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All analogue equalisers will introduce some phase shift when used and different equaliser bands
will also interact when used together. A graphic equaliser can be considered as a combination
of 30 distinct equalisers with fixed centre frequencies and in the case of the
dBQzero
with a
constant Q factor. You can only change the gain/attenuation of the filters. This should make it
clear why some equalisers (like the
dBQzero
) sound better and more accurate than others. The
centre frequencies should be very precisely set; the Q factor really constant and similar for all
bands or the interaction between all those filters will create an unpredictable result.
When using a graphic filter for adjusting your sound, start from the lower frequencies and work
your way up to the higher ones (work from left to right). Most individual sounds consist of a
fundamental frequency and more or less harmonics depending on the nature and/or origin of
that sound. When working from left to right you’ll make sure to first touch the fundamentals and
when altering those you will also act on their harmonics. A good example is mains hum (50Hz
or 60Hz), this is mostly a dirty sound with some harmonics: if you work from right to left you will
try to get rid of all the harmonics first to finally get to the fundamental. When working from left to
right you will get to the fundamental first and take out more or less some of the harmonics, so
you will actually use less correction. And with equalising: less is better.
Another good advise is: it is better to cut than to boost. When boosting frequencies or frequency
bands you will reduce the overall headroom of your system. If for example you think there is a
lack of high frequencies in your sound, you can either push those frequencies or you can cut
some of the low frequencies.
And as a last advice: avoid extreme settings between adjacent bands, they will create big phase
shifts. Try to make your equalising curve as smooth as possible.
The Level Control (2)
This is an overall gain control, which controls the input level.
The purpose of this control is to be able to adjust the level according to the used overall equali
-
sation. If you have boosted a lot of frequencies, your overall signal will be much hotter and could
overdrive the equaliser or the following equipment, adjust your signal with the level control. The
same goes of course if you have cut a lot of frequencies, use this control to boost the overall
level back to normal.
