The most universal use for equalisers is in complementary pairs to make the best use of a storage or transmission medium (Fig. 23.1). The ideal system reproduces sound with the various component frequencies in the same proportions received at the input to the system. But these proportions are not ideal for recording on disc or tape, or for radio transmission.
Fig. 23.1 This block diagram illustrates the basic purpose of the most universal form of equalisation
The principal factor in all equalisation theory is that the higher frequencies in the audio spectrum, while they are the most readily audible, possess the least energy ...