Why Power Tubes Arc

Tube arcing is not necessarily a result of a "bad" tube or a "bad" design. It is far more likely the result of using the tube longer than you should for the application you’re using it. This interesting article, published in audioXpress, November 2004, remains a great read. At the time it also originated a response from Eric Barbour and Ed. T. Dell regarding their experience with cathode stripping.

The situation in Ukraine and the sanctions imposed on Russia are having a significant impact on the global supply of tubes to the audio industry. Both Ukraine and Russia are important suppliers of raw materials, and the sanctions are likely to cause further strain over the supply of source materials that all manufacturers of tubes need. In China there are also significant disruptions caused by pandemic lockdowns, transportation challenges, and cost increases. How many tube manufacturing operations remain viable? Western Electric says there is hope... in the US!

When this great tube amp project was published originally in Glass Audio magazine, Ed Dell wrote “Joseph Norwood Still is pushing the envelope. His most recent triode design, which features the Svetlana 6550s and Hammond transformers, establishes new output limits—up to 100W.” Indeed, this would become a very popular project at the time, and still is, considering the frequent references. This article was originally published in Glass Audio 3, 2000.

This Class A tube headphone amp project, which the author created for Vintage Audio, includes a 6SL7GT for the input stage and a 6AS7G for the driver, and is able to drive headphones with impedance at or above 64Ω. The article provides a full description of design fundamentals and some useful guidance on the construction process. The result, as the author describes, should be “a satisfying headphone amp that will provide years of enjoyment.” This article was originally published in audioXpress, June 2008.

Attention, all first-time (or wanna be) builders of single ended directly heated triode amps. This project’s for you. This is an easy to build, simple direct-coupled input/driver circuit that provides the proper drive voltage to the grid of the 211. A nice way to experiment with a single-ended (SE) triode amplifier.