EB-604/410 All-JFET Line Amp Starter Kit

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.

Introduced in 1948, the Fender Champ single-ended 5 W guitar amplifier is “the” classic tube practice amplifier and it has been remade a few times over. In 1992, Kirk Elliott shared his take on the design, transforming the stock Champ into a quieter, safer, and more reliable studio amplifier. This article was originally published in Glass Audio Volume 4, Number 2, 1992.

A great solid-state project where National Semiconductor’s (since 2011, a part of Texas Instruments) LM4702 meets up with Renesas lateral MOSFETs, this article by Jack Walton was originally published in audioXpress July 2007 and it is still cited as a reference today. An ideal project for the DIY enthusiasts.

With little time to present a project for the annual Burning Amp Festival (BAF) in San Francisco, CA, Michael Rothacher decided to do a preamplifier project using static induction transistors (SITs). He wanted a versatile preamplifier that would work well in a variety of situations, and which could fit conveniently in a suitcase. This article was originally published in audioXpress, April 2014.

Bruce Brown explains his successful method of rebuilding a vintage W-7 tube amplifier from Heathkit. As the first power amplifier that broke $1 per watt barrier of listening power, the Heathkit W-7 was a major breakthrough for audiophiles. Introduced in 1958, it carried a list price of $54.95. This article was originally published in audioXpress, May 2007.

Here is a simple portable device from George Ntanavaras that can help answer the question about peak voltage and peak current requirements and whether or not your power amplifier is capable of driving your loudspeaker without clipping. This article was originally published in audioXpress March 2015 — Focus on Test & Measurement Edition. (Updated Dec 2015)

Erno Borbely shares with us his all-FET audio amplifier design. Following the original introductory "JFETs The New Frontier" Part 1 and 2 articles published in Audio Electronics - which we also include in this online post - the follow-up article focuses on DC-coupled amps. This article was published in audioXpress, May 2002.

When Noguchi, a Japanese audio transformer manufacturer, released its FINEMET core transformer FM-5P for less than $200, the author decided to try it in this four-parallel push-pull amplifier project. This article first appeared in the Japanese magazine Radio Technology, December 2011. It was published by audioXpress in March 2013.