That, believe it or not, is the gist of an article by Robert Carver of Phase Linear…
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Hey, kids, here's the Big News. We've been deluding ourselves all along, worrying about piddling little bits of distortion that we can't hear at all. How's your preamp distortion? 1% at 1 volt out? You have a perfect preamp—a veritable straight wire with gain! That ear-shattering shrillness is all in your mind, because it has now been demonstrated that the human ear cannot perceive distortion levels of less than 6–12% on "normally complex music." If you think you can hear 0.1%, you are deluding yourself.
If there's a phrase that increasingly gets my dander up, it's "mid-fi." I'm even starting to lose patience with the term "High End."
There are products I've heard audio snobs dismiss as "mid-fi"—Tyll Hertsens' delightful little HeadRoom headphone amplifiers, for example—purely because they're cheap enough to bring them in reach of those who don't have unlimited disposable income.
On the other hand, there are high-priced products—I'll draw a kindly veil over which ones, this not being the appropriate forum to add to their manufacturers' miseries—which audiophiles almost…
Some readers may feel that it is pushing poetic license beyond reasonable limits to call the Krell KSA-50 a "new-wave" amplifier. It has, after all, been around for several years. The Krell KSA-50 is new-wave enough, however, to be an incredibly stiff class-A design, rather than a pseudo–class-A circuit, and its 50 watts per channel are supported by enough of a power supply to drive an arc welder. You get about 70 watts of RMS power with 8 ohms, 150 watts with 4 ohms, and sufficient watts into 2 ohms to threaten my load resistors. There is almost enough power to drive a pair of Apogee…
Sidebar: Specifications
Description: Solid-state stereo power amplifier. Maximum power output: 50W into 8 ohms (17dBW), doubles with each halving of load impedance down to 1 ohm.
Dimensions: 19" W by 9" H (including feet) by 19" D (including handles). Weight: 60 lbs (net).
Serial number of unit tested: not noted.
Price: $1900 (1995); no longer available (2007).
Manufacturer: Krell Industries, Milford, CT 06460 (1985); Krell Industries, 45 Connair Drive, Orange, CT 06477. Tel: (203) 799-9954. Fax: (203) 799-9796. Web: www.krellonline.com.
There's always a certain amount of jockeying for position at the very top of the High End. Every few months, a new star burns brightly, getting all the attention. While the constant turnover at the cutting edge helps to define the state of the art, audiophiles should keep their eyes on the longer term. It's a company's track record—examined over a period of years—which defines its position in the market and the credibility of its products.
Ever since I made the acquaintance of my first Krell product—the KSA-50 power amplifier—I've been impressed by this Connecticut-based company'…
Early amplifier stages have fully regulated supplies, later ones distributed wide-bandwidth supply decoupling.
Once upon a time, Krell power amplifiers claimed and achieved low distortion factors. This wasn't a specific design feature, but a byproduct of their inherently linear circuitry. As good-sounding modern amplifiers continue to demonstrate, the link between sound quality and low distortion figures measured in the lab with continuous tones is a tenuous one. A low-feedback design will generally produce higher distortion; Krell has no qualms in revealing figures for full-power total…
The maximum output available from an amplifier, and, more pertinently, the maximum clean acoustic output it can achieve with the owner's chosen speakers in a specific room, are controlled by the true speaker loading, the true speaker sensitivity, and the capability of the power amplifier when driving this load.
In theory, an amplifier doesn't need to have a high power reserve, since most loudspeakers are specified as having a 4–8 ohm impedance, typically averaging 6 ohms. In practice, however, loudspeaker impedances can frequently be unexpectedly severe. A nominally 8 ohm loudspeaker…
Sidebar 1: Specifications
Description: solid-state stereo power amplifier with "Sustained Plateau" output-stage biasing. Power output: 200Wpc into 8 ohms, 400Wpc into 4 ohms, 800Wpc into 2 ohms, 1600Wpc into 1 ohm, one channel driven (all power outputs equivalent to 23dBW). Damping factor: 80. THD: 0.1% at 1kHz, 0.2–0.5% at 20kHz, at full power.
Dimensions: 19" W by 8.5" H by 21" D.
Price: $7500 (1994); no longer available (2007). Approximate number of dealers: 55. Warranty: 5 years parts and labor, limited transferable.
Manufacturer: Krell Industries, 45 Connair Drive, Orange,…
Sidebar 2: System
A wide selection of ancillary components was available for this review. Comparison preamplifiers ranged from the Audio Research LS-5 to Krell's own KRC-2, by way of a Conrad-Johnson PF1. Power amplifiers included the Audio Research VT150, the Krell KSA-100S, Meridian 605, Naim NAP250, and Conrad-Johnson Premier Eleven. Loudspeakers used were the Apogee Mini Grand system, Wilson WATT 3s/Puppy 2s, Quad ESL-63s, and Epos ES-11s.
Digital sources included the PS Lambda and Reference Link combination, the Krell MD10 and Reference 64 combination, an Accuphase DP70V,…
Sidebar 3: Measurements
An idling power consumption of 125W was noted, close to spec and confirming this amplifier's moderate standby consumption, especially in view of the high power and current capabilities. That massive transformer was mechanically silent even on the UK's 50Hz AC supply.
There was no denying this amplifier's big heart. The KSA-200S is rated as a 23dBW design, which is equivalent to an output power of 200Wpc, with one channel driven. The output is claimed to double with each successive halving of load impedance, right down to 1 ohm. Such was the reserve present…