A New RIAA Preamp for My BeoGram 4002

I’ve just finished the second SMD prototype of my custom RIAA preamp for the Bang & Olufsen BeoGram 4002, and it’s now tested and working.

The project started as a way for me to better understand RIAA equalization, op-amp behavior, and low-noise analog layout. Instead of just restoring vintage electronics, I wanted to design something from the ground up that integrates properly with the 4002 platform while respecting its original engineering philosophy.

The circuit is a dual-stage active RIAA design based on the classic LM833 topology, but implemented with the OPA2134. The goal was low noise, stable performance, and clean audio reproduction without unnecessary complexity. The board is fully SMD, compact, and designed for practical integration with the same form factor as the original.

Seeing the second revision powered up and performing as expected is incredibly satisfying. There’s still room for refinement and further measurements, but reaching a stable and working hardware revision is a big milestone.

Although the current revision performs well, there are several improvements planned:

• Measured RIAA accuracy validation with detailed frequency sweeps.

• THD and noise floor characterization under real cartridge loading.

• Further power supply refinement and filtering optimization.

• Possibly evaluating alternative op-amps for comparison

The project remains open-source, and I’ll continue refining it as I gather more measurements and listening impressions. You can contribute to the project here.

More updates soon.