I used DRA Labs' MLSSA system and a calibrated DPA 4006 microphone to measure the Audio Physic Step Plus's frequency response in the farfield, and an Earthworks QTC-40 for the nearfield responses. (I didn't use the grilles.) My estimate of the Audio Physic's voltage sensitivity was 84.2dB/2.83V/m, significantly lower than the specified 87dB/2.83V/m. While the specified nominal impedance is 8 ohms, the solid trace in fig.1 shows that the impedance magnitude drops slightly below 8 ohms in the midrange and to 6 ohms at 20kHz. The electrical phase angle (fig.1, dashed…
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Editor's Note: 24 years ago, in January 1995, we published the first issue of Stereophile Guide to Home Theater, a sister publication intended to appeal to the the growing number of home-theater enthusiasts. Stereophile's founder, the late J. Gordon Holt, had gotten early into the idea of accompanying movies with high-quality sound, and when I first visited his New Mexico home in January 1986, his system included an Advent NTSC-format video projector. Gordon and I went back and forth over the next few years, arguing about the role video played in a music-lovers system—click here and here—but…
It's a tense moment during a suspense thriller. A cannibalistic serial killer has escaped from a maximum-security detention unit and eluded capture for long enough to work up a healthy appetite. Two small children are playing hide-and-seek in an overgrown lot behind their home.
They have forgotten mother's admonition to stay indoors, but we haven't. One is hiding in a dense shrub, holding his breath in case the other is nearby. It's dead—quiet except for some distant crows. Off-screen somewhere, and very near, a twig snaps, and we jump out of our seat. Then we hear "I see you!" and the…
Once the surround signal is mixed into the stereo signals, it can never be completely separated out again. Instead of appearing behind you, surround effects might appear some where between where you're sitting and where your front speakers are, and sounds that belong in front will tend to "leak" into the surrounds. To improve the front-to-back separation, Dolby Stereo uses what's called logic steering. (The home version is called Dolby Surround.)
Logic steering measures the signal content in all three channels, compares each one with the others, and "decides" on the basis of their…
Sidebar: The Mathematics of Dolby's Mono Surround Sound
Even though it may come from two loudspeakers, the surround signal on Dolby-encoded recordings is a single channel—monophonic. To encode it into the main stereo channels, it is subtracted from each channel by inverting its electrical polarity and then adding it to the front-channel signals. (Adding a minus to a plus subtracts it.)
But it's not quite that simple. Since the surround effects often contain the same frequencies as front-channel sounds, simply subtracting the surround from the fronts would impair the sound in…
The main inherent advantage of the full-range electrostatic loud speaker system is that it allows a single diaphragm to embody the conflicting attributes needed for optimal performance at both extremes of the audio range. Its thin-membrane diaphragm can be made exceedingly light, for superb transient response and extended HF response, yet it can be about as large in area as desired, for extended LF response. And since that diaphragm is driven uniformly over its entire surface, instead of from a relatively small voice-coil, it circumvents the inherent problem of dynamic speakers in requiring…
Peter J. Walker (1916–2003), founder of Quad Electroacoustics and designer of some of the most well-regarded products in the history of domestic audio, famously believed that a properly designed audio-frequency amplifier should have no sound of its own. As for suggestions that his Quad II amplifier (1953–1971) sounded better than most, Walker was unmoved: "We designed our valve amplifier, manufactured it, put it on the market and never actually listened to it." (footnote 1)
I have an impression that some phonophiles feel the same way about tonearms: They want them to pivot and to move up…
Early on, I encountered a low hurdle that Phillip Holmes had predicted, and that I've encountered and written about before: As with so many other tonearms, it's difficult to make the height-adjustable ZA-12 sit low enough to fully accommodate the TD 124's platter, which is unusually low-slung relative to the armboard. Special emphasis on fully: the pairing proved ergonomically fine and sonically superb, but none of my cartridges was tall enough to allow lower-than-neutral vertical tracking angle (VTA)—ie, where the armtube is not parallel with the record, but slopes down from cartridge to…
Manufacturers' Comment
Editor: Thank you, Art Dudley, for your thought-provoking review of the Sorane ZA-12. It is a design that eschews complications, a product with quality materials and precision, at a fair price.
Complications in wristwatches are "cool" and add value. Complications in tonearms usually detract from the sound. The ZA-12 is simple for a reason. We didn't want to compromise the arm for compromised cartridges. If your cartridge needs azimuth adjustment, send it back for another, or to The Soundsmith for repair.
The leads are extra-long for retermination…
It's noon and a sunny 76º, and already people are setting up for the inaugural Florida Audio Expo at the Embassy Suites by Hilton Tampa Airport Westshore. No sooner do I walk into the Dynamic Sound Associates room than someone asks me if I can please hold three long and hefty Luminous Audio power cables. With those monsters hanging over one shoulder, I snap my first photo.
Next I encounter show promoter Bart Andeer in the lobby. Despite a few cancellations—one exhibitor has the flu, another is recovering from pneumonia, and a third, from Japan, encountered Visa issues—Bart believes we…