HoRNet ElliptiQ is an elliptic equalizer, this kind of tool is a very special case of equalizer that has its root in the vinyl cutting era. A tool like this is needed because if the bass frequencies goes in anti phase or the difference between left and right channel are too wide the needle may jump outside the groove in the final vinyl master, so an elliptic eq works on the difference of the two channels removing part of the low frequencies and preventing this problem.
