Marcelo Gd's Prototype and Test Rig Is Like a Breadboard for Vacuum Tubes

Electrical engineer Marcelo Gd has demonstrated how to turn upcycled parts and low-cost components into a handy prototyping board for vacuum tube projects.

"For a long time, I wanted to experiment and build amplifiers and other audio-related devices based on electron tubes," Gd explains. "To achieve this goal, I needed a suitable tool for testing and experimentation. That's why I made this simple device, the materials and components I used are mostly recycled or inexpensive. The main goal of this project is to be an instrument for developing and testing devices with valves, but it can also be used as a learning tool."

As anyone who has worked with vacuum tubes before will attest, they can be finicky beasts — there's a reason, after all, that the invention of the transistor saw their almost complete retirement from practical use. There are those, however, who swear by them still, particularly in the audio field where valve-based amplifiers are prized for their "warmer" tones compared to solid-state equivalents.

For anyone used to sticking parts in a breadboard for prototyping, working with vacuum tubes can be daunting — which is where Gd's creation comes in, effectively working as a breadboard dedicated to vacuum tubes. The chassis is made from metal salvaged from a discarded PC case, other parts from a scrapped CNC machine, and still more from and PC power supply unit. The tube sockets, at least, are new-old stock — you don't want to be trying to diagnose faulty valves when your socket is marginal, after all.

To prove the concept, Gd has already used the rig to build a "very basic" Class-A audio amplifier. "The distribution of the blocks on the chassis permits a quick assembly and modification of the arrangement of the components," he notes. It's also been put to work as a testbed for emission, transconductance, and curve-tracing tests.

The project is documented in full in Gd's Instructables post.