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Schoeps microphones, Denecke AD-20 preamplifier-converter, and The New Stereo Soundbook, Second Edition, available from: Jerry Bruck, Posthorn Recordings, Inc., 142 W. 26th St., 10th Floor, New York, NY 10001. Tel: (212) 242-3737.

Audio-Technica AT-825 stereo microphone, Sony PCM-R300 DAT recorder, K&M KM-201A2 microphone stand, Avenger AVG-A635B light stand, Sony MDR-7506 headphones, custom Canare digital cable, Tascam DA-P1 portable DAT recorder, Sony CDR-W33 CD recorder, and Marantz Professional PSD-300 CD-R recorder available from: Markertek, 4 High St.,…

The Audio Engineering Society held its 95th Convention in New York's Jacob Javits Convention Center in October 1993. The gathering is both a trade show for introducing new recording products and a forum for audio scientists presenting papers describing their research. Stereophile has found AES Conventions essential to keeping up with what's happening at the cutting edge of audio technology. Consequently, John Atkinson and I spent four days at the New York Convention, with Larry Archibald dropping by for a few papers and exhibits. Peter…

Until now, developers and reviewers of perceptual coders have relied only on listening tests, because conventional measurements provide little guidance. At the New York AES convention two new methods were demonstrated that can provide valuable information about audible flaws in low-bit-rate coders. Both operate on the same principle as the perceptual coders themselves—namely, the concept of "masking" in critical bands (see later).

The cochlea of the inner ear behaves as a bio-mechanical spectrum analyzer. A tone at any frequency…

This struggle is often in full force when I venture into the…

Description: Vacuum-tube monoblock amplifier. Tube complement (each monoblock): eight 6550C, four 6922, two 5687. Rated output power: 20Hz-20kHz, <1% THD, 220W into 8, 4, and 2 ohms (23.4, 20.4, and 17.4dBW, respectively). Frequency response: 5Hz-75kHz, ±0.5dB at 1W; 15Hz-60kHz, ±0.5dB at 220W. Input sensitivity for full output power: 2.2V, balanced or single-ended inputs. Voltage gain: 25.6dB into 8 ohms, 22.6dB into 4 ohms, 19.6dB into 2 ohms. Input impedance: 100k ohms single-ended, 200k ohms balanced. Output impedance: 0.25 ohms at 1kHz. Damping factor:…

Analog source: VPI TNT IV turntable, JMW Memorial 12" tonearm, Grado Reference cartridge.
Digital sources: Wadia 830, Ultech UCD-100 CD players.
Preamplification: Sonic Frontiers Phono 1 phono preamplifier, Line 3 line stage; VAC CPA1 Mk.III preamplifier.
Power amplifiers: VTL Ichiban and Mark Levinson No.20.6 monoblocks; VAC Renaissance 70/70, Krell KSA-250.
Loudspeakers: Magnepan MG3.6/R, Thiel CS7.2.
Cables: JPS Superconductor 2, Kimber BiFocal XL, Nirvana S-L. AC cords: JPS Power, Analog, and Digital.
Accessories: MIT Z-Systems…

A full set of measurements was made on the Sonic Frontiers Power 3 in its balanced mode, with selected measurements repeated in unbalanced (single-ended) mode. Unless noted otherwise, all measurements are for balanced configuration.

Following its one-hour warmup, the Power 3 was typically hot for a tube amplifier. Its input impedance measured a high 198k ohms (99.3k ohms unbalanced), its output impedance a maximum of 0.17 ohm at 20Hz and 1kHz, increasing to a maximum of 0.22 ohm at 20kHz. These are very low—and very good—values for a tube amplifier, and…