Märklin sound decoder MSD3. Conversion from Märklin/Trix H0 locomotives with built-in high-performance motor or other DC motors. The Märklin sound DECODER3 has a 21 pin interface and complimented by an interface plate designed to replace analog and digital locomotives. The Märklin sound DECODER3 supports the digital file formats MFX, mm1, mm2 and dcc. default sound an electric locomotive.