The OSDEHA: an Open-Source Directly-Heated Triode Electrostatic Headphone Amplifier

Mar 8, 2025 at 8:56 AM Thread Starter Post #1 of 2

mbrennwa

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Are you into electrostatic headphones and (directly heated) tubes? Say hello to the OSDEHA Amplifier!

Electrostatic headphones operate on audio signals characterized by high voltage and low current. This is the domain of vacuum tubes, making them most suitable as drivers for electrostatic headphones. While there exist a number of tube amplifiers for electrostatic headphones, many of these designs do not utilize directly-heated triodes (DHTs), which exhibit outstanding linearity and sound quality.

The OSDEHA uses DHT tubes for its output stage and implements the following design goals:
  • The audio output is taken directly from the anodes of the DHT output tubes. There are no transformer or capacitors to transfer the power to the headphones.
  • The amplifier input takes balanced input at signal levels of modern audio sources (mostly DACs these days).
  • The design prioritizes the quality of audio reproduction and electronic design rather than on low cost.
  • The amplifier should be reasonably compact. The power supply unit may be a separate unit to keep the amplifier unit reasonable compact.
The OSDEHA design files, along with supporting documents and data, are available in the OSDEHA file repository.

There is a thread over at diyAudio, where most of the technical aspects of the OSDEHA design are discussed.

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