If you are looking to make a track that contains a lot of instrumentation, it can become very difficult to fit everything in. When you start to look at things critically, you realize that in many situations (dependent upon which key you are in) you are really looking at two octaves (3-4) of tones to work within before things get kind of messy. Once you get into the fifth octave, tones sometimes become kind of harsh. You can deal with some of this problem by using a low pass filter, but then you aren’t left with many harmonics beyond the fundamental tone. This lack of harmonic content is very problematic if you are wanting to use any type of modulation. Going below the third octave is great for bass tones, but pairing multiple instruments in that octave would probably not be a great idea. So if you are looking to fit more than two tonal instruments (bass excluded) into the mix, you are probably going to have to put two of them in the same octave. This can be pretty tricky if you don’t approach the situation in the right manner. When two instruments take up the same frequency range, you really need to make sure that they stand out from each other. For starters you probably want to put the two instruments into the higher octave (4), as higher tones equal shorter and faster waves, which create more space. Once you have that figured out, you can look at these four elements to provide distinction between your tracks:
Pattern – It’s probably a good idea to make sure that each sequence of chords or melodies that you are playing occur at different rates. If you have a complex melody that touches on six or seven tones, you are probably best served to use fewer and longer chord/melody tones with the other instrument. If both instruments are playing elaborate patterns, they are going to confuse the listener. If both instruments are playing simple patterns, the listener will get bored. Ideally the listener is hooked by the more elaborate pattern, while the other pattern plays a supportive role. Another way of dealing with this is to have one pattern start out complex, while ending in a simpler manner. You can then have the other instrument start out simple, while ending in a complex manner.
Pan – When using different instruments within the same octave, you probably want to pan each instrument out in different directions. This will separate them from each other, providing each with its own place in the mix. It is also nice for providing a more stereo feel to your overall track. When doing this you probably don’t want to pan each instrument too far, as the mix will become lopsided if you leave out one of the two instruments at any given time. I try to find locations between 2-3 o’clock and 9-10 o’clock for this. When you are building up to the chorus, you might want to leave certain parts out of the mix at different times before having everything going for the chorus. Finding a balance where each instrument is separated but not isolated is important.
Reverb – The depth of each instrument within an octave is also something that provides a high level of distinction between the two. Having one up in your face while the other is more in the background will help define each as separate entities. When doing this you might want to use the same reverb settings for both instruments, while adjusting only the dry/wet parameter. This way the instruments will feel like they are in the same environment.
EQ – Ensuring that there is differentiation between the harmonics of each instrument is very important. With synthesizers, it is relatively ease to dictate the harmonic patterns of instruments. With natural instruments however, you are pretty much stuck with what you get. Something I have found success with, is focusing on one of the instruments second level harmonics while focusing on the other instruments upper level harmonics. For the instrument that I want to focus on the second level harmonics, I will use a low pass filter to take out the higher frequencies. For the instrument that I want to focus on the upper level frequencies, I will use an EQ notch to reduce the frequency range associated with the second level harmonics. Instead of boosting, you can cut the areas of the other instrument out. Although there is no way to get around the fact that both instruments fundamental tones will be dueling on a certain level, there is a lot that you can do to the following harmonics of each instrument to really differentiate the two instruments. When you are using synthesizers, these principals are a lot easier to implement than when you are using natural instruments. One way to deal with this is to use one natural instrument, and one synthesizer. You can then adjust the synthesizer’s harmonics in a complimentary role around the natural instrument.
Envelope – The envelope of each tone will also have a very drastic impact on differentiating the two instruments. You might be best served to make use of one instrument with a fast attack, and another with a slower attack. If one of your instruments sustains, then you are probably best served to have the other instrument decay. The idea is to provide each instrument with its own pattern of dynamics. When the envelopes are similar, it will be very difficult to tell the two instruments apart during parts where they each play a tone/chord. These same concepts for differentiating envelopes can also be applied to modulation principles with LFO’s.
The common theme with all of these parameters is CONTRAST. When using two instruments within the same octave/frequency range, you really need to go out of your way to make sure that they complement each other. I have found that adding a third instrument on top of the drums and bass adds a whole new dimension to your track. When I listen to the Chronic and 2001, most of Dre’s beats involve a third tonal instrument beyond the drums and bass. Learning to program synths is a very valuable skill, even if you are only doing it to compliment natural instruments. Synthesizers are very flexible when you know how to use them. Often times certain natural instruments just don’t work that great together, no matter how you mix them. Using synthesizers in a complimentary manner solves this problem.