You Can DIY!: An Ecological Power Supply for Power Amplifiers

This article describes an improved design for a power supply dedicated to audio power amplifiers that exhibits ecological and economical qualities, ideal for audio enthusiasts. In this truly DIY project, easy to build, the author, Vincent Thiernesse, proposes a power supply dimensioned for 100 W RMS/4 or 8 Ω power amplifiers, that behaves like a resistive load with respect to the mains network. This project was originally published in audioXpress, June 2016.

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.

I recently purchased a pair of MTX Audio Monitor 5i 5.25″ bookshelf speakers because I needed small monitors for a new computer. I do some audio restoration, so I wanted good sound quality when I wasn’t using headphones. My tests determined that the reviewers were right about the MTX 5i’s weakness in the midrange frequencies. I measured the response and it was not especially flat. This convinced me to update the drivers. This article was originally published in audioXpress, June 2013.

This article focuses on the Poddwatt Series II stereo integrated valve amplifier, a project with roots that go back several years. The design continues to be relevant and to evolve. I call the basic design an “Oddwatt” because of its “odd” configuration, using two stages. This article was originally published in audioXpress, May 2013.

Recently, I got bitten by the nostalgia bug and picked up a pair of old factory-wired Dynaco ST70s in pretty nice condition. On one of the Dynaco ST70s, I installed a new 6GH8 driver board instead of dealing with the rare 7199 issue, and I designed a small (3” × 3”) PCB to combine the bias supply and added the LED bias-setting circuit. This article was originally published in audioXpress, April 2013.

This versatile control circuit is pure Class A analog, allowing control over the ultra-high transparency SACD (Direct Stream Digital) or DVD-A multichannel surround formats with up to six power amp channels. As the author wrote when he experienced multichannel music in SACD, “With a good recording, this transparent naturalness extends to an enveloping soundfield that - at its best - can make you think you’ve been listening from just outside the concert hall doorway, and now you’ve walked inside!”

When this great tube amp project was published originally in Glass Audio magazine, Ed Dell wrote “Joseph Norwood Still is pushing the envelope. His most recent triode design, which features the Svetlana 6550s and Hammond transformers, establishes new output limits—up to 100W.” Indeed, this would become a very popular project at the time, and still is, considering the frequent references. This article was originally published in Glass Audio 3, 2000.