EQ bands which are set to a gain of 0db are essentially "off". Only when you drag a band away from 0 is it doing anything.

As Bonzi said, each band is parametric and you can adjust its width to your liking. So if you only want to adjust two or three bands, go for it.

In practice, however, more bands is always better. You might think all you want is a big smiley-face, but the truth is that fine corrections of narrow bands is where the most benefit happens.

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Tony Fabris