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The Basics of Setting Up Equalizers for Live Sound

Live sound board with equalizers

A live performances requires a lot for the sound quality to be crisp and pristine. This is the primary responsibility of the sound technicians at concerts or events. Part of that includes running the sound board, so a live sound engineer must have a keen mastery of the different functions including the equalizers. Having in-depth knowledge of equalizers helps audio professionals accomplish a lot.

What Is an Equalizer?

Simply put, equalization adjusts the balance between the frequency components that lie within an electrical signal. This signal is created once the sound hits a microphone, which duplicates the characteristics of the original sound. The signal then goes through cables into a channel preamp. Then that signal combines with others that are picked up through other microphones and makes its way to a power amplifier. At this stage, the signal is strengthened and sent out to the speakers with attention to the gain, or loudness of the audio signal.

Different Types of EQs in Live Sound

A live sound engineer can control the equalizer which processes the audio signal. There are different equalizers, or EQs the sound technician uses to make frequencies quieter or louder. This is done when the audio professional cuts (moves the frequency levels for negative gain) or boosts (puts the levels into positive gain). The EQs can be used in conjunction with filters that calibrates the frequencies and their tonal qualities.

There are three types of equalizers that are in use for music production and live shows:
  1. Graphic equalizer this equalizer uses a bank of sliders that cuts and boosts frequencies. This equalizer helps to match the kilohertz range of human hearing, which is from 20-20,000 kHz.
  2. Parametric equalizer – this equalizer has filters that monitors high and low shelves of frequencies. In addition, a parametric EQ uses one filter with variable peaking. This helps to address the tones of the mid-level frequencies.
  3. Semi-parametric equalizer – this equalizer combines the high and low shelving filters with the variable peaking filter to control the tonal qualities of the mid-level frequencies.

How Do You Know Which Equalizer to Use?

The equalizers raises or lowers the audio frequencies to a cutoff point designated by the user. High-pass filters are used to reduce that level, and low-pass filters are employed to boost it. High-pass filters are also referred to as low-cut filters, and low-pass filters are referred to as high-cut. The amounts of boosts or cuts are measured in decibels, or dB.

Shelving Filters

Shelving filters are apply an equal adjustment to the gain. A high shelf adjusts the gain of higher frequencies only. An example of this is a treble control. A low shelf adjusts the gain of lower frequencies. The bass control on some equipment is an example of this. There are also peaking filters.

These affect the bands of frequency that are on either end of the spectrum and they allow the audio professional to make needed adjustments using two controls. One of these sets the applied gain of the band, and the other works with the center-frequency band. These days, venues do utilize digital equalizer controls in their sound system as well but the same rules apply.

Preparing Equalizers for Live Sound

Getting the right effect from the equalizers that will be part of the sound system begins with the initial set up of the equipment. If working with a group of performers such as a band with a vocalist, the key is to make sure that the equalizers make everyone sound good as a unit. The audio engineer needs to rely heavily upon their ears. In doing so, they can ascertain what problems might arise.

How a Venue Impacts EQ Choices

In some cases, the dimensions of the venue can factor in. Once the board and front-of-house (FOH) is set up, the primary audio engineer should reset the board. This gives the engineer flat EQ’s to work with at the start of the sound checks for the performers. The equalizer sliders should be moved up halfway as they are listening to the master gains to detect any feedback. Once they hear it, then they should work to cut out whatever they deem is problematic first. Next, the audio engineer needs to observe the channel gain and boost it to about three-quarters up to gauge how the preamp is performing along with the lead microphone.

It’s important to make sure that the vocals are close to pristine as possible, because that is what the human ear will pick up on the most if they come off sounding harsh.

There are certain ranges that will help in finding the right frequencies:
  1. Body (200 – 500 Hz): this frequency range comes with a prevalence for muddiness, or a build-up that affects the clarity of the low-mids. This can be averted by cutting the low frequencies in this range. To add more warmth of tone to the vocals, boosting within this range helps.
  2. Nasal (1 -3 kHz): this range denotes all frequencies in the vocals that have a high and nasal pitch to them. This can be relieved by cutting the EQ.
  3. Presence (4 kHz): this is a vital quality to have when it comes to the vocals as it helps them come across with distinction. Audio engineers should be careful not to boost this too much so the vocals won’t come through with a jarring effect.
  4. Sibilance (5 – 8 kHz): this range is used to correct the tonal harshness that comes across in vocals when consonants are used.

How Live Sound Engineers Use Equalizers

These adjustments can be easier if the engineer is working on a simple mixing board. If they are manning a board that has multiple equalizer bands, then more attention should be paid to the overall mix. It removes the constant need to EQ the different audio channels in isolation and falls in line with making sure the performers sound great as a unit. Applying the high pass (low-cut) filters to any audio channel that doesn’t improve with extremely low frequencies can remove muddiness from the subwoofer in the sound system and enhances the bass-heavy sounds from your performers. Lastly, the audio engineer can utilize audio effects such as reverb and compression where they deem it necessary.

Equalizer Issues to Consider

Audio engineers in control of the mixing board and the equalizers for live shows prepare themselves for unexpected situations. For instance, boosts can be easier to hear than what needs cutting. If an engineer doesn’t apply filters well to clean up the mix from the outset, there can be a bit of wasted headroom.

One way of avoiding this is through communication with the band. For example, live sound engineers can have a run-through with a guitarist if their tonal frequencies are too rugged. If the performance venue happens to be outdoors, it’s good to note that humid air can mess with the highs in the audio.

Microphones Impact Equalizers

Another example that impacts equalizers is the equipment, such as microphones. This is because the wide variety of microphones has an impact on frequencies. Some can cut frequencies to a certain range where muddiness can occur. Additionally, the proximity of the vocalist to the microphone affects the tonal qualities.

Conclusion

Equalizers play a pretty important role in how dynamic live shows can sound to the ear. Audio professionals of any level commit themselves to knowing the terminology inside and out and putting it to practice during these events. In using equalizers to help hone the sound from different performers, the audio engineer is a valued factor in creating a captivating musical experience.

Want to Learn More?

As quality sound is important for live shows and other events, it’s necessary to have the skills to provide that sound for successful shows. Learning about equalizers and their proper usage in live show environments can enhance the aspirations of those aiming to be sound technicians. If working in the music industry as a sound technician or engineer interests you, take a moment to check out IPR’s Sound Production Program and the training that they provide.

Contact us today to learn more about the live show and sound production program and starting a rewarding career in the music industry.