We're in a golden age of sampled instruments; these days, you can find realistic-sounding samples of everything, including drums. Back in the day, programmed drums sounded artificial and mechanical. Today, drums only have to sound that way if you want them to — and that sound is perfect for certain tracks! But assuming you want realistic-sounding sampled drums for your productions, here are six tips on how to program your drums to sound more lifelike.
When a drummer attacks the skins, each hit sounds a bit different. He or she hits the drumhead in a slightly different location each time, the sticks hit at different angles, the velocity and power are a bit different, and there are differences between right- and left-hand strokes — even when playing just one drum. All of these things make a difference in the tone that is produced by the drum and contribute to the instrument sounding "live." To emulate this, make sure that each drum is represented by more than one sample — and while this is critical for preventing "machine-gun drum rolls," it's important every time a virtual drum is "hit." These days, many dedicated drum software instruments will handle mixing up samples automatically. But it can also be done by varying which sample is played based on the velocity of the hit. Many samplers and virtual instruments allow you to set up multiple samples in a round-robin, meaning that the sampler will choose a sample at random for each hit. If your instrument doesn't support this, you can use an LFO tied to velocity or even to a filter, an EQ, a pitch shifter, or another processor to subtly alter the pitch, tone, or shape of a triggered drum, to add variation.
Nothing makes programmed drums sound mechanical more than having every hit land exactly on a quantized grid. It's an instant recipe for rigid, robotic, metronomic drums with no "groove." Even the best human drummer playing along with a click track has slight variations in timing, coming in slightly ahead of or behind the beat, etc. — and they'll often do this intentionally to either drive a part forward or to lay it back. A drummer may even push certain drums forward and pull others back at the same time to create a certain groove. If your drum software has a "humanize" function, that may add just the right amount of slight variation that won't make any hit sound out of time, but will make it just off the grid enough to sound more alive. If there isn't a humanize function, you can duplicate the effect manually by pulling individual drums or hits a few clicks ahead or behind the beat. Some DAWs and drum softwarealso offer "groove" functions that allow you to apply a particular "feel" to your MIDI tracks. To make this easy, you might want to break the MIDI tracks that drive the drums out to individual tracks (a separate MIDI track for the kick, one for the snare, one for hi-hat, and so on), so you can adjust them independently.
Most drummers have two arms and two feet. That means that at any given point in time, they're only going to be able to play two hand-struck and two foot-struck drums or cymbals. When you're going for realism, remember that a drummer can't be playing a two-handed hi-hat pattern at the same time they're doing a two-handed tom fill. Or playing a double-kick pattern and a pedaled hi-hat pattern together. They can't strike two toms and a cymbal simultaneously. Having too many instruments attack at the same time is a dead giveaway that a part is programmed and not "real." Study the patterns and rhythms of real drummers to see how they're making the most of their four limbs, and make sure you don't "improve" on a human drummer by programming an extra arm or foot!
When you hear drums live or record a live drummer, there is a natural stereo field created by the drum set's physical positioning. Imagine standing dead center in front of the kit; some of the drums will be to the left of the kick drum, others to the right of the kick drum. If you place each drum in the stereo field the way that a real drum kit is set up, it will add a realistic sense of space to the kit. There are two "perspectives" you can use for this: the drummer's perspective looking at the kit (for a right-handed drummer, the hi-hat will be to the left, the floor toms to the right) and the audience perspective looking at the kit (a right-handed drummer will have the hi-hat on the right and the floor toms on the left). Either perspective is correct and fine; choose the one you prefer or that works best for your song. Also, if you have stereo overheads on the kit, make sure that the panning within those overheads is matched by the panning of the individual drums in the stereo field (if the hi-hat is halfway to the left in the overheads, the hi-hat track should also be panned halfway to the left), otherwise the instruments will not localize correctly in the speakers and may sound "smeared."
Real, physical drums have weight and take up space in the room. When you hit them, the sound bounces around the room, creating a natural ambience. That ambience will certainly be picked up if there are "room" mics, but the ambience is also audible in the overhead mics and even in the close mics on the drums. You may not immediately notice it, but if it's gone, you can tell the difference. Some drum samples include the ambience of the room they were recorded in or allow you to add it into the final mix. For those that were recorded dry, add a very slight amount of a room-type reverb to the drums, not enough to be heard as an effect, but enough to give the drum sounds a sense of space. Note that this is not the same thing as reverb processing you add for effect. You may, for example, include a room reverb for subtle ambience, and still use a gated reverb or a big plate reverb to create a special effect.