Like building a house, you need to start with a solid foundation – the kick drum and bass. Working with just these two tracks, zoom in tight so that you can easily see the waveforms. I like to cut each bass note and place it just behind the transient of the kick (a well-played track means much less cutting and moving of course). This allows the transient and upper harmonics of the kick’s attack to come punching through your speakers before the bass note starts to ring.
If the bass guitar precedes a kick, the punch in the track is lost.
In the mix, you might not hear that the bass is ahead of the kick, but this beat will noticeably lack the punch of a bass note sitting behind the kick transient. Conversely, if the bass note is too late, the attack becomes too long to be punchy or becomes a separate note. A little experimentation here is good, as this can sometimes be a nice effect, giving the track a relaxed quality.
The real magic happens when the two instruments blend to become a single punchy low-end transient that transforms from a kick into a thick fat bass note. If you are a real stickler for “perfection” and have LOTS of time on your hands, there is something to be said for zooming in really tight on your kick and bass waveforms and making sure the transients of both instruments are “in phase.” I strongly recommend finding a niece or nephew that you can trust and bribe with ice cream to do this tedious task … if they mess up even on note: “No ice cream for you!”
In attempting to phase align the two tracks, you are not likely to get all the peaks and valleys to line up because the bass wavelengths are going to vary with frequency. The important ones to line up are the early ones where the amplitude is highest. The science here lies in the fact that theses waveforms represent the voltage output from your digital to analog converters. If you prefer a more “physical model,” these waves symbolize the direction your speakers are going to be pushed (the flat line in the centre being the zero crossing where the speaker sits at rest). On a vast number of systems these frequencies are going to be played by a mono subwoofer. As the subwoofer can only go one direction at one time, if the bass and kick waves are in phase (pushing in the same direction) the mix is going to be much punchier than that of a mix with a bass and kick that are out of phase. Unfortunately, this magical fix is not going to save bad tone and sloppy playing.
In closing, I would like to point out to the percussive purists (drummers) that I didn’t even mention lining the kick drum up with the click track before going on to align the bass. Only an engineer that believes the covers of Maxim and Stuff are works of art would do such at thing! Hmm…
Alec a producer/engineer in Nanaimo, BC. He can be reached at Alec@Vinsynch.com.