The projects below eschew semiconductors (transistors) for conductors (tubes). Tube amplifiers are most often coveted for the way they overload, but don’t be fooled by marketing and “common knowledge”–tubes are just as useful for passing a clear, high-definition signal. Indeed, several of the following projects measure less harmonic distortion than the solid-state API and Neve designs. Because tube amps run on much higher voltages than their solid-state successors, these projects pose a higher risk of shock and require a more experienced hand to complete successfully.