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Application Notes
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16. APPLICATION NOTES
16.1. Dynamic EQ
Over the years a number of professional audio products have provided dynamic equalisation functions
of various types. What all these systems have in common is that the frequency response of the
device varies depending on the signal level. Many units are based on compressor/expander
technology with frequency selection, and the controls often resemble those of a dynamics processor.
The system developed by the Klark Teknik research and development team for the Helix series is
rather different. It draws on KT's unrivalled experience in equalisation, and uses the signal level to
directly control parametric equalisers. This purely EQ-based solution allows simple controls that
directly relate to the signal levels. As a result, it is very easy to set the point at which the dynamic
EQ starts to operate, and also to set precisely its maximum effect. We refer to this technique as
“Threshold Dependent Equalisation”.
In order to understand the operation, let us first consider a conventional parametric EQ section
(Figure 1). The three controls available to us are frequency, Q (or bandwidth), and the amount of cut
or boost.
This shows a series of responses for the parametric EQ with different input levels. As expected, there
is no change in the shape of the curve with different input levels. If the input is 10dB louder, the
output is 10dB louder at every frequency.