Tube Power Amp Reviews

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Herb Reichert  |  May 23, 2019  |  101 comments
I had never been alone with a Russian-manufactured 6C33C tube. At least not at night, in the dark. The first night Balanced Audio Technology's VK-56SE tubed amplifier was in my system, I sat on the floor studying the unusual shape and dark orange glow of its four 6C33C-B output tubes. I noticed their brightly lit, cathedral-like innards. My Russian neighbor told me they were used as regulator tubes in MiG jets during the Cold War. I could believe it—their exposed cathodes were the exact color of the Soviet flag. From more than a foot away, I could feel the heat from their high-amperage filaments.
Herb Reichert  |  Apr 04, 2019  |  15 comments
I will never forget.

In 1988 I had my first experience with Western Electric 300B tubes. It took place on a quiet, streetlights-and-snow night at my friend Ryoichi's apartment on Riverside Drive, in Manhattan.

I had never heard of the late Japanese amplifier designer Ken Shindo, of Shindo Laboratory. But that evening, Ryo's audio system was all Shindo: a hammertone gray Shindo-restored, grease-bearing Garrard 301 turntable sitting on a Shindo plinth of glossy wood, with a Shindo-modified Ortofon tonearm and SPU cartridge, a Shindo moving-coil step-up transformer, and a Shindo preamplifier with a moving-magnet phono stage.

Art Dudley  |  Jan 24, 2019  |  40 comments
To audio designers in Japan and elsewhere, the single-ended, 300B-tubed amplifier is like a haiku: an art form defined by both its prescribed limitations and the potential such restraint offers for artistic expression. Here, the only hard-and-fast rule is a simple one: output devices are limited to one 300B directly heated triode tube per channel. From there, it's a blank slate: Do you want AC or DC on the output-tube heaters? Tube or solid-state rectification? Low or high gain? Fixed or cathode bias? New parts, vintage parts, or a mix of both? Triode or pentode tubes as drivers? Capacitors or transformers—or nothing at all—between the plates of the driver tubes and the grids of the output tubes?
Art Dudley  |  Dec 20, 2018  |  5 comments
There's no place for fashion in epidemiology, aeronautical engineering, or the mining and storage of uranium. Fortunately, domestic audio is less serious, its goals more scattered and ambiguous, than those and a thousand other pursuits.

And so, throughout the 20th century, any number of trends in domestic audio popped up their heads, some remembered as fads, others as legitimate approaches to playback. Among the latter are amplifiers whose output sections operate in single-ended mode, in which the entire signal waveform is amplified by a single device.

Anthony H. Cordesman  |  Nov 15, 2018  |  First Published: Jun 01, 1986  |  4 comments
Some audio products deliver truly superb sound of a kind that really makes all the frustrations of building a high-end system worthwhile; they also require exceptional attention and care. The Counterpoint SA-4 is a case in point. With the right speakers, it competes for the title of "Most Transparent Amplifier Available at Any Price." On the other hand, this amplifier steadily loses output power as speaker impedance drops; it must be carefully matched to the right speaker. Then, and only then, can it produce one of the finest musical experiences available.
Steve Watkinson  |  Nov 13, 2018  |  First Published: Sep 01, 1986  |  0 comments
The great debate that has long separated audiophiles is tubes vs solid-state. Other topics, CD for example, may temporarily steal the spotlight, but year-in and year-out no other subject is the cause of as much controversy as whether tubed or solid-state circuitry produces the more accurate sound. As is typical with long-standing feuds, the split runs deep, and tempers often flare.
Jason Victor Serinus  |  Oct 23, 2018  |  16 comments
Doshi Audio first crossed my radar at the 2010 Rocky Mountain Audio Fest, where I wrote that the sound of the company's tubed monoblocks and preamp, connected to Wilson Audio Sasha loudspeakers via Transparent XL cables, "excelled in midrange strength as the system threw an exciting soundstage." After auditions of Doshi-Wilson pairings at many subsequent shows had convinced me that Doshi's products could truly sing, I contacted company owner and product designer Nishith "Nick" Doshi to inquire about reviewing one of his amps.
Herb Reichert  |  Oct 16, 2018  |  18 comments
When I began writing for Stereophile, I dreaded doing comparisons. They were stressful and tedious—and what if I got them wrong? But I quickly learned: Not only do readers enjoy comparisons, they need them. How else might they imagine the relative merits of the component under consideration? Once I realized this, I began acquiring a range of reference amplifiers.

But conspicuously missing from my audio menagerie has been a fast, neutral, 100Wpc tube amp to put more pop, fire, and maybe a little glow, into the Harbeth M30.2s.

Jason Victor Serinus  |  Sep 20, 2018  |  9 comments
At a recent dealer event in Seattle, after being impressed by the musical rightness of an Audio Research Corp. LS28 preamplifier and VT80SE power amplifier driving a pair of Sonus Faber Guarneri loudspeakers, I spoke with ARC's Dave Gordon about reviewing one of the company's new amplifiers. Less than a month later, two ARC Reference 160M tubed monoblock amplifiers ($30,000/pair) were headed my way.
Art Dudley  |  Aug 28, 2018  |  15 comments
For this month's column, I did something I've occasionally set out to do but never quite managed: I lived with a new power amplifier for nearly two months, used it to enjoy a variety of records, made scads of listening notes, and wrote most of the subjective portion of my review—all without knowing what was inside it.
Anthony H. Cordesman  |  Aug 07, 2018  |  First Published: Sep 01, 1986  |  15 comments
Few people in the high end know the difference between glorious excess and wretched folly as well as Harvey Rosenberg. Harvey's audio equipment always strives towards the glorious folly of providing the most romantic sound possible with modern technology. This may explain why his relatively small company, New York Audio Laboratories, can build an amplifier like the Futterman OTL-1, which costs a glorious $12,000 a stereo pair and actively competes for the title of best amplifier in the world.
Ken Micallef  |  Jun 21, 2018  |  111 comments
Back at the beginning of 2017, Greg Roberts, of Volti Audio, devised a clever way to bring his Rival floorstanders up to my penthouse pad, for what resulted in a rave review of those horn-loaded wunderspeakers.

I live on the top floor of a seven-story, elevatorless building on a busy street in Greenwich Village. A vertical challenge? No problem! Roberts is resourceful in many things, from speaker design to his former profession, the building of custom homes. Affixing a pair of unguent-saturated straps to the screws on each side of a Rival, we lifted and transported the 106-lb speaker high in the gritty Manhattan sky as if it were child's play.

Michael Fremer  |  Mar 22, 2018  |  18 comments
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 signal/noise ratio measured a healthy 95.4dB.

Jason Victor Serinus  |  Feb 01, 2018  |  16 comments
"How natural the sound," wrote Jonathan Scull in March 1994, in his Follow-Up on the original Jadis JA 200 monoblock amplifier, which then cost $18,990/pair. "How easy it was to follow the musical line and fall into the music. How deep, controlled, tight, and satisfying the bass. How magnifique the midrange—the traditional strength of the Jadis presentation. How full and satisfying the lower midrange. How open, airy, how right the highs—not at all hard, but very extended and natural. How involving their presentation. How full, how harmonically correct, how wonderfully compelling. How magical."
Dick Olsher  |  Nov 10, 2017  |  First Published: Nov 01, 1993  |  10 comments
Ron Cox, Zen master and good friend from Zuni, New Mexico, gingerly navigated the crowded streets of Amp City—the essentially all-tube amp collection sprawled on my listening-room floor between the speakers. Ron had no trouble spotting the four chrome-and-black chassis of the JA 200s. He pointed a tentative finger: "Are those the Jedi?"

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