Integrated Amp Reviews

I asked about the output impedance. "Actual output impedance at 20Hz is 2.36 ohms. At 1kHz, it's 2 ohms. At 20kHz, 1.83 ohms. The output impedance is a little higher than it could be because we don't use a whole lot of global feedback."

And that fixed 5-ohm transformer tap? "We have always designed the transformers with a single secondary fixed setting. As the feedback includes the entire output transformer, everything is optimized around that one wind. Five ohms has been our standard forever. We can recalculate and provide 4 or 8 [ohms] or any other optimized impedance tranny on request, since we design and manufacture the output transformers in-house."

I noticed that the output transformers are quite small. EveAnna: "We started with that size output transformer because that's the size we were using in prior EL84-based amplifiers. But the old transformer designs had no balls. The older amps—Manley Tiny Triodes, 35W and 50W monoblocks—were always characterized as 'sweet' and 'detailed' sounding, but 'had no bass.'

"Why was this?" EveAnna asked herself, so I didn't have to. "The output transformers were the first culprit and the input stage was the second. We measured what we had been using and then made a new design with a lot higher inductance in order to improve the low-frequency performance.

"Now we had swell-measuring bass, but it didn't set our toes tapping. So we purposely throttled back the inductance to where it still measured respectably, while allowing a little bit of saturation to creep in like pepper on the chicken. This calculated balance between empirical measurements and subjective listening yielded some real slam and boogie factor to the amplifier design."

Boogie factor. That's a big thing with Bach or Boccherini. Or Telemann or Titz. The Stingray II worked well with my reference Harbeth Compact 7 ES-3 and Dynaudio Excite X12 speakers. But boogie factor? I dunno. I think a balls-out solid-state integrated amp does this better, like the NAD C375BEE. And sometimes even I like the boogie factor of balls-to-the-wall solid-state. Not really on offer here.

EveAnna continued: "I think the worst sin is not having enough power, so when using a lower-powered amplifier [like the Stingray II], it is imperative to make wise speaker choices. You want fairly efficient speakers, and ones that exhibit fairly benign impedance vs frequency curves. Gravitate toward gentle Z curves over steep slopes and hard phase angles. The Harbeths are totally a smart choice for the Stingray amplifiers. Their nominal 6 ohm impedance is especially well matched to our design."

I asked about the headphone jack. "The output impedance is 53 ohms. The signal is taken off the final output amplifier and sent through a voltage divider before it hits the headphone jack. So, yes, the signal runs through the EL84 tubes and the output transformer. It runs through the whole amplifier."

Plug a set of Audio-Technica ATH-AD700s into the Stingray II for headphone sound that's almost as good as it gets. You could pay more, of course. I got my second set, refurbished, for $65 (free shipping) from Beach Camera. My online friend Mordy, who put me on to Beach Camera, agrees: Why aspire to more? Too big for travel, though, and way too big and loose for the gym.

More technical stuff from EveAnna: "The main bank of B+ capacitors used in the Stingray iTube and Stingray II are huge compared to what these similar designs used 20 years ago. The old Tiny Triodes used only 150µF capacitance in the main B+ bank. The Stingray II and Stingray iTube quadruple the energy storage (in Joules). The compact 1200µF Cornell-Dublier capacitors we use today were not available 20 years ago. Same-diameter part, just lots taller, with four times more capacitance. This specifically leads to better bass impact."

You can build a better tube amp today than you could in the early 1960s, that great era of tube amps. Today's version of the McIntosh MC275 power amp is way better than the original: better bass, more open, greater resolution, etc. The Golden Age of tube amps is now—just as the Golden Age of turntables is now, for those who like to fremer with cartridges, tracking angles, and stuff. In my dotage, I don't.

I turned to the Hoffmeister Quartet's String Quartets for the Imperial Court of St. Petersburg, Vol.2, and the quartets of Anton Ferdinand Titz (CD, Hnssler Profil PH09046). Born in Nuremberg, Germany, Titz (1742–1810), a virtuoso violinist, was employed at Russia's imperial court for 40 years, during the time of Catherine the Great and Alexander I. He gave violin lessons to Grand Duke Alexander Petrovich, who became Czar Alexander I. After four decades there, he apparently went a little crazy; living in Leningrad can do that. Apparently, there's a Titz revival going on. This disc demonstrates why, but it also demonstrates why he was forgotten. I enjoy the music while it's playing, then forget it completely. Just perfect for the Czar.

Titz was made for tubes: beautiful string tones, slightly warmer and more shimmering in triode than in ultralinear mode through the Stingray II. This disc is certain to titillate.

Do you like Rachmaninoff? If so, I have another disc for you, a cheap one ($8 or so on sale). It's Symphony 2, performed by the Detroit Symphony Orchestra conducted by Leonard Slatkin (CD, Naxos 8.572458), who recorded a superb set of Rachmaninoff orchestral works for Vox (remember them?) with the St. Louis Symphony some 30 years ago. This recording is more sumptuous still.

I wallow in the late romantics. Sheer decadence—perfect for a tube amp. I felt that the sound, with my Harbeths, was surprisingly dynamic and expansive, given the Stingray II's limited power. My only criticism is that the Manley didn't offer me the tightest, tautest bass. It wasn't loose or anything; it just didn't wallop. And that's what I want with Rachmaninoff—I want to wallow and I want wallop. A powerful solid-state amp like the NAD C375BEE integrated can boogie better. But with its spacious sound and relaxed, romantic color, the Stingray II excelled at choral works.

One of the joys of classical music is that, once you think you've heard everything, Anton Ferdinand Titz turns up . . . or another treasure by the baroque composer Georg Phillip Telemann, who, like Vivaldi, seems never to have slept. Don't let the German title of this oratorio put you off: Der aus der Löwengrube errettete Daniel (Daniel Delivered from the Lion's Den). Great, gory Old Testament stuff—lots of meat—performed by La Stagione Frankfurt, led by Michael Schneider (CD, CPO 777397-2). The superb recording quality is typical of CPO, and the text of this obscure oratorio is translated into English—it's easy to know exactly when Daniel is thrown into the pit. This recently ranked 335,212 in music sales on Amazon USA; only 1 left in stock. More on the way. You can tell Telemann dug the Old Testament (he was fond of Jewish folk themes, especially in his wind concertos).

Whatever the advantages of the Stingray II's EL84 output tubes—cheap, rugged, reliable, plentiful—there just might be some sonic drawback to using four per channel to produce fewer watts than, say, two EL34s per side. The more tubes, the less each tube is stressed; but the more tubes, the less an amp might resolve.

In my experience, the best-sounding tube amps are single-ended and use a single output tube per channel: the less power, the better—2Wpc is about right. Obviously, EveAnna Manley disagrees. I'm not convinced that the EL84—or the EL34, for that matter—is the most resolving tube.

Still, the Stingray II sang. There was none of the glassy, hard-edged tube glare that can arise when, say, a set of 6550 or KT88 output tubes is pushed to deliver a maximum of power and a minimum of music. Tubes have their own way of sometimes turning nasty, and here they didn't. So whatever I just wrote about the EL84, it could be that there's almost no way of making a bad-sounding EL84-based amp. On the other hand, I've never heard outstanding resolution from the EL84 output tube; the closest was the MiniWatt N3 ($378), with one EL84 per channel.

The Stingray II offered a warmer, richer sound than my solid-state reference LFD Integrated Zero Mk.III LE. The Stingray II was like a well-fed woman who loves to cook, while the LFD seemed leaner—a little hungry, even. Yet the Stingray—whether the II or the iTube version—might be better suited to MP3 files, which the LFD doesn't suffer gladly. A new version of the LFD is in the works and I hope to get it soon. Meanwhile, I'm not selling the version I have.

The Stingray II puts me in a pickle. I'd love to keep it, but I feel I need something more resolving in order to evaluate various source components, such as CD players and DACs, not to mention Anton Ferdinand Titz. Your needs, of course, might differ.

All told, my hedonic well-being registers a 9 out of 10 with the Stingray II—exactly where it rests with the LFD. Strangely, each has a way of pushing me back to the other.

Maybe you should consider the Stingray iTube version after all. This type of sound and level of performance seems optimized for hedonic well-being rather than—um—intense analysis on the part of a "distinguished" senior contributing editor.—Sam Tellig