The knob “Q” on a parametric equalizer stands for “quality factor” and it adjusts the range of the frequencies affected by the filter.
A lower Q factor of 0.5 will have a much wider scope of influence than for example, a Q factor of 2 on a generic/standard parametric equalizer.
This means a Q factor of 0.5 will be more suitable for a broader influence on the frequency spectrum than a higher Q factor of 2 and vice versa.
Surgical EQ and Quality Factor
The end game of using a parametric equalizer for surgical mixing/mastering purpose is that you will more likely end up using a higher Q factor setting.
Obviously that’s because a higher Q factor allows you to precisely focus on the target offending frequency with affecting the surrounding frequencies.
Therefore the rule of thumb is for surgical equalizing you ought to use a clean equalizer which offers a higher variable Q factor to suit your needs.
Quality Factor & Frequency Octaves
The following is a simple list of Q factors paired with their approximate ‘width’ in octaves:
- 0.7 = 2 octaves
- 1 = 1 1/3 octaves
- 1.4 = 1 octave
- 2.8 = 1/2 octave
- 4.3 = 1/3 octave
- 8.6 = 1/6 octave