My estimate of the Dynaudio's sensitivity was 84dB(B)/2.83V/m, a little lower than the specified figure. This puzzled me, as my estimate of the original Contour 1.3's sensitivity was 3dB higher, and the drive-units are identical. The Mk.II's impedance is shown in fig.1. The minimum value is 3.43 ohms at 177Hz, with a moderate electrical phase angle above that frequency. The saddle at 43Hz in the magnitude trace indicates the tuning of the port, while the combination of 5.3 ohms impedance and a 42 degrees phase angle at 90Hz implies that a good 4 ohm-rated…
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The Mk.II's lateral dispersion (not shown) was basically the same as the 1.3 Mk.I's, the speaker's high-frequency output falling off progressively to the sides of the tweeter axis in an almost textbook manner. In my experience, this measured behavior always correlates with excellent imaging precision. The vertical dispersion (not shown) was also identical to that of the Mk.I, suckouts in the crossover region developing above and below the tweeter axis. The listening window is relatively large, however, at +5, -10 degrees.
In my Santa Fe listening room, the speaker's spatially averaged…
Sidebar 4: Dynaudio's Contour 1.3 Special Edition, from Vol.22 No.12, December 1999
If you're looking to put together an all-Scandinavian system, you might want to pair the Electrocompaniet ECI 3 with the new Dynaudio Contour 1.3 Special Edition.
Dynaudio builds the drivers used in some of the world's best speakers. Speaker drivers seem to be a Danish specialty—ScanSpeak and Vifa, too, are located in Denmark. Anyone can become a speaker "manufacturer" by buying drivers and stuffing them in a box. But to build your own speakers from scratch, as it were—that's another story.
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If your audiophile habit goes back more than a couple of decades, you're probably doing a double take looking at the Smart Devices 2X150VT. Looks like a Hafler DH-200, doesn't it? That's because, at its core, a Hafler DH-200 is exactly what it is. Smart Devices doesn't name names in its brochure, but they do say that "You may recognize this amplifier as one of the dominant premium performers of the 1970s and '80s"—a reasonable enough description of the MOSFET-output DH-200, which combined outstanding sound with a very reasonable price—especially if you built the kit.
Smart then…
The input stage of the "VT" version of the 2X150 uses a single, dual-triode Sovtek 6922 placed somewhat gaudily in a window cut out of the front of the stainless-steel cover, so you can bask in its glow.
The rear panel includes an IEC AC jack, a pair of speaker protection fuses, five-way binding posts, an AC input fuse, bridging and ground-lift switches, gold-plated RCA input jacks, and two volume pots. The 2X150VT's home-theater pedigree is apparent in its labeling: Input 1 and Input 2, as opposed to the retro (art deco?) Left and Right found on most audiophile gear. Up front are the On…
I recently found a mint original Capitol pressing of Frank Sinatra Sings for Only the Lonely (SW-1053), and the recording of Nelson Riddle's desolate arrangements—redolent with such "soft" instruments as French horns, trombones, oboes, and bassoons—is appropriately distant and "back-of-the-studio." Compared to my reference Musical Fidelity Nu-Vista 300, the 2X150VT tended to obscure the sensation of the short reflection time off the studio back wall while, for example, smoothing over the timbral distinction between the four trombones and the single "lonely" trumpet on "What's New." But…
Sidebar 1: Specifications
Description: Hybrid vacuum-tube/MOSFET power amplifier. Output power (20Hz-20kHz): 150Wpc into 8 ohms (21.8dBW), 240W into 4 ohms (20.8dBW); 500W into 8 ohms (27dBW), bridged. Frequency response: 2Hz-160kHz, -3dB, at 1W; 6Hz-100kHz, -3dB, at 100W. THD: <0.9%, 20Hz-20kHz, both channels driven. Input impedance: 50k ohms. Input sensitivity: 1.95V RMS for 150W into 8 ohms. Voltage gain: 25dB. Slew rate (10kHz, 60V p-p squarewave): 30V/µs. S/N ratio: unweighted, exceeds 100dB referenced to full output into 8 ohms.
Dimensions: 15.8" W by 5.8" H by 10.1" D.…
Sidebar 2: Associated Equipment
Analog sources: Simon Yorke turntable; Graham 2.2, Immedia RPM2 tonearms; Lyra Helikon LE, Helikon mono, Benz Glider L2 cartridges.
Digital sources: Musical Fidelity Nu-Vista 3D CD player, Marantz SA14 SACD player.
Preamplification: Hovland HP-100 preamplifier; Pass Xono, Manley Steelhead, Musical Surroundings Phonomena, Camelot Technology Lancelot Pro phono stages.
Power amplifier: Musical Fidelity Nu-Vista 300.
Loudspeakers: Audio Physic Avanti III.
Cables: DIN/RCA and RCA/RCA phono: Hovland Music Groove. Interconnect: Harmonic Technology…
Sidebar 3: Measurements
When I opened up the chassis of the Smart Devices 2X150VT—the input tube had come loose in transit—I flashed back to the early 1980s. Other than Sovtek 6922 tube mounted behind the window in the front panel, I appeared to be holding in my hands a Hafler DH-200, right down to the bird's nest of components wired to the output MOSFETs. Ivor Humphreys, my friend and colleague at Hi-Fi News back in the early '80s, had built and modified many DH-200s, and I had got well familiar with this high-value design.
Following about 30 minutes of preconditioning at one-…
Fig.6 confirms the almost pure second-harmonic nature of the 2X150VT's distortion signature—at -63dB (0.07%), this won't be heard by anyone—and intermodulation distortion was also low in level (fig.7). The graph in fig.7 was taken into 8 ohms; halving the load and keeping the output voltage the same didn't result in the 1kHz difference component rising above -66dB (0.05%), but some 60Hz sidebands did appear around the intermod products, suggesting that at the measured power level with this demanding signal (close to clipping at 163W into 4 ohms), the Smart amplifier was starting to break a…