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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…
Threshold also makes a point of the fact that their STASIS designs maintain a constant (and high) damping factor over the full audio band. Contributing to this is the lack of overall feedback and the elimination of the ubiquitous output inductor (between the final output stage and the output terminal) required in most conventional designs.
Sound
OK, so we know that the big Thresholds are built like tanks compared with the go-cart construction of more real-world (pricewise) amplifiers. Two questions must be answered here. Are they among the best amplifiers in the world? (They better…
Sidebar 1: Specifications
Description: Class-A monoblock power amplifier. Power output: 250Wpc (24dBW) continuous, 500W peak into 8 ohms (resistive or reactive) from 20Hz-20kHz at no more than 0.1% THD. Power bandwidth: DC to 100kHz. Slew rate: 50V/us. Output current capability: 70A continuous (200A peak). Input impedance: 50k ohms unbalanced, 600 ohms balanced. Noise: minimum -100dB, unweighted, against rated output.
Dimensions: 19" W by 8.72" H by 27.75" D. Weight: 130 lbs.
Price: $14,400/pair (1990); no longer available (2007). Approximate number of dealers: 75.
Manufacturer…
Sidebar 2: System
I used the SA/12es in a system consisting of the Oracle Delphi Mk.IV turntable with Oracle 345 arm and Dynavector XX-1L cartridge, Sony CDP-X77ES CD player used as a transport with coaxial link to an Esoteric D-2 D/A converter, Rowland Consonance preamp, and B&W 801 Matrix Series 2 loudspeakers (no LF equalizer used).
Interconnects were AudioQuest Lapis (with the exception of the coaxial CD transport to processor link, which was a garden variety but 75 ohm video cable); loudspeaker cables were AudioQuest Clear Hyperlitz (bi-wire pair). The preamp-to-power-…
Sidebar 3: Measurements
I didn't really expect any surprises in our measurements of the Threshold SA/12e, and none were found. It would, in fact, be hard to imagine better objective performance at the current state of the art. Frequency response was a total non-event—that is, flat within 0.1dB from 20Hz–20kHz (fig.1). Fig.2 shows the Threshold's THD+noise. The three lowest curves indicate (respectively) the low power figures of 1W into 8 ohms, 2W into 4 ohms, and 4W into 2 ohms. The third curve from the top is the 250W into 8 ohm measurement. It edges just barely over the 0.1%…
Stereophile September 1991, Vol.14 No.9, Followup
When John Atkinson asked what I'd like to review for the September issue, I responded immediately that I had some unfinished business to attend to. When I reviewed the Threshold SA/12e monoblock (Vol.13 No.12) and Rowland Model One (Vol.14 No.4) stereo amplifiers, I left a few threads hanging. I'd promised a follow-up comparing the big Thresholds with one of that company's less pricey (though still far from cheap) stereo amplifiers, and I had yet to try a pair of Model Ones bridged as monoblocks. Hence this update.
Associated…
Since he joined Snell Acoustics in the mid-1980s, Kevin Voecks, their chief designer (footnote 1), has been involved in the design or redesign of the entire Snell line, from the minor revision of the Type A/III (incorporation of a new tweeter), to the complete redesign of the Type C (now the CIII). Snell Acoustics is located in Massachusetts, and although Kevin spends a good deal of time there or at the measurement and analysis facilities of the Canadian National Research Council (NRC) in Ottawa, he does a great deal of his conceptual and preliminary design work, as well as his listening, in…
Norton: I guess every designer approaches it differently, but when you originally conceive a new loudspeaker design, where do you generally start your process—how does your conceptual process work?
Voecks: The conceptual process is the part I like—by far—the most, because it's the really creative part, and comes pretty easily. You usually say that you need a speaker in a certain price range—that's usually the direction that you start in—then you start to think about what kind of things could be done for that price. For instance—at $2000 for the CIII, what can we do to make it demonstrably…