EQ

Specifies the frequencies (dB) across the spectrum of EQ (Hz)

Short for equalisation, is the process of amplifying or attenuating specific or groups of frequencies to alter the tone of targeted audio signal.

LPF

An EQ Filter which reduces/ removes high frequencies whilst allowing the low frequencies to pass unedited.

Lowpass filters affect signals, attenuating above a set frequency with a progressive gain slop per octave.

HPF

An EQ Filter which reduces/ removes low frequencies whilst allowing the high frequencies to pass unedited.\

Highpass filters affect signals, attenuating below a set frequency with a progressive gain slop per octave.

BPF

An EQ Filter which signals between to specific frequencies to pass – inner – whilst discriminating against signals at other frequencies.

Affect signals, amplifying or attenuating either side of a specified centre frequency, the scope of which is determined by a bandwidth control (Q)

Notch Filters

Passes most frequencies unaltered whilst attenuating certain frequencies of a specific range to very low levels.

A more intense form of BDF, it focuses on a very specific frequency with a narrow bandwidth (Q) to help remove noises.

Shelving Filters

A shelving filter applies cut or boost to frequencies above or below the filter cut-off point.

These affect signals both above (high shelving) and below (low shelving) with equal gain curves, measured as a bandwidth (Q).

Frequency is created from the dot (along the middle of the curve) – not on the line etc. gain slope etc.

Parametric EQ

Devices that allow the control of multiple frequencies, often with multiple BPFs that amplify or attenuate a specific narrow spectrum of frequencies.

Graphic EQ

Devices that amplify or attenuate set frequencies across the spectrum. These were commonly found on associated with domestic hi-fi units.

Frequency

Number of vibrations per second, measured in hertz (Hz).4

Centre Frequency

A specific frequency, e.g. 400Hz

Gain

Measured in dB, used to amplify or attenuate targeted frequencies.

Bandwidth (Q)

Used to control the scope of frequencies affect (wide or narrow).

Slope

Extent by which a LPF or HPF attenuates a signal in dB per octave.

Cut-off frequency

Frequency at which a LPF HPF or BPF impacts upon signal.

Resonance

Involves the amplification of frequencies around the centre frequency, often with a BPF, often producing/amplifying harmonics/overtones.

White noise in synthesis : Frequencies of white noise – amplify different points through alternating cutoff. Resonance amplifies centre frequency. Moving cutoff value creates additional overtones/harmonics – pitch.

	Created by ben keynes about 7 years ago

Definitions

EQ and Frequency