Índice para Feb-18 em Stereophile

EXPLORING THE ANALOG ADVENTURE THIS ISSUE:New LP playback gear from MoFi Electronics & Lounge Audio. It’s taken me way too long to get this well- deserved story into print. In my October 2017 column I reported on two turntables, the Palmer 2.5 and AMG Giro G9, each costing $10,000 and up, depending on ancillaries. It wasn’t that I wanted to get all Mikey Fremer Uptown on you; I wanted to refine my listening skills and familiarize my senses with what my own humble system would sound like with a pair of world-class record players. Armed with those experiences, I continued my research—with MoFi Electronics’ new UltraDeck turntable ($1799 with MoFi Ultra tonearm) and their top-of-the-line moving-magnet cartridge, the MasterTracker. Separately, the MasterTracker costs $699; it can also be purchased preinstalled…

For all its faults—complex grammar, inconsistent rules of pronunciation, burdensomely endless vocabulary—English has proven itself a commendably plastic language. This is good for audio enthusiasts, in the US and elsewhere, whose choices in playback gear continue to evolve not only in substance and function but in name: Unlike many of the people who speak it, English can keep pace with the changes. The sound was so good and so musically compelling that I had to stop and listen. Consider: Less than three years ago, when I began working full-time as one of Stereophile’s editors, product descriptions were still simple things, even in the world of digital audio. Seldom would I have to write a product-review heading more complex than CD player or D/A converter. But, as you may have noticed,…

I used DRA Labs’ MLSSA system and a calibrated DPA 4006 microphone to measure the TAD Micro Evolution One’s frequency response in the farfield, and an Earthworks QTC-40 for the nearfield responses. My estimate of the TAD’s sensitivity was 86.2dB(B)/2.83V/m, slightly higher than the specified figure of 85dB. Fig.1 shows how the impedance and electrical phase vary with frequency. Though the impedance has a minimum value of 3.9 ohms between 120 and 155Hz, and there’s a combination of 5 ohms and –43° phase angle at 33Hz, the ME1 is a relatively easy load for amplifiers to drive. The traces in fig.1 are free from the small discontinuities that would suggest the presence of panel resonances. However, when I investigated the enclosure’s vibrational behavior with a plastic-tape accelerometer, I did find…

I measured the Pass Laboratories XA25 with my Audio Precision SYS2722 system (see the January 2008 “As We See It,” http://tinyurl.com/4ffpve4). Before performing any tests, I ran it at one-third its clipping power (see later) into 8 ohms for an hour. At the end of that time, the top panel was warm, at 102.3°F (39°C), and the heatsink fins were hotter, at 122.2°F (50.1°C). The gain at the speaker terminals was to spec at 20.4dB, and the output preserved absolute polarity (ie, was non-inverting). The XA25’s unbalanced input impedance was the specified 47k ohms at low and middle frequencies, dropping inconsequentially to 34k ohms at the top of the audioband. The output impedance (including 6’ of speaker cable) was low, at 0.08 ohm at 20Hz and 1kHz, rising very slightly…

After I’d concluded my critical listening sessions with the PS Audio Stellar M700s, I got a call from Dave Morrison of IsoAcoustics, in Markham, Ontario, makers of the Gaia loudspeaker isolation feet.1 He told me that they had a new product, the Orea, that applies to audio electronics—preamps, power amps, DACs—the isolation technology used in the Gaia. (Orea is a simplified form of Ourea, for the nine primordial mountain gods of Greek mythology, all progeny of Gaia: the Earth.) He suggested that I try the Oreas under the Stellar M700s. My experience with the Gaias had been very positive; if the Oreas were anything like that, I had to try them. Oreas are available in two versions, depending on the weight of the component supported: the standard model, suitable for…

I measured the Jadis JA200 Mk.II with my Audio Precision SYS2722 system (see the January 2008 “As We See It,” http://tinyurl.com/4ffpve4). One point to note is that with 10 KT150 tubes packed closely together on the amplifier chassis, the JA200 Mk.II gets very hot. After a couple of hours, the temperature of the top panel by the output transformer was 169°F (76.2°C)! The voltage gain into 8 ohms was 30.5dB, and the Jadis preserved absolute polarity (ie, was non-inverting). The input impedance was very high, at >500k ohms at low and middle frequencies, and still 300k ohms at the top of the audioband. The output impedance (including 6' of speaker cable) was very low for a transformer-coupled tube amplifier, at 0.18 ohm at 20Hz and 1kHz, and 0.14 ohm at…

At this year’s Rocky Mountain Audio Fest, Ray Kimber was beginning to feel a little antsy. He’d just released his first LP, Chopin’s Last Waltz, an all-Chopin program performed by pianist Robert Silverman, and while being part of the rush to re-embrace vinyl sounds great, pressing your first-ever long player can be a bit nerve-racking. “No one had listened to it,” Kimber told me from his home in Utah. “The LP pressing finishes the day before Rocky Mountain starts. They are driven over from Quality Record Pressing in Kansas in the QRP company truck. We had never used a turntable for any of our demos—we’d always just played back files out of the workstation. Once the records are set up and displayed, the night before the show starts, I kind…

INSIDER VIEWS ON EVERYTHING VINYL THIS ISSUE:Rega Research’s RP10 turntable and Aphelion MC phono cartridge. In February 2017, for the first time in almost 20 years, I visited Rega Research’s factory in Southend-on-Sea, UK. I found a company that had added to its just-built factory a second building of the same size, had added an upper level within that space, and already was running out of space. Corridors and walkways were being used for assembly and storage. Rega was finding it a challenge to meet the growing demand for new turntables, while continuing to design and manufacture lines of loudspeakers and electronics. Nonetheless, Rega’s commitment to maintain and improve quality control remained apparent in their vigorous regimen of tests for each of their current turntable models: the Planar 1, 2,…

 What’s your favorite record? It’s a simple enough question, but one that dedicated music consumers never tire of asking each other. And so, every year, we ask the distinguished writing staff of this magazine to choose a pair of favorites and tell us a little of what seems so compelling about them. Music in any recorded format is fair game, the only restriction being that it must still be available, if only in the deep, dark recesses of the Internet. Of course, favorites come and go in minds and hearts—speaking of dark recesses—but these are Stereophile’s takes on the essential music of the moment. Enjoy! NOTE: If a recording listed here was previously reviewed in Stereophile, whether in “Record Reviews” or in a past edition of “Records to Die For,”…

I measured the MBL N31 with my Audio Precision SYS2722 system (see the January 2008 “As We See It,” http://tinyurl.com/4ffpve4), using both the Audio Precision’s optical and electrical digital outputs and USB data sourced from my MacBook Pro running on battery power with Pure Music 3.0 playing WAV and AIFF test-tone files. Apple’s USB Prober utility identified the N31 as “MBL USB Audio Class 2” from “MBL Akustikgerate, Berlin,” and its serial number as “Streamlength(tm).” The MBL’s USB port operated in the optimal isochronous asynchronous mode. Apple’s AudioMIDI utility revealed that, via USB, the N31 accepted 24-bit integer data. The optical input accepted datastreams with sample rates up to 96kHz, and the USB 2.0, AES/EBU, and S/PDIF inputs accepted streams of up to 192kHz. The CD drive’s error correction was…

The XA25 stereo amplifier is the latest addition to Pass Laboratories’ XA series of amplifiers and, at $4900, the lowest priced. It weighs only 45 lbs, has single-ended inputs only, and outputs 25Wpc into 8 ohms, 50Wpc into 4 ohms, or 100Wpc (!) into 2 ohms. According the XA25’s well-written owner’s manual, it will deliver 50W peaks into 2, 4, or 8 ohms—in class-A. As Nelson Pass, founder of Pass Labs and the XA25’s designer, writes in that manual: “The signal path from input to output has been simplified to fewer components. Degeneration, ‘the other form of feedback’ has been eliminated. The output stage consists of a single pair of 700 watt new generation output transistors operating push-pull Class A. We still use the same ‘New Old Stock’ of small…

I measured the PS Audio Stellar M700 with my Audio Precision SYS2722 system (see the January 2008 “As We See It,” http://tinyurl.com/4ffpve4). Before performing any tests of an amplifier, I usually precondition it by running it at one-third the clipping power into 8 ohms for an hour. As the Stellar M700 has a class-D output stage, this was not necessary. But I did take the temperature of its case: the top panel was slightly warm, at 80°F (30°C). The voltage gain into 8 ohms was 30.5dB for both the balanced and unbalanced inputs, and the M700 preserved absolute polarity (ie, was non-inverting) for both inputs, meaning that the XLR jack is wired with pin 2 hot. The unbalanced input impedance was close to the specified 50k ohms, measuring 47k ohms…

“How natural the sound,” wrote Jonathan Scull in March 1994, in his Follow-Up on the original Jadis JA 200 monoblock amplifier, which then cost $18,990/pair. “How easy it was to follow the musical line and fall into the music. How deep, controlled, tight, and satisfying the bass. How magnifique the midrange—the traditional strength of the Jadis presentation. How full and satisfying the lower midrange. How open, airy, how right the highs—not at all hard, but very extended and natural. How involving their presentation. How full, how harmonically correct, how wonderfully compelling. How magical.”1 Dick Olsher’s original review of the JA 200, published in November 1993, hadn’t been as sunny. Dick had found the lower midrange “somewhat meager,” the sweetness, sheen, and vitality of violin overtones and soprano voices “blunted” and…

ANY CLOD CAN HAVE THE FACTS; HAVING OPINIONS IS AN ART THIS ISSUE:MoFi, PS Audio, and MQA respond to our coverage of their products. MoFi Electronics UltraDeck Editor: Thank you to Stereophile and Herb Reichert for reviewing our first turntable. It has taken us a long time to get here. Building a product under the Mobile Fidelity banner requires great respect for the company’s mission to be as faithful as possible to the original master tapes, and in turn, the artists’ intentions for how their music should be heard. We walk in the footsteps of giants like Brad Miller, Stan Ricker, Tim de Paravicini, and the current team of mastering engineers at MoFi, who, when it comes to the quality of what they do, are the most uncompromising people you’ll…

SUBMISSIONS: Those promoting audio-related seminars, shows, and meetings should e-mail the when, where, and who to JAtkinson@enthusiastnetwork.com at least eight weeks before the month of the event. The deadline for the April 2018 issue is January 20, 2018. US: BOULDER, COLORADO John Atkinson In 1990, when Stereophile was still headquartered in Santa Fe, New Mexico, I was reviewing the Eclipse loudspeaker from a new Coloradan company, Avalon. The company’s principals, Neil Patel and Charley Hansen, visited to set up the speakers in my listening room, and during that visit Charley and I talked speakers. And more speakers. And even more speakers. I was enormously impressed by his grasp not only of the engineering involved, but also of the larger issues of audio reproduction. I felt that what had taken me…

IN SEARCH OF THE EXCEPTIONAL THIS ISSUE:Audio-Creative’s GrooveMaster II tonearm is taken for a test drive. In my youth, I unwittingly trained myself in the art of deferred pleasure. I did this by investing my allowance in every mail-order product that caught my eye—things I saw in the back pages of the magazines and comic books I loved—then settling in for a wait that always seemed interminable. This happened most often in summer months, when extra chores brought extra cash, and when school didn’t interfere with keeping vigil at the mailbox. Surely the screen door of our old house still bears the imprint of my nose, stamped as I waited for the mailman to deliver booklets on the secrets of the world’s foremost hypnotists (advice that never rose above the…

I measured the AVM Ovation MP 8.2 with my Audio Precision SYS2722 system (see the January 2008 “As We See It,” http://tinyurl.com/4ffpve4), using both the Audio Precision’s optical and electrical digital outputs and USB data sourced from my MacBook Pro running on battery power with Pure Music 3.0 playing WAV and AIFF test-tone files. I measured the behavior with both the MP 8.2’s Steep and Smooth reconstruction filters in “native” mode, the output level set to “fixed,” and the USB port set to Type 2. Apple’s USB Prober utility identified the AVM as “AVM Class 2 Audio” from “XMOS,” and the serial number as “0 (none).” The USB port operated in the optimal isochronous asynchronous mode. Apple’s AudioMIDI utility revealed that, via USB, the AVM accepted 16- or 24-bit integer…

Although PS Audio’s Stellar M700 monoblock power amplifier ($2998/pair) is a brand-new design from a team led by engineer Darren Myers, it draws on the company’s extensive experience with class-D amplification. Sam Tellig and Kalman Rubinson reviewed PSA’s HCA-2 power amp in, respectively, the October1 and December 20022 issues, and I reviewed their GCC-100 integrated amp in January 2006.3 The Stellar M700’s input stage is the latest version of PS Audio’s Gain Cell, which they describe as a “proprietary, fully differential, zero feedback, discrete, class-A MOSFET circuit.” In the Stellar M700, the Gain Cell drives a 700ASC class-D power module from the Danish company ICEpower. I asked Paul McGowan, CEO of PS Audio, why they chose this module rather than, say, one from Hypex, another class-D specialist. He said that…

THIS ISSUE:Is the MQA codec lossy or lossless? MQA PART TWO: INTO THE FOLD Loss is nothing else but change, and change is Nature’s delight. —Marcus Aurelius Master Quality Authenticated (MQA), the audio codec from industry veterans Bob Stuart and Peter Craven, rests on two pillars: improved time-domain behavior, which is said to improve sound quality, and what MQA Ltd. calls “audio origami,” which yields reduced file size (for downloads) and data rate (for streaming). Last month I took a first peek at those time-domain issues, examining the impulse response of MQA’s “upsampling renderer,” the output side of this analog-to-analog system.1 This month I take a first look at the second pillar: MQA’s approach to data-rate reduction. In particular, I’ll consider critics’ claims that MQA is a “lossy” codec. Is…

THERE’S ONLY TWO KINDS OF MUSIC: THE BLUES AND ZIPPETY DOO-DAH. —TOWNES VAN ZANDT “I’m so old I remember when fame was a by-product of having talent.” —MY NEW FAVORITE REFRIGERATOR MAGNET The word die in the title of this issue of Stereophile, our annual celebration of music, has always given me a shiver, and never more so than as I write this at the end of 2017, a year of momentous change. In music—the reason we got into high-end audio and the pursuit of better sound in the first place—these changes and the endless musician passings have led me to elemental ponderables: the oft-forgotten fragility of life, the terrible finality of death, and twinges of regret for now-departed geniuses whose losses I know I will mourn. While “they don’t…