New Projects

In addition to the projects described in the book, the author has documented additional projects and posted the results on this site. So far, three new audio projects have been completed: a 20 W stereo integrated hybrid amplifier, a 60 W stereo amplifier, and a tube-based AM/FM stereo tuner.

Outside the realm of strictly tube-based audio gear, other related projects have been completed and documented here. Those include refurbishing a reel-to-reel tape recorder and refurbishing a classic Heathkit IM 5248 intermodulation distortion analyzer.

While the reel-to-reel recorder and the vintage test equipment may seem a bit off-topic, they all date back to the tube era. The recorder makes a nice input device for the preamplifier. The refurbished test equipment is used for performance measurements on completed audio gear. So, it all works together..

For readers that have a specific question about the projects described on these pages, feel free to contact the author. The individual new project pages can be selected from the drop-down menu bar above. Shown on the right is the AM/FM stereo tuner.

AM/FM stereo tuner

Some Comments on the New Projects

When I was finishing the book, I had plans to build a number of tube-based projects, which included tuners and test equipment. The tuner projects have been largely accomplished with the AM/FM stereo tuner shown above and described on this site. I also had plans to build a shortwave receiver, but I've taken that off the table (or workbench as the case may be) because it is unlikely I would get much use from it.

Another tube-based project class that I had initially planned to build was audio test equipment, such as an audio frequency generator, audio voltmeter, and distortion analyzer. Those projects seemed like an interesting exercise; however, with additional thought I have taken those off the table as well. The selection of available vacuum tube audio test equipment on eBay and elsewhere is really quite sufficient. And, like the shortwave radio, while building a piece of test equipment would be an interesting project, it would likely see limited use. Although no projects are planned for building up new test instruments, a number of instruments have been refurbished. One is project is described here—refurbishing a Heathkit IM 5248 intermodulation distortion analyzer. A gallery of other refurbished instruments can also be found on this site.

One of the things I have learned while building the products described in the book and on this site is that, if you want to do it right, it usually takes a long time. And it is expensive. Back when I was in high school and building all kinds of electronics gadgets, I focused strictly on building and not documenting. Many decades later, I focus as much on documentation as on building. In fact, my experience has been that for each of the completed projects, far more than half of the time spent has been focused on documentation. By documentation I include developing the schematic, parts list, layouts, key construction/assembly items, setup/alignment, and measured performance. All this takes time. As such, it has been necessary to choose my projects wisely. Unfortunately, time is never unlimited (and neither is money).