BSS Audio FCS-966 Owner's Manual - Manual (Page 19)

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Figure 7.1 shows very approximately the sliders that have most effect on some
common instruments - having an effect is related to the harmonic richness
of the sound. A flute for example, generating relatively pure tones, will only
have energy in a small number of bands at a given time, whereas a guitar has
harmonics covering most bands. When applied to the guitar, the equalizer will
be capable of completely changing the sound.
A graphic equalizer may be used for both creative and corrective use. Both
these uses can apply to whole sound systems or individual instruments.
When used creatively, it may be set to change the timbre of an instrument
and so alter its character. Used in a corrective manner, maybe on the same
instrument, it can be used to remove a resonance that is making the instrument
sound muddy or shrill. Graphic equalizers are also used extensively to treat
the human voice and, by 'flattening' irregularities, can improve the perceived
quality of inexperienced performers.
Generally creative uses utilise gradual changes with small differences in
position between adjacent sliders. Radical corrective surgery is usually
indicated by larger adjustments to individual sliders, thereby treating the
problem whilst leaving all other areas unaffected. See section 8 for some
examples.
7.3 What does
constant Q mean?
The ‘Q’ of a filter is a technical term which corresponds to the measurement of
its width, hence the term constant Q implies that as a slider is moved, the Q or
width of the applied filter stays the same - refer to figure 7.2.
Fig 7.2 difference between
constant and non-constant
Q sliders
If the width varies with slider position, as it does with non constant Q
equalizers, accurately summing the result from a number of sliders will be
impossible except at one position, the position when the Q or width equals the
space between two adjacent bands. It should be self evident that this type of
operation is highly undesirable, as the effect of one slider will depend on the
position of many others making the total effect unpredictable.