NF10

About the NF10

The Grundig NF10 is a stereo tube amplifier produced by Grundig (Radio-Vertrieb, RVF, Radiowerke) in Germany between 1964 and 1966. It uses four tubes: two ECC83 and two ELL80 valves. The amplifier delivers a sinusoidal output power of 2 x 8.5 watts, with a maximum music power of 2 x 10 watts. It features two push-pull end stages with separate output transformers for each channel, optimized for 4 ohm speakers but with slightly higher output power on 8 ohm loads. The NF10 does not use printed circuit boards but is built with point-to-point wiring, allowing a compact design with improved frequency response and lower distortion at low frequencies compared to its predecessor, the NF1. It was intended for connection to stereo receivers or tuners such as the Grundig HF10 or HF20. The amplifier is housed in a metal case with dimensions approximately 330 x 120 x 90 mm (13 x 4.7 x 3.5 inches). The design includes a combination of fixed and automatic grid bias voltage generation to reduce heat dissipation and improve reliability. Users should be cautious about the original selenium rectifier and electrolytic capacitors, which tend to fail and may endanger the power transformer. The NF10 is considered a classic tube amplifier with a warm sound characteristic of its era.