High End 120W MOSFET IC Driven Amp

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.

When we connect audio components, interference may occur from various power and signal grounds. This circuit enables the full galvanic isolation of sound frequency signals with optical transmission in excellent quality, eliminating interference. This article was originally published in audioXpress October 2004.

This design by Joseph Norwood Still is a control unit that the author described as offering “lifelike concert-hall performance for a modest cost”. A great tube-based amplifier for phono and line sources, featuring a very subtle bass enhancement control using negative feedback to enhance only selected frequencies, below 400Hz. As the author described, a great project for discriminating audiophiles.

Inspired by debates on the Internet about quarter wave designs with Tang Band 3˝ full-range drivers, the author decided to design its own quarter wave loudspeakers. This article was published in audioXpress, March 2007 and the results were simply spectacular, generating worldwide interest. Recently, Bjorn Johannesen created a successful business with his own speaker company, called KVART & BØLGE, which means Quarter & Wave in Norwegian and Danish.

Ron Tipton explains how he built his sound level meter and spectrum analyzer, the Model 527, around a Velleman Audio Analyzer kit (K8098). This is a barebones kit with no enclosure or power supply, but for the price, it is very versatile. Originally published in audioxpress, December 2013.