Valve amplifiers, also known as tube amplifiers, use vacuum tubes to amplify audio signals. These tubes work by controlling the flow of electrons in a vacuum, allowing for a warm and rich sound quality that many audiophiles appreciate. They are commonly used in guitar amplifiers and high-fidelity audio systems. Unlike solid-state amplifiers, which use transistors, valve amplifiers can produce a natural compression and harmonic distortion that some listeners find pleasing. However, they tend to be larger, heavier, and require more maintenance due to the need for replacing tubes over time. Despite these drawbacks, their unique sound continues to attract enthusiasts.