🔍 Key Concepts

• Grid bias in vacuum tube / valve amplifiers • How bias affects distortion, operating class (A, B, AB, C), and plate dissipation • Relationship between bias point and the load line on tube characteristic curves

💭 Think About

• Think about what happens to the output waveform if the grid is not biased at the correct point on the tube’s characteristic curve. • How does changing the grid bias shift the tube between Class A, B, AB, or C operation? What does that do to fidelity and efficiency? • What happens to tube temperature and plate power dissipation if the grid is biased too positive or too negative?

✅ Before You Answer

• For each option, ask: Does correct grid bias directly influence this effect (distortion, class of operation, plate dissipation) in a practical audio amplifier? • Remember that an audio frequency amplifier usually aims for low distortion and safe tube operating limits—how does bias contribute to each goal? • Verify whether grid bias is used for only one of these purposes or whether in practice it affects all of them simultaneously.