Everybody knows that, if there is one characteristic that really makes a Hip Hop beat stick out from any other genre of music, it´s that instantly recognizable booming bass drum that marks the focal points of the rhythm, and gives the beat that certain “thump”. In urban music (and hip hop in particular) the rhythmic and percussive elements are truly at the forefront, and this has a lot to do with the musical heritage and identity of the genre as a whole.
Hip hop has always been chiefly centered around the three biggest elements of a drum kit: the bass drum, the snare drum and the hi-hat. What is most specific to the genre is the heavy use of classic drum samplers and drum machines to create these sounds, especially the now almost legendary vintage Roland TR-808. This machine, and others like it, was and still is used in most urban music production environments as a chief sound source (alongside other classics, like the Akai MPC series units).
The one timbre that has become most deeply associated with the 808, and with modern hip hop and trap music in general, is the sub kick. It is, as its name implies, a recreation of a bass drum (or kick drum), but as with most gear produced in the analog days of synthesis and drum machines, it of course ended up sounding nothing like the real thing! But that actually became it´s biggest strength: people became increasingly enamored with the 808 sub kick, and its ability to be able to tune the sine wave that constituted the “body” of the bass sound to any desired note. Thus, you have a double sound: an initial, more percussive sound (known as the attack transient), followed by a low, tuned bass sound that extends as long as the sound remains audible (this is referred to as sustain and decay).
What is especially powerful about 808 sub kicks, in the broader context of mixing drums in a hip hop production, is the fact that, since it is both percussive AND melodic in nature, it can be used both in the capacity of a kick drum (marking the downbeats, in opposition to the snare) and at the same time as a bass instrument (since it is tuneable). Modern 808 sub kick libraries usually include both tuned and un-tuned options, with the tuned ones typically being playable chromatically along the keys of your midi controller keyboard. This allows the savvy producer to actually “skip” over the bass track completely, since a well produced and properly mixed tuned 808 sub kick can really deliver as a main bass tone, while at the same time providing the necessary “boom factor” when it comes to mixing drums.
Now, when it comes to mixing the 808 sub kick and really making it pop the way it should, there are a few things you should keep in mind:
* first of all, while it is commonly knows as “the 808 kick” sound, it does not necessarily have to originate from a sampled 808 to be such. Basically, all you need is a good attack transient and a decent sine wave (any professional synthesizer should be able to generate an isolated sine wave). Then it is only a matter of proper tuning and levels.
* depending on what kind of 808 sound and general mix you´re looking for, you may want to make the arrangement in such a way that the low end and mid-range remain rather sparse, so as to allow the deep booming sub kick to really take center stage, so to speak. On the other hand, if you´re after a tighter and more substance-oriented sound, you may want to beef up the 808 with a separate “proper” kick drum sample, to give it more punch and a more aggressive percussive edge.
* one very interesting thing to play around with, and which can produce frankly mind boggling results, is processing the kick / sub through distortion effects or overdrive, as well as compression and EQ. Especially the effect that a really well rounded distorted 808 creates in a mix can really make the track stand out. Don´t be afraid to use effect pedals, analog gear or even guitar effects processors to experiment. The sky is literally the limit, when it comes to distorted 808´s!
You can also try other possibilities, such as saturation, bit crushing, multiband compression, etc. to find interesting results that work musically. Also, don´t forget to try enhancing the bass frequencies with any mastering plugin (such as those by Waves Audio), or maybe some harmonic excitement or overtone enhancement will do the trick. There is really no “right way” to mix 808 sub kick drums in hip hop or trap music, you just gotta keep your ears open, find what sounds good… and always keep in mind the role you want the 808 to play in your specific project, as this will determine the nature and “feel” you should aim for.