The RIAA created a special frequency characteristic way to cut master lp's to reduce meandering of the record grooves at ultra low frequencies. Meandering decreases the recording time of a master record. This special way of cutting also reduces noise during playback of the record.
It works as follows: the lowest frequency range is reduced by 20 dB and the highest frequency range is amplified by 20 db. The pre-amplifier of the playback device uses the opposite characteristic to compensate this measure(lowest range plus 20 dB and highest range minus 20 dB0).
Every standard hifi amplifier with a phono in-plug has this special frequency correction built-in.