XTA D2 Operator's Manual - page 11
D2
Operators Manual
Page 11
What is Dynamic EQ?
Dynamic EQ is essentially a compressor or expander that can be set to respond and
act upon only a certain range of frequencies. Its behaviour is dependent on the
operating mode chosen: the operating modes are explained in detail below.
Mode I: “Cut Above”
Having selected the frequency band to work with, the dynamic eq will listen to this
band and act upon it by cutting(compressing) any frequencies present in it that go
above the predetermined threshold. Consider the example below where the
threshold is set to –20dB, and the selected frequency band is centred around 1kHz,
with a ‘Q’ of 1.0.
Signals below the threshold will pass unaltered, but as increasing signal is applied,
those frequencies centred around 1kHz will be cut or compressed. The ratio in the
above example is set at 2:1 so, as with any compressor, the amount of gain reduction
applied depends on how much the signal exceeds the threshold. The
red
line
represents a signal at 0dB, which is 20dB above the threshold. At 1kHz, therefore,
the signal has been compressed to –10dB or 2:1.
Uses of “Cut Above” mode.
Traditional use of ‘frequency conscious’ compression is to control or ‘tame’ a certain
band of frequencies within the program material. Insertion of EQ into the sidechain
will make the compressor respond to the required band, but it will cause broadband
compression of the signal, so any peaks will cause the entire signal to be compressed.
This produces the familiar problem of dulling the material if it is bass-heavy, or
causing unnecessary dips and changes in ambience when attempting to remove
sibilance.
The difference with dynamic EQ is that only the band selected is compressed. This
means that it becomes possible to compress the low frequency content of material
without affecting the high frequencies at all. The result is increased volume and
perceived level with out sacrificing clarity. Any instance where the desired result is to
control a band of frequencies, such as de-essing, or de-popping, without affecting the
surrounding frequency ranges is an ideal use for this mode.