From the Vault: The Borbely Preamp

"Designing a preamp is probably the most challenging engineering task in the audio chain, and many designers have invested a lot of time and effort in it," wrote Erno Borbely in this original 1985 article for the Audio Amateur. "My reason for designing this preamp is quite simple: I wanted to have a top-quality preamp without paying megabucks for a Levinson or Accuphase unit. It is up to you to decide whether or not I have succeeded in achieving the same quality." This article was originally published in The Audio Amateur Issue 4, 1985, and is still frequently referenced.

Our late and much esteemed author, Ron Tipton, shared a fascinating project on testing Class-T or Tripath power amplifiers on the pages of audioXpress. As he characterized, these "small, inexpensive, and power-efficient units," sounded good "but testing them is problematic." The article also discusses the story of Tripath Technology and speculates on the reasons why the Tripath ICs remained popular among the DIY audio community. This article was originally published in audioXpress, March 2014.

In this high quality project, Robert Nance Dee designs a potentiometer for accuracy and flexibility. A pot with 64 levels and precision metal film resistors that is hard to beat for sound or facility, as he describes it. The project started with a clean sheet, looking to address potentiometer design with a quality that rivaled existing designs while maintaining a reasonable cost. This article was originally published in audioXpress, September 2011.

Here’s a do-it-yourselfer’s dream in tube amp design: four operating modes, high quality, low cost, and low distortion. An article originally published by audioXpress in May 2007. A true versatile project which we think deserves to be shared.