Using Low-Shelf/High-Shelf EQ in Home Recording Mixing
Low-shelf/high-shelf EQ (equalization) is good for enhancing or reducing high or low frequencies in your recording’s mix, such as adding a sense of presence to cymbals (add a few dBs at 10 kHz). In the context of EQ, shelf means that the EQ effects are on the frequencies above (high shelf) or below (low shelf) your setting (called the corner frequency).
To use low-shelf/high-shelf EQ, click the Low Shelf and High Shelf buttons in the EQ plug-in window. These buttons look like sideways tuning forks located second from the left and second from the right above the EQ graph. When you use low-shelf/high-shelf EQ, you have three parameters to adjust in both Pro Tools and Logic:
Gain: This is the amount of boost or cut that you apply to the signal. In Pro Tools, you can either type in the amount in the text box next to the shelf button or use the knob to the right.
In Logic, to set the boost (gain), you can either point your mouse over the parameter and click and drag up or down, or click in the EQ graph above the parameter controls and drag up or down.
Freq: This is the starting frequency for the shelf. In Pro Tools, you can either type the frequency in the text box or use the knob to make your adjustment.
In Logic, to set your desired frequency, you can either point your mouse over the parameter and click and drag up or down, or click in the EQ graph above the parameter controls and drag left or right.
Q: This is the steepness of the shelf of your EQ. The higher the number, the steeper the shelf that’s applied — meaning that the range of frequencies affected to get the gain change of the shelf is narrower. To adjust this parameter in Logic, you can point your mouse over the parameter and click and drag up or down to get the Q value you want.
Your settings can be anywhere from .10 to 2. In Pro Tools, you adjust this setting either by moving the knob or by clicking in the box and typing a value between .1 and 2.