September 2009

Belles Statement SA-30 Stereo Amplifier

Associated Equipment Loudspeakers -- MaxxHorn Lumination Preamplifier -- Audio Research LS26 Power amplifiers -- Audio Research VS115, Bel Canto e.One REF 500 monoblocks Analog sources -- Linn LP12 turntable, Graham 2.2 tonearm, van den Hul Frog cartridge, Audio Research PH5 phono stage Digital sources -- Meridian 508.24 CD player, Sony SCD-XA5400ES SACD/CD player Interconnects -- Audience Au24 e, Blue Marble Audio Blue IC, Clarity Cables Organic, Crystal Cable Piccolo, Purist Audio Design Venustas, TG Audio High Purity Revised Speaker cables -- Audience Au24 e, Blue Marble Audio, Clarity Cables Passion, Crystal Cable CrystalSpeak Micro, Purist Audio Design Venustas Power cords -- Audience powerChord e, Blue Marble Audio Lightning, Clarity Cables Vortex, Purist Audio Design Venustas Accessories -- VPI HW-16.5 record cleaner, Walker Audio Talisman LP/CD treatment

I hate vacuum tubes. They break, become noisy, gradually wear out, fail -- sometimes catastrophically -- and are generally a pain in the posterior. However, I have heretofore found that tubes have advantages in audio applications that make putting up with all those drawbacks worthwhile. Some say that tubes produce better tonal and spatial images, and a warmer sound free from the harsh, sterile characteristics of early solid-state amplifiers. The bandwidth of solid-state amps is usually wider than that of tube amps, although better tube models may have bass that sounds more like real instruments. There are lots of opinions on the relative merits of glass (tube) and sand (solid-state) amplifiers, all strongly held and defended. Me, I believe that what sounds good is good -- glass, sand, even digits.

Solid-state amplifiers can drive speakers directly without the need for distortion-causing output transformers, and can exert much better control, or damping, over the motions of a cone loudspeaker -- a good thing for dynamic speakers with large, heavy cones that need lots of help. But for inherently self-damped speakers such as horns, high amplifier damping factors can actually be a detriment, making bass sound lean and dry. That’s one of the reasons that users of horn speakers often prefer tube amplifiers.

When David Belles offered his Statement SA-30 amplifier for review, I was intrigued by his claim that this 30Wpc, class-A amplifier ($4695 USD) was designed as a solid-state alternative to tube designs, competing with them by offering sonic excellence, lower distortion, solid bass, clearer highs, and excellent reliability. Belles also claims that the SA-30 will enhance the performance of any high-efficiency speaker, particularly horn designs. If these claims are true, it could be a panacea for us horn-speaker fans. Of course, I’ve heard such claims about other solid-state amplifiers, and still have nothing but tube or hybrid amplifiers. But I’m always ready to give another contender a shot, especially one from such a distinguished builder.

David Belles is an enduring star in the audio firmament. He has been in the audio business over 30 years, designing preamplifiers, amplifiers, DACs, even tuners. I’ve heard most of his designs of the last five years, and while I’ve liked some better than others, I can tell you that they have steadily improved sonically. Belles says he’s been working on this class-A design for many years, and it’s finally ready for production. It’s part of his Statement line, which now includes the VT-01 tube preamp (review in progress) and the SA-100 100Wpc power amplifier, built on the same chassis as the SA-30 but running in class-AB.

With a shipping weight of 48 pounds, just a couple of pounds less than the 300Wpc Bryston 4B SST² amplifier so favorably reviewed in our July 2009 issue, the SA-30 measures 17" inches wide by 5.25" high by 13.5" deep, excluding binding posts and feet. Its circuits are exclusively unbalanced, meaning that a single circuit amplifies both the positive and negative halves of the signal. Some amplifiers use two sets of circuits to separately amplify the positive and negative signals, then either combine the signals into a single output at the output stage, or possibly even drive the positive and negative speaker terminals from the positive and negative sections of the amplifier. Belles feels that using differential balanced amplifier sections gains nothing sonically, while nearly doubling the parts cost. And he’s passionate about parts selection; after trying out numerous expensive designer capacitors in the SA-30, he had custom Teflon capacitors designed to meet his own sonic preferences. Another indication of Belles’ insistence on using the best parts can be seen in the feet he chose for the SA-30. Instead of the usual nondescript rubber feet found supporting so many amps, the SA-30 has Stillpoints OEM feet. I’m a big Stillpoints fan, having used their aftermarket supports under most of my equipment because they work better than anything else I’ve tried. Including Stillpoints as a standard part of the amplifier is a big plus for me.

Input jacks are a pair of sturdy gold-plated RCAs, while output jacks are a pair of all-metal, gold-plated, five-way binding posts -- both pretty standard for solid-state amps. Input and output jacks are on the rear panel so that the speaker and input cables have plenty of space and don’t overlap each other. If you use unshielded interconnects, it’s a good idea to keep them away from speaker cables; the SA-30’s thoughtful layout makes that easy.

As should befit a member of any manufacturer’s Statement line, the SA-30’s casework qualifies as genuine audio jewelry, making many far more expensive products look cheap. A thick front panel with beveled edges sports Belles’ hallmark keyhole design, which also appears on the top plate, where it’s perforated with ventilation holes. The case is available in silver (the review model) or black. I thought silver showed off the chassis contours better than black, but if black is what you prefer, it’s available.

Class-A amplification circuits run quite a bit hotter than the class-AB circuits often used in other push-pull designs, so in addition to cooling vents similar to those seen in other recent Belles designs, heatsinks along the side help rid the SA-30 of the considerable heat it generates.

Internally, the circuit is laid out in dual-mono fashion, each channel having its own toroidal power transformer. The only parts shared by the two channels are the power cord and the IEC jack it plugs into. Although the IEC socket lets you use the power cord of your choice, the standard, 14-gauge, heavy molded power cord is not a throwaway (although I suspect most audiophiles will treat it as such).

The SA-30 has an extremely high damping factor of 5000, and needs only 0.74V input into its 100k ohm input impedance to produce its rated output. Those specifications predict that the SA-30 will have a lively yet well-controlled sound, and will easily be driven by solid-state or tube preamps. In view of the SA-30’s high input sensitivity, even a passive volume control should work with it.

Setting up

The relatively compact SA-30 slid easily onto the bottom shelf of my equipment rack. Grasping the amplifier from the front and rear panels made it easy to lift and maneuver it into position. The side-mounted heatsinks aren’t razor-edged, so you could pick the amp up from the sides, but I try not to handle amps by their heatsinks, to avoid damaging thermal connections between the output transistors and the sinks.

The SA-30 was connected to my Audio Research LS26 preamplifier via Clarity Cables Organic RCA interconnects. I tried the stock power cord, but, like most audiophiles, I found that an aftermarket cord, in this case the Purist Audio Designs Venustas, produced much better sound. This represents a switch from my former practice of using only stock cords in reviews. Aftermarket cords almost always yield better sound, and I believe our readers want to know just how good a component can really sound. All too often, its stock power cord just doesn’t let a component reach its true potential.

Although the SA-30 is rated at 30Wpc, Belles amplifiers have traditionally produced way more power than their rated output. It will be interesting to see what the SA-30’s actual measured power output turns out to be. Since my MaxxHorn Lumination loudspeakers are rated at 103dB sensitivity, they were no challenge to drive, although, into their impedance of 16 ohms, the actual power delivered would be lower than the SA-30’s 8-ohm specification.

Since I received the review sample from my local Belles dealer, Blue Marble Audio, it was already broken in, eliminating that unpleasant but necessary task. Just to be sure, I gave the SA-30 another 100 hours’ playing time. The dealer had been driving Reference 3A Episode speakers with the SA-30 -- to my ears, a superb pairing.

The SA-30 starts playing as soon as you throw the switch, but it definitely needs a good bit of time -- around 45 minutes -- to reach thermal equilibrium every time you turn it on. While it’s warming up (in the literal sense), it sounds muffled. That’s not a problem, just an observation. Like most class-A amplifiers, it runs hot; I doubt that touching it would cause third-degree burns, but you’ll want to let it cool off -- or use oven mitts -- before trying to pick it up.

The Stillpoints feet must be adjusted to ensure that the SA-30 doesn’t rock back and forth, but this onetime adjustment took all of a minute. Its upside is that you won’t have to obsess about finding a good support system for the amplifier -- it’s built-in!

Sound

I attribute the SA-30’s particularly vivid sound to two related traits: extremely wide dynamic swings, and very fast reproduction of leading-edge transients. Music seemed to leap from the speakers. I don’t mean that the sustain and decay parts of musical notes were slighted; they, too, were quite accurately portrayed, so that the whole envelope of a musical note sounded very realistic. The dynamic strength of the SA-30 was illustrated by the title track of Jennifer Warnes’ The Well (CD, Music Force SD8960). I’ve always thought this recording has quite realistic-sounding percussion instruments, but the SA-30’s stunning transient wavefronts and explosive dynamic punch made them particularly dramatic, as if the drummer was whacking the drums harder than usual. (Incidentally, I recently compared the CD version of this recording to the CD track on the SACD version, and the former sounded considerably better.)

One might expect a solid-state amplifier to have a wide frequency response, and the SA-30 lived up to that expectation. It extracted the best bass response I’ve heard from my MaxxHorn speakers. When I say best, I mean fast, relatively deep, and supple bass; not the overly lean bass I feared the high damping factor would produce, but not fat and shapeless bass like some tube amplifiers, either.

At the other end of the spectrum, the treble was extended but without sounding dry or bleached. This is an area where I still find some sand amplifiers lacking, but the SA-30 produced realistic highs. They weren’t excessively sweetened or rolled off, as they are through some tube amps, but neither were they a bit threadbare, as through lesser solid-state devices. It seemed to me that the SA-30’s reproduction of high frequencies struck a near-ideal balance. Warnes’ own "The Panther," from The Well, begins with a glissando from the chimes, and the SA-30 reproduced it realistically, without any extra emphasis.

Even more important than the frequency extremes is the all-important midrange, and the SA-30’s midrange didn’t disappoint. It was fast and detailed, yet replete with the luscious tonal richness usually found only in better tube amplifiers. It didn’t fatten the sound with extraneous second harmonics, but neither did it skimp on displaying a rich tonal palette. On Hilary Hahn’s performance of the Barber Violin Concerto (Sony Classical SK 89029), the SA-30’s vivid musicality made this music sound more coherent than it sometimes does. Of course, Hahn’s performance had a lot to do with that, as did the accompaniment by the St. Luke Chamber Orchestra, directed by Hugh Wolff. Hahn’s burnished tone perfectly complemented this autumnal 20th-century composition, and the SA-30 portrayed it superbly, without extraneous tonal embellishments.

So far, the SA-30 was batting a thousand -- but what about another popular audiophile parameter, soundstaging? Into the CD player went my current fave soundstage evaluation disc, a collection of masses and motets by Gregorio Allegri, including his famous Miserere, performed by A Sei Voci (CD, Astrée E 8524). The sound was spacious and open, but there was a slight tendency for the voices to clump together in the center of the soundstage. It didn’t sound like a mono recording, but I’ve heard amplifiers that spread out the individual voices more precisely, with better localization of individual singers.

I hate noise. Fortunately, the SA-30 more than lived up to the Belles’ reputation for total silence. My tube amplifiers aren’t noisy, but the SA-30 just seemed to deliver blacker backgrounds from which music emerged unsullied by noise -- just the way I like it.

Comparison

Like the SA-30, Atma-Sphere’s S-30 Mk.III is a class-A amplifier rated at 30Wpc. It costs $3750; add $500 to upgrade it with VH Audio V-Cap Teflon capacitors. Also like the SA-30, the Atma-Sphere has first-rate parts: those V-Cap capacitors and two toroidal power transformers. But that’s where the similarity ends; the Atma-Sphere has a fully balanced circuit with 6AS7G triode tubes for amplification. Since the Atma-Sphere uses a balanced circuit, I used balanced interconnects to connect it to the preamp. Fortunately, I had on hand some balanced interconnects from Clarity Cables, equivalent to the unbalanced interconnects I used on the SA-30; the different interconnects caused vanishingly little difference.

The Atma-Sphere’s ten output tubes and six 6SN7 driver tubes make the SA-30’s heat output seem positively arctic. On my equipment rack, the SA-30 heated up the shelf above the one where it was placed; the Atma-Sphere heated not only the shelf above, but also the preamp sitting on that shelf, and even the shelf above the preamp. While the Atma-Sphere’s output-transformerless circuit won’t drive 4-ohm speakers, it delivered extra power into the MaxxHorns’ higher impedance. But given the speakers’ high sensitivity of 103dB, both amps had power to spare.

Thanks to its lack of output transformers, the Atma-Sphere amp doesn’t sound like a typical tube amp. Its beefy power supply results in a wide dynamic envelope, and without output transformers to round off the leading edges of waveforms, the Atma-Sphere reproduces steep transients particularly well. So in many respects, the Atma-Sphere’s strengths match those of the Belles. Both amps exhibit superb tonal richness.

Its lack of output transformers makes the Atma-Sphere’s bandwidth unusually wide for a tube amp. Bass, in particular, is outstanding: deep, punchy, and detailed. Treble is also excellent, but on Jennifer Warnes’ "The Panther," the SA-30’s treble seemed just slightly -- and I mean slightly -- more extended and detailed.

One area where the Atma-Sphere S-30 outperformed the Belles SA-30 was in soundstaging. It outlined wide, spacious depictions of performing venues, with performers existing in their own spaces. This is an area where tubes are reputed to excel, and the Atma-Sphere sustained that reputation. That’s not to say the Belles couldn’t produce a spacious soundstage; but the Atma-Sphere’s seemed slightly more precise, with individual musicians better located within the recording venue.

The Belles SA-30 and the Atma-Sphere S-30 Mk.III proved surprisingly similar. But the Atma-Sphere has a lot of tubes, which produce more heat and, like any tubes, sometimes fail. I don’t mean to suggest that the Atma-Sphere is unusually prone to tube failures, just that the tubes in any tube amplifier will, inevitably, fail.

Style-wise, the Belles and Atma-Sphere amplifiers couldn’t be further apart. Each made a statement in its own way: the Belles is a finely crafted example of the metalworker’s art, while the Atma-Sphere’s black crackle finish is defiantly retro. Which appearance is preferable is a matter of taste; I tend to go with sound rather than looks.

Bottom line

For a long while I’ve said that I’d love to find a solid-state amp that sounded as good as my beloved tube amplifiers, but after years of searching, I’d sort of given up ever hearing one. Lo and behold, here it is. However, the Belles Statement SA-30 doesn’t sound like a tube amplifier; it’s very clean and distortion-free, with a tonal balance almost as rich as that of a single-ended-triode tube amp.

Unless you find the romanticism of glowing tubes irresistible -- and, more important, assuming the SA-30’s relatively low power will drive your speakers -- you owe it to yourself to audition this amplifier. Its price of $4695 isn’t really cheap, especially on a dollar-per-watt basis, but that’s not what the SA-30 is about; it’s about producing sound equal to or better than that of low-powered tube amplifiers, with the maintenance-free convenience of a solid-state unit. If you compare its total cost of ownership to that of tube amps of the same output and sound quality, it’s definitely competitively priced. It’s easily the best amplifier I’ve heard from Belles, and it’s the best solid-state amplifier I’ve heard, period.

So: fairly priced, terrific sounding, trivially easy to set up and maintain -- what are you waiting for? If the family treasury allowed me to add another amplifier to the seven (!) already in my arsenal, this amplifier would not go back to the manufacturer.

. . . Vade Forrester
vadef@soundstage.com