R&D Stories: The Korg Nutube 6P1

This article provides an overview of the Korg Nutube 6P1, a new, miniature, low-power dual directly-heated triode device. It was developed by Korg (of musical instrument fame) and Noritake Itron, a manufacturer of vacuum fluorescent displays, in Japan. Although it is a true directly heated triode, it is manufactured differently than traditional vacuum tubes, which gives it some unique attributes. This article was originally published in audioXpress, May 2017.

This simple single-ended amp project by Pete Millett is a great performer and a very well documented project that was immediately adopted by many DIY'er's. The amplifier achieves good power output and low distortion by employing “E-linear” feedback in the output stage. This article was published in audioXpress, April 2005.

Here’s a simple, safe, inexpensive project for beginners and those who wish to “try tubes.” Meanwhile the project has been tried, tested, approved and improved, become one of the classic DIY audio projects from the author. This article was originally published in audioXpress magazine, November 2002.

In this article, author Pete Millett explores the different types of power transformers, and why you might choose to use each type in audio equipment. The article addresses issues with low-frequency (50–60Hz) line transformers, but many of the same issues apply to audio-frequency transformers as well.

In this article, originally published in audioXpress, February 2004, the author describes how to achieve low distortion from power triodes. As he explains, his preamp is “a little different from most, using low-mu power triodes to get good performance with only one amplifier stage, and no negative feedback. This achieves the modest gain required along with very low output impedance.”