The elliptical equalizer sums low-frequency energy toward mono to prevent groove damage during vinyl cutting

The elliptical equalizer (or low-frequency crossover) is a relic of the record era that takes excessive stereo low-frequency energy and progressively sums it toward mono below a chosen frequency. Because vertical (out-of-phase) low-frequency modulation can throw the stylus out of the groove or collapse groove walls, concentrating bass in the lateral (mono) plane makes the cut mechanically safe while preserving stereo width in the mids and highs.

Examples

A dance track with heavy stereo bass is sent to vinyl mastering; the elliptical EQ makes the low bass mono, preventing overcutting while keeping the rest of the mix wide.

Assessment

What problem does an elliptical equalizer solve in vinyl mastering, and how does it solve it?