How to create better sampled electric bass parts

July 25, 2014
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Electric bass guitar is a very different animal than synth bass. If you’re playing sampled bass from a keyboard or virtual instrument (see Figure 1 above) and the goal is realism, then these tips—involving tone, MIDI, and technique—will help you create compelling bass lines.


The Bass Signal Chain

Start with a dry, unprocessed sampled bass instrument, then enhance it with suitable processing. This takes more work than calling up a preset, but “baking” an effect into a sample isn’t how a real bass works. Bass interacts with its environment.

Bass recording usually involves a direct box (DI) running straight into your console or audio interface, a miked amp, or both. The dry sound is essential for a DI emulation. An LA-2A or 1176-type compressor, which can give a more “aggressive” sound for rock and R&B than an SSL-type bus compressor, is typically next in the signal chain. Bassists use compression for several reasons (sustain, even response, touch) but because many playback systems and the human ear lose response in the bass range, consistent bass levels have a better chance of being heard. Some bassists prefer limiters over compressors because taming only the peaks can give a more natural sound.

Regarding EQ, a significant high-end boost emphasizes pick noise and overtones. Psycho-acoustically, the ear can fill in the fundamental better if it receives this additional high-frequency information. When mixing, this also leaves a little more room for the kick. For the DI sound, I prefer EQ after compression (see Figure 2 at left).

For the miked-amp sound, run a bass amp simulation in parallel with the dry track and blend them instead of using a sample that incorporates an amp sound. The sampled bass will interact with the simulation, so there will be less distortion when you play more softly. Also, many amp sims let you vary virtual mic placement in relation to the simulated cabinet’s speaker cone: centered gives fuller lows, to the side gives a tighter sound, and off-axis makes the sound more diffuse. As in real life, I generally place one mic close to the speaker and just a bit off-center, with a second mic back, perpendicular to the cone’s edge, and mixed lower. Reversing the second mic’s phase can also provide useful effects. I almost never add room sound to bass.

 

Unlike guitars, bass sims don’t need to produce heavy distortion—which is very difficult to get right. All the main players (IK, Native Instruments, Softube, Waves, Line 6, Overloud, Studio Devil, Peavey, etc.) make fine bass amp sims; IK’s SVX model in AmpliTube 3 (see Figure 3 below) nails several classic Ampeg bass amp sounds.


 

MIDI Timing

One of MIDI bass’s big advantages is being able to tweak timing. Traditionally, kick and bass compete for the audio spectrum’s low end, and because bass is non-directional on playback, they’re both panned center—so they potentially obscure each other even more. Try this: To emphasize the bass and the melody, move the bass a few ticks ahead of the beat, but not enough to hear any kind of delay. To emphasize the kick and rhythm, move the bass slightly late. The bass actually sounds softer when late and louder when ahead.


Slides

Slides are an important bass technique—not just up or down a string, but over a semitone or more when transitioning between notes. For example, when going from A to C, you can extend the A MIDI note and use pitch-bend to slide it up to C (remember to add a pitch-bend of 0 after the note ends).

Unless you’re emulating a fretless bass, you want a stepped, not continuous, slide to emulate sliding over frets. Quantizing pitch-bend slide messages so they’re stepped is one solution (see Figure 4 at left). Even if they’re not exact half-steps, they go by quickly enough to be perceived as non-continuous. For example, with a virtual instrument’s pitch-bend set to +/-12 semitones, quantizing the bend to 32nd-note triplets will give exactly 12 steps in a one-beat octave slide up, while a sixteenth-note triplet gives 12 steps over a two-beat octave slide. Make sure there’s no smoothing enabled for the pitch bend function.

For precise slides, the following table shows the amount of pitch-bend change per semitone. For example, if an octave is a pitch-bend value of 8,191, and you want to start a slide three semitones above the note where you want to “land,” start at a pitch-bend value of +2,048 and add equally-spaced events at +1,366, +683, and just before the final note, 0. This assumes your virtual instrument has a pitch-bend range of +/- 12 semitones, which is what I use for bass to make these kinds of slides possible. (Note that pitch-bend has a resolution of 14 bits with two bytes, which is why we’re dealing with these big numbers, not the usual MIDI CC values of 0 to 127.)

Semitones

Pitch-bend value

0

0

1

683

2

1,366

3

2,048

4

2,731

5

3,413

6

4,096

7

4,779

8

5,461

9

6,144

10

6,826

11

7,509

12

8,191


Another option to add realism: Borrow a real bass, and record slides (it’s not that hard) into a sampler or SFZ instrument (see last month’s issue for my column on rolling your own samples). I created several bass instruments for Cakewalk’s Dimension Pro around a Gibson EB 5-string, and each one dedicated one octave to slides—five downward, and five up/down. Occasionally adding these promotes a realistic vibe—and you can download ten free EB slides online.


Mod Wheel Options


If your modulation wheel controls vibrato, reprogram it to one of these alternatives for more realistic performance control.

Drive amount. Tie the wheel to drive amount so that rolling the wheel forward adds  “growl.”

Treble pullback. Pull down the highs by lowering a lowpass filter cutoff or tone control frequency when the bass needs to sit more demurely in a mix.

Hard picking. Roll the mod wheel forward to increase amplitude of an envelope spiking a lowpass filter to give a quick, bright transient. If you can control more than one parameter at once, a very slight upward pitch bend from the same envelope can enhance the realism.

Sub-octave. Some bassists play higher on the neck and use an octave divider for a huge “eight-string” bass. Roll the mod wheel forward to add the sub-octave at dramatic moments. [This is a signature sound of renowned bassist Pino Palladino. —Ed.]

Wah. Create another layer with the wah, and overlay the wah on top of your main layer. Addin wah to the main bass sound dilutes its power.


Playing Technique

There are bass fingerings that allow seamless transitions between notes, but it often takes some time to lift a finger off a string, push down on another string, and pluck it. To simulate this, leave spaces between notes, especially when you want to emphasize a song’s rhythm.

Most importantly, remember that bass straddles the rhythmic and melodic worlds, with different music emphasizing different elements. Bass can do anything from acting like a melodic kick drum to providing harmonic counterpoint—but a good bassist (or virtual bassist!) never forgets that bass is part of the rhythm section.

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