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What I heard at home more or less confirmed what I heard at RMAF (though the home experience was considerably better than the already fine performance I heard under typically lousy show conditions)—that is, once the "whining, beeping, buzzing" issues had been solved. That's not a product indictment! It's more about Myers's "no compromise" design philosophy, which is well documented in the instruction manual: As I immediately discovered, and as Myers and Leebens also heard, the Stellar is extremely sensitive to grounding, ultralow-capacitance cables, RF, and other kinds of interference.
Sidebar 1: Specifications
Description: Solid-state phono preamplifier with unbalanced inputs and both balanced and unbalanced outputs. Overall voltage gain: MM: 44dB, 50dB, 56dB. MC: 60dB, 66dB, 72dB. Input loading: MM: 47k ohms (100pf). MC: 60, 100, 200, 47k ohms, Custom, 1 ohm–1k ohms. Output impedance: unbalanced <200 ohms, balanced <200 ohms per leg. (All measurements are with both channels operating, gain set to low, and balanced outputs. Input frequency is 1kHz.) Frequency response: 20Hz–20kHz ±0.25dB. THD @0.5V, 1kHz: <0.01%. Maximum output: @1%THD: 24VRMS. Overload…
Sidebar 2: Associated Equipment
Analog sources: Continuum Audio Labs Caliburn, & Castellon turntable & stand; VPI HW-40 Air Force One Premium turntables; SAT CF1-09, Graham Elite, and VPI Fatboy tonearms; Lyra Atlas, Atlas SL, Atlas SL mono, Etna, and Etna SL, Ortofon MC Century, Anna Diamond, A95, Miyajima Labs Infinity (mono) and Destiny (stereo) Grado Epoch (mono).
Digital sources: dCS Vivaldi One SACD player DAC; Lynx Hilo A/D-D/A converter, Roon Nucleus; Pure Vinyl and Vinyl Studio software.
Preamplification: darTZeel NHB-18S, Ypsilon MC-10L, MC-16L, Consolidated…
Sidebar 1: Measurements
I measured the PS Audio Stellar Phono phono preamplifier using my Audio Precision SYS2722 system (see the January 2008 "As We See It"). For logistical reasons, I tested a different sample (serial number SPH-B-9J0100) from that auditioned by Michael Fremer. To get the lowest measured noise, I floated the signal generator's unbalanced output from ground and ran a separate connection from the analyzer's ground to the grounding post on the preamplifier's rear panel.
PS Audio specifies the voltage gain for the moving-magnet input as Low (44dB), Medium (50dB),…
When I performed the measurements of the Q Acoustics Concept 500 loudspeaker to accompany Thomas J. Norton's review in March 2019, I was impressed by what I found. The floorstanding Concept 500 offers a high level of audio engineering excellence for its price of $5999.99/pair. When I attended a Q Acoustics press briefing a few months back, where the English company announced the US availability of their stand-mounted Concept 300, I didn't hesitate to ask for a pair to review.
Design
The Concept 300 costs $4499.99/pair, including a pair of unique stands: skeletal, 26"-tall Tensegrity…
Low-level detail in the sound of the piano was well-preserved by the Concept 300s, even when Jarrett was comping at high levels with his left hand. I followed "Kyoto" with The Carnegie Concert (16/44.1k ALAC files, ripped from CD, ECM 07362), for which I had been in the audience back in 2005. Whereas the Sun Bear improvisations are unbroken stretches, sometimes lasting more than 40 minutes, Carnegie comprises shorter pieces, more akin, dare I say it, to songs. The image of the piano is wider and closer than it is on "Kyoto," and the instrument has more low-frequency power. Again, the Concept…
Sidebar 1: A Sprung Suspension on a Loudspeaker?
After I attended the launch event for the Q Acoustics Concept 300 with John Atkinson, I found myself interested in this speaker's unique stands—which, as JA points out in his review, incorporate a sprung, low-pass vibration filter to isolate the speaker from its surroundings, much as a suspended turntable isolates the platter from floor-borne vibrations.
It's an interesting idea—especially in the context of a dynamic loudspeaker, which has drivers moving in and out over a wide range of frequencies. When a driver cone moves, its…
Sidebar 2: Specifications
Description: Two-way, stand-mounted, reflex-loaded loudspeaker. Drive-units: 1.1" (28mm) fabric-dome tweeter, 6.5" (165mm) coated paper-cone woofer. Crossover frequency: 2.5kHz. Frequency response: 55Hz–30kHz, +3dB, –6dB. Nominal impedance: 6 ohms. Minimum impedance: 3.7 ohms. Sensitivity: 84dB/W/m. Recommended power: 25–200W.
Dimensions: Loudspeaker: 14" (355mm) H × 8.6" (220mm) W × 15.7" (400mm) D. Effective internal volume: 11.4 liters. Weight: 31.9lb (14.5kg) each. Shipping weight: 36.3lb (16.5kg) each. Tensegrity stand: 27.2" (690mm) H × 18.1" (460mm) W…
Sidebar 3: Associated Equipment
Analog source: Linn Sondek LP12 turntable with Lingo power supply, Linn Ekos tonearm, Linn Arkiv B cartridge, Channel D Seta L phono preamplifier.
Digital sources: Roon Nucleus+ file server; Ayre Acoustics C-5xeMP universal player; PS Audio PerfectWave DirectStream D/A converter.
Power amplifiers: Lamm Industries M1.2 Reference, Vandersteen M5-HPA (both monoblocks).
Integrated amplifier: NAD M10.
Loudspeakers: KEF LS50.
Cables: Digital: AudioQuest Vodka (Ethernet), DH Labs (1m, AES/EBU). Interconnect: AudioQuest Wild Blue (balanced,…
Sidebar 4: Measurements
I used DRA Labs' MLSSA system and a calibrated DPA 4006 microphone to measure the Q Acoustics Concept 300's frequency response in the farfield, and an Earthworks QTC-40 mike for the nearfield and in-room responses.
Q Acoustics specifies the Concept 300's sensitivity as 84dB/W/m. My estimate was slightly higher, at 86dB(B)/2.83V/m. The Concept 300's impedance is specified as 6 ohms, with a minimum value of 3.7 ohms (on the website) or 4.7 ohms (in the product's white paper). My impedance measurements, which I took with MLSSA then checked with Dayton Audio's…