Inside BATTERY, the Virtual Drum Instrument

Inside BATTERY, the Virtual Drum Instrument (continued)

Splits and Layers

Sure, you can just play back a sample...but that's not very real-world. With acoustic drums, playing a drum softly produces a different timbre than bashing it as hard as you can. With electronic drums, you'd want to use at least two (and preferably many more) samples, which would be triggered at certain velocities. For example, you might have the "soft" sample trigger at velocities between 1 and 100, and the "loud" sample trigger at velocities from 101 to 127. This is called velocity switching, and produces a more expressive sound than using a single sample.

Fig. 1 shows three velocity-switched samples. As the velocity increases, first you hear sample 1. Then it switches over to sample 2, and finally, to sample 3.

However, unless you use many samples, the transitions between hits might be too obvious. Velocity crossfading helps "blur" any transitions. You do this by setting a sample's upper velocity limit higher than the next sample's lower velocity limit, so that the two samples overlap for a portion of the velocity range. During this overlap, as the lower sample fades out, the higher sample fades in. Fig. 2 shows how this works: the three samples crossfade into each other. Battery has a fade button which, when enabled, crossfades any overlapping velocity regions for samples within a cell.

Let's look at a typical application with three different snare sounds (soft, medium, and hard hit). Audio example 1 plays these, one after another.

Now let's see how these work in conjunction with Battery's Layer section. Layer 1 is called Snare Lo Fig. 3), and its velocity range is from 1 to 104. The display shows [1/3], which means it is one of three samples assigned to this cell. Layer 2 [2/3] is called Snare Mid Fig. 4), which triggers at velocities from 75 to 115. Note that this overlaps with Snare Lo in the range of 75 to 104. Because the fade button is enabled, these two samples will crossfade over this range.

The final sample, Layer 3 [3/3], is called Snare Hi Fig. 5). It covers the velocity range of 105 to 127, which overlaps with Sample Mid over the range of 105 to 115. Again, because the cell's fade button is enabled, these two samples crossfade into each other.

To hear the result of crossfading among three samples, listen to audio example 2, which plays a series of snare hits from low to high velocity. Note how the snare's timbre changes as the velocities increase. (Also note that velocity is set as a modulation source for the overall level so that the cell's overall level increases with increasing velocity.) Battery lets you place up to 127 samples in a single cell, and each one can be assigned to a particular velocity range.

When more than one sample is in a cell, each sample is assigned to its own layer. However, there is also a sampling technique called layering, which is slightly different. With layering, two or more samples sound simultaneously. This can be done within a cell by simply setting all samples to respond to the full velocity range (1-127).

Or, you can combine layering with velocity splits or crossfades. For example, two snare samples could be layered by responding to velocities from 1 to 127. A third sample of a hard hit "crack" could be layered with the other two so that it comes on only for velocities above 120. That way, only the loudest hits will bring in the "crack."

Yet another variation on layering is to assign different sounds to different cells, but trigger these with the same MIDI note. Thus, one note can trigger multiple sounds. The difference with this approach is that each cell can have individual pitch, waveshaping, bits, modulation sources, and the like. When samples are all within one cell, they are all processed simultaneously.