Another Solid-State Single-Ended Power Amplifier

This project is based on a previous audioXpress article: “A Solid-State Single-Ended Power Amp” by Ed Simon, published in the April 2006 issue. Ron Tipton was deeply impressed with this amplifier project which used only five transistors per channel, two of them being current sources. This article was originally published in the old audioXpress website as a PDF, but was never reposted. Now we make available online with updated references and links.

In this simple amplifier project, Ed Simon describes a Class-A amplifier design that mainly intends to reproduce music with reinforced emotional expression. That's what you normally get with a quality design, but to achieve it, the author shares the complete concept, power requirements, circuit topology, construction and testing of this single-ended amp... in a solid-state design. This article was originally published in audioXpress, April 2006.

This project is based on Erno Borbely’s EB-602/210 single-ended pure Class A amplifier and is capable of driving headphones between 32 and 600Ω. It consists of two identical but separate amps laid out on the same PCB. The schematic is the same as Erno’s extremely popular hybrid tube/MOSFET line amp, published in Glass Audio 1/98. However, the dual triode at the input is replaced by a dual JFET (SK389). This article was originally published in audioXpress, July 2004.

TERESA amplifier is a simple and cascadable Class-AB design. The name is an acronym for manufacturers TExas Instruments and REneSAs, who provided the parts for the core of this amplifier. The result is worth seeing and hearing! This DIY project does not require any special experience in detailed analog circuit technology to build. This article was originally published in audioXpress, November 2014.

Stuart Yaniger wrote a great article for audioXpress in February 2009, The ImPasse Preamplifier, describing a tube preamp to drive a pair of Nelson Pass’ First Watt F4’s (or other low-to-unity-gain power amplifiers) in balanced mono. Yaniger’s preamp is truly an elegant design with very, very low distortion, using a 6SN7 to drive a 6922 in balanced mode. There are LED’s, NE2H neon lamps and depletion MOSFETs in the design.

This article continues the classic JFETs series of articles by Erno Borbely and introduces one of his starter kits with an all-JFET line amp. Originally published in audioXpress March 2005 this is an essential reading to understand the “building blocks” of the “Borbely amplifiers”.

The basic circuits on which Erno Borbely based most of his projects are described in “JFETs: The New Frontiers, Part I and II,” published in Audio Electronics AE 5/99 and 6/99, and “All-FET Line Amp,” published in audioXpress May 2002. As the author admits, these were the “building blocks” on which many - if not all - of his amplifiers are based. This articles continues his JFETs series and was originally published in Audio Electronics, Vol 5 1999.

The basic circuits on which Erno Borbely based most of his projects are described in “JFETs: The New Frontiers, Part I and II,” published in Audio Electronics AE 5/99 and 6/99. Referring to these articles frequently, the author admits, these were the “building blocks” on which many - if not all - of his amplifiers are based. This article is the first part, as originally published in Audio Electronics, Vol. 5 1999.

Over the years, some of the best Nelson Pass projects have been featured by Audio Amateur and audioXpress magazines. The A40 power amp article was published in The Audio Amateur, 4/78, and the A75 power amplifier appears in The Audio Amateur 4/92 and 1/93. His other works are posted at passdiy.com. Originally published by audioXpress on May 2010.

With a little know-how and some basic parts, you can design a hybrid amplifier in fairly short order. This project combines the best attributes of both tube and transistor technologies.