Tube Power Amp Reviews

Currently, Ypsilon ships to EU countries Aeliuses equipped with 6C45s. More significant, the amps are manufactured with the 6C45 tube-socket base, making them incompatible with the C3g (which Ypsilon also uses in their VPS-100 phono and PST-100 line preamplifiers). Amps shipped to the US are fitted with the C3g base and are normally shipped with that tube, which Backlavas admits has "greater openness and transparency." However, he thinks which tube sounds best will depend on the system the Aelius is used in. He assumed that I'd be reviewing his amps with the less lush-sounding Wilson MAXX 3s, and so shipped the review samples equipped with 6C45s. So glad I asked!

When I'd replaced the input tubes with the C3gs and spent some time listening, I understood Backlavas's tube rolling—though I think it was an unnecessary defensive posture, even had I been listening through the MAXX 3s.

Clean and Direct
With the C3g tubes in place, and after about an hour's warm-up (both before and after the tube swap, I left the amps on continually), I sat down and listened. At first, they sounded like completely different amplifiers; later, the Aeliuses revealed themselves to be the same amps, but their soft and fluffy gatekeeper had gotten out of the way. The C3g tightened the screws on the musical framework, producing a punchier, more direct, more insistent sound. Little remained of those soft billows.

The Aelius's solid-state-ness now asserted itself more intensely, particularly on the bottom, where excess bloom gave way to grip and punch. The amps came rhythmically alive and physically assertive in a most pleasing and immediate way, yet in no way was the sound clinical or harmonically bleached.

I didn't hear the effect of the C3g as an identifiable "tubeyness" but rather as a graceful, gentle, infinitesimal rounding of transients and sculpting of images that produced mesmerizing three-dimensionality with zero negative consequences. It just sounded right. Instrumental attacks became alarmingly urgent and precise, but never clinical or etched. Sustain was still generous—though not like before, when it was too much—and decays were effervescent, fading into pitch-dark backdrops. The Aelius was very quiet and super-transparent, and its microdynamic performance was as good as I've heard.

Like the Ypsilon VPS-100 phono preamp, which sounds like neither solid-state nor tubes, the Aeliuses, fitted with the same tube, sounded likewise: neither warm and fuzzy nor cool and clinical, but with a distinctly direct and upfront sound that perhaps had influenced the designer's decision to fit the amps with the 6C45 tube.

If Dan D'Agostino's Momentum amps were liquid and demanded an almost feminine listening melt, the Aelius amps produced the opposite sensation: a bracing masculine steeling and grip, a rush of adrenaline vs the Momentums' flood of endorphins.

A test pressing of Analogue Productions' upcoming vinyl reissue of Ray Brown's Soular Energy (it was reissued in 2002 on two LPs by Pure Audiophile, and before that in a Super Analogue edition from King Records Japan) produced exceptional clarity, hair-raising speed and transparency, and a profusion of accurate tonal colors from Ray Brown's double bass, Gene Harris's piano, and Gerryck King's drums, the cymbals being particularly spotlit (in a good way). The amplifier's proficient microdynamic expression, combined with its taut rhythm'n'pacing abilities, proved ideal for this trio recording. Harris is all over the keyboard in "Cry Me a River," and when he goes for the very top, where the "pingy" notes are, the Ypsilons fully fleshed them out. The sound of the hammer striking the strings, the excitation of the instrument's metal frame and the high-frequency wooden resonance of the soundboard were accurately reproduced in terms of time, space, tonality, and texture—not too hard, not too soft. If you've ever plinked those upper keys yourself, you'd recognize how right they sounded as reproduced by these amps—not that the rest of the piano sounded any less convincing.

Guitarist Grant Green's version of "My Favorite Things," from his The Complete Quartets with Sonny Clark, recorded by Rudy Van Gelder (2 CDs, Blue Note CDP 8 57194 2), produced a different sonic picture. There was definitely greater emphasis of the transient pluck and less on the three-dimensional aura around each pluck. As I wrote in the Momentum review, "A faster, more clinical-sounding amp might emphasize the transient at the expense of the aura; a slower, softer-sounding one might get the aura but fail to cleanly delineate it. Given that choice, I'd go for clinical over mush. . . ."

The Aelius with C3g tube definitely sounded more clinical than the Momentum (which produced more relaxed transients). I suspect that with the other input tube the Aelius would have properly reproduced the aura around Green's guitar, but would have failed to delineate it cleanly in space, and would have softened the transient. That's why I thought the C3g tube produced better sound with my system. I prefer correct, clean attacks, and that's something at which the c3G-equipped Aelius excelled, without sounding clinical or hard—unless the recording itself did.

Closer to the Action
The overall sonic perspective produced by the Aelius was more forward than that of the D'Agostino Momentum or the darTZeel NHB-458 or the Musical Fidelity Titan—not in-my-face, but definitely more upfront. Yet compared to the darTZeels', the Ypsilons' images were somewhat more gracefully rounded, more three-dimensional, and texturally more supple.

I'm always happy to play Lorin Maazel and the Cleveland Orchestra's recording of Gershwin's Porgy and Bess (LP, UK Decca SET 609-11), to hear how a system handles space. This recording, engineered by Kenneth Wilkinson, produces an enormous, well-delineated space and an exquisitely well-focused orchestral picture. The solo vocalists are also well back in space on the stage, as you'd hear in concert, and superbly focused and solidly three-dimensional, surrounded by a cushion of natural reverberation. If you're trying to stop someone in his or her tracks with music, it's a can't-miss record.

After a short opening fanfare (which, years later, Charles Strouse stole for the opening of Bye Bye Birdie) that highlights the brass and percussion, there's a long solo for upright piano, the piano in the distance, on the right. The Aelius excelled at reproducing the lesser-quality piano's somewhat tinny tonality, but pushed the instrument farther forward than usual. This was more than made up for by the well-focused image of the piano and the transient clarity of individual notes. When the chorus unexpectedly enters at center stage, their "Dah-doo-dahs" hovering in space, they, too, appeared farther forward than usual. (In this opening sequence of Gershwin's opera, which includes "Summertime," you can also hear where Peter Knight got his ideas for the orchestral arrangements he wrote for the Moody Blues' Days of Future Past, and even elements of Bernstein's West Side Story.)

Vocal and instrumental timbres also were spot on, thanks to the Aelius's robust, full-bodied midrange. Overall, the amp's presentation of this sonic spectacular was tonally, spatially, dynamically, and rhythmically mesmerizing, and its transient purity and transparency only added to my pleasure. However, if the other components in your system exhibit even a hint of hardness, the Aelius with C3g tubes will accentuate it.

Norah Jones's The Vinyl Collection (7 LPs, Blue Note/Analogue Productions AAPP NJBOX 33) demonstrated the Ypsilon's superb midrange palpability. These records, remastered by Kevin Gray and pressed at QRP, are so quiet, their sound so velvety, that it seems as if you're listening on the other side of the mike, hearing Jones's voice before it's captured.

The Aeliuses put Jones's voice dramatically up front, tightly focused in three dimensions and as texturally full-bodied as it needs to be to sound real. Getting that means that there can be no audible leading edges to transients, no lower-midrange emphasis that might add a chesty quality, no sustain anything less than generous, no decay into black anything less than ideal. Jones whistles in "Little Room," and through the Ypsilons I'd swear she was whistling in my room. Not an easy illusion to create.

Switching to the darTZeels produced different sonic pleasures. The perspective was a bit less forward, the overall picture somewhat more relaxed. Images were somewhat less intensely focused, yet the articulation of transients was more precise, and there was a greater sense of the space around Jones's voice—as well as around Grant Green's guitar in The Complete Quartets with Sonny Clark.

Unique Circuit, Unique Sound
The Ypsilon Aelius, the D'Agostino Momentum, the darTZeel NHB-458, the Musical Fidelity Titan—all accomplished amplifiers, each with a different sound. Which is "correct"?

In the world of recorded sound and complex combinations of gear, there's no such thing as the "correct" sound. Certainly, some amplifiers are wrong, producing gross tonal colorations, transient artifacts, glaze, grain, glare, smear, etc. But at the level of the models I've just listed, none of those should be present, and none are.

The problem with absolutism in reproduced sound is that if you judge a component using your 20 favorite recordings, you're judging it against those recordings' tonal balances, and you end up in a maddening sonic feedback loop. That's why, in addition to my favorites, I include in my listening dozens of unfamiliar recordings, plus some that I know sound bad.

At an audio show a few years back, I'd just finished listening, through Krell amps and speakers, to a wide variety of sonically reliable LP tracks that I'd previously recorded to CD and that I'd already heard through dozens, if not hundreds, of good systems. They sounded superb. A guy walked in and asked to hear his favorite recording, an opera. Within a few bars, it was obvious that this recording was awful: bright, glazed, hard, and spatially compressed. This was not the inherent sound of those components in that room. Yet this was the single recording with which he gauged a system's performance. He stopped the disc, declared the sound in the room "awful," left, then spent the rest of the show telling everyone how bad the sound in Krell's room was. But what was clearly awful was his CD.

The Ypsilon Aelius's sonic character, like that of the D'Agostino Momentum, was obvious early on, but so fully realized from top to bottom as to be unnoticeable after a short period of acclimatization. That left only the enjoyment produced by an amplifier that is unique in both design and sound. The Aelius's top-to-bottom rhythmic agility may be in a class of its own. Its bottom end was nimble, clean, and well extended, and did the best job of controlling the woofers of the Wilson Alexandria XLFs of any amplifier that's been here since those speakers arrived, though the darTZeel NHB-485 was close enough. The D'Agostino Momentum was somewhat softer, the Musical Fidelity Titan softer yet.

With the C3g tube, the Aelius's reproduction of the highs was as fast, clean, extended, and assertive as its reproduction of the rest of the audioband. It all added up to a rhythmically spectacular amplifier that was like a shot of adrenaline. That might not appeal to the Lincoln Town Car sound crowd, but definitely will to those who like to press the pedal to the metal, even when listening to chamber music. On second thought, maybe with the alternate input tube, the limo crowd might like it too. The great thing is, if you're in America, you have freedom of choice, and with it, Two! Two! Two amps in one!

Conclusions
After installing the stock C3g tubes, it took me a while to warm up to the Ypsilon Aelius monoblocks. But with the tubes originally supplied, the sound was too warm (though perhaps not for you). With the C3gs, the Aeliuses were definitely not too warm. Coming from the polar-opposite D'Agostino Momentums required a period of adjustment—but not because the Aeliuses were too bright, too fast, or too anything. Their sound was simply too different—but equally valid.

The Aelius amps were just right if you like a tight, fast, nimble top-to-bottom ride, if you like sounds so transparent it's almost alarming, convincingly yet not analytically precise transients, and three-dimensional imaging—all without paying the high price of too-sharply-defined edges or a clinical, soulless, harmonically bleached sound.

The Aelius is yet another spectacular sonic and technological achievement from Ypsilon Electronics. I remain impressed by everything they do.