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Even as digital/analog processors were becoming a hot product category in the early 1990s, audiophiles were also learning that timing uncertainties in the AES/EBU and S/PDIF serial datastreams—jitter—would compromise any improvement in sound quality offered by these DACs. Some companies therefore introduced products to reduce or eliminate jitter—in the November 1994 issue of Stereophile, Robert Harley reviewed three such products: the Audio Alchemy DTI Pro, the Digital Domain VSP, and the Sonic Frontiers UltrajitterBug. I still have Stereophile's review samples of the UltraJitterBug and VSP…
This, our February issue, is the first Stereophile issue to arrive during the year 2020, which marks the 50th anniversary of the founding of Audio Research—in my view one of the key events in the history of high-end audio. So it makes sense for this issue to include an Audio Research review—in this case, of the $20,000 Reference 160 S stereo amplifier.
Following an auspicious start, hi-fi in the '60s got complicated. It went backward by going forward. Hi-fi expanded to reach a larger audience. But it did so partly by going mid-fi, with a focus on style, convenience, and broad appeal.…
In Ultralinear mode, a smaller (lower-voltage) version of the audio signal is taken from a tap on the output transformer primary winding and applied to the second grid. The keys to Ultralinear operation are choosing just the right signal level to apply and choosing precisely where on that coil—usually expressed as a percentage—you want the tap. Get those things right and distortion is minimized. Ultralinear is a form of feedback.
The other big advantage to Ultralinear operation is that you get more power. The 160 is specified to put out twice as much—140W—in Ultralinear mode than in…
Sidebar 1: Specifications
Description: Fully balanced, class-AB tubed stereo power amplifier. Tube complement: four KT150 (output), two 6H30 (gain stage) per channel. Inputs: unbalanced (RCA), balanced (XLR). Three sets of speaker output taps: 4, 8, 16 ohms. Output power: 140Wpc continuous, 20Hz–20kHz (21.5dBW). Frequency response: 0.5Hz–110kHz –3dB at 1W. Power bandwidth: –3dB at 5Hz and 70kHz,. Input sensitivity: 2.4V RMS balanced for rated output (25.5dB gain into 8 ohms). Input impedance: 300k ohms balanced, 100k ohms single-ended. Output regulation: ca 0.6dB into 16 ohm load to open…
Sidebar 2: Associated Equipment
Analog sources: Thorens TD 124 turntable (reconditioned by Schopper AG), Thomas Schick 12" tonearm; Ortofon Xpression cartridge.
Digital sources: Intel NUC computer with SSD drive running Roon Optimized Core Kit; Synology DS918+ DISKSTATION 4-BAY Network Attached Storage device with 16TB; TP-Link 8-Port Gigabit network switch (unmanaged); ProJect CD Box RS2 T CD Transport; PS Audio DirectStream DAC.
Preamplification: Auditorium 23 Standard step-up transformer, EAR 834P phono stage, Pass Labs XP-22 and Audio Research Reference 6 preamplifiers.
…
Sidebar 3: Measurements
As with the Audio Research Reference 160 M amplifier that was reviewed in the October 2018 issue of Stereophile, measuring the Reference 160 S was a complicated business. The amplifier has balanced and single-ended inputs, output stages that can be run in either triode or Ultralinear mode, and three output-transformer taps. In effect, it is 12 different amplifiers. I performed full sets of tests using the balanced inputs in both triode and Ultralinear modes from the 4 ohm, 8 ohm, and 16 ohm output taps, then repeated some of the tests using the single-ended…
For a decade, the sound of the Vivid Giya loudspeakers, which I had heard only at CES in private demonstration suites, beguiled me. My positive impressions were completely consistent from one show to the next—but then, so were the host and the surroundings. I had to wonder how much those factors contributed to my impressions.
I had a similarly positive reaction to the sound of the new Vivid Kaya speakers in a tiny demo room on the show floor at the 2018 High End Show in Munich. Smaller and simpler in appearance than Vivid's flagship Giyas, the Kayas are also significantly less expensive…
One can generalize from that to other female voices—and to male voices, too. The latter were endowed with appropriate body but without unnatural resonance. I was particularly struck by the massed male voices in a recent recording, with Hannu Lintu and the Finnish Radio Symphony Orchestra, of Sibelius's choral work Kullervo (SACD, Ondine ODE 1338-5). From the pictures in the recording's accompanying booklet, I estimate there are about 90 men in the combined Estonian National Male Choir and Polytech Choir—and no, I cannot distinguish them all individually by ear. However, the Kaya 45s did…
Sidebar 1: Specifications
Description: Three-way reflex-loaded floorstanding loudspeaker. Drive-units: 1" (26mm) tapered-tube–loaded aluminum dome tweeter, 4" (100mm) tapered-tube–loaded alloy cone midrange driver, 2 × 5" (125mm) alloy-cone bass drivers with exponential tapered-tube/ bass-reflex loading. Crossover frequencies: 300Hz, 3kHz. Frequency response: 37Hz–25kHz (–6dB). Nominal impedance: 6 ohms. Minimum impedance: 2.8 ohms. Sensitivity: 87dB/2.83V/1m. Recommended amplifier power: 25–250Wpc. Peak power handling: not specified.
Dimensions: 45.39" (1153mm) H × 11.75" (298mm) W…
Sidebar 2: Associated Equipment
Digital sources: Oppo Digital UDP-105 universal disc player, Baetis Prodigy-X PC-based music server running JRiver Media Center v25 and Roon, exaSound e38 Mark II D/A processor, QNAP TVS-873 NAS.
Preamplifiers: Audio Research MP1, Parasound P7.
Power amplifiers: Benchmark AHB2, Hegel C-53, Classé Sigma Mono, Parasound Halo A 31.
Loudspeakers: Revel Ultima2 Studio, GoldenEar Triton One.R, Revel Performa F228Be, Dutch & Dutch 8c.
Cables: Digital, AudioQuest Coffee (USB); interconnects; AudioQuest Earth/DBS balanced, Kubala-Sosna…