The Tube CAD Journal is a monthly online magazine devoted to tube audio circuit design. Each month we will present some fresh looks at some old tube circuits and some altogether fresh tube circuits as well (yes, new tube circuits are possible). Circuits and more circuits. While we plan on covering complex tube circuits, like phono preamps or power amplifiers, our focus will be primarily on elemental circuits. Elemental circuits are the primary topologies, or part configurations, arrangements that can stand on their own as recognizable functional circuits although they may be part of a larger circuit. A power amplifier circuit, such as the famous Williamson, comprises several sub-circuits: the Grounded Cathode amplifier, the Split-Load phase splitter, the Differential amplifier and finally a push-pull output stage. Just as we must understand how a resistor or a capacitor functions in a simple circuit, we must understand the function and logic of these elemental circuits before we can understand more complex compound circuits.
Why a Webzine?
The original intent was to print a conventional magazine. We knew there was a need. A query on our Tube CAD registration cards that a magazine devoted to tube circuit design drew an overwhelmingly loud "YES." Still, we knew the difficulty and impracticality of starting yet another underground tube audio magazine.
The Web offers the publisher some great advantages over the traditional approach: worldwide distribution, free subscriptions, no paper (for those who must own a paper version, the size of the journal has been left small enough to be printed on A4 or 8.5" by 11" three-hole punched paper for compilation in a three-ring binder), live forums, no Post Office, color, motion, a glossary.
Schematics can now evolve, as the web allows for the easy display of animated GIF's, which display color and motion. Schematics can now show more than just part connections, they can reveal voltage potentials, current flow directions, and possibly, relative impedances.
Math errors and typos will not live indefinitely on a paper page; once spotted, the Web page can be corrected quickly.
We look forward to your letters, suggestions and contributions.