What is the proper way to set an equalizer? This is a very good question that should be asked a lot more often. Let’s start with a quiz. Which of these pictures would you choose as a starting point for your EQ Curve?
#1: The Smiley Face
#2: The Flat Line
#3: The Comb Filter
So, which one would you start with? Would you choose #1, #2, or #3? Why do I have a funny feeling that most of you will choose #1? Well, isn’t that the way you ALWAYS set an EQ? With more bass, more treble, and less midrange - after all, we want our audio to be clearer and really “pound”, right?
Here is a breakdown of these 3 curves: #1: The "Smiley Face"
You've SEEN this curve a hundred times, if not more. You perhaps even VISUALIZE doing it whenever you approach an equalizer. If you could SEE sound, it might look very nice; however, sound needs to be set with the ears, not the eyes! #2: "Flat Line"
With this one comes an obvious question: Why would I set my EQ to "neutral" or "flat line"? Of course, the issue here is that the equalizer is doing absolutely nothing. With this curve, try bypassing the EQ....it sounds exactly the same! #3: "Comb Filter"
This term comes from the fact that every other slider is up, and every other adjacent one is down, much like a comb’s alternating teeth and spaces. Although I’ve used this technique on really mushy, cluttered audio to “thin it out”, and it’s great for doing that, most audio in general is not that “crowded” across the sound spectrum. Where do I Start?
OK, so what’s the correct answer? When it comes to a starting point, the only answer is #2 - The Flat Line! I always use the flat line as a starting point for equalizing anything for several reasons. The main reason for this is that I WANT to hear the sound the way it actually is before altering it. I use my ears to pick out where there is too much bass, midrange, not enough treble, harsh frequencies not pleasing to the ear, etc... so I already get a general idea of which frequencies need adjusting. Next, I start at the bottom by lowering 20-30 Hz, anything below 40. Most speaker systems can’t reproduce frequencies below 40 Hz anyway, and that’s why most EQ’s have a high pass filter so you can set the frequency at which below this setting, the EQ is going to automatically lower the volume of those frequencies, and more so the farther below the filter’s setting they are. These frequencies are usually unhearable, but their upper harmonics can wreak havoc in the hearable spectrum by distorting and cancelling some of the good frequencies we CAN hear.
Curve of Bass Roll Off Control at 63Hz
Next, starting at around 40 Hz, I raise the slider to hear what too much 40 Hz sounds like, and then lower it to hear what too little sounds like. I then slowly raise it back up until it sounds “just enough”. Then I go to the next frequency, let’s say 50 Hz. I raise it up until I hear too much 50, and then all the way down to hear not enough 50, and then gradually up until it sounds “just right”. I continue this process with 63, 80, 100, 125 Hz etc...until I get to 20 Khz. The very LAST thing I do when I’m all done, and happy with how my sound spectrum sounds now, is LOOK at it. This method works great for beginners as well as pros because you are not only hearing what too much of, and too little of each frequency sounds like, you are also hearing where in the sound spectrum you are adjusting, so you don’t have to have perfect pitch and just “know” which frequencies you don’t like. You get to sample them all by hearing where it is you are affecting, and what too much and too little of it sounds like, and then you can find the happy medium where a frequency sounds “just right” to you. Once in awhile I will go through this process a 2nd time if I’m still not happy with it, or just go back and tweak certain frequencies. In this article, I am using a 31 band EQ for reference, however it doesn't matter how many bands your particular equalizer has, the process and concept is exactly the same, you just listen to and set less frequencies. What About Volume Levels?
One other question I get from time to time is “where do I set the volume control on the equalizer?”. The answer to this is usually “Set it so when you hit the bypass button, the volume doesn't go up or down from the equalized signal.” If you raise a lot of bands above zero, this adds volume, so you will want to turn it down to match the original (bypassed) signal’s volume, and if you make mostly cuts, raise it to compensate. It’s OK to go lower or higher to get more or less signal into the next piece of equipment on purpose, just be careful not to overload it! You don’t want to set your EQ volume to 10 and then can’t get the next piece of gear in the chain even up to 1. 5 & 5 will sound much better. Conclusion:
In summary, never use your eyes to set an equalizer, always use your ears. It is always best to start out with a neutral "flat line" curve to hear the sound unaltered before making any adjustments to the EQ. By progressively moving from low to high frequencies raising and lowering each, you can get a really good feel for where each one sounds most natural. Always use a high pass or low cut filter to roll off inaudible sub-bass frequencies as these can wreak havoc in the hearable spectrum, and make your amps and speakers work way harder than they should be “trying” to reproduce sound below their rated response range.
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About the Author
Patrick Smolinksi is a recording industry veteran with over 15 years of pro audio retail sales experience, over 11 years of running his own recording studio in central Wisconsin, and is a multi-instrumentalist playing all of the instruments on songwriter demos. Pat is a musician at heart and has also found himself playing gigs with several bands over the past 30 years. He loves his twins, the Packers, music, and pro audio gear.