No.26: Dual monaural preamplifier with remote power supply. As supplied: one MC phono input with adjustable gain and loading; five line-level inputs. (Can be supplied with six line-level inputs, one of which can optionally be balanced; phono input can also be supplied in MM/low-gain form.) Input impedance: see text. THD: less than 0.005%. IMD: less than 0.005%. RIAA accuracy: <0.2dB. Maximum output: greater than 13V (balanced).
Dimensions: (preamplifier chassis): 17.5" (445mm) W x 3" (76mm) H x 13.375" (340mm) D (add 3" for connecting plugs). Dimensions (…
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Sidebar 1: Specifications
Sidebar 2: No.20.5 Measurements
According to the specifications in the heading, the No.20.5 appears to be a "perfect" amplifier in that its output power almost exactly doubles when the load impedance is halved from 8 to 4 ohms, and again when it drops from 4 to 2 ohms. On the test bench, the measured continuous maximum output power into 8 ohms (actually 8.1 ohms) for a 1% distortion figure was 139.3W (21.4dBW footnote 1). Into 4 ohms, it raised 258.5W (21.1dBW), and into 2 ohms, 410.5W (20.1dBW), which is not far removed from the specification. (That these figures are a little higher…
The Glimmer Twins were right: If you can't always get what you want, sometimes, you just might find, you get what you need. Take Ayre's K-1 preamplifier, for instance. I'd been trying to get Ayre to send me their $3750 V-3 power amplifier since the moment I started writing for Stereophile; after approximately a year and a half, I finally got a phone call from then Marketing Director Bruce Van Allen.
"So when are you going to send me that verklempt amplifier?" I demanded.
"Actually, we're more excited about our new K-1 preamplifier. Let us send you that instead."
…
Empty
Looking inside the K-1, one is tempted to comment upon how empty the box seems. There's a circuit board attached to the front panel to handle logic functions, and affixed to both the right and left side-walls are the phono modules. But what dominates the interior is the massive, component-packed board that runs across the height and breadth of the rear panel. Attached to it is a second panel that houses the Rube Goldberg-like gears and ladder-belts which connect the motor to the complementary volume controls and allow for stereo source and recording switching. The device looks…
Looking inside the K-1, one is tempted to comment upon how empty the box seems. There's a circuit board attached to the front panel to handle logic functions, and affixed to both the right and left side-walls are the phono modules. But what dominates the interior is the massive, component-packed board that runs across the height and breadth of the rear panel. Attached to it is a second panel that houses the Rube Goldberg-like gears and ladder-belts which connect the motor to the complementary volume controls and allow for stereo source and recording switching. The device looks…
The rear panel is divided down the center. Each side handles inputs and outputs for one channel, and the two sides are flipped 180 degrees so that one is upside-down in relation to the other. Those who, like me, have become used to making connections by "Braille" are in for a rough time of it. Since the input-selectors on the front panel have changeable labels, the inputs on the rear are labeled a straightforward 1 through 6. An 8' umbilical sprouts from the center of the panel, connecting the preamp to a very hefty power supply. That power supply, Hansen told me, was responsible for much of…
For instance, I've been listening to Blue Note's superb Dexter Gordon: The Complete Blue Note Sixties Sessions (Blue Note 8 34200 2, six CDs) a lot lately—almost constantly, in fact. Dex was unbelievably good at that time—his tone was lushly vibrant and his harmonic awareness of what was happening around him made him seem like he had the musical equivalent of "eyes in the back of his head." He sprinkled wry quotes into nearly every solo, and had a readily identifiable penchant for phrasing ever so slightly behind the beat. I've never actually heard a preamp that wouldn't present most of that…
Sidebar 1: Specifications
Description: Full-function, solid-state control preamplifier. Maximum voltage gain: 16dB (line); adjustable, 40dB, 50dB, 60dB (phono stage). Input impedance: 10k ohms (line, each phase); adjustable, 50k ohms (default), 100, 250, 500, 1000 ohms supplied—other values available (phono). Output impedance: 300 ohms (each phase). Power consumption: 20W.
Dimensions: 18" W by 5.5" H by 11" D (main unit); 13" W by 3" H by 8" D (power supply). Weight: 45 lbs (20kg).
Serial number of unit reviewed: 2B0125.
Price: $5250; remote volume control adds $250; phono stage…
Sidebar 2: WP's 1997 Associated Equipment
Digital Front-End: Krell KPS 20i/l.
Analog Front-End: Linn Sondek LP12 turntable with Naim Armageddon power supply, Naim ARO tonearm, Transfiguration Temper cartridge; or VPI TNT Mk.III turntable with JMW Memorial Tonearm, van den Hul Grasshopper cartridge.
Phono Section: Naim Prefix/HiCap, Audio Research PH3, or Krell Reference.
Power Amplifiers: Ayre V3, Conrad-Johnson Premier Twelve, Krell Audio Standard.
Loudspeakers: Hales Concept Five, Martin-Logan SL-3.
Cables: MIT balanced 350 interconnect, Cardas balanced phono interconnect…
Sidebar 3: Measurements
Unless otherwise noted, the measurements presented here are for balanced operation. The output impedance of the K-1 at its line output measured to specification at 556 ohms (279 ohms unbalanced) in the left channel and insignificantly higher in the right. The setting of the level control had virtually no effect on the output impedance. The line-level input impedance measured 21k ohms (9.8k ohms unbalanced), again with virtually no change with level setting or channel.
Phono input impedance measured 1108 ohms (this may be internally altered by the user).…
Paul Bolin wrote about the Ayre K-1x in June 2002 (Vol.25 No.6):
From the time it appeared several years ago, the Ayre K-1 preamplifier was hailed by the audio world as a significant advance in the art and science of solid-state electronics. Stereophile's Wes Phillips was mightily impressed with it back in the March 1997 issue (Vol.20 No.3), as was I when I reviewed it for The Abso!ute Sound. For me, the K-1 was a landmark: the first piece of solid-state gear that this die-hard tubeophile heavily and unabashedly fell for. The K-1 quickly made its way into Stereophile's "Recommended…