Low-Cost Headphone Amp

Looking for a headphone amplifier—and a challenge? You can build the design presented in this article with easily obtainable components.

In this article, George Ntanavaras describes the design and operation of a system consisting of the ACH-01 accelerometer and a preamplifier with an integrated analog signal processor. With this system, it will be possible to measure at the low frequencies the acceleration, the velocity, and the excursion of a loudspeaker cone. Also the panel vibrations of a loudspeaker cabinet will be very easily obtained. Originally published on audioXpress June 2011.

You can build a tube amplifier that's similar to the original Nardeux Stereomatic 302 S. Follow these steps to create a powerful amplifier that produces satisfying music output.

With a circuit configuration known as series regulated push-pull (SRPP), you can build a low-power tube amplifier that doesn't require the infamous output transformer.

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.

Dave Erickson built his first multi-zone audio system in the early 1990s using C microprocessor code he developed on Freescale MC68HC11 microprocessors. In early 2014, he detailed how he upgraded the eight-zone system, which uses microprocessor-controlled analog circuitry.

Bill Reeve’s article, “Repurposing Antique Radios as Tube Amplifiers,” provides vintage radio resources, simple circuit diagrams, and essential part info. He also covers the topics of external audio mixing and audio switching. The article appeared in the May 2012 edition of audioXpress magazine.

Charles Hansen described a DIY phase meter calibrator using all-pass, phase-shift filters in a November 2006 article published in audioXpress magazine. Being able to measure phase angle is often helpful, so Ron Tipton decided to build the calibrator as described. In Hansen's design, there was a set of five calibrations frequencies: 10 Hz, 100 Hz, 1000 Hz, 10 kHz, and 100 kHz. Hansen relied on an external oscillator to drive the calibrator at these input frequencies. Ron Tipton made some modifications that better suited his needs, described in this article.