A Single-Ended 6550 Amplifier

Many articles have appeared regarding projects using one of the most sturdy, versatile, and trustworthy audio tubes ever made — the 6550. Most of them show these audio beauties used in the push-pull configuration in order to obtain the greatest efficiency and the most power output. In this article, the 6550 is used in a clean, sweet-sounding, single-ended design. The amplifier has very few parts, is easy to build and repair, and the cost of the project is nominal when you consider the kind of sound that is produced. This article was originally published in audioXPress, September 2001.

June 2015 is – we have to say it – undoubtedly one of the most diverse and interesting issues we have put together. The magazine has something for everyone and lots of great content we are certain will be greatly appreciated by our community. Discover the “outside-the-box” thinking that resulted in one of the most interesting loudspeaker designs in recent times and much more.

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.