Hz (Hertz) : The number of cycles per second in reference to sound waves. Human hearing ranges roughly from 20 Hz (20 cycles per second of a sound wave) to 20,000 Hz (20 kHz – kilohertz).
The lower the frequency in hertz, the greater the size of the wave form. A 20 Hz signal is produced by subwoofers or speakers with large bass drivers. The drivers of these speakers are large in order to create the large sound waves necessary to reproduce a 20 Hz or similar low bass signal.
On the other end of the human hearing spectrum (topping out at around 20 kHz and less for many people) the sound waves are very small. Small tweeters, normally around 1 to 2 inches in diameter, are used to reproduce these high frequencies’ small waves.
Each cycle can be thought of as a wave, with a 20 Hz signal pushing out 20 large waves per second while a 20,000 Hz signal produces 20,000 very small waves per second. The lower frequency range (around 20 Hz) can be felt as well as heard adding gut impact to movies and music. (Speaker permitting)
Sometimes, Less is More
Your bass may sounds fat. The guitar punchy. The kick is in your face. The snare is... well, it's very "snarey" sounding. So, how come your mix sounds like oatmeal?
Equalization, or EQ, is a process by which a specific parts or parts of the audible frequency spectrum are either cut or boosted, in order to change a sound.
Having EQ capabilities is not an excuse to get lazy! Getting good sound first is a matter of mic placement instrument quality & playing quality. Trying to EQ a kick drum that is tuned loose can be a nightmare. You can't effectively boost what isn't there in the first place. Good miking makes EQ adjustments almost unnecessary. If you've done everything right, you may very well find that the best EQ is none at all! (Though getting that great miking can be rather difficult.)
As we all know, time and budget limits will create conditions that are not always ideal. You won't always have the perfect mic at your disposal. Not every acoustic guitar you will be using is going to be a $2,000 Taylor. And it can be detrimental to your happiness to spend 30 minutes experimenting with your mike. In situations like this, EQ is often your only solution. When you've done the best you can, yet that timbre isn't exactly what you were going for, careful use of EQ can mean the difference between greatness and so-so-ness.
Musical Shoehorn
It's often useful to think of mixing as putting together a giant sonic jigsaw puzzle.
Your job is to take all of the "pieces" spread across your "desk" and make them all fit into a beautifully assembled. (A good sounding mix of your band.)
When listening to a single player, all by his lonesome left, he may sound real cool.
But take all these beautiful colors and play & mix them together, and you'll likely get what you'd see if you mixed all of these beautiful separate colors together-- a yucky brown goop!
The idea is to allow each instrument to occupy it's own "place" in the mix so that, like a great painting, it has powerful impact as a whole, yet you can "see" (or, in our case, hear) all the individual parts as well. There are generally to accomplish this:
> Volume (the setting of levels)
> Sound staging (Panning or balance between left & right)
> Time (the use of delay, reverb and effects to separate sounds in time);
> Equalizing (the use of EQ to separate sounds across the spectrum).
The next time you listen to a great record, try to see if you can figure out which of these three techniques are being used. Chances are, you'll hear all four at the same time! But since this is an article about EQ, we'll focus on that technique.
A lot of people like to build a mix from the bottom-up.
So let's say you've got this bass player, and you've also got that groovy kick-drum.
On most records, the bass and kick together represent the foundation of the song, which greatly effects the feel of the song in general.
The kick-&-bass relationship is one of the critical signals that all listeners key in on, whether they realize it or not!
So it makes sense to have a very clear idea of the style of the music your playing. Because if you don’t have those 2 elements in your band, you need to decide what if your foundation instrument. This is very important, as if you have no idea where you are going, you are not likely to end up where you wanted to be.
So, lets say you have bass & drums in your band.
1. The roundness of the bass lies in the 60 Hz to 150 Hz range. And that pop'n'snap thing is up there around 2.0 kHz to 3 kHz range or so. But on a lot of electric bass frequencies around 250Hz can mud up the sound.
So cut a little around 250 Hz and you hear the meat of the kick drum a little better now. The bass and drums aren't stepping on each other so much
any more because you've cut out a little part on the bass for the kick to come through.
Now you bring in the acoustic guitar, so cut the low frequencies below 80 Hz out of it. This leaves the guitar feel intact, yet leaves plenty of room for the bass and kick to still breathe. Are you starting to get the idea?
Cool! Your mix is starting to come together! You continue to EQ in this manner until the song is done.
All sounds contain several frequencies -- in fact, usually many thousands of different frequencies, each at different volume levels. A simple sine wave is the only type of sound that contains one and only one frequency.
It's important to learn with practice, the "sound" of each frequency and the number of Hz that corresponds to it. To be able to identify frequencies and frequency ranges by ear is as great skill.
One thing to remember is that when you cut or boost using an equalizer, you are affecting not a single frequency, but a range of frequencies near it.
It could be a narrow band, or a wide band.
("Q" is not a musical concept, though widely used, it’s actually called octaves.)
I find that one octave is a good bandwidth to start out with for most general EQ tasks.
An octave is generally narrow enough to get close to the frequencies you're after, while wide enough to not have too radical an effect.
A wider bandwidth (two or three octaves) is good for less specific overall coloration.
A narrower bandwidth (1/3 octave or less) is generally used for cutting problem frequencies.
Stage Feedback tuning
Set you graphic equalizer to flat position.
Turn up the main vocal microphones (un equalized).
Slowly bring up the overall system level until your system starts to ring (do not let your system to ring too loudly or you will damage your speakers and/or your hearing).
Pull down the EQ slider that makes the feedback stop (but only few dB).
Turn the volume up again and another frequency will begin to feedback. Pull down the corresponding EQ again (only few dB again).
Repeat this procedure three times (not more). Otherwise you’ll end up sounding un-natural.
When you have completed this you have the equalized the speakers to a flatter response for the room. However, keep in mind that when people come into your room, it will greatly alter the tone and abortion of the room. So don’t over EQ your mix trying to cut out the feedback.
It’s recommend to someone new to EQ, to not use more than 6 dB cut or boost.
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