When it comes to shaping the tone of an audio signal, parametric equalisers are very effective. The controls allow the user to choose a frequency to boost or cut precisely, which is useful if the signal is feeding back or has an unpleasant overtone. Parametric equalisers can be found on mixing boards, amplifiers, and, most notably, in audio editing software. Here’s some advice on how to use a parametric equaliser for tone shaping and feedback protection.
Method 1 Parametric Equalizer Tone Shaping
1. Make use of the high-pass and low-pass filters.
There is a high-pass and a low-pass function in many software programmes. The high-pass filter will generally cut any frequencies below 100Hz and, in some cases, even below 80Hz.
In general, the low-pass button will cut any frequencies above around 10kHz. Many live mixing boards include a high-pass button that performs the same function as the software version.
These buttons enable the user to eliminate any unwanted high and low harmonics that may be present in the mix.
2. Decide on a frequency. Software programmes allow the user to cut or boost 3 to 7 frequencies at the same time. These are referred to as bands. Begin by using only one band at a time. By clicking on the frequency spectrum screen, you can enable the bandwidth.
3. Calculate the bandwidth.
The bandwidth of a band is the frequency range over which it will boost or cut. The bandwidth is also known as the “Q.” The narrower the bandwidth, the higher the Q.
The Q can be set to anything from 1/30 of an octave to 3 octaves. A wider Q allows you to get more basic tone shaping out of the band.
By narrowing the Q, you can eliminate frequencies that may be problematic, such as an unpleasant sound or overtone.
By lowering or raising the number, you can widen or narrow the Q.
4. Reduce or increase the band’s width. After you’ve determined your frequency and Q width, you can reduce or increase the bandwidth. Use the parametric’s gain function to cut the band by lowering the gain below zero or boost the gain by raising the gain above zero. Make only minor changes until the desired sound is achieved.
Method 2 Parametric Equalizer Feedback Elimination
1. Set up the Q. This step is only necessary if the channel strip on the board has a Q knob. In a live situation, you can raise the Q as far as it will go to make a precise cut.
2. Raise the gain on the channel. Boost the channels gain up until you start hearing the channel feedback.
3. Determine the frequency that is causing the feedback. Turn the frequency knob until the feed back is clearly visible.
4. Cut out the feedback. Lower the gain level on the EQ until the feedback stops.
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