Four Hybrid Solid-State Power Amplifiers

In this article from audioXpress archives, originally published in July 2003, Charles Hansen describes four hybrid power amps that anyone might consider for their own designs. Starting from the idea that an op amp provides both a differential input stage and high overall gain in one package, Hansen explores the ramifications of using an op amp as a combined input and voltage amplifier stage in power amplifiers. As he writes, “I did not build the four amplifiers shown in this article, but I did run a SPICE simulation to verify that they did perform as audio amplifiers."

Here’s the final section in our series on parts reliability, how to choose them and how to estimate their life expectancy. In the third part of this article, the author continues to examine electronic components, and discusses what we can do about reliability. This article series was published in audioXpress, from November 2001 to January 2002.

Everything you need to know about how parts function, and how to select and maintain them. In the second part of this article, the author continues to examine electronic circuits with a look at some common circuit components, like resistors, semiconductors, diodes, small signal transistors, power Semiconductors, and microelectronics. This article series was published in audioXpress, from November 2001 to January 2002.

Everything you need to know about how parts function, and how to select and maintain them. In the first part of this article, the author discusses damaging effects of high temperatures, why things fail, MTBF, component tolerances and the effects of shock and vibration. This article series was published in audioXpress, from November 2001 to January 2002.

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.