Probably the most misunderstood, misused, and downright abused of all the fundamentals of recording, EQ (equalization), is the easiest to remedy. All that’s required is some knowledge of the fundamental principal of EQ, and a bit of experience.
Have you ever said “My mixes sound bottom heavy on other monitors”? “Everything sounds all squashed together, and no definition”? “My mixes sound dull and lifeless”? All may be fixed through the proper application of EQ. And, I am talking about during the mixing stage of our project. This is NOT something best left to mastering. Before we can intelligently discuss the proper application of EQ, we have to have a clear understanding of just what we are equalizing. Every note played by any instrument consists of a series of frequencies known as the fundamental and upper harmonic structure. The upper partial harmonics are why a piano doesn’t sound like a Tenor Saxophone when both play the same note. The unique length and amplitude of each instruments harmonic structure is what yields the specific timbre of every voice in the orchestra. Every instrument has its fundamental frequency range, and then its harmonic structure as follows.
- 1st Harmonic: One octave above the fundamental
- 2nd Harmonic: a fifth above that
- 3rd Harmonic: the next octave
- 4th Harmonic: yet another fifth up
- 5th Harmonic: the dominant seventh above that
- And so on…
Let’s take the fundamental frequency of A 440 Hertz. That’s the A above middle C. On the guitar, 1st string, 5th fret. If we apply EQ at say, 5000 Hertz (5kHz) to that note, even though the entire fundamental range of the guitar doesn’t go much above 1100 Hertz, we will make a substantial change to the quality of that note, as we are altering one or more of the upper partials.
So Now, On To the Application of the EQ Itself.
OK, what follows is a broad general description of frequencies and how they translate to recorded music. These are indeed broad parameters, and are very much impacted by bandwidth, (Q), bell curve, and so on. Let me reiterate, these are GENERAL approximations of the frequency range(s), and should not be taken as law, just a guideline.
Starting from the bottom up, here’s your “map”:
- 50Hz “Hip Hop” bottom. Stay away from this unless you are mixing with and for subs.
- 80Hz Solid bottom end.
- 100Hz “Warmth” for low end, use SPARINGLY!
- 125 to 250Hz Mud. Lose it.
- 300 to 600Hz Fundamental frequencies for most instruments, best left alone for the most part.
- 600 to 900Hz Almost always subtractive to lose “nasal” quality.
- 1 to 2kHz Irritating. Perceived by dummies as “loud”. (Peavey guitar amps, sorry Hartley)
- 2k and up a bit more can be useful for Bass Guitar presence/definition.
- 3 to 4k Presence for low-end instruments. Read: kick drum.
- 5k Presence for mid range instruments. Near all of 'em.
- 6 - 8k Sparkle.
- 8 - 10k Shine.
- 10k and up, Air. The higher you go, the more you can use. Season to taste.
OK, now that we have discussed the frequencies that we will concern ourselves the most with, let’s discuss how to treat those frequencies. Fundamental through mid range tweaks are almost always SUBSTRACTIVE. Adding EQ in these areas will yield mostly disastrous results. For instance, boosting the low end of both the Bass and Kick Drum in quest of that “big bottom” end, will completely overpower the rest of your track, and no amount of mastering compression et al will ever be able to overcome that. You are far better off to get the low end from the Bass, and use the Kick as definition! Actually cut some low end from the Kick, and listen as the interaction between Kick and Bass tightens up and becomes solid.
Do not fall into the trap of locating your favorite sounds in the track and accentuating them. Just the opposite is best, and in that light let me forward to you the worlds oldest, and best, engineering tip: Find what you DON’T like and diminish it. Solo your instrument, boost level, narrowest Q possible, then sweep through the frequencies till you find what you hate, and cut it. (A little, don’t go overboard).
For this month, let me just quickly cover these important EQ principals.
- Use as little EQ as possible, applied in very small increments.
- Use subtractive EQ whenever possible.
- Try not to duplicate EQ from instrument to instrument.
- ALWAYS make your final EQ decisions in the mix, not soloed.
In trying to keep this column to a reasonable length, I have discovered what a gigantic subject EQ is, to say nothing of how subjective the topic is as well. We have only scratched the surface of the uses of EQ in this article, but luckily, each of you posses the most important learning tool of all, your ears. Experiment with EQ. Notice how changing EQ on one track impacts others. See how you can alter the sonic space of an instrument simply with the application of EQ. And so on, and so on…
Remember, with EQ as with everything else in the recording world, “Less Is More!” Don’t overdo.