Jadis, an audiophile company specializing in all-tube amplifiers and operating out of a small French town, has enjoyed a good reputation for some years, even if some of its models have suffered from the reliability problems that occasionally afflict the largest tube amps. Another problem area is that of power consumption and heat output. In common with class-A amplifiers and high-bias A/B types, including solid-state models…
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Owning a powerful tube amplifier is like owning a classic automobile. Great pleasure may be had, but ownership involves a little more care and maintenance than usual.
Notwithstanding the printed circuit board layout, the ground is firmly defined for both channels by a hardwired stack of solder tags securely bolted together. All the main ground lines, speaker transformer, supply chassis, pcb, and other ground lines assemble here in recognition of the importance of this central star-ground concept.
Listening tests
The Defy-7 was run in for a few days after delivery. Once burned in, 15 minutes' warmup from cold seemed sufficient for it to reach a good operating plateau. Its sound grows noticeably better in the first five minutes after turn-on.
Sidebar 1: Review System
Though a selection of preamplifiers was on hand, the Defy-7's unusually high input impedance particularly suited it to two models: the tubed Jadis JPL (favorably reviewed by DO last January) and a passive controller, the admirable new Audio Synthesis Passion. The Audio Research LS2 helped deliver the maximum information from the Defy-7 and was ultimately preferred to the JPL on this basis. The latter was certainly highly sympathetic to the power amplifier's character but did not allow it to "breathe" fully; nor was the bass so impressive. In addition, the full…
Sidebar 2: Measurements
In the world of tubed amplifiers, designers don't need to be told about the weaknesses of our understanding of psychoacoustics and the relationship between steady-state measurement standards and sound quality. This is reflected in Jadis's specifications, which are sparse and, frankly, uninspiring. The output is quoted at 100Wpc into a matched load for 0.6% distortion, specified at 1kHz only. The high input sensitivity is ideal for passive control use for sources down to 2V output, while the input impedance is loosely quoted as >100k ohms. The frequency response…
Sidebar 3: Specifications
Description: Rated output power: 100Wpc into 8 ohms or 4 ohms (20dBW/17dBW) at 1kHz for 0.6% THD+noise. Rated frequency response at 1W (–3dB points): 15Hz–100kHz. Measured specifications: Maximum output power at 1kHz: 16W into 8 ohms for 1% THD (12dBW), one channel driven, 96W into 8 ohms for visual clipping, one channel driven (19.8dBW); 56Wpc into 4 ohms for visual clipping, both channels driven (14.5dBW). Peak current output: +8.5A, –8A. Output impedance at 1kHz: 0.4 ohms. S/N ratio ref. 0dBW: 75dB (22Hz–22kHz), 83dB (CCIR-weighted). S/N ratio ref. 20dBW:…
Back when the CD was a pup, I used to hear people say, "I refuse to buy a CD player until they can record." Ha ha, I thought, smart-ass audiophile that I was, they're gonna wait for a long time—that's never gonna happen. I was half right—it has been a long time coming. But I was also, as my football coach used to insist, half-fast. "Never" has arrived.
Of course, CD-R "burners" are de rigueur these days in the PC power user community, and there have been other standalone CD recorders—Stereophile reviewed the Meridian CDR (way back in Vol.15 No.11 and Vol.16 No.11) and, more recently, the…
Pretty well, overall, but it was a puzzling machine in some ways. If bits is bits, and all we do when we record from a digital source to the copy is transfer the ones and zeros, then there should be no difference between the copy and the original—or between copies made on different machines. That much seems obvious.
But there's a pair of overalls in the chowder: I could consistently hear minor differences between the original and the copies made on the CDR880, and I could hear differences between copies made on the '880 and copies made on Stereophile's sample of the Meridian CDR. Big…
Sidebar 1: Two Types of Disc
When CD was first developed, its protocols were codified in the Philips "Red Book," the book of specifications sent to CD licensees. CD-R and another technique, MO-R, were codified in the "Orange Book," which ensured compatibility with the Red Book standard. Therefore, CD-R and CD-RW discs have similar structures; the difference is in the details.
CD-R discs have a recording layer based on deformable dye with a reflectivity of 40–70%, while CD-RW discs have a phase-change recording layer boasting a reflectivity of 15–25%. Both types have an additional…
Sidebar 2: Sneaky People
I doubt that SCMS is at all effective against piracy. For one thing, there are lots of professional CD recorders out there without SCMS; for another, pirates don't really care much about sound quality. By now, everyone knows someone who has bought a bootleg videotape of Titanic. Were any of them even watchable? (New York magazine reported that 30% of the pirated copies of Titanic that have been seized by the NYPD were blank.)
Nah, SCMS penalizes ordinary folks who want to record their own, legally purchased CDs for their personal reuse.
Phooey, I…
Sidebar 3: Associated Equipment
LP Playback: Linn LP12 turntable with Naim Armageddon Power Supply, Naim ARO tonearm, van den Hul Frog phono cartridge; and Linn LP12, Lingo, Cirkus, Ekos, Arkiv.
CD Playback: Arcam Alpha 9, Meridian 508.24, Audio Research CD2.
Phono Preamplifiers: Conrad-Johnson Premier Fifteen, Sutherland PH-2000, Naim Prefix.
Power Amplifier: Audio Research VT200.
Integrated Amplifiers: Arcam Alpha 10, Creek 4330R.
Loudspeakers: B&W Silver Signature, REL Studio II subwoofer.
Cables: Siltech and WireWorld Gold Eclipse III interconnects, and…