🔍 Key Concepts

• Impedance matching between audio source (like a tube plate circuit) and headphones • Difference between high-impedance and low-impedance headphone windings • Role of transformers in matching impedances in tube audio circuits

💭 Think About

• Think about what impedance the plate circuit of a vacuum tube typically wants to see, and which type of headphones (high or low impedance) will naturally be closer to that value. • Ask yourself when you need an audio transformer in a tube circuit: is it usually when the load impedance is very different from the tube’s preferred plate load impedance? • Consider whether high-impedance headphones make it easier or harder to connect directly to the tube plate circuit without extra components.

✅ Before You Answer

• Compare typical plate load impedance values of small audio tubes (thousands of ohms) with typical headphone impedances (tens vs. thousands of ohms). • Decide whether a high-impedance winding makes an impedance matching transformer more or less necessary. • Verify whether both statements in options A and B can be true at the same time, or if one contradicts the basic idea of impedance matching.