Jazz musicians use many different types of scales when improvising. It can be overwhelming at first to try to assimilate so many scales into your playing/improvising. Many musicians don’t really have a system for learning all of these important scales. However, there is an easier way than just trying to memorize a whole bunch of different scales.
One helpful way of learning scales is to break them into smaller chunks of four notes, called tetrachords. This article is the first in a two-part series on using tetrachords to learn and master your scales. This first article primarily deals with the different types of tetrachords. The second article shows how to combine the different tetrachords into scales.
Tetrachords are a great way to learn scales. Even young children can learn basic major and minor scales easily with tetrachords, and tetrachords are great for conceptualizing all of the different types of scales that we need to learn as jazz musicians!
Tetrachords are a group of four notes that make up a mini-scale. Tetrachords can actually be thought of as HALF of a scale. All of the scales jazz musicians typically use are made up of two tetrachords!
SOME definitions of tetrachords require that the four notes of a tetrachord have to be within the range of a perfect fourth (5 half-steps). While that definition works well for major and minor scales, jazz musicians should have a number of scales at their disposal, more than the major and several types of minor scales that classical musicians typically practice. For our purposes, we need to expand the definition of a tetrachord by an extra half-step.
Here is our definition of a tetrachord:
A tetrachord is four pitches within the span of 6 half-steps (the interval of a tritone).
Most scales are made up of two tetrachords. All of the scales that jazz musicians commonly use when improvising can be put together with two tetrachords (although you must add a 9th note, the doubled root, at the top or bottom of certain scales, especially diminished and bebop scales).
To combine two tetrachords into a scale, you’ll start the first tetrachord on the root. You’ll start the second tetrachord on the 5th OR the #4/b5.
There are different types of tetrachords. Here are some of the most important:
All of these tetrachords are comprised of half-steps (H), whole-steps (W), and minor thirds (b3).
- The Major Tetrachords is 1234. The intervals are WWH.
- The Minor Tetrachord is 12b34. The intervals are WHW.
- The Phrygian Tetrachord is 1b2b34. The intervals are HWW.
- The Whole Tone (or Lydian) Tetrachord is 123#4. The intervals are WWW.
- The Diminished Tetrachord is 1b2b33. The intervals are HWH.
- The Harmonic Tetrachord is 1b234. The intervals are Hb3H
- The Mixolydian Blues Tetrachord is 12b33. The intervals are WHH.
- The Blues 1 Tetrachord is 1b34#4. The intervals are b3WH.
- The Blues 2 is 1b23#4. The intervals are Hb3W.
- The Chromatic Tetrachord is 1b22b3. The intervals are HHH.
Now that we know some different types of tetrachords, let’s combine them together in various ways to assemble different useful scales commonly used in jazz. On to Mastering Scales with Tetrachords, Part 2!