soundstage 的测评
I confess: I don’t really enjoy writing about electronics all that much. It’s work! As Bill Cowen remarked in his review of the Herron Audio VTSP-1 preamp, writing about speakers is easier as they have a more easily definable character. The other problem with electronics, and power amplifiers in particular, is that they only have a voice when hooked up to a pair of speakers. Varying load characteristics of speakers can have a very dramatic effect on the performance of an amplifier. An amp can sound one way into an easy-to-drive, high-efficiency speaker and completely different into a low-efficiency speaker with a load that varies widely with frequency. You should always keep this in mind, especially when reading a review of an amplifier that utilizes only one pair of speakers.
There are also other factors involved that are more difficult to explain. Behind the scenes, the Soundstage! writers have been embroiled in some discussions regarding product break-in vs. listener acclimation -- and about matters of bias. Without a "control" piece against which you can compare a broken-in product, it’s difficult to say for sure whether a component has broken in or whether the writer has just become accustomed to what he or she is hearing -- to the point of being able to accept it or even to fully understand its virtues. It’s a difficult issue to come to grips with, and I bring it up now because I’ve had the Odyssey Audio Stratos power amplifier in my home for longer than any other review piece, and I’ve done the biggest about-face regarding its sound. But a good friend of mine gave me a bit of sage advice: "Never attribute an effect unless you know with absolute certainty the cause." So with his words in mind, I now embark on a sharing of my experiences with the Stratos amplifier, trying very hard to stick to the facts and nothing but the facts.
Details
When the Odyssey Audio Stratos arrived, I couldn’t help but be impressed. The amp's fit and finish and build quality are what consumers look for, but don't always find, in amps selling for three times the Stratos' $995 USD factory-direct-only price. The amp has a .4"-thick face plate and 1/4"-thick rear plate; hazard-free heatsinks that are thick, smooth to the touch, and run end to end; high-quality gold-plated binding posts; both XLR and RCA inputs; and a weight of 54 pounds. It's the most hardware for the money that I’ve ever encountered, and it's truly beautiful in an "audiophiles will understand" kind of way. It's even available in a large variety of domestically friendly colors and carries a 20-year warranty, both of which only add to its allure.
The Stratos is rated at 150Wpc into 8 ohms (260Wpc into 4 ohms) and is said to be heavily biased into class A, which means that it should do an excellent job as a space-heater. But it didn’t. Even when driven fairly hard (and never when allowed to loaf along), the Stratos never got more than mildly warm to the touch. Pop the top and you see a spacious, neat and orderly layout that dispels fears of electrical or RF interplay.
Round one
When I put the Stratos into my system, things became difficult very quickly. Odyssey Audio recommends an extensive break-in period for the Stratos, and I gave the amp a couple weeks in peripheral duty, breaking in a pair of speakers. By then I would have thought that it was ready to go. But when I inserted a Classé Model 5 preamp up front and a pair of Ohm Walsh 300 Mk II speakers behind, I was disappointed. On the plus side was a pleasant tonal balance with smooth and grain-free treble, fairly good midrange detail, imaging and soundstaging; but tipping the scales in the other direction were loose, soggy bass and an utter lack of microdynamics. The music sounded like wallpaper: flat and lifeless. This was a first impression that the Stratos was going to have to work hard to overcome.
Round two
Over the course of the next couple of months, the Stratos was matched with a variety of speakers: Silverline SR17, Audio Concepts Jaguar 2000, the Tyler Acoustics 7u, the original Silverline Sonatina and later the Sonatina Mk II, and JMlab Mini Utopia. Primary preamplification duties became the responsibility of a Conrad-Johnson PV12A for most of the evaluation period before it was replaced by the Herron Audio VTSP-1. Interconnects and speaker wires were from DH Labs. Digital sound was most often provided by a Sony DVD S500P feeding a Meridian 563 DAC. A Sota Jewel turntable with a Premier FT3 tonearm and Benz-Micro MC Silver cartridge rounded out the system.
Many more miles were placed on the Odyssey’s odometer, and over time I became enamored with some of the amplifier's qualities. For one, the amp never misbehaved -- never ran hot and was always dead quiet. For another, it demonstrated a velvety smoothness with no harshness or edge. Sometimes this sound is found in amplifiers with a shelved treble, but this was not the case with the Stratos. The treble was in full account, but there was a distinct lack of the upper-midrange glare often found in affordable solid-state products. Bass with admittedly less-than-full-range speakers was weighty. The ACI Jaguar 2000s and the Silverline SR17s, in particular, exhibited a tight and punchy bass with previously unheard sock. Soundstaging was truly marvelous. Particularly when the amp was used with the Silverline Sonatina Mk IIs, the sense of space was spectacular in both the horizontal and vertical planes. Stage width was panoramic and tall with generally very good depth. Image specificity was good as was palpability, but more on these later. The sense of air and recorded venue were also very good.
Well, three months of almost constant use went by, and one question persisted in my mind: Of what use is a powerhouse amp that can only do justice to limited-bandwidth and efficient speakers?" It was with questions of amplifier break-in in mind that I dragged out the Ohm Walsh 300 Mk IIs again. First up was Patricia Barber’s Companion CD [Premonition 7243 5 22963 2 3] and "Use Me." The track starts off with a well-recorded solo upright acoustic bass. Miking is close enough that you hear every nuance, from the slapping of the strings against the fingerboard to the full-bodied sound that plumbs the depths with authority. "Wow" was my response. This is definitely not what I remembered hearing over three months ago. The speaker/amp combo now exhibited both speed and articulation. Weight was excellent too and what I expected from the Walsh 300 Mk IIs, but the point is that the 150Wpc Stratos was now giving it to me.
I skipped to "Black Magic Woman," and roughly seven minutes into the track there is a percussion dual between drummer and bongo player. What I now heard was microdynamic intensity that was also previously missing in action. Each drumbeat was presented in its own right, with no slurring and with an excellent sense of transient attack -- all of which emerged out of a near-black silence. And James Taylor’s "Gaia" from his Hourglass CD [Columbia CK 67912] answered the last remaining question regarding the available brute force of the Stratos. About four minutes into the otherwise rather subdued track there is a powerful drum line that not only shakes the room, but travels side to side across the soundstage. Well, the sheer power and slam articulated by the Walsh 300 Mk IIs brought my father-in-law in from the next room with a big smile on his face, and the focused sonic image traveling across the stage put one on my face too.
Round three
Late in the review period I took delivery of the Herron Audio VTSP-1, a preamp that Bill Cowen reviewed for SoundStage! last year. Bill was absolutely right -- this unit comes closer to having no sound than anything I’ve ever used, and with the Herron preamp in my system along with the Silverline Sonatina Mk II speakers, I could better focus in on exactly what the Stratos was doing. As it was closer in price than anything I had in the house, the first amp I compared to the Stratos was the Classé CA-100, with 100Wpc. At roughly 150% of the price of the Stratos amp and 66% of the power, the Classé amp was as close as I could get. Where the CA-100 shone in comparison to the Stratos was in the area of image specificity. The Classé amp cast better-defined images, particularly in the center of the soundstage. Center images were more stable and more there. But this doesn’t tell the whole story. While the images with the Classé were more delineated, the presentation overall was much dryer. The Stratos delivered soundstaging with greater air, a more expansive sense of space, and greater depth. Bass from the Stratos also had more grunt. Bass lines from the aforementioned Patricia Barber CD had more weight and punch. The Classé CA-100 is a very sweet-sounding amplifier, but one that sounds slightly dark too. The Stratos has the same glare-free upper regions, but offers subjectively more extended and tangible treble. The chimes at the opening of James Taylor’s "Gaia" were more palpable and conspicuous over the Odyssey Audio amp than they were with the CA-100.
Having outclassed the Classé in most areas, the Stratos faced my Conrad-Johnson MV100 -- an EL34-based 90Wpc tube amplifier. I paid over three times the price of the Stratos for the C-J amp almost ten years ago, and after comparing it to the Conrad-Johnson Premier Eleven A some years ago, I decided that I would keep the MV100. It's not that it really outclassed the more expensive C-J amp, but it did offer the same strengths important to me at the time as well as a more neutral tonal balance when used with my speakers of the day. The results of the Stratos/MV100 comparison were more of a mixed bag, as one would expect, with the CJ amp outclassing the Stratos in some areas, but with the Stratos eclipsing the C-J’s performance in others. But speaking well for the Stratos was the fact that most of the perceived differences were rather small. The C-J amp couldn’t match the sheer brute force and authority of the Stratos down low, and Stratos was just edged out by the CJ was in the treble. The Odyssey Audio amp almost split the difference between the slightly brighter C-J and the darker Classé amps while maintaining a closer proximity to the sound of the C-J. Again, the extended treble of the Stratos and its glare-free midrange go a long way toward providing neutral and utterly enjoyable listening.
My last serious music session during the review process included a listen to the Yo-Yo Ma Premieres CD [Sony SK 66299]. This recording of the Philadelphia Orchestra with David Zinman at the helm is spectacularly recorded. Christopher Rouse’s Violoncelloo Concerto is a dark and menacing piece with abrupt and explosive dynamics. At this point in the Stratos' review process, I wasn’t all that surprised that the amp had no problem keeping up with the festivities, but what caught me almost totally off guard was the soundstaging. From my seat, I’m not sure I could have thrown a stone and hit the rear wall of the hall in the recording -- it was so far back. And wide? Yes, almost to the point of straining credulity given the depth of the stage and the distant, yet highly detailed perspective on the orchestra. Did the Stratos guarantee such a presentation? No, it delivered only when the recording called for it. The Deutche Grammophone recording of Gustav Holst’s "The Planets" [Deutche Grammophone 103835] gave just the opposite depiction: no stage clearly defined, no depth, and a very forward and indistinct presentation. Clearly, with the Stratos, what you have on your recordings is what you will get from your speakers -- provided they're up to the task.
Conclusion
Am I confident regarding to what I can attribute the slow start I had with the Odyssey Audio Stratos amplifier? Not really. It may have been a break-in issue or it could even have been an unrealized bad mood on my part that colored my initial experience and biased me against the amplifier, thus requiring an extended audition that eventually withered that bias away. Whatever it was, it’s a testament to the quality of the Stratos that I was indeed able to overcome that initial bias and become quite fond of the sound the amplifier produced. But I do advise potential purchasers to drive the amp long and hard before making any final judgments, even if you think it sounds good out of the box.
In the end, I found the Odyssey Audio Stratos amplifier to be an excellent all-around performer. If it has an Achilles heel it may be that the amp takes such a long time to break in, but ultimately I found its overall performance unimpeachable. Given its sub-$1000 price, it gets my caveat-free recommendation. When the Stratos is stacked up against amps twice its price, you still can’t go wrong with it. Beyond that, as I heard with my Conrad-Johnson tube amp, it can become a real slugfest, but the Stratos remains competitive and even excels in certain areas. Add to the mix the excellent fit and finish with bulletproof construction and I can only conclude that for many reasons and in many systems, the Odyssey Audio Stratos will be a fine choice.
...John Potis
