The Solid State Logic LMC+ is an enhanced 500 Series version of the "Listen Mic Compressor" from the SSL 4000E console. The console had a compression circuit built-in to prevent feedback from the studio communication mic, but this was quickly found to be a neat special effect for drum mixes and ambient microphones. The 500 Series version adds a wet/dry blend, sidechain filters, and a switch that inverts the polarity on the wet signal.