search

Paradigm specifies the Atom v.3's anechoic sensitivity as 86dB/2.83V/m, which is just below average. My estimate was 86.5dB(B), which is within experimental error of the specified figure. The Atom's electrical impedance (fig.1) changes considerably over the audioband, with a minimum value of 4.4 ohms at 220Hz. The small glitch just above 30kHz indicates the presence of the tweeter's main dome resonance, which is higher in frequency than we usually see. The saddle in the magnitude trace at 66Hz indicates the tuning frequency of the port.

The fig.1 traces…

Twenty years ago, in a grungy, badly lit club in Edinburgh, Scotland, I saw a show that changed my musical life forever. There, packed together on a stage the size of a postage stamp and looking every bit as young and green as I was, were The Edge, Bono, Larry, and Adam, bashing out their bombastic new single, "Pride (In the Name Of Love)." I was smitten.…

The fully balanced gain section, rated at 2V RMS balanced (maximum output is 30V RMS) and 1V single-ended, uses eight specially selected Sovtek dual-triode 6922 tubes,…

Like a plush, comfortable chair, the Ref 2 put a soft cushion around the music's bottom end—not so cushy that the deep bass sank in and disappeared into the foam, but enough to add a warm,…

The Sonus Faber Amati leans toward rich and lush in the midrange, and is slightly…

Description: Remote-controlled, fully balanced, vacuum-tube preamplifier. Tube complement: eight 6922 dual-triodes; in power supply, one each 5AR4, 6L6GC, and 6922. Voltage Gain: 18dB balanced, 12dB single-ended. Frequency response: 0.5Hz-60kHz, +0/-3dB at rated output. Hum and noise: 20µV RMS residual IHF-weighted noise output with gain control set to its minimum (100dB below 2V RMS balanced output, 97dB below 1V RMS SE output). Distortion: 0.015% at 2V RMS balanced output. Output impedance: 400 ohms balanced, 200 ohms single-ended. Recommended load: 20k ohms…

Analog sources: Simon Yorke turntable, Graham 2.0 and Immedia RPM2 tonearms; Rockport Technologies System III Sirius record player; Lyra Helikon, van del Hul Black Beauty Colibri cartridges.
Digital sources: Musical Fidelity X-Ray CD player, Marantz DR17 HDCD recorder, EAD DSP-9000 Mk.3 DAC.
Preamplification: Audio Research Reference and Zanden phono stages, Lyra Arion step-up transformer, Ayre K-1x preamplifier.
Power amplifiers: Musical Fidelity Nu-Vista 300.
Loudspeakers: Sonus Faber Amati Homage, ProAc Future 1.
Cables: Phono: XLO…

I measured the performance of the Reference Two in both full single-ended and full balanced modes. Maximum voltage gains were 15.2dB balanced in to balanced out, and 13.8dB single-ended in to single-ended out. With a single-ended input, the maximum gain available from the balanced outputs was just under 20dB. The preamp was non-inverting from both sets of outputs. The unity-gain settings of the volume control were 2:00 balanced, 2:30 unbalanced.

The preamp's input impedance varied from 52.5k ohms (unbalanced at 20kHz) through 66.5k ohms (unbalanced, bass…

Fig.6 Audio Research Reference Two, balanced HF intermodulation spectrum, DC-22kHz, 19+20kHz at 2V into 100k ohms (linear frequency scale).

Finally, the Reference Two can output very high levels of low-distortion signal into high impedances. Fig.7 shows the THD+noise percentage plotted against balanced output voltage into 100k ohms (bottom trace) and 600 ohms (top trace). The preamplifier doesn't clip (…