This Ling Electronics Model EG-10-B tube graphic equalizer was built in the 1950s and has amazing mil-spec build quality throughout. It has inductors on every EQ band and precision wire controlled faders that I've only seen in older Cinema Engineering/Western Electric equipment. All the faders have been lubricated/cleaned/aligned and the power supply filter capacitors have been replaced. The sound is very similar to a Pultec EQH-2: smooth and saturated, soft and beautiful on the top end/warm and full on the low end, but more versatile and to my ears much nicer sounding. All the tubes work perfectly and this unit sounds incredibly great. This is a world-class and unique-sounding EQ - a very special unit originally made for the military. The EQ points were doubled at some point to: 4, 8, 16, 32, 64, 125, 250, 500, 1000, 2000, 8000, and 16000. Although this unit has interstage transformers, the input and output are both unbalanced, currently wired for pin 3 hot, but this can be changed to pin 2 if the buyer so desires. The unit is fully passive with the exception of the input and output stages which are completely tube based. It has XLR input / output