Emotional breakdown
Toward the end of my audition, the PA80/80 failed. I was listening to a test pressing of Analogue Productions' Lay Me Down by Nancy Bryan (AAPO 2002) when things went quiet. Glancing up, I noticed that the biasing lights were extinguished. Hmmm, I thought, the preamp must have passed some DC. I'll just change the fuse. Repeated attempts to power up the amp—with tubes in place and without—just blew a handful of fuses. Notice how uneventful the failure was: it just muted and powered down—no rude noises and speaker pyrotechnics. I'm impressed. The amplifier has gone…
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Sidebar 1: Specifications
Description: Single-chassis wide-band low-feedback stereo power amplifier. Tube complement: 4 12AU7; 4 KT88. Maximum output power at 1kHz: 83W into 8 ohms (19.2dBW). Frequency response: 12Hz-64kHz -0.5dB; 3Hz-115kHz -3dB. Power bandwidth (80W):12Hz-50kHz -0.5dB; 8.5Hz-85kHz -3dB. THD: ±0.25% at 1kHz at 10W. Sensitivity: 775mV for full power. Negative feedback: fixed at approximately 6dB. Polarity: non-inverting. Power consumption: 300W at idle; 516W at full power.
Dimensions: 18" W by 7.5" H by 15" D. Weight: 65 lbs.
Serial number of unit reviewed: 434817…
Sidebar 2: Measurements
All measurements for the VAC PA 80/80 were made with the load connected to its appropriate output tap; ie, 8 ohm load to the 8 ohm tap, etc. The VAC was warmed up for 1 hour at 1/3 of its rated power of 80W; it ran typically hot for a tube amplifier.
The PA 80/80's input impedance measured a high 96k ohms at 1kHz. The output impedance was also high, at between 3.3 and 3.5 ohms (from the 8 ohm tap), depending on frequency. The system frequency response will thus be highly dependent on the loudspeaker load. Voltage gain into 8 ohms measured 30.6dB. S/N ratio…
Canadian electronics manufacturer Bryston Limited has been producing consumer and professional amplifiers since 1974 [see Robert Deutsch's interview elsewhere in this issue—Ed.]. Bryston amps are engineered to be physically and electrically rugged, to meet the stringent demands of professionals, many of whom leave their studio amplifiers turned on for years. While chassis had to be light instead of the audiophile massiveness found in some high-end consumer amplifiers, studio engineers and concert pros continued to favor Bryston amps, which easily passed the "steel toe" test. The 4B, for…
Sidebar 1: Specifications
Description: Solid-state stereo power amplifier. Output power: 120W continuous into 8 ohms (20.8dBW), 200Wpc continuous into 4 ohms (20dBW); 400W continuous into 8 ohms in bridged mode (26dBW). Distortion: 0.007% at 120W, 20Hz-20kHz, IM (60Hz+7kHz, 4:1, SMPTE method) or THD. S/N ratio: 106dB ref. rated output, 90dB IHF. Slew rate: >60V/µs. Damping factor: >500 at 20Hz ref. 8 ohms, equivalent to an output impedance of 0.016 ohms. Input sensitivity: 1V for 120Wpc into 8 ohms; 2V for full output, balanced. Input impedance: 50k ohms unbalanced, 20k ohms…
Sidebar 2: System and Room Context
Because first impressions can be misleading, I believe that audio equipment should be auditioned over a long period of time. The Bryston power amplifiers did service for a good six months, driving a variety of loudspeakers. The amplifiers were run both single-ended and balanced, and, when used in a bi-amplified system, as both main and subwoofer amplifiers.
Comparison solid-state electronics were chosen for the listening sessions to match the Bryston gear in power ratings. Comparison amplifiers included two Mark Levinson 100Wpc dual-mono units:…
Sidebar 3: Measurements
I made a full set of measurements of the Bryston 3B-ST using its unbalanced inputs, with selected measurements repeated in the balanced mode, as noted below.
Following its 1/3-power, one-hour preconditioning test, the 3B-ST's heatsinks were very hot, though not outside the normal range of temperatures usually encountered in this test. The 3B-ST is non-inverting when driven from its positive, unbalanced input; at the balanced, XLR input terminal, pin 2 is positive as specified. DC offset measured 5.5mV in the left channel, 4.1mV in the right.
The…
The audio community's "Great Debate" has reached an amazing level of absurdity. On one side are the Objectivists, whose rationalist argument insists that all human auditory experience is the result of electro-physical phenomena which can be measured and mapped using established scientific methods. On the other side are the Subjectivists, romantics who believe in the synergistic interplay of music, room, equipment, and listener, and whose attempts to describe their experiences tend toward the florid and metaphorical.
This debate—over so plausibly silly an issue as "Do cables sound…
If the objectivist posture is one of logical and moral superiority, then the aesthetic high ground certainly belongs to the subjectivists. Their claim was staked at the expense of credibility with a mainstream readership, due partially to their prolonged dismissal of the significance of specifications and objective measurements, partially by their willingness to entertain crackpot theorists (and their products), and partially by their encouragement of the practice of ritual magic. To date, no one who has published the results of his attempts to correlate the perceived effects of any of the…
The old advertising jingle "Who put eight great tomatoes in that itty-bitty can?" bubbled through my head as Musical Fidelity's Antony Michaelson proudly unboxed the new $4500 M3 Nu-Vista integrated amplifier. How did they cram it all in there?
The M3 packs improved versions of the English company's acclaimed Nu-Vista preamplifier and Nu-Vista 300 power amplifier (minus 25Wpc) into a surprisingly compact and dramatic-looking package. As with the separates, the integrated's power supply is outboard to keep transformer magnetic fields from interfering with low-level signals, but…