Dynaco Stereo 70 Tube Amp Reviewed

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Dynaco Stereo 70 Tube Amp Reviewed

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Retro -- makes me glad to be alive. While I wasn't surprised to find Rollei and Contax exploiting nostalgia for camera collectors, or Fortis and Jaeger-LeCoultre playing to the horologists, I continue to register surprise whenever a piece of aged hi-fi equipment is Lazarus'd. After the Radford STA25 Mk IV, a couple of revived moving-coils, the (japanese) Marantz valve gear and some cabinets to turn JBL drivers into 1950s horn systems, I figured that was all we'd ever see.

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Imagine, then, my glee upon learning that one of my all-time faves, the Dynaco Stereo 70, was -- Gary Glitter-like -- back, back as a matter of fact. Said to be the best-selling valve amp of all time (according to legend, more three times as many Stereo 70s were sold than Quad IIs), the Dynaco was a humble, affordable, easy-to-assemble work-horse which probably fed sound to more American college dormitory rooms than any amp of its era. 25 years later, it's still a mover in the used amp market and still the subject of as many modifications as the Austin Seven.

Dynaco circa 1992 has nothing to do with David Hafler; the blurb describes Dynaco as 'a division of Panor Corp', about which I know nothing. But I gather that a diehard fan wrested the name and the design from the indignity its suffered since David Hafler sold the company 20 years ago. Along the way, Stereo Cost Cutters (who kept the spirit alive with parts and kits) got involved. Whatever the manouevres, the result is a bona fide Stereo 70, instantly recognizable despite new colour schemes.

It's the same 13x9.5x7in (WDH) chassis, crowned with a perforated cage, compact, utilitarian and so frill-free that 'agricultural' is the first term to spring to mind.would you believe revived moving-coils, the (J I.

Stereo 70s were sold thanof a kit ' But, in keeping with modern sensibilites and a price far higher than that of a decent second-hand original, the unit has been tarted up with an all-black finish, or a chrome-plated chassis as a #100 optional extra. Oh, and the rubber feet are new, too.

Underneath the lid, it's still recognizable, but obviously updated. For one thing, the parts quality far surpasses that of the original, and even the most fastidious of assemblers would have had to purchase superior aftermarket parts to allow an original to approach the calibre of the Series II. But it's shy a couple of valves, which suggests some solid-statery to yank the Stereo 70 into its thirtysomething decade. And these physical changes, be it due to parts availability or a well-meaning attempt to update the sound, have altered the sonic character in virtually every area.

The basic circuit has been 'largely retained', as have the legendary output transformers (the current cost of which must have contributed to the current base price of #1070 inc VAT). The output tubes are the warmly regarded EL34s, the review sample sporting superb German-made examples. Changes include new parts of far higher quality than those used in the original, which was -- after all -- designed to be affordable. Among them are precision metal-film resistors, poly-composition capacitors and power supply electrolytics which weren't even a twinkle in Radio Shack's eyes way back when the Beatles wore a silver prefix.

Filter capacitance has tripled and the power transformer is all-new and overspecified so as to run cooler than the original (which it does). The power supply is far stiffer, for definition and bass, the latter so taut as to cause alarm among anachrophiles. All of the components are mounted directly to a single double-sided motherboard, with the tube bases mounted directly to it, thus eliminating a fair bit of wiring. (The overall reduction in wiring is said to be 70%.) And the new driver tubes are Chinese 6GH8As. Best news of all is ultra-simplified user-adjustment of the bias: a screwdriver is all that's neededd, for turning two front-panel-mounted pots until the red tell-tales glow equally. So put away your AVO meter. Although the biasing employs semiconductor circuitry, the company states, in upper case, that ABSOLTELY NO SEMICONDUCTORS ARE UTILIZED IN THE AMPLIFIER SIGNAL PATH. Ahem.

Modern audiophile practices are self-evident. Hot damn: gold-plated sockets on a Dyna Stereo 70! Proper five-way binding posts...for all three impedances! Bye-bye rectifier tube, thanks to the new transformer! And hello, three-year warranty and 12 months on the tubes!

Continue reading about the Dynaco Stereo 70 tube amp on Page 2.

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