Fresh From the Bench: The Linear Audio Autoranger Mk II Measurement Interface

Stuart Yaniger explores new possibilities in audio measurement systems, expanding on the basics of using sound cards combined with new accessible-to-all software tools, such as REW, and a recently improved measurement interface option. That option is the Linear Audio Autoranger Mk II Interface, which audioXpress’ Technical Editor Jan Didden designed a few years ago and which is now available as an improved Mk II version. This article was originally published in audioxpress, April 2020.

Following the publication of its original SE 6C33C amplifier in audioXpress July 2004, Ari Polisois returned with more information on how to further simplify the whole construction and reduce the costs. The results, as the author describes, "combine the advantage(s) of the push-pull (mainly power) to the wonderful character of the SE: sensitivity, smoothness, simplicity, and warmth (due to the 2nd harmonic content, easily tolerated by our ears, as against the third, fifth, seventh, and so on harmonics produced by the push-pull)." This article was originally published in audioXpress, February 2008.

This article from respected author Ari Polisois deals with a single-ended amplifier with enough power to drive even the most difficult speaker systems - delivering 50W per channel. This is a project that quickly became the focus in lots of tube-oriented forums and has inspired long threads and many iterations, including further articles published in audioXpress from the author himself. This article was published in audioXpress, July 2004.

A popular hybrid amp design available for headphone use, this single-ended (SE) pure Class-A amplifier is capable of driving headphones between 32 and 600Ω, and was derived from an original tube/MOSFET line amplifier project, published by Erno Borbely in Glass Audio (1/98). Originally published in audioXpress in April 2005, this project was meanwhile extensively discussed in multiple DIY audio forums all over the world and is probably one of the most tested of Erno Borbely's designs, with multiple iterations frequently published on blogs and other publications.

Keeping things small and inexpensive — and at the beginner’s level — Rick Spencer shows you how to build your own single-ended amp. For about $10 worth of tubes and some small transformers, you can build this neat little amp in one weekend. This article was originally published in audioXpress, April 2004.

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.

Here’s an amp project especially for first-time builders featuring the 6BQ5 tube. As Rick Spencer writes in its introduction, "In order for this beloved hobby of ours to thrive and survive well into the future, we must always strive to make it interesting to newcomers." With this in mind, Rick Spencer created this single-ended design using the 6BQ5/EL84 tube in triode mode. This article was originally published in audioXpress, October 2008.

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.

"There is nothing quite like a quality tube amplifier," states the author in the introduction to this directly heated triode amplifier project. The idea for the amplifier started from the author's discovery of the Loftin-White circuit. The author chose the 2A3 directly heated triode power tube to implement the Loftin-White circuit. The 2A3 vacuum tube is a power triode capable of outputting 3.5 W in a single-ended Class A configuration. This article was originally published in audioXpress, August 2013.

Many articles have appeared regarding projects using one of the most sturdy, versatile, and trustworthy audio tubes ever made — the 6550. Most of them show these audio beauties used in the push-pull configuration in order to obtain the greatest efficiency and the most power output. In this article, the 6550 is used in a clean, sweet-sounding, single-ended design. The amplifier has very few parts, is easy to build and repair, and the cost of the project is nominal when you consider the kind of sound that is produced. This article was originally published in audioXPress, September 2001.