The Bel Canto eVo4 Amplifier
|The Bel Canto eVo4 Amplifier|
Could This Be Real, Or Am I Only Dreaming?
10 October 2002
@ 8 Ohms 120
W x 4 or 360 W x 2
@ 4 Ohms 200
W x 4 or 500 W x 2
Bandwidth: 1Hz – 80KHz -3dB
THD and Noise: Less than 1% THD at rated power
Damping Factor: >100, below 100Hz
Input Impedance: >100, below 100Hz
Inputs: XLR & RCA
Idle Power Draw: 65 Watts
Dimensions: 17.5″W ×14.5″D × 4.5″H
Weight: 40lbs (18Kg)
What a Wonderful World We Live In
Imagine a world where Krell made vacuum tube amplifiers. Effortless power. Bass with extension and slam. Transparent and detailed treble. Yet, with a midrange shimmering with harmonics and presence, and a soundstage billowing with air. And what if in this dream world a dealer was willing to sell you this amp for 75% of its retail price. This is the Bel Canto eVo4 in a nutshell-and it’s not a dream.
Publisher Clement Perry has been raving about Bel Canto’s eVo series of amplifiers for quite awhile. Indeed he was one of the first to laud their ability to combine the best of transistors with the best that tubes had to offer. Before I moved from Connecticut to Los Angeles, he and I spent some time jamming with his monoblocked 200.2s, and this is exactly what I heard as well. World-class clarity and an organic rightness just not heard in transistor amplifiers. I also alluded to the performance of the eVo4s in my recent review of the Quad ESL-989s, but even with both mentions, the eVo4s deserve a review of their own. Perry claims that the 200.2s run in monobloc are a steal, so you could imagine where that leaves the eVo4 at about 2/3s the cost of a pair of 200.2s.
First, I should mention that I auditioned the Bel Canto eVo 200.4, which is the predecessor to the eVo4. The difference between the two is simply a restyled face panel and, well, a new name. Since there is no real change, and since the 200.4 face panel version is no longer made, I will refer to the eVo4 from here on out. Perry already went into detail about the technical aspects of the eVo’s Tripath digital technology, so I shall refer you to his review for the nitty gritty. It is worth reiterating that the build quality of the eVo4 is impeccable; a half-inch thick faceplate and a heavy-duty chassis with nary a rattle. It was kind of ironic (or perhaps reassuring) that an efficient digital amp that did not require the usual size transformers or capacitors could be so heavy and solid. There were XLR inputs, especially solid RCA inputs, and there were knurled metal speaking binding posts.
The eVo4 is a four channel, 120 Wpc amplifier. I imagine that it could be used in a variety of home theater situations, since two or all of the channels can be bridged. I can also see it being used in situations where speakers need to be biamplified. However, its real value is in its ability to match the capabilities of Perry’s bridged 200.2s at nearly $6,000, for only $4,000. In addition, the eVo4 incorporates an updated circuit design over the 200.2, which gives it a much larger power supply per channel. Thus, by Perry’s reasoning, you not only get the performance of a $20,000 amp for $6,000, but you get it for $4,000, and you get the increased performance that comes with a larger power supply, and you get it in the convenience of a single chassis. (I’ll leave the theoretical sonic downside of having a single chassis versus dual monoblocs to someone else to explore).
Also, it is worth reiterating Perry’s assertions that the eVo sounds better bridged than in stereo, because I believe this is the heart of what makes the eVo so special. Typically when an amp is bridged, its distortion doubles along with a theoretical quadrupling of output wattage. Bel Canto chose to run each stereo pair of channels out of phase with each other so as to minimize the power supply demands and to maximize power efficiency and performance. In stereo mode, one of the output wires is reversed so that the channels are brought back to proper phase alignment. I don’t know if this has anything to do with the digital nature of the amp, but few designs incorporate this principle. When bridged, however, the unit becomes balanced bridged (AKA differential bridged, AKA balanced output), meaning that not only is the output wattage increased, but also one channel is driving the positive lead of the speaker while the other channel is simultaneously driving the negative lead of the speaker. My understanding is that this is different from standard bridged designs, which drive the positive and negative slopes of the signal waveform, but not the positive and negative speaker terminals. Like the out of phase power supply, very few other designs have used this method either. Sumo amplifiers used to do this, and Krell and some Mark Levinson designs use it as well. I can even remember a few years back that MIT and Spectral had some wiring mechanism which allowed Spectral amps to be balanced-bridged via speaker cables, and they made some pretty lofty claims about the resulting sound improvements. I also noticed that REL subwoofers have a separate balanced-bridged speaker-level input on their pricier model subwoofers. I don’t understand why this setup isn’t used more often, because the results are spectacular.
After hearing Perry’s monoblocked eVos, I was curious to hear how the eVo4 would mate with the purity and transparency of the Quad ESL-989s. After a couple of days of 24-hour playback, I was ready to give the pairing a listen. I initially ran two 120-watt channels of the amp into the Quads. Clarity, detail and overall very good sound. At that point though, I couldn’t help but to wonder if hypothetically the two channels of the eVo4 in my listening room were instead the 2 channel eVo 200.2 at roughly $3,000, would it be worth nearly double the cost of the Quad 909 amplifier I was comparing it to? Tough call. In direct comparison, the Quad 909 was not clearly outclassed by 2 channels of the eVo4. No, they did not sound identical-with the Quad’s midrange emphasis-but voicing choices aside, I probably could have lived with the $1,500 Quad 909 if I were short on cash. (Did I just pose the hypothetical “…if I were short on cash”)? With a bit more money (Now there is a hypothetical!), I probably would have sprung for the 200.2. However, when I bridged the eVo4’s four channels into two balanced bridged channels, the differences were not subtle. In fact, hypothetical financial situations aside, I felt I would beg borrow or steal to keep this amp. That said, I did all the rest of my auditioning in balanced bridge mode.
What I first heard was an immense opening up of the soundstage. The soundstage became much larger and all encompassing. The soundstage was cavernous from front to back, and side to side. The interesting thing is that although the soundstage got bigger, the individual sound sources did not significantly enlarge. The net result is that there was simply more space between performers. There was a massive amount of air within the soundstage. There was certainly treble purity and air, but I have heard airier treble. But to me, this seemed to be the proper amount of treble air-contrasted with the artificial injection of air that I have sometimes heard in audiophile designs. Although this soundstaging prowess seemed to be a spatial phenomenon, it contributed to the clarity of the presentation. With the performers more spread out, it was easier to focus on the musical details of each instrument-kind of a “decongestant” for your sound system. This worked to great effect on Joe Ely’s Letter to Laredo[MCAD 11222]. This album epitomizes Tex-Mex and you really feel as though Ely is singing the blues in some cantina in Mexico. I can’t really say I am a fan of this genre, but I really love this disc. A plethora of instruments such as a plucked Spanish guitar, woodblocks, cymbals and multiple drums come from deep within and throughout the soundstage. The decay of the instruments’ notes, as well as Ely’s voice, hang in the air like the smoke in the bar room in which he is playing. Ely himself is authentic, as was his performance, and so was its replay.
To put this in perspective, I had another amp come through my listening room that I was unable to formally review. That particular amp derived its clarity from the starkness in which it portrayed the performers within the rest of the soundstage, and in that sense it may have been more “transparent” as we have come to use the term. But the eVo sounded more lifelike. In terms of a video analogy, that amp got its clarity from an increase in contrast, whereas the eVo got its clarity from just plain moving you closer to the screen. Indeed, the perspective of the eVo was a bit more forward than I was used to. With the increase in soundstage came the feeling that the soundstage increased in all dimensions-including moving closer into the room. Although I felt as though I was in closer proximity to the performance, the soundstage’s increase was balanced in all directions, so I generally did not feel as though the perspective was now too upfront. In fact, I would say for the Quad ESL-989s, it was just right.
“Just right” also describes the depiction of harmonics by the eVo. In bridged mode, the eVo brought a tube-like richness to the harmonic presentation. I never felt as though harmonics became euphonic colorations, but rather that they added dimensionality without subtracting clarity. I would call this presence, and this trick, my friends, is a tough job to pull off-let alone for solid state. This was an intensely musical amp that not only presented a remarkable soundstage, but also fleshed out the individual performers with its dimensionality. In that sense, this amp really did sound tube-like. Once again, not because it was colored or deviated from tonally neutral in any way, but because it had a richness that contributed to the performers sounding more organic, more real. Combined with a completely smooth presentation that lacked any kind of harshness or edge, this was one musical amp, not because it glossed over any details or somehow made recordings sound better, but rather because it somehow made instruments sound more real and performers more present. As with the Audio Harmony Six that I previously reviewed, all of my 80s compilations sounded more lifelike with the additional harmonic textures and lushness. But unlike the ‘Six, the eVo4 did not make already rich recordings like Sade’s Love Deluxe [Epic EK53178] sound overly so. Similarly, the eVo added an organic realism to Joe Ely’s Letter to Laredo without making this intentionally stark recording sound lush. I should also mention that I have heard k. d. lang’s Save Me from her Ingénue disc [Sire 9268402] too many times to count, since it was one of the house’s reference tracks when I sold high-end retail. The opening slide guitar never swept me away the way it did through the eVo.
The bass presentation of the amp also sounded more real than I have heard elsewhere. It was not tube-like, but much more in the deep-but-controlled solid state mold. It was pretty heavy on impact, certainly deep, and never boomy, but it was not the tightest I have heard. However, it was definitely in the realm of subjective preference rather than objective right-or-wrong. In fact, I cannot say that this choice in bass voicing by Bel Canto was wrong, but just that it was rich without being overly so. Once again, for my tastes “just right.” It also seemed “just right” for the Quads as well; they once had what I thought was about a 50-70 Hz hump, but the eVo tightened this hump down to almost non-existence. Yet, the Quads retained rhythmic drive (or rather they portrayed the eVo’s rhythmic drive) and did not sound overdamped or dry. The bass richness combined with depth and impact to sound again, well, real. On Joe Ely’s Letter to Laredo, the first track opens up with some heavy bass chords, and although the bass did not become overwhelmingly boomy as I have heard it portrayed other amps, it did have a certain resonance to it. Probably the resonance you would hear if you were hearing Ely playing live.
Enter the Electrostat
If you haven’t already caught my hints, the eVo was an ideal match for the Quad ESL-989s. In fact, it was a synergistic whole that brought the listener much closer to best-at-any-price performance than $12,000 may ever have. As I mentioned in my Quad review, the eVo took an already legendary performing speaker and kicked it up another notch with capabilities that I did not know the Quad possessed. The Quad is like clear water in its presentation, so the eVo’s soundstage and harmonic richness came through beautifully-absolutely stunning. What I did not expect were the dynamics, slam and ease I got from the pairing. I don’t know if it was the power supply phasing or the control from simultaneous pushing and pulling, but these amps squeezed out performance like the last bit of juice from an orange. I speculate that just as the inversion of phase between the channels makes the power supply more efficient, the same technique makes the electrostatic element more tolerant to high wattages. Granted, the Quads still felt a bit restrained at high volumes, but with the eVo, the high volumes got much higher-much higher in fact than I ever listen. At anything less than the highest volumes, they had an ease that made them sound as though they were simply coasting through the finish line. I just could not believe the added dynamics and headroom. The Quads already are extremely articulate through the bass, but the eVos made them even more impactful. This is just what you would expect when going from about a 100 Wpc amp to a 400 Wpc one-but that scenario is simply just not ever mentioned in the same phrase as “Quad.” I can’t help but to wonder if this phenomenon would occur with Martin Logans or other electrostatics, let alone Magnepans or even traditional dynamic speakers. As I mentioned earlier, with this clear increase in performance, I just cannot understand why other amps do not use the same balance bridging technique.
This amp accomplished miracles with the Quad 989, and I wish I could have heard what it could have done for other speaker designs. However, I did have had the opportunity to hear a few other amplifiers that actually exceeded the eVo’s transparency, detail and deep bass control. But I still have yet to hear an amp that is so exceptional in all areas. I have a feeling this amp could steal quite a few tube-lovers’ hearts as well as those who are inclined to remain within the solid state. You would expect this from a $20,000 design, but not from $4,000. Call it a miracle, call it a steal or call it a dream. This is the Bel Canto eVo4 in a nutshell-and it’s not a dream.
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