Equalization
From WikiRecording
Equalization means boosting or cutting specific frequencies within an audio signal. A device that performs equalization is called an Equalizer, or more commonly, simply an EQ. This article is an overview of the terms and various types of EQ, for general tips on the use of EQ check out the article: EQ Mixing tips
Contents |
Equalizer Settings
Boost/Cut. The amount (usually in decibels) that the specific frequency is boosted or cut.
Frequency. The specific frequency (in Hz or KHz) that is being boosted or cut.
Q (Bandwidth). Q is the range of frequencies around the center point that is boosted or cut. Low Q settings indicate a wider bandwidth and are useful for gentle, sweeping EQ settings.
The formula for conversion from bandwidth in octaves to Q is:
, where n is the bandwidth in octaves.
High Q indicates a narrower bandwidth, and is useful for working with a more specific frequency range.
Graphic Equalizers
Graphic Equalizers are so-called because the controls are meant to represent a graph along the frequency ranges that they boost and cut. Graphic EQ's are easy to use, but have fixed frequency ranges and Q, so are less flexible.
Parameteric Equalizers
Parametric Equalizers offer you greater flexibility than graphical EQ's, as they typically have separate controls for boost/cut, frequency, and Q. This allows you to tailor the EQ curve to your needs.
Shelving
Shelving means to boost/cut all frequencies above or below a set frequency range.
A Low Shelf cuts or boosts all frequencies below the specified freqency. For example, a low shelf set at 250 Hz will affect all frequencies below 250 Hz.
A High Shelf cuts or boosts all frequencies above the specificed frequency. A high shelf set a 12 KHz will affect all frequencies above 12 KHz.
Pass Filters
A Pass Filter is an extreme type of shelf that cuts off all signal above or below the chosen frequency (or, in the case of the Band Pass Filter, above AND below the chosen frequency).
A High Pass (Low Cut) Filter is used to cut off frequencies below the set frequency. It can be used to eliminate low-frequency rumbles. It's useful during mixing to high-pass instruments such as vocals and guitar so they don't compete with the instruments that are in the low frequency space.
A Low Pass (High Cut) Filter is used to cut off frequencies above the set frequency.
A Band Pass Filter is a special type of filter that attenuates frequencies on both sides of a frequency point. A graphic equalizer is essentially a bank of band pass filters. A band pass filter can be simulated by combining a high pass filter and a low pass filter, effectively removing all frequencies around the center frequency.
