Simple Circuits: Turn a Vintage Tube Radio Into a Great Tube Amp!

Bill Reeve’s article, “Repurposing Antique Radios as Tube Amplifiers,” provides vintage radio resources, simple circuit diagrams, and essential part info. He also covers the topics of external audio mixing and audio switching. The article appeared in the May 2012 edition of audioXpress magazine.

Charles Hansen described a DIY phase meter calibrator using all-pass, phase-shift filters in a November 2006 article published in audioXpress magazine. Being able to measure phase angle is often helpful, so Ron Tipton decided to build the calibrator as described. In Hansen's design, there was a set of five calibrations frequencies: 10 Hz, 100 Hz, 1000 Hz, 10 kHz, and 100 kHz. Hansen relied on an external oscillator to drive the calibrator at these input frequencies. Ron Tipton made some modifications that better suited his needs, described in this article.