music, which often confirmed the slight congestion I heard in the Requiem. Reproducing the two-channel layer of the SACD of Iván Fischer and the Budapest Festival Orchestra’s recording of Brahms’s Symphony No.1 (SACD/CD, Channel Classics 28309), the REF500M failed to deliver the midbass clarity of my reference Jadis, nor did it fully conquer the touch of congestion in my old standby for judging transparency in the reproduction of large-scale works, the Te Deum scene in Pappano’s terrific recording of Puccini’s Tosca, with the Royal Opera House Covent Garden Orchestra and Chorus (CD, EMI 57173). I don’t want to make too much of this, because it’s not an area of special sensitivity for me -- unlike, say, mid-treble glare.

But the e.One REF500M excelled with one of my favorite discs of 2009, Michael Daugherty’s Fire & Blood (CD, Naxos 8.559372), which offers plenty of challenges for amplifiers and systems -- it does triple service, providing musical truth, stirring transients, and a test of system transparency. Daugherty, one of America’s most creative composers, gets his inspiration from pop and jazz -- his works are infused with rhythmic life, accessible melodies, and imaginative orchestrations, all splendidly captured in these live concert recordings by the Detroit Symphony conducted by Neeme Järvi.

The three works on this disc feature violin and timpani soloists, wailing trumpet and brass sections, and lots of opportunities for glare in the highs and congestion in the lows. The REF500M showed nary a sign of either, delivering transparency and punch in music that demands both. The last work, Daugherty’s aptly titled Raise the Roof, boasts precise placement of instruments (e.g., trombones in the right rear, bells in the left rear), and both the background and foreground of the aural picture are filled with activity. The REF500Ms demonstrated good depth -- the timpani soloist, at the rear of a wide soundstage, came alive as instrumental groups kicked rhythmic motifs from section to section. That said, the soundstage was a bit less deep and wide than when I listen to this disc with my reference amps, but it was while playing Fire & Blood that I felt I understood just how well the e.One REF500Ms were delivering the goods.

After the high excitement of Daugherty’s music I turned to more intimate fare -- another extraordinary disc, Neharót (ECM New Series 2065), featuring violist Kim Kashkashian in haunting works by contemporary Armenian and Israeli composers. In Eitan Steinberg’s Rava Deravin, for viola and string quartet (here the Kuss Quartett), Kashkashian’s wide leaps between registers -- wailing in the treble, plush velvet in the lower range -- were true to the viola’s timbre, with no hint of harshness at the top or untoward gruffness at the bottom.

With Schubert’s "Trout" Quintet (Pentatone 5186334) the REF500Ms further demonstrated their prowess in conveying the subtleties of chamber music. The playing of an all-star group of renowned European soloists -- Martin Helmchen, Antoine Tamestit, Christian Tetzlaff, Alois Posch, and Marie-Elisabeth Hecker -- is enhanced by Pentatone’s superb engineering, which, heard via the stereo SACD layer, offered wide dynamic range and sweet violin timbres. The double-bass part, an indistinct low-register rumble in too many recordings of the "Trout," is a solid presence here, Posch’s bowing easy to follow as it lays down a firm foundation for the other strings. In Schubert’s Variations on "Trockne Blumen," a welcome bonus here, the mellifluous timbres of Aldo Baerten’s wooden flute were captured in perfect balance with Helmchen’s piano accompaniment, reinforcing my impression of the REF500M’s excellence at conveying intimate music.

But I was really blown away by one of the best solo-piano recordings of the year, Piotr Anderszewski at Carnegie Hall (CD, Virgin 67291). I’m a frequent attendee at Carnegie piano recitals, and it was heartening -- and impressive -- to hear how accurately the sound of a piano in that big hall had been captured. In a wide-ranging program of Bach, Schumann, Beethoven, Janácek, and Bartók, all played with brilliance and stylistic perfection, the resonance of the space bonded with the bright treble, solid bass, and creamy midrange of Anderszewski’s Steinway. The Bel Cantos easily conveyed the clarity of Anderszewski’s articulation, and the ways pianissimos float and loud passages bloom in Carnegie. If my reference amps reproduced the piano with a bit more solidity, the REF500Ms came close enough to still make this set a thrilling listening experience.

Finally, a pair of new releases on Chesky reinforces the label’s reputation for top-notch music and state-of-the-art engineering. The first is Jen Chapin’s latest, reVisions: Songs of Stevie Wonder (Chesky SACD347), fresh interpretations of classic songs by one of our top singers and songwriters, backed by Stephen Crump on double bass and Chris Cheek on tenor, baritone, and soprano saxophones. As is typical of Chesky recordings, there’s a startling immediacy to the sound. In both the "Red Book" and hi-rez two-channel layers, Chapin and the instrumentalists have a presence that compels attention -- and engenders joy in the vibrancy of their performances. The double bass comes across woody and deep, with a visceral gutsiness. And Chapin’s voice was right there in the room with me, despite the faintest touch of glare at the top on some tracks via the REF500Ms -- though not via the Jadises.

The sheer amount of detail and microdynamic information contained in reVisions is impressive. The disc’s booklet includes a diagram showing the precise location of the trio in relation to the single-point microphone, a modified Soundfield. But with the REF500Ms in the system, that diagram was superfluous -- I could have accurately drawn it myself just from what I heard from this disc.

The same went for another recent Chesky release, Rough & Tough (Chesky SACD346), a solo recital by veteran blues singer John Hammond, accompanying himself on a variety of guitars and harmonicas in songs by Howlin’ Wolf, Blind Willie McTell, and Muddy Waters, along with his own takes on the genre. Once more, there was that "he’s in my room" immediacy -- the instruments were vivid, Hammond’s voice grittily present.


My extended time with the Bel Canto e.One REF500Ms put to rest all doubts or misconceptions I’d had about class-D switching amplifiers -- they could play with the big amps of any class. The REF500Ms displayed excellent transients and dynamics, legitimate high-end microdynamics, and good depth and soundstaging, among their other attributes. And for Manhattan apartment dwellers and others with limited space, their small size is a huge asset.

But if class-D amplification isn’t a negative when implemented with the care and skills Bel Canto has brought to the party, it does lack, along with most solid-state amplifiers I’ve heard, some of the tonal depth and soundstaging prowess of tubes. Whenever I switched from the Bel Cantos to my reference tube amps, I was more impressed by the Jadises’ ability to get right my audio preferences, among them microdynamics, tonal depth, midrange smoothness, treble ease, and midbass solidity. Yes, the differences might have been slight to a more casual listener, but the superiority of the Jadis JA80s was clearly audible to me, and added up to somewhat greater involvement in the music itself. To put that in perspective, a pair of JA80s retails for triple the price of the Bel Cantos; if you don’t share my enthusiasm for tubes, this observation need not deter you from putting the e.One REF500M on your short list of amplifiers to audition.

For me, the bottom line for any audio component, from a CD player to a loudspeaker, is whether or not I can imagine myself living with it. I wouldn’t want to replace my reference amps with the REF500Ms, but if I had to live with the Bel Cantos, or if my budget restricted me to real-world price tags for amplifiers, I would find myself camping very happily with them. The e.One REF500M represents good value for what, these days, is a reasonable price in high-end audio. It’s hard to go wrong with these beauties; they prove that small can be beautiful, even in the high end.

. . . Dan Davis

Bel Canto Design e.One REF500M Mono Amplifiers
Price: $3990 USD per pair.
Warranty: Two years parts and labor (nontransferable).

Bel Canto Design
212 Third Avenue N., Suite 274
Minneapolis, MN 55401
Phone: (612) 317-4550
Fax: (612) 359-9358

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