The Golden Age of HiFi Kits - Dynaco and Heathkit

There was a time when if you wanted the best HiFi amplifier available, you built a vacuum tube kit amp, likely a Heathkit or Dynakit. This was the Golden Age of HiFi kits, and the sound quality of these kit amplifiers has held up to this day. Tube amp aficionado Bill Tomkiewicz takes us on a deep dive into the Heathkit and Dynakit vacuum tube HiFi audio amplifiers of the 1950s through 1970s in this presentation from the Antique Wireless Museum.
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[@davidbarker5957]

I'm really enjoying this presentation. I graduated high school in 1962 with a major interest in electronics. I watched this all happen.

[@williamballad1291]

A fine review of these amps. One addendum I would like to add is an article I found in the October 1955 issue of AUDIO magazine. It is in a section titled Audio Patents by Richard H. Dorf. The patent is 2,710312 by David Hafler and Herbert I. Keroes of the Acro Products Company. The article is an excellent description of the theory of the ultralinear circuit taken from the patent. The point here is Hafler had a central role as coinventer of this design. The Dynaco amplifiers were a direct result of this as were the Acro amplifiers. The use of the circuit by Heath and others must have involved some sort of license from the Acro Products Company. I don't know what the arrangements were between Acro and Dynaco.

[@materialsguy2002]

Thumbs up well deserved. Thanks!

[@davidcrowell2750]

EICO also sold high quality tube HIFI and stereo amplifier kits. They are still highly regarded and bring high prices today regardless of condition. I had an EICO HF-87 with four EL-34 output tubes at one time, but stupidly sold it years ago!

[@mackfisher4487]

Bill well done sir Thank You

[@donmoore7785]

Nice. Oddly, the Mark VI discussion included a schematic labelled Mark IV.

[@pcar5]

Still have an ST70 and will not trade it for anything.