Tube Amplifiers Explained, Part 1: Introduction

This is a series of blog posts to explain how a tube amplifier works. I'm using the circuit from the Analog Ethos AE1 Kit and this is the same explanation used in the kit instructions, but made available online since the principles apply to other similar circuits. My goal for the kit was to not only have a great sounding and looking amplifier, but that builders would really understand how the circuit and tube amplification works as empowerment to do more in the future!

I will not attempt to provide a comprehensive explanation of all the physics, electronics theory and math equations that would make a more robust reference. I’m not best suited to do this, and there are excellent other resources online or in books that can teach the theory better and more extensively than I can, and much broader than this one type of single-ended tube circuit. This is intended for a non-technical audience, but I will assume that you have basic knowledge of electric circuits and components such as resistors and capacitors.

Here are the sections in this series:

Part 1: Introduction (this page)

Part 2: Core Concepts - What is Sound, Voltage and Ohm's Law

Part 3: Core Concepts - Common Electronic Components Used

Part 4: Big Picture of the Single-Ended Circuit

Part 5: How Does a Vacuum Tube Work?

Part 6: Tube Characteristics, Load Line and Operating Point

Part 7: Coupling, AC Load Line, and Cathode Bypass Capacitor

Part 8: Output Stage and Pentode Tubes

Part 9: Screen Voltage and Ultralinear Mode

Part 10: Understanding Distortion

Part 11: Negative Feedback

Part 12: Power Supply, Rectification and Filtering

Part 13: Bringing it All Together

I hope you find this helpful, please do share comments if you notice any errors or things that need better explanation. I'm continually trying to refine this educational content.