Thinking inside the Box:
A complete EQ and Compression tutorial
Part Four: EQ: Practical Applications 1: Adding and Layering Sounds
Layering sounds
To prove it, I shall now illustrate how thinking in this fashion can help fix the badly made track described above, within even touching an EQ plugin. Lets take the snare. How would you describe the timbre of the ideal drumnbass snare? Well, its got to be hard, its got to be smacking. Remembering that timbre equates to the shape of our splodge, this our first clue as towards what shape splodge we're looking for. Given that a sound will generally sound bigger and louder whenever any one of its dimensions inside the box is increased, we will need a fairly wide splodge, covering a large range of frequencies, on order to produce a sound which will really smack the listeners head up. The ideal snare should have a crispness or 'snap' to it - this translates to healthy response in the upper-mid regions, and it should also have some 'weight' or 'beef' to its 'thunk' - this equates to a healthy response in the lower-mid regions.Now, I dont want to go overboard giving out actual frequencies, because I fear people may take them as magically 'true' values, when the truth is that every sound must be evaluated individually within the context of each unique track. But to give you a general idea of what I'm talking about, I find the 'thunk' is usually around 200-400hz. I usually get a good 'crack' around 2-3khz, whereas general sparkle and crispness can be found all the way up to 7-8khz. I repeat: your mileage may vary.
Lets look at our weak, tinny snare:
Imagine that the producer of this not-very-good track is not just smoking crack. This isnt an awful, awful snare sample. In fact, lets imagine its quite good. It has a rather decent 'snap' to it. It is just too thin and tinny, lacking any weight. In the real world, this is entirely unsurprising. Very few samples will be sufficiently 'larger than life' to become our 'dream snare' in one go. Instead, we look out for another snare which is the opposite of the one we have. A snare which may lack all the good points of our first selection - but that doesnt matter - our first selection has them locked down. What matters is that our second snare succeeds where the first fails. In this case, provides a nice beefy lower thunk. Add the two together, and we are in business:
In practice, it may require more than two samples, but that is the general idea. Adding multiple sounds together can produce a 'fatter' result than a single sound, and is best done by choosing different sounds which complement each other, each possessing desirable characterics in different regions of the frequency spectrum.
Now we shall look at some of the possible problems that come from layering sounds together.
Adding sounds together
A common mistake made by beginners is to try and gain more 'fatness' by layering the same sound on top of itself, or layering sounds which are rather ssimilar. This is nothing but trouble- it will not make your sound any louder in the ear of the listener, it may cause phasing problems, and it will waste your headroom. Lets see why this is.Remember I said it was important that most splodges are wider than you might imagine? To see why this matters, we go back to the box. Your sounds are physical objects being placed into a physical box, and there is only so much room for them. This analogy can be carried further, for there is only so much room at each given point in the box for objects to be placed on top of each other, before the stack becomes too high for the lid. Its almost like Tetris...! Imagine you have laid this arrangement of bricks in your box, and you have another arrangement of bricks next to the box which you want to put into the box in the same formation.
 In the box |
 Due to be put in the box |
If our box were only tall enough to accomadate a stack of two bricks in height, we would have problems, since we now have a stack that is three bricks high. We cannot fit the lid on. It is the same with digital audio. Just as we found a "peak" was created when we tried to fill the same spot in our box with bricks from two different piles, so we will find sounds add together and create a "peak" when you try to fill the same spot along the frequency scale, with content from two different sounds. There are however two key differences. First, we of course do not really have discrete bricks, we just have continuous splodges. Second, it is not possible to simply "leave the lid off". The lid is absolute. So, what effectively happens instead is that your highest stack of bricks becomes 0db, and everything else becomes proportionately quieter. This is quite important: an EQ (frequency) issue turns out to impact on the dynamics (volume) of the track! I told you everything was closely inter-related. Now, since everyone wants their track to be nice and loud (right?), we'll investigate this 'adding together' problem imminently...
First, however, I should make absolutely clear than sounds "adding to each other" in this fashion is entirely natural. Do not get over-paranoid about separation, and attempt to viciously restrict your splodges from ever overlapping with each other altogether. My splodges in the "well produced" track were badly airbrushed together for a reason - overlap in itself is normal. It is only sometimes problematic.
In the next part we shall investigate some scenarios where unwanted or unnecessary frequency content causes problems, and how EQ can help.