Project Brief: Stereo Tube Amplifier Design (From Scratch)

The goal of this project is to design a complete stereo tube amplifier from scratch, with a focus on proper engineering, stable operation, and high-quality audio performance. The design should be practical to build and test, with clear documentation and predictable results.

Given Requirements / Constraints:

Preamp: 1 × 6SN7 (shared between both channels)

Power stage: 2 × 6V6 (one per channel, single-ended)

Rectifier: 5U4

Power transformer: Hammond 272DX (144mA B+ max)

Output transformers: Custom, 5kΩ primary, 55mA max, gapped for 20Hz–20kHz HiFi use

Input signal: 1–1.5V nominal (2V max line level)

Target output: ~5W per channel at 2V input

Voicing: Final tonal shaping can be adjusted via coupling capacitor selection

Scope of Work:

Full circuit design of the preamp and power stages

Proper biasing of all tubes (preamp and power)

Power supply design including rectification and filtering

Gain structure design to meet input/output targets

Operating point calculations and validation

Integration of all stages for stable and optimal performance

Deliverables:

Complete, clean schematic (build-ready)

Clearly defined component values and operating points

Notes on design choices and expected performance

Guidance for implementation, testing, and initial troubleshooting

Objective: To create a well-balanced, reliable amplifier design that meets the specified performance targets, minimizes distortion and noise, and avoids iterative trial-and-error during the build process.