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A salute to Dickie and Macovski

Posted by cpotl on November 4, 2012 at 06:05:53:

I'm not sure of the detailed history of the OTL amplifier, but I think Dickie and Macovski must have been amongst the earliest pioneers. They published an article in June 1954 on a "Transformerless 25W Amplifier for Conventional Loudspeakers." The sub-text below the title of the article is "A Low-Cost High-Quality Amplifier Using No Iron-Cored Components." And that is literally true.

I've just finished building something similar, using an OTL amplifier design by Christian Lopes, but with the same power-supply idea of Dickie and Macovski. Four 6082 output tubes per channel (equivalent to 6AS7, except 26.5V heaters). It sounds great. Picture attached.

Does anyone know the early history of the OTL? Who was the first to build an OTL amp for low-impedance speakers? Are there any such published designs predating Dickie and Macovski?

Chris