On the test bench, the dedicated active crossover (DAX) had a gain of 3.4dB ±0.05dB in the unbalanced mode for either channel on both the high- and low-pass legs (taken at 1kHz and 40Hz, respectively). Its gain in the balanced mode was virtually the same (about 0.1dB higher). The balanced and unbalanced output impedance also measured the same: 50-51 ohms. The input impedance measured just under 7.4k ohms, unbalanced, and between 8k ohms and 8.2k ohms, balanced, for either channel, high- or low-pass. The latter is moderately low, but should only be a problem…
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Sidebar 3: Specifications
Apogee Stage: Two-way dipole speaker system with a 12" by 26", electromagnetic film-diaphragm woofer and a 0.7" by 26" ribbon midrange/tweeter. Crossover frequency: 600Hz. Crossover slope: 6dB/octave gradually increasing to 12dB/octave. Frequency range: 30Hz-20kHz (no tolerance specified). Sensitivity: not specified. Nominal impedance: 3 ohms. Recommended minimum amplifier power: 100W.
Dimensions: 37" H by 26" W by 2" D (without stands) Weight: 60 lbs each..
Finish: optional parchment, anthracite, or black sand, with or without mahogany or basswood trim.…
The debates may be old, but they're not tired. They rage on with a virulence that suggests there's plenty of life in these old dogs yet. Online forums and Letters to the Editor are filled with them: objectivist vs subjectivist, engineer vs audiophile, double-bind vs doubly blind. The divisions may be artificial or downright specious—false dichotomies perfectly set up for cheap shots—but that doesn't dissuade people from drawing sides, driving stakes into the ground, and firing off volley after volley of accusation and retaliation.
Anyone who has observed or engaged in these debates while…
We were having trouble with the power in our home—the wall current, I mean, not the dynamics of our marriage—so I called the local utility. While the technician was here, he let me watch what he was doing. I had a chance to look inside our meter box, which is the junction between the utility's power lines and the circuit-breaker box in the cellar.
With the meter box open and the meter itself pried from its moorings, there wasn't much to see: two hot legs (sounds like a bad Rod Stewart record, doesn't it?) and one neutral, plus a braided ground lead. The hot and neutral legs are extremely…
JPS Labs The Digital AC
As I write this, my family and I are preparing to move. That means I've finally had to get off my duff and ship several dozen cable samples back to the manufacturers, who, understandably, would rather I kept them.
As I write this, my family and I are preparing to move. That means I've finally had to get off my duff and ship several dozen cable samples back to the manufacturers, who, understandably, would rather I kept them.
After I shipped most of them out, I found a stray in our basement: Mixed in with some of my own cables was a long, black power cord from JPS Labs, labeled The Digital AC (footnote 1). The cable itself is no thicker than average, although it's encased in the sort of braided jacket that makes it look big and somewhat reptilian. Both the plug end and…
Explanations
I called Joe at JPS Labs, to get a few technical explanations. He told me a little more about The Digital AC and how it works.
I called Joe at JPS Labs, to get a few technical explanations. He told me a little more about The Digital AC and how it works.
First, at the heart of this cord are three "very-high-purity" stranded copper conductors, insulated to a 300V rating for approval by UL and CSA. That insulation is also said to contain a special compound that absorbs and, to some extent, dissipates high-frequency energy. But its the energy absorption that is key: The idea is for The Digital AC to act like a sponge for electrical noise, instead of either reflecting noise the way ferrite rings do…
The X-DAC v3 replaces Musical Fidelity's Tri-Vista 21 DAC, which is no longer in production, although you might find some on dealer's shelves. The Tri-Vista 21 used two pairs of subminiature 5703 WB military tubes in the analog output stage. MF's Antony Michaelson called this Cold War tube, which is no longer made, a trivistor. The Tri-Vista 21 was last seen selling for $2395.
When the Tri-Vista 21 was introduced a little over a year ago, Antony told me it was about as good as a digital processor gets. It got a Class A recommendation from Stereophile. (There's also an A+ category…
Sidebar 1: Specifications
Description: Solid-state D/A processor with one electrical and one Toslink optical S/PDIF inputs, one pass-through digital output, and one pair of unbalanced analog outputs. Sampling frequencies accommodated: 8–kHz. Word lengths accommodated: 16, 20, 24 bits. Frequency response: 10Hz–20kHz +0/–0.2dB. S/N ratio: >121dB, A-weighted ref. 0dBFS. THD: <0.002%, 10Hz–20kHz. Total correlated jitter: <135ps. Channel separation: >110dB, 20Hz–20kHz. Maximum output level: 2.2V RMS at 1kHz. Output impedance: 50 ohms. Power requirements: ±12V, 0V via…
Sidebar 2: Measurements (from May 2005, Vol.28 No.5):
I consistently get requests from readers that we publish measurements for the components reviewed in Stereophile's "Sam's Space," "Analog Corner," "Listening," "The Fifth Element," and "Music in the Round" columns. As much as I would like to do this, I don't have the resources to do anything more than scratch the surface of the gear that Sam, Mikey, Art, John, and Kal write about. But I do try to get samples when my interest has been piqued by what they've said. Sam Tellig's report on the Musical Fidelity X-DACV3 in December 2004 was…
Stereophile Editor John Atkinson walked into our office brandishing a CD (footnote 1). "Guess what Ken Kantor did? He took a year off from running NHT (footnote 2) to make this disc."
"That's really cool," I responded, drifting into a fantasy about what I'd do with a year off. "I'd like to meet a guy who'd do that."
"You could go visit NHT's factory when you're in San Francisco for HI-FI '97."
So I did. It wasn't a typical manufacturing plant, but NHT—like its founder—doesn't aim for the typical. It revels in its quirkiness. As I was shown around the factory, I observed…