I measured Bel Canto Design's Black ACI 600 using my Audio Precision SYS2722 system (see the January 2008 "As We See It"). Usually, before I test an amplifier, I precondition it with both channels driving a 1kHz tone at one-third power into 8 ohms for an hour, but this is relevant only for an amplifier with a conventional output stage. As the ACI 600 uses class-D output modules, I began testing it soon after turning it on. However, as class-D amplifiers produce RF noise that could drive my analyzer's input circuitry into slew-rate limiting, I inserted, between the…
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Designers of hybrid amplifiers can use solid-state devices in an amp's input stage and tubes in its driver and output stages, as Music Reference's Roger Modjeski did in his RM-200 Mk.II—or they can use tubes in the input and transistors in the output, as Ypsilon Electronics' Demetris Baklavas prefers.
The advantage of solid-state at the input stage can be lower noise. In the RM-200 Mk.II's fully balanced design, carefully matched input devices result in high common-mode rejection and low-noise operation close to the levels achieved with the best input transformers. The RM-200 Mk.II's…
The recording sounds simply miked, à la Decca's microphone "tree," with a strong, stable center image: the piano was locked firmly in place, despite the rich field of reverberation surrounding it, and presented the orchestra convincingly arrayed behind and to the sides of it. The Hyperions' presentation was intensely holographic, and harmonically generous and convincing without sounding overripe. The sensation of "hearing" the air in the recording space produced a strong feeling of being in the Mariinsky Theater during these performances.
Playing an original pressing of Fritz Reiner and…
Sidebar 1: Specifications
Description: Hybrid monoblock power amplifier. Tube complement: one 6H30 Pi or 5687 (input), one 6CA4 or EZ81 (rectifier). Inputs: unbalanced (RCA), balanced (XLR). Output power at 1kHz: 370W into 8 ohms (25.7dBW, (first 100W in class-A), 650W into 4 ohms (25.1dBW), 1150W into 2 ohms (24.6dBW). Frequency response: 6Hz–80kHz, –3dB (input transformer peak: +2.5dB at 50kHz). Voltage gain: 26dB (x20). Input impedance: 47k ohms. Output impedance: 0.3 ohm. THD (1kHz into 8 ohms, 6H30 Pi tube): 0.7% at 100W, 1.2% at 300W. THD (1kHz into 8 ohms, 5687 tube): 1% at 300W.…
Sidebar 2: Associated Equipment
Analog Sources: Continuum Audio Labs Caliburn turntable & Castellon stand; Kuzma 4Point, Swedish Analog Technologies tonearms; Kuzma CAR 60, Lyra Atlas & Atlas SL & Etna & Etna SL, Miyajima Labs Zero (mono) & Madake & Madake Snakewood, Ortofon Anna & A95, Transfiguration Proteus D cartridges.
Digital Sources: Audio Alchemy DDSPro CD transport, Simaudio Moon Evolution 780D streaming DAC, dCS Rossini streaming DAC/CD player, Lynx Hilo A/D–D/A converter, Meridian Digital Media System, Pure Vinyl & Vinyl Studio software.…
Sidebar 3: Measurements
I measured the Ypsilon Hyperion with my Audio Precision SYS2722 system (see the January 2008 "As We See It"). Before performing any tests, I ran it at one-third its specified clipping power into 8 ohms for an hour. At the end of that time the top panel was warm, at 104.4°F (40.3°C), the heatsinks slightly hotter at 109.8°F (43.3°C). With the 6H30 Pi input-stage tube, with which I did almost all the testing, the gain at 1kHz at the speaker terminals was 26.4dB for both the balanced and single-ended inputs. With the alternative 5687 tube the gain was 0.5dB higher.…
Things change. Montreal's annual hi-fi show used to be called Salon Son et Image, but now it's called Salon Audio Montreal—or, for non-Quebecois, the Montreal Audio Fest. It takes place in a Hotel that used to be called the Hilton Bonaventure, but is now called the Bonaventure Hotel. It's a consumer-oriented show that used to charge admission, but is now open to the public, free of charge. You can bring the whole family for all three days of the show and still have money left over for smoked-meat sandwiches and poutine: think of it!
Speaking of change—and families—the show's tireless…
Canadian Prime Minister Justin Trudeau really is a swell guy, especially to audiophiles. Having heard that one of his country's own would be covering the Montreal Audio Fest this year on behalf of Stereophile, Trudeau called me personally to insist that he arrange my transport to the show's venue, the Bonaventure Hotel, by way of "Royal Escort,' an honorary custom normally reserved for dignitaries of ally countries.
Which is why, barely six hours of this writing, I was whisked by air for the show's Friday morning opening in a Ferrari-red Airbus AS365 N3+ helicopter, my backseat companion…
I love Tannoy loudspeakers—more than most other brands that have been around since the late Devonian, their contemporary products retain many of the qualities that made their forebears famous, not to mention great—but for whatever reason, every year in Montreal I tend to visit the room co-sponsored by Quebec Tannoy distributor Zidel Marketing fairly late in the show. This year they were first on my list, even before going record shopping.
I was not disappointed. As last year, the demonstration system was built around the huge Tannoy Kingdom Royal ($CAD90,000/pair), with a Krell Digital…
As I expected, the show on Saturday quickly devolved into a fisticuff free-for-all, especially in rooms exhibiting the level of pricy gear no one gets to hear in real life except at an audio show, with desperate patrons taking it upon themselves to physically remove "seat campers" out of listening chairs meant for all. Just kidding, of course. Well, mostly kidding. Indeed, as far as I know, it never came to punches or hostile seat take-overs among audiophiles; the prevailing mood on Saturday was one of joviality and eager anticipation. Rudeness was low, attendance high, coffee aplenty, and…