search

When I first read Mikey's introduction to this review, I was struck by his matter-of-fact statement that class-D isn't digital. Really? Are you sure?

Yes, I know the D in class-D doesn't stand for digital, but that doesn't mean the technology isn't digital. After all, in a class-D amplifier, the signal fluctuates rapidly between two levels, just as it does in DSD—what could be more digital than that?

Fact is, I've always thought of class-D as digital, and of class-D–isn't-digital claims as marketing propaganda propagated by people who want…

Description: Hybrid class-D monoblock power amplifier. One 12AU7 vacuum tube, ICEedge ouput module. Inputs: 1 balanced (XLR), 1 single-ended (RCA), DC trigger. Outputs: 2 pair five-way binding posts. Output power (1kHz, 1% THD): 600W into 8 ohms, 1200W into 4 ohms (both 27.8dBW). Frequency response (2.8V RMS into 4 ohms): 10Hz–45kHz, ±3dB. Voltage gain: 30.5dB, ±0.5dB. Sensitivity: 2.08V for rated output power. Input impedance: single-ended, 50k ohms; balanced, 100k ohms. Damping factor (50Hz, 2.8V RMS), 8 ohms: >1100; 4 ohms: >550. THD: <0.005% (1kHz,…

Analog sources: Continuum Audio Labs Caliburn & Castellon turntable & stand; SAT XD1 direct-drive turntable, OMA K3 direct-drive turntable, SAT CF1-09, CF1Ti-09, Schroeder OMA, and Kuzma 4Point tonearms; Lyra Atlas Lambda SL, Ortofon MC Century, Anna Diamond, A95, A90, Grado Epoch3, Miyajima Labs Infinity (mono), Grado Epoch (mono), Aidas Audio Gala Gold LE cartridges.
Digital sources: dCS Vivaldi One SACD player DAC; Lynx Hilo A/D-D/A converter; Roon Nucleus server; Pure Vinyl and Vinyl Studio software.
Preamplification: darTZeel NHB-18S,…

I performed a full suite of measurements on one of the PS Audio Stellar M1200s (serial no. 12-A1-0G0033), using my Audio Precision SYS2722 system (see the January 2008 "As We See It"). Because the Stellar M1200 features a class-D output stage, all the measurements other than the frequency response tests and one of the squarewave tests were taken with Audio Precision's AUX-0025 auxiliary passive low-pass filter, which eliminates much of the ultrasonic noise that might otherwise drive the analyzer's input into slew-rate limiting. Without the filter, 373mV of…

Decades ago, integrated amplifiers were full-featured beasts—and then there was…

Description: Two-channel, class-AB integrated amplifier with DAC, Bluetooth. Analog inputs: 4 pair unbalanced (RCA), 1 pair balanced (XLR). Outputs: 2 sets custom speaker posts, 3.5mm headphone, 1 pair unbalanced (RCA) preamp out, unbalanced (RCA) subwoofer out. Power output: 80Wpc into 8 ohms (19dBW); 120Wpc into 4 ohms (17.8dBW). Frequency response: 5Hz–60kHz, ±1dB. THD (unweighted, at 80% of rated power): <0.002% 1kHz; <0.02% 20Hz–20kHz. S/N ratio (ref. 1W into 8 ohms): >93dB, (ref. full power): >105dB. Input sensitivity: Input A1–A4 (unbalanced…

Analog sources: Thorens TD 124 and Kuzma turntables, Jelco TS-350S Mk.II tonearm, Hana EL MC phono cartridge, Luxman EQ-500 phono stage.
Digital sources: BorderPatrol DAC SE, Asus laptop computer.
Integrated amplifiers: Schiit Ragnarok 2.
Loudspeakers: Polk Audio Legend L100, Quad S2.
Headphones: Master & Dynamic MH40.
Cables: Interconnect: Shindo Laboratory, Triode Wire Labs Spirit II, Furutech GT2 Pro Series USB cable. Speaker: Auditorium 23. AC: Triode Wire Labs Obsession NCF power cord, manufacturers' own.
Accessories: Kuzma…

I tested the Cambridge Audio CXA81 with my Audio Precision SYS2722 system (see the January 2008 "As We See It"). I first preconditioned the amplifier by following the CEA's recommendation of operating it at one-eighth the specified power into 8 ohms for 30 minutes. At the end of that time, the top panel was warm, at 98°F (36.7°C), with the grille over the heatsinks and transformer hotter, at 133.1°F (56.2°C). I then performed my usual thermal stress test by running the amplifier at one-third power into 8 ohms for an hour. After 30 minutes, the grille's temperature…

Sanford "Sandy" Gross, co-founder of Polk Audio and former CEO of GoldenEar Audio, has said that "in general, the best audio systems will sound…