Neumann NN48 Power Supply for M49 – Fully Serviced, Restored & Calibrated 1952 - 1974

Original Neumann NN48 power supply, made in Germany. This unit has been carefully restored over many hours with reliability and originality in mind. The aim was to retain as much of the original character as possible while ensuring it performs correctly. Work carried out includes: • Original filter choke was completely rewound from scratch after the original winding had failed. The replacement was wound to match the original inductance, gapped, tested and calibrated before installation. • All original electrolytic capacitors have been professionally restored internally, retaining their original aluminium cans and authentic vintage appearance while providing the reliability of rebuilt capacitors. • Heater supply has been calibrated under load and adjusted to approximately 4.0V, making it suitable for AC701 based microphones. • HT supply has been checked under load and verified for correct operation. • Original Siemens components have been retained wherever possible to preserve authenticity. • The power supply has been compensated for modern UK mains voltage to ensure the correct operating voltages. • All operating voltages were measured and verified under load rather than relying on unloaded measurements. • Internal wiring has been inspected, repaired where necessary and the unit thoroughly tested. The restoration required many hours of careful work and several iterations to achieve the correct choke characteristics and operating voltages. This is not simply a cleaned unit, but a properly restored and calibrated original Neumann power supply. The unit is in good working condition and operates quietly. It retains its original industrial finish with the expected cosmetic wear from over 60 years of use. Please study the photographs carefully as they form part of the description. A modern mains lead has been fitted for convenience while preserving the original functionality. An increasingly difficult to find original Neumann NN48 power supply, ideal for use with a period Neumann microphone or as part of a high quality restoration. Please note this is vintage electronic equipment and, due to its age, it should be operated by someone familiar with valve equipment.