4 things your mixer EQ shouldn’t fix

Updated: Sep 20, 2019

I was recently hired to look at a sound system in a church that was recently treated with sound panels. The church wanted to make sure the audio system was optimized following the new sound treatment.

We asked the worship band to head up to the stage so we could sound check and listen to the system with a more dynamic source. As the band was preparing to start, I noticed the front of house engineer started setting dramatic EQs curves before the musicians played the first note. I ask "Why are you changing the EQs when you haven't heard the instruments yet". He replied "I know what it needs, these are my normal eq curves".

Now....I'm not saying it's wrong, just different. I can understand the normal channel prep like setting high pass filters and maybe doing some notches where you know the instrument on that channel has some offensive frequencies. Extreme EQ changes in the blind was a little surprising. Especially when the room was just treated and the audio system tuned.

There is an artistic side to EQing that I'm not going to cover in this post. Most engineers will use EQ to create space within a mix with multiple instruments in the same frequency bandwidth. You can also add "color" or "air" to a vocal or instrument to make it stand out. EQ is not a bad thing. I'm trying to point out some areas where we're reaching for an EQ when we should be looking at fixing a problem. The majority of this post is for a fixed installation venue, touring engineers have very little control over the space.

One, The Room

I remember being on the road and mixing on a different system each night. Most were not very optimal and some were barely hanging onto life. More memorable than the mix match of systems was the variation of room types. I remember setting up in a High School Gym and legend has it, it's still reverberating from our show. There was no way to fix this room with EQ. So what can you do? Not much as the touring engineer. However, if you're the venue owner or Church you can try to improve the space.

Venues should have adequate sound treatment for the rooms intended purpose. The target amount of RT60 (the amount of time it takes for sound to decrease 60dB) depends on the use of the space. A cathedral church is going to sound more "live" than a movie theater, and so it should.

Adding sound treatment is key to a well designed space. It's advised to send your room dimensions and an impulse response to a manufacturer of sound panels for an evaluation and design. I'll go into more detail on treatment in another post. Let us know if you'd like more information about doing this.

Two, Poor Mic placement

I over used EQ when I first started mixing. I used EQ to get the sound I was looking for, not necessarily the sound of the instrument playing on stage. Over time I wanted my mixes to sound more natural and found that Mic placement got me closer to the sound of the instrument than trying to fix with EQ.

So what is EQ? In it's simplest terms...It's the electronic balancing of sound frequencies. So the main purpose of the EQ is to balance the difference in sound between the instrument and how it sounds coming out of the PA...Assuming it's been tuned flat first. Our task, as a sound engineer, is to increase the level of an instrument (or vocal) through a PA system without changing too much of its tonal qualities. The rest is Art.

Three, PA system is not tuned

When you have a venue with engineered sound treatment, a properly tuned speaker system, and correct microphones selected for the application placed correctly, you're not going to need much EQ at all. A matter of fact, I recently tuned a system, and after sound check we were completely happy with only high pass filters on the vocal mics.

The system was tuned to have a flat response. This means the difference between the input source and sound from the PA had minimal variance. The microphones selected were designed for the application and placed properly. I placed a high pass filter at the lowest frequency the instrument could reproduce, and I put a low pass filter at the highest frequency the instrument could reproduce.

The HPF (High Pass Filter) only allows frequencies above the set frequency to pass and the LPF (Low pass Filter) only allows frequencies below the set frequency to pass.

HPF and LPF eliminates unwanted stage noise and only allows the microphone to only hear what the instrument is producing.

TIP: If you notice every channel having the same EQ cuts or EQ boosts...your system probably needs to be tuned.

Four, Garbage in - Louder Garbage out

I don't recall a time when a microphone has made a bad source sound good. If I was asked what microphone would be a good choice to improve the sound of a kick drum. I'd say I have my favorites, but I'd ask the person, “How does the kick drum sound by itself without a microphone?”

Getting the source to sound its best first is key

Tony Flammia is a systems engineer who travels the country optimizing audio systems and training tech teams. If you'd like more information

If you have any questions please feel free to post them below

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