Some History
Dating as far back as the 1930's, the equaliser is the oldest and probably the most extensively used signal
processing device availible to the recording or sound reinforcement engineer. Today there are many types of
equilisers availible, and these vary greatly in sophistication, from the simple bass and treble tone control of
the fifties to advanced equipment like the modern multi-band graphic equaliser and the more complex
parametric types. Basically, an equaliser consists of a number of electronic filters which allow frequency
response of a sound system or signal chain to be altered. Over the past half century, equalisers design has
grown increasingly sophisticated. Designs began with the basic 'shelving filter', but have since evolved to
meet the requirements of today's audio industry.