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With both balanced and unbalanced inputs and the capability of being switched on the fly between class-AB and class-A output-stage operation—I would prefer to say "high-bias current" rather than "class-A," as the amplifier does not operate in true class-A up to its specified output power in this mode—the Plinius SA-Reference offers a lot of variety for measurement options. I did a full set of measurements in balanced, class-A mode, with spot checks in unbalanced and class-AB operation.

I preconditioned the amplifier by running both channels at one-third…

Looking at the progression from Aerius to Quest, a definite trend is apparent. First, the woofer increases in size…

What a first impression! Was this true? Were the Quests, at a third the price, indeed superior to the A-1s? That observation stuck in the back of my mind, and for the next several weeks I digested its significance. You know, young DO was right—in some respects the Quests were better than the A…

Description: Hybrid loudspeaker system. Drive-units: 12" cone woofer in a sealed enclosure; electrostatic panel, 15" W by 44.5" H. Crossover frequency: 125Hz. Crossover slopes: second-order, 12dB/octave. Frequency response: 28Hz–22kHz, ±2dB. Presence control switch: +2dB, 1–5kHz. Bass control switch: –5dB, 60–150Hz. Nominal impedance: 8 ohms (minimum 2 ohms). Phase angle: less than 45 degrees. Sensitivity: 90dB/W/m (2.83V). Recommended amplifier power: 80–200Wpc.
Dimensions: 72.75" H by 19" W by 13" D. Weight: 125 lbs each.
Finishes available: light oak,…

Martin Colloms's discussion last year of some of the imponderable elements of loudspeaker reproduction (Stereophile, November 1992, Vol.15 No.11, p.76) reminded me of something written nearly a quarter-century ago (in Wireless World, November 1970) by metal-cone speaker pioneer Ted Jordan. Ted asked the rhetorical question: "What is the aim of a loudspeaker?" He then proceeded to examine a number of possible answers. The most objective answer possible, and one that would surely impress our engineering alter egos, was: to reproduce the electrical input signal…

Despite the Z modification making the Quest easier to drive, it's still a demanding load for an amplifier, the impedance dropping to 2.7 ohms in the midbass and lower midrange and dropping below 2 ohms above 16kHz (fig.1). The minimum value is a punishing 1.4 ohms at 25kHz—fortunately, there is no high-level musical information up there. Note the moderate phase angle, however, which ameliorates matters. With the bass set to –5dB, the impedance does become a little kinder in the bass, staying above 4 ohms below 160Hz. The woofer tuning is revealed by the peak at…

Dream on, Steve.

While the Diamante is quite a bit more expensive than my $1000/pair ideal…

Description: Floorstanding loudspeaker system with cast onyx-resin "Anechoic Transmission Line" enclosure and separate base. Drive-units: 8" polymer-laminated cone woofer with a vented coil; 4" Nomex/Kevlar/honeycomb cone midrange unit with carbon-fiber frame; 1.1" linen-dome tweeter with ferrofluid-cooled aluminum voice-coil. Crossover frequencies: 350Hz, 3.2kHz; first-order, 6dB/octave slopes. Frequency range: 42Hz–23kHz (no tolerance given). Impedance: 5.3–18.9 ohms. Sensitivity: 88dB/W/m. Recommended amplifier power: 35–350Wpc. Dynamic range: >115dB/pair…

I don't make drastic changes to my audio system from month to month, because then it would be very difficult to tell what component is doing what to the sound. If the following list looks similar to my system list in prior reviews, that's because it largely is. The following equipment was used:

Analog sources: Thorens/Chadwick 125 Mk.II turntable mounted with a Graham 1.5 tonearm, with arm tubes fitted with Denon 103 C/van den Hul, EMT/van den Hul, Fidelity Research FR-1 Mk.III van den Hul, and AudioQuest BH-200 cartridges; in my large listening room, I used a…

The Diamante's impedance magnitude and phase are shown in fig.1. The single rise in the bass, to 15.5 ohms, suggests that the ATL loading does act as a true transmission line rather than as some kind of perverted reflex, though its frequency, 51Hz, implies limited low-frequency extension overall, as SS found during his auditioning. When the speaker is used with an amplifier having a high output impedance, this 51Hz impedance peak will result in an effective boost at this frequency. I suspect that this is why SS found his Atma-Sphere tube amplifier not to be a good…