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AX April: Improving a Classic

March 27 2013, 13:01

Editors’ note: Just prior to printing this issue, we learned that Ed Dell, founder of Audio Amateur, had passed away. He was 90 years old. Ed was a remarkable man whose talents ranged from DIY audio to publishing to writing. We’ll celebrate Ed’s work in the May issue of audioXpress. Our thoughts are with his family and friends.

Recently, Patrick Brunner found a pair of Dynaco ST70s—once known as the best-selling tube power amplifier—in good condition. As an engineer, he couldn’t resist adding some tweaks to the old classic. In this issue, learn how he installed a new 6GH8 driver board to the ST70 and updated its relatively weak bias supply (p. 12). You can do the same for $25 or less.

There is a dizzying array of tubes out there. But if your interest is in audio amplifiers, you need detailed knowledge of only a few models—including critical audio preamplifier tubes. Find out more in Richard Honeycutt’s article (p. 22).

Mike Klasco and Steve Tatarunis call high-polymer piezoelectric film “the lost technology.” In the first of a two-part article, Klasco and Tatarunis introduce you to the often-overlooked technology and its promises and drawbacks for audio applications (p. 8).

Also in this issue, Vance Dickason reviews Scan-Speak’s D2908/714000, the company’s second 30-mm beryllium dome tweeter (p. 18).

In another review, Victor Staggs looks at the Spin-Clean Record Washer System MKII. He says the affordable system enables you to expand the lifetime of irreplaceable LPs (p. 25).

Geoff Boyd, co-founder one of the UK’s first personal computer companies, relaunched his entrepreneurial career in the Silicon Valley, establishing Coleridge Design Associates to develop innovations in consumer electronics audio and sound reproduction. Check out our interview (p. 28).

Finally, David J. Weinberg provides his full take on the 2013 International CES trade show in Las Vegas (p. 33).


Mary Wilson

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