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leslie
- 论坛博士后
- 19720110
- 27155
- 28495
- 2003-01-24
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8#
t
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发表于 2011-04-25 15:08
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Harry Pearson McIntosh 275
This is a legendary amplifier, and from a legendary company, whose commitment to quality of construction and design has never wavered, not even during its long dark night of solid-state electronics. The earliest Mc’s were built around the transformer that Frank McIntosh and Gordon Gow designed (and patented), one that allowed them to move beyond the power limitations of Class A design and into the region of much higher outputs, without the audible and ugly “notch” distortion that had thwarted such efforts in the past. Historically important. The 275 has been restored as the company in the past several years has finally moved back into tubed amplification production, and with stunning results (I think its 300/300 watt 2301 unit is the purest sounding amplifier in my experience—to date.)
Citation Two
I have chosen just one of Stewart Hegeman’s many amplifier designs. There are many worthies. The Two was a 60-watt mono tube amplifier that came out in the days of high-fidelity (as opposed to high-end) sound. It was designed by the man whose 550 pure-pentode design was the breakthrough and the basis for today’s best tubed designs. (The 550 got around the stranglehold McIntosh and Gow had on transformer designs—they patented their breakthroughs and used them to build their own amplifiers exclusively.) What Hegeman did, after studying the transformer issue, was devise an alternate way to eliminate notch distortion and build a different transformer winding, thus allowing higher power output. (It also happens that as a very young man I tried to build one of these from its kit version, to drive my acoustic-suspension speakers. Of course, I had to have help with the project, since then, as now, I was/am a technical klutz. The amplifier was, to me, an astonishment in the form of sound.) Hegeman was a freewheeling rover, who loved music and never made an amp (or anything else) that didn’t pay tribute to the real thing. He later, under the Citation rubric, designed the first serious solid-state design, the Citation B. Pioneering? Yes. A sonic breakthrough? No. But a class act.
Marantz Model 9
You might want to add in the 8B as well, since it and the 60-watt Model 9 are still considered classics, and bring in prices in excess of what they cost during the early days of high fidelity (as opposed to the more recent days of high end), especially in Japan where they go for insanely high prices. These were designed by Sid Smith (of Sea Cliff, no less) under the watchful eye of Saul Marantz, who was always in and ahead of the vanguard of state-of-the-art sound (from his marketing of the first straight-line-tracking arm/turntable—a commercial failure—to his early sponsorship of Jon Dahlquist and the DQ-10 speaker). The amps, to this day, sound amazingly good, powerful, and more than a tad romantic—they live on, though Smith and Marantz do not.
Dynaco Stereo 70
If we want to talk about influence—and a long-lasting one—we’d start with this seventy-watt stereo unit, which, during its 20 year (or so) life span was studied and copied by many young designers. It was a diving board for some, like William Z. Johnson (of Audio Research) whose earliest tubed units were built around the Dynaco chassis and parts (highly modified, of course). The 70, and its descendants the Mk2 and 3 versions—came along just as stereo sound was being born. Fortuitously, its compact size, full-bodied sound (throughout most of the frequency range) put it in direct competition with the much more expensive Marantz and McIntosh units. David Hafler oversaw many amps later on, including the Stereo 120, which I thought the least transistory-sounding solid-state of its day. Then there was the 400 that came down the road later, and did at first sound transistory, thus it was subject to the golden touch of modifiers like Frank Van Alstine and became a formidable contender in the high powered solid-state amp sweepstakes. It wasn’t a Stereo 120 or a Phase Linear 700 though.
Phase Linear 700
One of the first high-powered blockbuster amps of the modern (read: high-end) era. It was designed by Bobby Carver, one of the brightest and most innovative thinkers ever to grace audio. The 700 outpowered the Crown DC 300, the first high-powered transistor design, and was cleaner and less colored than the Crown, to boot. Carver wondered why his home-built big tubed amp of the day sounded much better than solid-state designs. He learned, through his measurements, that tube amps could swing 200 volts, while their solid-state counterparts only 35 or so. And he thought, at the time, that the high-voltage output was the decided advantage tube designs had. So he built into the 700 a very wide voltage swing. He engineered the unit’s power supply in a novel way—one too complex for me to discuss here (even if I did fully understand it). An accidental contribution to the 700’s excellent, low-distortion, and uncolored sound: Its biasing transistor sat very near to the unit’s massive heat sinks, so the longer you played it, the better the 700 sounded. Also, not incidentally in Carver’s mind, the 700 came along during the two-channel era when smaller and much, much less efficient speakers (especially the so-called “air-suspension” designs) were in vogue. These now could be driven to life-like levels, with greater control over the normally bloomy bass of such designs, The 700 also allowed reproduction of troublesome high frequencies with greater cleanness and lower distortion.
Source: The Absolute Sound[table=460][/table].jpg)
Audio Research D-150T
His huge stereo amplifier was, in its time, a breakthrough in tubed design, both in power output, and, in the more elusive aspects of reproducing a facsimile of a concert hall sound. Even the best solid-state designs could not then reproduce the three dimensions, the depth, of a real-world soundfield, much less its width, and reproduce these with something like the full range of dynamic contrasts. This amplifier could. Not only that, but throughout most of its range, the 150 captured the fundamentals and harmonics of the music, particularly the frequencies from the midrange on up. Thus, it had a hard-to-define (then) quality of naturalness, call it rightness, that made it unique. For experienced listeners, the 150 was such an overpowering (literally as well) experience by contrast, that its audible flaws were overlooked (highly colored bass, overly romantic midrange colorations, and a drooping top octave). Did I forget to mention the heat it generated and the number of tubes that failed? Yes, I did, but it had its teeth into the essential truth of music and it wouldn’t let go. In that regard, it was a singularity.
Mark Levinson ML-2
The ultimate in snob appeal for its sky-high cost (in the day), the quality of both parts and build, the momentous and cutting heat sinks, all designed to offset its Class A power output of less than 35 watts. Those watts were clean, clean, clean and analytic in a way other solid-states weren’t. At its best and in the areas in which it excelled, it gave new weight to the word “transparency.” (The ML-2 was created before Mark Levinson and its designer, Tom Colangelo, were absorbed into the innards of the Harman-Kardon octopus.)The ML-2 worked best as a mid-range amp, and its virtues show to fullest extent on an electrostatic (it was designed, it is said, for the Quads). I heard it at its best as the central speaker in Levinson’s massive HQD speaker system (H: Hartley, the woofer; Q: the midrange Quad electrostatic; and D: Decca ribbon tweeter), awesome in its day and an inspiration for the creation of the QRS-1D.
Electro Research A-75
This unit was designed by John Iverson, one of the high-end’s most memorable characters, around whom many a story, even legend hath sprung up. The solid-state A-75 was built for the military, perhaps for a radar installation. It was thus built to military specs (and overbuilt for audio listening purposes). So, it was said only a few units were left over for Iverson to sell to the general public. When they worked without breaking down, they were unlike, in sound, anything else on the market. The thing I remember best about them was their incredible purity, both at the tightly defined and taut bass frequencies on up into the, like their designer, ethereal ionospheric regions. Iverson was also legendary for developing a “force-field” speaker that, it is said, the military had its evil eye upon for some dark purposes. (Legend: It could make solid-objects disappear into a nowhere dimension.) There were other designs that did not quite materialize either, including a strain-gauge cartridge/preamp. No one, to my knowledge, ever heard one of those gizmodos. Later on, Iverson simply disappeared, after one or more runs in with the law, or, perhaps, to his alternate business base in Singapore. Many have tried to find him but no one has, so complete is the mystery. (Legend: He was assassinated. Maybe not. Maybe he simply fed himself into his force-field speaker.)
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Conrad-Johnson Premier One
This was the first high-powered tube amplifier designed by Lewis Johnson and it had a quality I had not encountered in a tubed unit before: authority. It spoke with a kind of dynamic truth that was undeniable. I’ve been re-reading the review I wrote, wondering whence that authority. Perhaps the quality of “authority” here that was distinctive and that so impressed me lay in the basics. That is, Johnson had got the midbass right, which, to this point, no tubed amplifier had done. The critical range of the midbass (say 40 to 80 Hertz) is where the fundamentals of music lie, and this is exactly the region in which other tubed designs sounded either bloated and bloomy, or anemic and antiseptic. The Premier One, however, got these basic frequencies right and more importantly, their resulting harmonics. And, simultaneously it also got the dynamics right—yes, the other units could play midbass notes at the loud end of the ffff spectrum, but not fully at both ends, including the softest. Dynamics contrasts, those going from microsoft (not MSNBC) to very loud, are the defining characteristic of the real thing. So when you heard the Premier One play music, you believed it. Conrad-johnson has never produced an amplifier, even its solid-state ones, that sounds less than believable. Thus its gear you can almost buy blind-folded, knowing you’ll get something true.
Threshold 400a
The follow-up to the Threshold 800, a not-easy-to-find big amp that introduced Nelson Pass as a coming star in the field of audio. What made it an interesting product, aside from its unusually smooth sonics, was the fact that it was called a Class A (high-powered) unit. About which there was some controversy, particularly from other designers, who thought Pass had pulled a sleight of hand. The trick here lay in the biasing of the unit—one then unconventional in the extreme. The use of shifting bias allowed the unit to stay in Class A as the demands on its power output shifted. The 400 would go into Class AB if the sonic demands exceeded its capabilities (said to be a rarity). What interested me then was just how closely it sounded like Class A, but with considerable power up to a quite loud point, it had most of the advantages of Class A sound, with few flaws (the unconvincing bass, lack of sparkle in the upper midrange) as well as a tendency to oscillate and blow fuses.
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