cathodyne

A cathodyne, also known as a split-load phase inverter, is an electronic circuit used to convert a single-ended input signal into two out-of-phase output signals. It is commonly employed in audio amplification and vacuum tube amplifier designs to drive push-pull output stages, ensuring efficient power transfer and improved linearity.

The cathodyne configuration typically utilizes a single vacuum tube, such as a triode, with its anode (plate) connected to a positive voltage supply and its cathode connected to ground through a load resistor. The input signal is fed to the grid of the tube. The output is taken from the anode (plate) and the cathode, which are presented as out-of-phase signals due to the tube’s gain characteristics. The design inherently provides phase inversion with minimal component complexity.

Compared to other phase inverter circuits, the cathodyne offers advantages such as simplicity, low component count, and balanced output signals. However, it can have limitations in terms of maximum output voltage swing and drive capability, especially in high-power applications. Its performance is also dependent on the tube’s characteristics, making it sensitive to component variations.

The cathodyne was extensively used in vintage tube amplifiers, especially in audio applications, due to its straightforward design and effective phase splitting. While modern solid-state implementations have largely replaced tube-based circuits, the cathodyne remains a notable concept in the study of electronic amplification and phase inverter design.