Accordion Bass Button Chart - Stradella Layout for 120 Bass

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The Stradella system in one page

The left hand of a piano accordion plays bass buttons, not keys. The Stradella system arranges those buttons in a grid where each column is a root note and each row is a type of button. Columns run in the circle of fifths, so neighbouring columns are the most useful chords in a key. Rows run from the bellows outward: counterbass, fundamental bass, major chord, minor chord, dominant seventh, and diminished seventh. Learn this grid and you can accompany almost any tune.

This chart shows the whole system. Pick a root note and a row, and the tool tells you which notes the button plays. It also shows the full grid for the twelve main roots, with the C button marked, because C has a dimple you can feel without looking. A 120-bass accordion repeats this pattern across twenty columns; smaller instruments use fewer columns of the same layout.

The rows

The two rows nearest the bellows play single notes. The fundamental row plays the root itself, deep and plain. The counterbass row plays the major third above the root, which lets you play bass runs and inversions without moving far. The four outer rows play chords: major, minor, dominant seventh, and diminished seventh. Each chord button sounds several reeds at once, in several octaves, so one finger gives you a full chord.

Modern accordions leave the fifth out of seventh and diminished chords. That omission is deliberate: it makes the chords more flexible, because you can add the fifth, or an altered note, from the right hand or from a bass button. Older accordions sounded four notes in these chords, and some players still prefer that fuller sound. Know which type yours is, because it changes what you hear.

The columns and the circle of fifths

Columns follow the circle of fifths: C sits between F and G, G between C and D, and so on around the circle. This is not an accident. In any key, the three most important chords, the tonic, subdominant and dominant, sit in three adjacent columns. In C major, C, F and G are neighbours. In G major, G, C and D are neighbours. You can accompany a whole song by moving one column at a time, without ever looking at your left hand.

The C button has a dimple, hole, or rough patch so you can find it by touch, and many accordions mark E and Ab the same way, four columns away in each direction. Learn to find C blind, then count columns by feel: up a fifth in one direction, down a fifth in the other. Blind navigation is the skill that makes the bass side musical instead of mechanical.

Playing bass patterns

The classic accordion accompaniment alternates a fundamental bass note with a chord: bass, chord, bass, chord, in waltz time, or bass, chord, chord, chord in march time. Play the bass note on the beat and the chord off it, and keep the bellows moving steadily. The pattern is simple, but the musicality is in the details: which bass note you choose, how long you hold the chord, and how the bellows shapes the phrase.

For variety, use the counterbass row for passing notes between roots. Moving from C to G, play C, then the counterbass E, then G, and the bass line walks smoothly instead of jumping. For minor keys, use the minor chord row with the same bass pattern. For blues and jazz, add the dominant seventh row on the fifth chord of the key.

Which fingers to use

Use the second or third finger for single bass notes, and the third, fourth or fifth finger for chords. The thumb stays on the side board and does not play buttons. Keep the hand relaxed and the wrist straight, and let the fingers curve naturally over the buttons. Reaching for a distant column with a stretched hand causes mistakes; instead, move the whole hand smoothly and keep the fingers near the buttons.

Beginners often press too hard, which tires the hand and makes the bellows jerk. Bass buttons need only a light, definite press. Practise scales on the bass side alone, slowly, until the columns feel as familiar as piano keys feel to the right hand.

Common mistakes

Looking at the left hand, which breaks posture and slows you down.
Playing the chord on the beat instead of the bass note.
Using the wrong row, such as major instead of minor, in a minor key.
Pressing buttons too hard and jerking the bellows.
Ignoring the counterbass row, which makes bass lines jumpy.

How to practise with this chart

Find C by touch, then play the C major, C minor and C seventh buttons in turn, listening to how each chord sounds. Then play a I-IV-V pattern in C, then in G, then in F, moving one column at a time. Add a simple right-hand melody over the bass pattern, and you are playing the accordion properly. Use the chart to check any chord you are unsure of, and learn one new key per week until the whole circle feels familiar.

Accordion Bass Button Chart – Stradella Layout for 120 Bass