The High-Octane phono preamp

Hannes Allmaier likes to design phono preamps because of the interesting mix of conflicting requirements of low noise, correction accuracy, headroom and dynamic range requirements and others. For this article he reaches back to a simple circuit due to Peter Walker of QUAD fame, designed in the 60-ies and that has an amazing performance despite containing only three active devices, BJTs. However, the circuit does have its limitations and Hannes embarked upon this project to update this circuit based on modern insights in the requirements and circuit interactions, dubbing the result the High Octane phono preamp. It still has only three active devices.