Keep in mind that rock music is very high-energy high-intensity music. It drives the body as well as the soul. And it relies heavily on the low frequencies provided by the kick drum and bass. Low frequency sound waves are generally the most powerful part of the music spectrum. With wave lengths longer than we are tall, low frequencies are felt as well as heard. We humans seem to get a kick out of this. The fact that human-sized bass drums existed before the year 3,000 BC. suggests this is not a new trend. Today we go to dance clubs and live concerts for that special low frequency full-body sensation. For a special thrill I personally like to go to the Fourth of July celebration at out local military-industrial complex, Fort Devens. It is a truly different experience (kind of like riding a rocket sled after driving around in a Yugo) to hear/feel the 5” howitzers let off a 21 round salute from, say, 300 yards away. YIKES!
Power in the Mix
The kick drum is the driving force, the rock and roll motor that makes our body move (in a contemporary echo of the primeval march of the nomad...). Its powerful impact cuts and slams through the rest of the music with a beat which drives our bodies into movement: anywhere from foot tapping to slam dancing. The pulse of music lies in the kick drum.
The bass guitar is the key communicator of harmony in almost any tune. Its deep fat sustained tone is easy for our ears to find in almost any kind of music and it provides a musical foundation on which the harmonies and melodies are built. Add rhythm and words and you've got a song.
In general, the kick drum produces a hard, loud musical attack with little or no pitch, while the bass guitar produces pitch with little attack. As a result, the kick drum is typically rhythmic and the bass usually harmonic. However, they certainly aren't limited to these functions. The bass guitar provides much of the rhythmic force and drive in many styles of music. Slap and pop techniques are a direct attempt to give bass more attack, and this is very effective. At the same time, drummers can provide melodies and harmonies through roto-toms and the various drums (real and synthesized) with definite or implied pitch. In fact, one can do almost anything with these instruments in special situations (move walls, fry eggs, achieve world peace and so on - that’s a joke), but in pop music these instruments really focus on their primary functions. With this in mind, let's consider the implications for mixdown.