LM3875  LM3875 is a 56 watt amplifier chip made by Texas Instruments (previously National Semiconductor) that has become very popular in the DIY audio community for its low parts count and its high-performance audio capabilities. It is the main chip inside many gainclone amplifiers which are based on the Gaincard amplifier which surprised many high-end audio reviewers. This part has become obsolete and an EOL notice has been issued for it. The functional equivalent IC, the LM3886, has two additional signals that must be addressed before it can be substituted, the "mute" function and a virtual "gnd" pin.