Zen Variations 9 — Nelson Pass / 2006

In ZV8 we dipped our toes into the waters of power JFET transistors using the new Lovoltech LU1014D in a simple circuit. The focus of the project was on the JFET itself, and except for a cascode transistor the rest of the amplifier used only passive components. Here in four installments we will increase the complexity of the circuitry around the JFET with an eye toward distortion performance surpassing any of the Zen projects to date. Much of this project will make reference to ZV8 (AudioXpress, January 2006 and www.passdiy.com), which discusses the characteristics of the LU1014D power JFET and… More...

A75 Part 1 — Norman Thagard & Nelson Pass / 1992

READERS' REQUESTS FOR more power are reasonable, but not interesting enough to justify another article. Hanging some output transistors on the original and beefing up the power supply is best left as an exercise to the reader. While the A75 delivers more power, particularly into low-impedance loads, that is not the primary goal of this project. We wish to introduce more advanced concepts in amplifier design, including balanced inputs, dual differential inputs, true DC response, cascode and folded cascode operation, tiered and regulated supplies, operation with and without feedback, and details of designing with the new generation of power MOSFETS.… More...