Equalization is one of the most common processes used to adjust audio in the studio. It refers to the adjustment of specific frequency bands in an audio signal to alter its tonal balance or to remove unwanted frequencies. The abbreviation EQ can be used as a noun to refer to equalization or an equalizer or to the verb equalize. Equalization was first used by telephone companies to correct for the uneven frequency response of their transmission systems. By applying a filter, they could restore the fidelity of the signal, so that all frequencies would be equal, resulting in the term “equalization.”
In the recording studio today, equalizers (the hardware or software devices used to achieve equalization) are used for a variety of purposes. They can be used to enhance the tone of a signal. For example, you can boost the signal of a vocal track in the range of frequencies where it is weak. This may be due to the singer's voice or an inadequate response from the microphone in that range.
Another use for equalization is to make room for the various instruments so that they do not cover up one another. For example, a male vocal track often occupies much of the same frequency range as an acoustic guitar. Reducing a portion of the frequencies on the guitar track, while boosting the same range in the vocal can allow the vocal to come through, rather than being buried. You need to make the adjustments while listening to both tracks together, since it is quite likely that neither will sound very good when soloed. This process is sometimes call sound sculpting, not to be confused with sound sculpture, which is using sounds to create artificial art.
A similar use for equalization is spectral balancing. That is the process of adjusting the equalization of each track in a mix to achieve an overall well-balanced sound. A balanced sound has no excessive bass, harsh cymbals, nor overbearing midtones, but an overall smooth and pleasing sound. Every mix should strive for a good spectral balance.
Equalizers consist of a series of filters. Filters are used to isolate and reduce a given frequency range. Filters can be either active or passive. An active filter has an amplifier and can boost as well as cut frequencies, whereas a passive filter can only reduce frequencies. Active filters can be constructed of smaller, less expensive components than passive filters. However, the disadvantage is they require external power, require more parts, and introduce a small amount of noise. Today most equalizers contain active filters.
Next month in Part 2, we will take a look at the terminology associated with equalizers.
• The Beatles' “Strawberry Fields Forever” was originally intended to be included on the Sgt. Pepper's Lonely Hearts Club Band album. However, because of pressure from the record label to release a single, it was issued in February 1967 as a double-sided single with “Penny Lane.“ The record reached No. 2 on the UK Chart, which broke the Beatles' four-year string of No. 1 hits in the UK. It peaked at No. 8 in the US.
• The Beatles recorded two different versions of “Strawberry Fields Forever”—one in a key a half-step higher and with a slightly faster tempo than the other. They could not decide which version they liked better. So they asked producer George Martin to make the decision. He slowed down the faster version and perfectly blended it together with the slower one to produce the final version that was released.
• The first album of Lesley Gore was entitled I'll Cry If I Want To. Every track was about crying, including “It's My Party,” “Judy's Turn to Cry,” “Misty,” and “Cry Me a River.“
• In a 2010 interview with Howard Stern, Billy Joel, who was a young session musician in 1964, said that he played piano on one of the demos for the Shangri-Las' “Leader of the Pack,“ but he was not sure if any of his playing ended up in the final recording. However, Roger Rossi, a staff musician for the studio said he had played the part. It reached No. 1 on the Billboard charts.