Because the monitors often move to different positions on the platform, and the “set” and surroundings change as well, so too will EQ likely need some adjustment.
But note that major adjustments (+/-10 dB or more) shouldn’t be necessary – if this is the case, you should look at other aspects to identify potential problems.
The other common type of equalization is parametric. It offers adjustable frequency filters, which means that instead of having filters on set frequencies – the case with 1/3-octave – the operator decides what frequency (or frequencies) need to be cut or boosted.
And not only can you decide what frequency needs to be adjusted, you can also decide how many frequencies around the center frequency will be affected by your adjustment.
Now let’s move along to parametric EQ… (next page)
Parametric EQ is not for the beginner, nor is it likely needed for each performance. It is, however, a very useful tool and one that every system operator should be familiar with.
On many parametric EQs, including the one shown below, there are at least three controls.
One control allows selection of the frequency at which to insert a filter.
Another control allows adjustment of how wide or narrow that filter will be. A wider filter affects more frequencies around the center frequency, a narrow filter, less frequencies – more pinpoint adjustments and/or broader overall adjustments.
Finally, the third control is for cut/boost of that particular filter.
Often following installation, the sound contractor or designer will use a parametric EQ for tuning the system. This assists in identifying problem frequencies and helping to correct them without affecting the surrounding frequencies.
Parametric EQ (click to enlarge)
It’s also helpful if the system needs a broad spectrum of frequencies adjusted, because this too can be accomplished using perhaps just maybe one filter.
I use a parametric EQ when doing overhead miking, and it helps me identify frequencies that tend to feedback too soon, and then I set filters to notch them out.
The only problem I have is finding the frequency of that out-of-tune choir member and trying to notch it out!
But I keep trying…
Click here to read Joe’s article about the equalization (EQ) section on your mixing console.