Description: Power output: 100W into 8 ohms (20dBW), doubles with each halving of load impedance down to 1 ohm. Frequency response: 20Hz–20kHz, +0.0/– .1dB; 1Hz–150kHz, +0.0/–3dB. Distortion: <0.1% at 1kHz; <0.5%, 20kHz, full power. Slew rate: 100V/µs. Input sensitivity: 1.4V RMS. Gain: 26dB. Damping factor: >60. Input impedance: 47k ohms. Power consumption: 100W, idle; 1400W, full power.
Dimensions: 19" W by 8.5" H by 19.25" D. Weight: 80 lbs (net).
Serial number of unit tested: 32-20216.
Price: $5500 (1994); no longer available (2007).…
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Sidebar 3: Specifications
Sidebar 2: Measurements
I measured the Krell KSA-100S in its balanced mode, repeating selected measurements in the unbalanced configuration.
Following the 1/3-power, one-hour preconditioning test, the KSA-100S's heatsinks were only moderately warm.
The KSA-100S's input impedance measured 47.3k ohms unbalanced, and just under 95k ohms balanced; its output impedance varied between 0.095 and 0.11 ohms, depending on the frequency and load (with the higher values at 20kHz). Voltage gain into 8 ohms measured 26dB, balanced or unbalanced. DC offset, though fluctuating slowly…
The great format battle of our time continues to rage between the Blu-ray and HD DVD camps. For many reasons, some discussed in the July installment of this column, this battle may be the last one waged over physical media formats. But whether either or neither format wins, the outcome will be decided on the basis of video quality—issues of audio quality are being ignored. This is unfortunate for audiophiles for two reasons. First, we have a big stake in whatever will be the standard medium for movies and music, but second, this battle makes it apparent that the major forces in the…
Me, I'm still a music guy. As my wife said, after watching and appreciating the drop-dead-gorgeous quality of HD video, "It's nice, but I don't see the big deal." I guess she's a music gal. On the horizon—perhaps to be unveiled this month, at the 2007 CEDIA Expo—is a new generation of players and processors that will take full advantage of the audio capabilities of these media. I hope that that will encourage the recording industry to release music titles of equal quality.
Audio Research MP1 multichannel preamplifier
Y'see? There's still a need for analog multichannel, and the…
Sidebar: Recordings In The Round
BERLIOZ: Requiem Toby Spence, tenor; Roger Norrington, Stuttgart Radio Symphony Orchestra, Stuttgart Southwest German Radio Vocal Ensemble Hänssler Classic SACD 93.131 (2 SACDs)
What an exciting surprise! Roger Norrington's earlier Berlioz struck me as lightweight, but this is a phenomenal Requiem that I find musically and sonically superior to the multichannel competition from Robert Spano (Telarc) and Maurice Abravanel (Silverline, Vanguard). While the big moments are thrilling, with the most intense Tuba Mirum I have experienced from a…
A moment of silence, please, for the mouse in my shed: I've had a trap there for weeks, baited with peanut butter—I should have just waited for the food poisoning to do its work—and the poor little bastard finally found it.
It was a bad end, but not as bad as starvation, or being swallowed by a snake, or torn apart by a house cat. He might also have died from a severe blow to the head, had the glass jar I threw at him three Saturdays ago found its target instead of the wall behind him. (That dumb stunt was made even more exquisitely stupid by the fact that the jar still had a little…
We've also spoken of transformer impedances—numbers that describe their primary and secondary coils—but those, too, can't be understood in isolation of the gear with which these coils will be used, or even each other. It's possible to describe the DC resistance of a coil simply by measuring it, but it isn't possible to describe the AC impedance of a coil without observing it at work, in a complete circuit with an exemplary source or load. Consequently, the impedance specifications published by transformer manufacturers should be thought of abstractly: For the most part, primary impedance…
Tweaks come and go. When a new one creates a buzz in audiophile circles, I generally prefer to wait and see if it's still around after the initial excitement has subsided. I'd heard about "audiophile" fuses some time ago, and although the likelihood of them making a significant difference didn't seem as farfetched as such tweaks as the "intelligent chip" or the "clever little clock," I didn't feel inclined to try them. I was persuaded otherwise by the confluence of two separate influences: a report by Michael Fremer, in the February 2007 Stereophile, that the HiFi-Tuning fuses produced a "…
"Tomorrow we'll go over to Larry Archibald's house and pick up the Threshold amplifiers."
It seemed like an intimidating project to me, but Danny Sandoval, Stereophile's intrepid chief of Shipping and Receiving, didn't bat an eye. But then, anyone who'd schlepped the Thiel CS-5s out to the desert in the predawn hours—to be photographed for Stereophile's June 1990 cover—wasn't likely to be defeated by a pair of measly 130-pound amplifiers.
As for me, well, I've been known to go into training at the prospect of moving loudspeakers half that weight. Still, the anticipation of…
Design
There's more to the SA/12e than just quality parts and fortress-like build quality. The design thoroughness begins at turn-on, in which internal components are protected against surges by a controlled power-supply charge-up. To give you an idea of the initial current draw of these amplifiers, turning one of them on caused the line voltage to dip from 118 to 106V for an instant; with both amplifiers idling, the line voltage stabilized at about 114V—a 4V drop from the level sans Thresholds. The SA/12e, being fully class-A from input through to and including output stage, draws its…
There's more to the SA/12e than just quality parts and fortress-like build quality. The design thoroughness begins at turn-on, in which internal components are protected against surges by a controlled power-supply charge-up. To give you an idea of the initial current draw of these amplifiers, turning one of them on caused the line voltage to dip from 118 to 106V for an instant; with both amplifiers idling, the line voltage stabilized at about 114V—a 4V drop from the level sans Thresholds. The SA/12e, being fully class-A from input through to and including output stage, draws its…