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Imitate Guitar Techniques With MIDI Part 3 – Glissando (1 Octave)

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This post is part of a series called Manipulating MIDI: Setup, Sequencing and Secrets.
Imitate Guitar Techniques With MIDI Part 2 - Glissando (3-4 Semitones)
Using MIDI Controller Data

In this tutorial Oleg Berg concludes his series on achieving realistic guitar sliding sounds with a MIDI keyboard. Like the previous two parts, this tut is very detailed, and gets technical in places, but is a very worthwhile read if you're aiming to get the ultimate realism out of your MIDI setup.

Achieving a realistic whole-octave guitar slide requires different techniques to shorter slides. This tutorial will explain how step by step.


If you missed the earlier parts of the series, you can find them here:


Step 1

The most interesting fact about this glissando range is that, unlike the shorter ranges we discussed in Parts 1 and 2, there is no initial music fragment needed here. We only have to play one single note. However, the listener will hear 13 notes - 12 semitones plus initial note. This job will be done by our good old friend, the pitch bend controller.


Step 2

In this case pitch wheel range of 2 is not enough. In Step 4 of Part 1 of this tutorial I described how to set a needed value to pitch wheel range (in this case 12). Keep in mind that any changes to this parameter will change the scale interval of the pitchbend graph (the difference between two pitch values).

It is not hard to calculate the value corresponding one semitone changing. The entire pitchbend range from the bottom (minimum) to middle (zero value) always equals 8192. This number corresponds 2 semitones when the pitch wheel range is 2. One semitone is 4096. When pitch wheel is set to 12, then the whole range (8192) will represent 12 semitones. Therefore, one semitone will be 8192/12 ≈ 682.7.

As you see, the number we get for one semitone is not exact, and we'll have to round it, but this can lead to accumulation of round-off error as a result. To avoid it, we can first draw the points where there are integer numbers. For example, we can obtain some integer values by calculating:

  • 3 semitones: 8192 / 12 * 3 = 8192 / 4 = 2048
  • 6 semitones: 8192 / 12 * 6 = 8192 / 2 = 4096
  • 9 semitones: 8192 / 12 * 9 = 8192 / 4 * 3 = 6144

Therefore, we can set several points first (3, 6, 9, and 12 semitones) and then proceed with other in between points considering the interval we found (≈ 682,7).


Step 3

Drawing all the precise values manually is difficult. So we'll use one of methods we discussed before (in Step 9 of Part 1). One way is editing the values of selected event parameters in the MIDI Inspector window. The other method is selecting the note we need in the Piano Roll window and open List Editor - here in the next "Pitchbend" line enter the correct value.

To set the actual time intervals between the points of changing pitch, we should imagine how the guitarist finger moves during a long slide. It gradually accelerates, speeding up at the end. So the time intervals between the points must gradually decrease.

A similar principle is used to play sliding down.


Step 4

You may have noticed in the example images above that the main note is the last one. We first altered the Pitchbend value, changing the pitch up or down for an octave. Then using small semitone portions we adjusted the Pitchbend to zero.

We can conversely choose the first note to be the main one. In this case, take a note with Pitchbend value = 0, and then using the methods described here move down or up an octave with semitone portions.

It's up to you what option to choose between these two. Here's a third option.


Step 5

Instead of choosing the first or last note as the main one, I advise you to pick a note from the middle of range instead. Changing a sample's pitch up or down an entire octave will sound less realistic than playing it at the original pitch. We can minimize this problem by choosing a note in the middle of the range, that will be changed up or down by only half an octave.

For example, sliding down an octave from G3-G2. Make D-flat (C#3) the main note, and the Pitchbend parameter will range from +4096 to -4096, with a scale interval ≈ 682.7.

Another example - sliding up an octave from F2 to F3. Here the best main note will be B2. The range of changing the Pitchbend parameter here will be from -4096 to +4096, with scale interval ≈ 682.7.


Step 6

This technique will be less effective if the sound you are using has a limited pitch range. For example, if the manufacturer supplied a set of samples with G4 at the top of the range, then you will not be able to slide from E4-E5 using a note in the middle as a main one.

For instance, A#4 - the middle note in this range - will simply not sound in this case, as it is outside the instrument's range. It is better to choose a main note closest to maximum possible one - G4.

Interestingly, the value of Pitch Wheel range = 12 is rather universal number, as using this value it is possible to imitate both long and short sliding. Keep in mind that when sliding for two semitones with PW = 12, the numbers we set for Pitchbend (unlike ±8192 and ±4096 we used in Part 1) should be accordingly ±682 (683) and ±1365 (1366).

I hope you understand where we got these numbers: the entire range is divided to number of semitones to get the needed value. For a 3-4 semitone glissando you can also use this pitch wheel range, and calculate Pitchbend values relatively.

If in your music you like to combine both long, short, and medium glissando, it is up to you which pitch wheel range to use. You can leave PW = 12 for all ranges, or you may want to use PW = 2 for short glissando for more flexible manual work. In this case for long glissando you could simply change the pitch wheel range from 2 to 12 either in List Editor window, or working with automation (if you find the needed parameter on your instrument and if it is possible technically).


Conclusion

You've made it to the end of the series! You learned how to imitate a realistic guitar sliding technique with a MIDI keyboard in any MIDI editor. We dissused several glissando ranges: from 2 semitones, to 3-4 semitones, to entire octave (12 semitones). The tutorial was long and detailed with many graphs and calculations, but I hope it gave you some useful tips and you've enjoyed it. Use it to create your own live guitar tracks with MIDI editor.

Using these techniques allows you to achieve unbelievably realistic guitar tracks - with slides, bends and whammy bar. Let's finish by listening to our example tracks one last time.

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