Ypsilon Electronics Aelius Mono Amplifiers
psilon is the twentieth letter of the Greek alphabet and Aelius was a noted Greek scholar and orator, so it will come as no surprise that the Ypsilon Aelius mono amps come from the cradle of Western civilization. These 200-watt push-pull monoblocks are sophisticated hybrids, featuring a tube input stage using a single C3g -- a fairly obscure metal-sleeve tube -- and a MOSFET output stage. They output 60 watts of their power in class A, which means they'll run this way for the majority of listening, but perhaps even more significant is Ypsilon's claim that the amps offer single-ended sonic purity and push-pull power. While this sounds immediately like marketing hyperbole, Demetris Backlavas, the amp's university-trained design engineer, can back it up. He cites the Aelius's "balanced (or you may call it bridged) single-ended output stage," for which both phases, plus and minus, carry signal. "The difficulty of implementing this output stage," Backlavas went on, "is that it requires to be driven with a perfectly balanced signal. And this was done with an interstage transformer, which took a long time and many trials to bring it to the level of performance we wanted (-3dB@13Hz-70kHz)."
What this means in non-engineering speak is that the Aelius's circuit is sort of a double hybrid: tube and solid state, balanced and single ended -- with no feedback, an important design consideration for Backlavas. All of this makes for an amplifier that is unlike any other produced today -- at least among the ones I'm aware of. Ypsilon itself is just as unique. First, the company manufactures its own transformers. The cores are outsourced, but the design and winding happens at the Ypsilon factory. Second, the solid-silver hook-up wire used in each Ypsilon product is proprietary, drawn from bars of silver. A jeweler does this to Backlavas's specifications.
Connection to the Aelius is via RCA or XLR input, but counterintuitive perhaps to what I've divulged so far, only the former is recommended for achieving the highest performance from the amps. The balanced input for the review amps included a transformer not manufactured at Ypsilon, and this led to an obvious veiling -- with this "veiling" not being part of the Aelius's sound through the single-ended input. It honestly did sound like something additional was in the signal path, which was literally the case. Realizing this, Backlavas will be removing the transformer in future production runs. For connection to the speakers, the amps use binding posts with frosted caps that look like they were made specially for the frosted-silver Aelius.
One feature of the Aelius that I applaud loudly is its ground-lift switch, which could save you the time and inconvenience of using cheater plugs if you have a ground-loop issue with your system. This is also an outward sign of one of Backlavas's preoccupations: eliminating noise. He seems to have hit his mark. After initially installing the amps in my system, connecting to the preamp and speakers, and turning everything on, I thought I had overlooked something, because there was absolutely no background noise -- not even the omnipresent tube rush I had gotten used to hearing. I put my ear up to the tweeter and heard complete silence. I hit play on the CD player, expecting nothing to happen, and music poured forth. Luckily I didn't do something dumb like crank up the volume when I thought things were amiss.
The amps definitely needed warm-up after turn on, sounding sterile when they were cold and then coming into character after 30 minutes. However, they seemed so stable, so imperturbable, that I left them on almost indefinitely, unless I knew I wouldn't be listening for days, the amps always being ready to make music.
The Aeliuses I reviewed were actually the second I pair received. The first arrived almost a year earlier, right after the amps were introduced. I heard in them much of what the review amps achieved, along with a couple of aberrations that were not befitting their pedigree and especially their cost. Most notable among these was a combination of thinness and dryness in the mids that leaned out voices, making them sound more reproduced than real. Demetris Backlavas evidently heard the same things, because a couple of months after I received the amps and completely out of the blue, a revision was announced and the review amps were retrieved.
Lest conspiracy theorists think that I had something to do with this, I had zero contact with either Ypsilon or US distributor Aaudio Imports, from whom I received the amps, while I did that initial listening. I was proceeding as usual when, one day, the call came and the amps were picked up. As for why I didn't just write the review, what would have been the point? That Aelius wasn't a product any longer.
However, as you may have noted, a third version of the Aelius is now on the way, although this time with unchanged sonics (unless you listen balanced, that is). Thus, what I heard and describe, the product of listening single ended, will mirror what you hear from a pair of Aelius monoblocks bought today.
The second time around
he sound of the Aelius monoblocks embodied seeming opposites. On the one hand there was an overwhelming clarity, which mixed supreme retrieval of musical detail, transient definition, and front-and-center tonal neutrality. On the other hand, there was an inherent robustness and density that tracked from the highest highs, through the mids and into the bass. Add in that nonexistent noise floor and you have, I'm confident, one of the most complete amps extant -- an amp whose personality was literally devoid of obvious weaknesses. This is not to say that the Aelius did everything better than all other amps -- that beast has yet to be created. However, within a broad level of performance, the Aelius competes with any amp I've heard -- and I suspect any amp made today.
Hearing familiar recordings was often an act of discovery, especially those whose sound is stellar in an absolute sense. They could sound both fresh in specific ways and true to life generally. One recent and lucky addition to my collection is the Mobile Fidelity version of Led Zeppelin II [Atlantic/Mobile Fidelity MFSL 1-065], the only one of Zeppelin's albums reissued by MoFi (thus far -- we can always cross our fingers for the future). It has become the album I play for non-audiophiles who want to either experience my system or hear the difference between digital and analog, and it never, ever leaves them in anything short of complete awe. I paid a mere $35 for my near-mint copy -- more than its original selling price, but $100 less than the going rate on eBay.
If you grew up in the 1970s or 1980s listening to FM rock radio, you know side two -- beginning with "Ramble On" and closing with "Bring It On Home" -- by heart. It was a new experience with the Aelius monoblocks. The guitars had more pummeling bite and the bass and drums were better defined and weightier. On side one, the ping-pong stereo effects of "Heartbreaker" whizzed between the speakers with dizzying suddenness. No matter its version, this LP will never be a test of dynamic range, as the music commences at loud and proceeds to louder still, but that's part of its relentless charm. As much as the Mobile Fidelity remastering, I'm convinced, the Aelius monoblocks made this blues-rock war-horse sound exhilarating.
An amp that can do that is a rare thing -- if and only if it doesn't skew the spectral balance by goosing a particular region or adding some amusical artifact that can enliven in the short term but wear thin over time. About the most that can be said about the Aelius monoblocks in this regard is that their perspective is more forward of midhall, giving them an insistence that imparts an agreeable vividness to the music. This is easier to appreciate at lower listening levels, where you won't have to aurally squint to discern microdynamic contrasts, than higher ones, but the amps' inherent grainlessness never made it an issue. When Miles Davis pulls out his mute, forwardness and especially treble grain have nowhere to hide. While Someday My Prince Will Come is not Miles at his vital best, it's still has some lovely playing, including John Coltrane's final work for the leader's first quintet. I have both the 45rpm LP [Columbia/Analogue Productions APJ 8456-45] and SACD [Columbia/Analogue Productions CAPJ 8456 SA] and, as with Led Zeppelin II, the music was rendered with such excitement with the Aeliuses that I began to reevaluate the playing. The digital version didn't have quite the same lateral spread and the treble was a little less liquid -- both of which the Aelius amps revealed.
Roy Gregory likes to talk about how great components actually make orchestras, ensembles and bands sound like they play better -- more true to the music and their own intentions. This idea popped into my head as I listened to Someday My Prince Will Come with the Ypsilon monos in the system -- the sound being infinitely well resolved for sure, but the playing also being tighter and (for lack of a better way to express it) more effervescent. This was also apparent with the 45rpm version of Seven Steps to Heaven [Columbia/Analogue Productions APJ 8851-45] -- the second incarnation of Miles' quintet and a much more formidable session. This is what great audio gear should do: make the work of great musicians sound greater still.
While the Aeliuses may have a tube in their signal path, there was nothing classically tubey about their sound -- no cloying midrange, no bass bloom at the expense of speed and slam. Perceived linearity ruled, the mids having a meatiness that, once again, is rare for an amp that's as tonally evenhanded as the Aelius. The bass was taut and muscular, more deep than bloomy and warm, and it possessed real power, especially with kick drum like that on Keith Richards' Main Offender [Virgin V2-86499]. The realism quotient of this recording is something to behold, the Ypsilon amps conveying not just the pop and sock of the drum kit but also the sharp barrage of the electric guitars. In fact, if you've heard this CD (it's also available on vinyl, but expect to pay dearly for it), you have a sense of the personality of the Aeliuses: a slightly forward perspective, vividness throughout the music's entire range, fleet transients that decay into blackness, roaring power.
And copious air throughout the soundstage. Darker-sounding amps can cramp things, conveying the presence of the musicians better than a well-rendered sense of the space in which they perform. While the Ypsilon amps leaned to the latter, they weren't devoid of warmth and dimensionality. At the recommendation of Richard Gerberg, the US ProAc distributor, I've been listening to a lot Sun Kil Moon, the moniker of Mark Kozelek, founder of the Red House Painters. His music and voice are reminiscent of Harvest-era Neil Young, and both bordered on luscious with the Aeliuses, which neither turned his singing into sugary mush nor emphasized the nasal quality that gives it character.
The presentation was both truthful and beautiful, and this is what the best components achieve -- a balance in portions so nearly ideal that any deviations are trifles in light of the totality of their performance. This is the Ypsilon Aelius in summary. While no amp will please everyone equally, the Aelius has a better chance of achieving this than any amp I've heard to date.
hile hybrid amps like the Ypsilon Aelius make a great deal of sense, because they hold the promise of combining tubes and solid state, there are surprisingly few of them. The dean of this select group is the Lamm M1.2 Reference ($22,290), which, if you include its previous version, the M1.1 (and the Madison-Fielding M1 before that), has been on the market for almost twenty years. Obviously, the core design of this amp has great validity, both in terms of sonics and reliability: a tube input stage using a single 6922 followed by a MOSFET output stage running in class A. There's much common ground with the Aelius here, although Vladimir Lamm has never manufactured his own transformers or spec'd his own hookup wire, and the price of the M1.2s is less than two-thirds of the price of the Ypsilon amps.
I've used the M1.2s as my reference for over five years. For reviewing, they offer great flexibility, as they have both RCA and XLR inputs and there is no discernible sonic difference between them. They also have a switch on the back that adjusts the idle current of the output stage, this depending on speaker impedance and ensuring that more of the amp's output is in class A. Even without all of these niceties, the M1.2s would still be very high on my personal list of amps because they sound glorious; I've often pointed out that they, along with other Lamm equipment, have as nearly ideal a tonal balance as possible -- one that mimics the color, dimension and weight of real life. Absolute neutrality is a thought construct; so many of the amps that are deemed "neutral" sound lean and tonally threadbare -- exactly what the M1.2s do not.
From this you probably can guess that the Ypsilon and Lamm amps do not sound like the near relatives that they are. While it's possible to discern the tube and transistor sides of each amp's personality, the Lamm amps take on more of the traditional traits of tubes, displaying greater richness and warmth, a meatier and more expansive bottom end, and sweeter treble than the Ypsilon amps. The Aeliuses have less of an overt tonal signature, though the density of their mids might make you question this. They are faster into and out of each note, and their decay is more apparent, likely due to their lower actual and perceived noise floor.
Main Offender illustrated the differences of the two amps well, the Lamms imparting greater heft to the Richards' lead playing and that of the bassists, while the Ypsilons positively launched each drum strike into the room, portraying more skin than the Lamm amps and, once again, conveying greater decay amidst a wide, deep soundstage.
Yet, these differences don't invalidate the notion that both amps offer a wide-ranging set of strengths and a completeness of purpose. They prove once again the immutable law that similar design goals can lead to different sonic outcomes. Such is the diversity of human nature -- and the variety of sounds that can still be deemed hi-fi.
The promise of promise
ruly great amps, like their equals in other product categories, are complex sonic entities. Some distinguish themselves by pushing ahead the performance in one area, while others build on a defined set of traits, shoving them all to new heights. The Ypsilon Aeliuses fit into neither of these camps, and yet they are certainly "truly great amps." With them, it is the sum total of everything they do -- all to a very high level -- that's distinguishing, and that so much of what they achieve is rare among amplifiers no matter the price. I've heard amps that track the signal with as much speed as the Aeliuses and amps that are as quiet as the Aeliuses, but not amps that possess these qualities along with the same midrange dimension and the same bass power -- the same level of overall realism -- as the Aeliuses, all in one package.
The Greeks have been responsible for advancements in engineering, transportation, mathematics, sport, cartography, philosophy, literature -- the list goes on and on. Even more upscale in the Ypsilon lineup are the SET 100 Ultimate monoblocks, which are as large as computer servers and cost as much luxury cars -- each. Until I hear for myself that they fulfill their enormous promise, the Aelius monoblocks will more than ably represent the audio advancements of the Greeks -- and Ypsilon.
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