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Dynaco Stereo 70 II power amplifier Measurements

Measurements

The ST70 Series II, like most tube amplifiers, ran quite warm after its preconditioning test and in normal operation. It was noninverting, and though the measured DC offset was generally below 10mV, it was also unstable, as it was with the Nobis. The unweighted wide-band S/N ratio of the ST70 II measured 60dB, referenced to 1W into 8 ohms.

The input impedance of the ST70 II was quite high—over 330k ohms—which is typical of many tube amplifiers. Matching to the output of any reasonably designed preamplifier should present no problem. Its output impedance from the 8…

Dynaco Stereo 70 II power amplifier Manufacturer's Comment

Manufacturer's Comment

Editor: My response to Corey's incompetent review of the Stereo 70/II should be just that—a letter to Corey:

Point/Counterpoint: Corey. You incredibly misguided wordmeister. If, as you say, you want to find the best-sounding affordable tube gear, the new Stereo 70/II should have lit your fire. After all, every major audiophile publication in the world has rated the ST-70 as a great value, with The Abso!ute Sound concluding that its "clarity and detail are nothing less than stunning."

First of all, using a ProAc Response Two with a sensitivity of 86dB…

The Fifth Element #20

Lera Auerbach is an important new classical composer.

Stop!!! Freeze!!! Do not run from the room in search of silver bullets, wooden stakes, garlic, or a crucifix. Defenses, supernatural or otherwise, will not be necessary. For two reasons.

First, Ms. Auerbach's music, at least as represented on her new BIS CD, 24 Preludes for Violin and Piano (BIS CD 1242), is tonal and melodic. While they exhibit touches of modernism in their nods in the directions of Prokofiev, Shostakovich, Schnittke, and Messaien, on the whole Auerbach's 24 Preludes hark back to the 19th-century tradition of…

The Fifth Element #20 Page 2

A different-drummer loudspeaker
To judge from his Arpeggione loudspeaker, Jean-Marie Reynaud (footnote 3) is an individualistic and perhaps even idiosyncratic loudspeaker designer in the mold of Paul Klipsch, Amar Bose, Irving M. "Bud" Fried, and Dick Shahinian. The Arpeggione is the floorstanding version of the Twin Mk.3 bookshelf speaker, having the same 6.5" mid-woofer and 1.5" soft-dome tweeter. The differences being cabinet volume and woofer loading, the Arpeggione has more bass extension and volume than the Twin. Its price increment over the Twin ($1200 vs $895) seems quite…

Music in the Round #12

Ever since I installed dedicated power lines for my multichannel system, I've been wrestling with the issues of surge protection, power conditioning, and voltage regulation. I start with a bias based on decades of happy listening without being concerned about any of these problems, and my belief that competent electronic components must be, and are, designed to perform in the real world. After all, whether the device's AC power supply is a traditional transformer-bridge-reservoir or a switching supply, its output should be a DC source that is sufficient to let the active circuitry meet its…

Music in the Round #12 Page 2

The PS Audio Power Director 3.5 ($995) contains three of PS Audio's high-current Ultimate Outlets: two connected to four receptacles each, and the third connected to two, for a total of 10. The UO technology is based on a large balun (transformer) to block line noise. However, useful bells and whistles have been added: 1) Each of the three UOs can be programmed for on/off delay or to remain always powered; 2) additional filtering and isolation are added between the UOs; and 3) coax connections on the rear panel serve to block voltage surges that might otherwise enter through a cable or…

Music in the Round #12 Records in the Round

Sidebar: Records in the Round

REVUELTAS: Homenaje a Revueltas Werner Herbers, Ebony Band; Juan Carlos Tajes, reciter Channel Classic CCS SA21104 (SACD) This selection of Revueltas' works includes his most famous, Sensemayá, and, arguably, his greatest, Homenaje a Federico Garcia Lorca. Played with style and sympathy and recorded with transparency and impact, this is one of the most satisfying multichannel discs yet.

GRAHAM ASHTON BRASS ENSEMBLE: Music for Organ, Brass, and Timpani Duncan Patton, timpani; Anthony Newman, organ; Graham Ashton Brass Ensemble Sonoma CSNR 001 SA (…

Speed Limits & the Music Biz

"Bugger!" A Pennsylvania state trooper had stepped out from behind the overpass on the Turnpike and was aiming his radar gun straight at me. I reflexively jammed on the anchors, which was a) pointless and b) downright dangerous, considering I was in the middle of a phalanx of cars and trucks all cruising 5-10mph over the speed limit. But what can you do?

I was driving home from Indianapolis, where I'd had an intense three days at Expo 2004, the trade show promoted by the Custom Electronic Design and Installation Association (CEDIA). The 12-hour car trip allows for a more effective…

Vandersteen Audio 3A loudspeaker

High-end-audio manufacturers are both more and less adventurous than their more mainstream contemporaries. While mainstream-audio manufacturers will almost invariably change their models every year, the changes are more often than not cosmetic—at least in between successive models. High-end manufacturers, on the other hand, will keep the same model in the line for several years, but make cosmetically invisible refinements along the way.

Vandersteen has been one of the most conservative companies in that respect; the original Model 2 underwent only one significant cosmetic change in over…

Vandersteen Audio 3A loudspeaker Page 2

Dual-input, screw-type barrier terminals, for either the recommended bi-wiring or for bi-amping, are located at the rear of the enclosure, along with level controls for both the midrange and tweeter. These level controls are limited to a useful range of +2 to -3dB.

So far, the description of the 3A tracks that of the 3 almost down the line. But the 3A incorporates a number of those invisible refinements. The woofer/acoustic coupler interaction has been modified for a more extended bass response (though the specs don't reflect any change here). The acoustic coupler itself has benefited…