The Accordion Bass Project

The accordion bass being proposed here is something in between a free-bass and the usual Stradella bass. The complete lack of preset chords puts an instrument equipped with this kind of bass in a different category from nearly all other accordions, including ordinary accordions and convertor accordions.

A convertor accordion that features both Stradella and free-bass requires that you change your mindset when switching between its two bass modes; but if the accordion only sports this new type of layout, then you only have one layout to adapt to.

It is intended for those who would like to have the freedom to create their own chords on an accordion bass that has no preset chords in any of its working modes. You can basically get the same full sound that a Stradella provides, but you'll find that there are more possibilities. It may require a little more skill to operate than the usual Stradella bass – and fast chord changes will be somewhat more challenging – but it will be rewarding once fully mastered.

The layout is fingering consistent/invariant. It basically consists of the usual two bass rows near the bellows, and an additional four rows of what is henceforth referred to as harmony buttons. Unlike a converter bass with chromatic free basses, all buttons in the bass belong to a consistent pattern; it's not an arbitrary combination of two layouts. Although the proposed layout is quite sufficient as it is, it could nevertheless also be combined with a chromatic layout in a converter bass.

The harmony buttons could provide tones that are sufficiently high-pitched so that most combinations of harmony notes will give a nice sound. Combining a low bass note with higher pitched notes is what the new bass does really well, in a way that is much more difficult to achieve on a chromatic free-bass.

The PDF (nydanabass.pdf), that you find further down on this page, shows the new layout.

The fortunate thing about the proposed bass layout is that you can actually have it by modifying an existing accordion. The register combinations that you would get, however, depend on the accordion you choose to modify. The whole procedure is somewhat laborious and risky, so you could also consider having a professional do the work for you.

How to modify a conventional accordion is explained here:

DIY accordion bass modification


High and low notes can be played simultaneously, using only your left hand. You can, for instance, play higher notes over a pedal point bass note; or keep a higher note sounding continuously while a melody is being played in the bass register. Compared to a chromatic free-bass layout, it will be much more convenient to combine high and low notes.

There are many possible ways to play scales on the harmony buttons. You can play a scale by just using a single row (a harmony row has the same sequence of perfect fifths found in the bass rows). Although you will not find the same relationship between rows among the harmony buttons, compared to the bass rows, a more efficient way to play scales comfortably is perhaps to focus mostly on the second and third harmony row.

All notes are usually within easy reach. The hand can often be kept comparatively still under the bass strap. For instance, going back and forth between a C major chord and an E minor chord does not necessarily have to involve sliding your hand up and down quite as much as you would on a Stradella. Also note that the minor third bass-note is not necessarily the same stretch as it often is on the Stradella.

The alternating root/fifth bass technique, ordinarily associated with the Stradella bass, can be mimicked on the proposed layout quite well. A nice thing is that your index finger no longer crosses over the middle finger the way you typically do on a Stradella when reaching for a major chord's fifth.

Since you now have to play each note in a chord manually, the advantage is that you can depress each button independently. This allows each note's attack and release to be precisely controlled. It also allows notes to be arpeggiated in various ways (holding down a chord button too long on a Stradella can make the sound a bit thick and static).

You will most likely be able to play just about any possible type of chord, provided that it doesn't contain more notes than you have fingers available. The following are some examples of chords (bass note included) that will be possible to play on the proposed layout (but not on a Stradella): Csus4, C6sus4, C7sus4, Csus2, C+, C7+, C[9], C6[9]. Furthermore, compared to a Stradella, it will be easier to reach chords like Cmaj7 and C6, making these chords more accessible than before. You can also play major/minor chords without the third, or a major or minor chord without the fifth. In other words, there is plenty of room for variation in the left hand.

One way to find alternate ways to finger things, is to play the notes you want, and then lean backwards and identify the buttons that collapse. Usually, however, one will only have to learn one or two shapes for any particular chord type. Although it may seem somewhat difficult to have to depress all the buttons that make part of, for instance, a C9sus4, it will usually not be necessary to do this. It will actually sound better if you play, for example, C in the bass and add only D and Bb as harmony notes.

An interesting thing about the proposed layout is that someone who is used to playing the Stradella, can play the new layout as if it were a Stradella, without experiencing any unwanted notes: some notes will be left out, but then you discover that it is relatively easy to add more notes as you become ever more proficient. Soon you will find ways to express yourself that are simply not possible to do effectively on any other layout.

The layout is the result of trying out a great number of different button arrangements throughout the years. There are so many considerations when designing a layout that is supposed to be able to support all the things that you may want to do with it. One such aspect is being able to comfortably play a major chord in its different inversions by alternately using either the major third or the perfect fifth in the bass. This is something that the proposed layout handles quite well.

There are countless ways to design a button layout. If we just focus on removing two notes from every chord button on the Stradella, then there are 81 possible layouts. If we could choose any specific note for each harmony button (while still using the same sequence of perfect fifths), we would have 20736 possible layouts. So, is the proposed layout really the best possible solution? Well, it might very well be, because there are certain design criteria that have to be met, and the proposed layout appears to be the best possible solution. The layout is not a compromise in the sense that it was the best option that could be achieved with an ordinary Stradella – it's simply a fluke that the layout is possible to have by modifying the standard bass layout.

Chord fingerings

The notation that will be used for describing how to finger various chords is illustrated by the following example of a C major chord:

C [C G] [] [E] []

What it means is that C is the bass note; then C and G inside brackets are harmony notes to be picked from the first row of harmony buttons (the first row is the one that is closest to the bass rows). E should be picked from the third harmony row. An empty pair of brackets represents a harmony row that is not used. Please note that it is usually not necessary to play the C harmony note unless you alternate between bass note and chord. Actually, many times it will suffice to play fewer notes than suggested below - and often the result will be better, too.

This is the general format:

Bass [row #1] [row #2] [row #3] [row #4]

The bass note is picked from the fundamental bass row. If the bass note belongs to the counterbass row, an underscore sign would be added:

C_ [...] [...] [...] [...]

Using this notation, here are some chord fingering suggestions:

C: C [C] [] [G E] [] or C [C G] [] [E] [] or C [G] [C] [E] []

C6: C [C] [] [G A E] [] (G can be left out)

C7: C [C G] [Bb] [E] [] (G can be left out; play Bb with your little finger)

C9: C [C D E] [Bb] [] [] or C [C D] [Bb] [] [E]

C11: C [Bb F C D] [] [] []

C13: C [] [Bb] [A E] [] etc.

Csus4: C [F C G] [] [] []

C6sus4: C [F C G A] [] [] []

C7sus4: C [Bb F C G] [] [] []

C9sus4: C [F C G D] [] [] [Bb] (play Bb with your thumb)

C+: C [C] [G#] [E] [] or C [C] [] [E] [G#] (play G# with your thumb)

C7+: C [C] [Bb] [] [E G#] or C [C] [Bb] [E] [G#] (play G# with your thumb)

Cmaj7: C [C] [] [G E B] [] (G can be left out) or C [G] [] [E] [B] (play B with your little finger)

Cm: C [C G] [Eb] [] [] or C [C G] [] [] [Eb] or C [G] [C] [] [Eb] or C [] [Eb C] [G] []

Cm6: C [C] [] [G A] [Eb] (G can be left out) or C [C] [Eb] [A] []

Cm7: C [C G] [Eb Bb] [] [] or C [] [Bb C] [G] [Eb] (G can be left out) or C [] [Eb Bb C] [] []

Cm7-: C [] [Bb] [] [Gb Eb]

Cdim: C [] [] [A] [Eb Gb] or C [] [Eb] [] [A Gb]

If the prospect of having to learn these fingerings seems daunting, then start off with learning just these two chord shapes:

C7: C [C G] [Bb] [E] [] (play Bb with your little finger)

Cm7: C [C G] [Eb Bb] [] []

From those, you can omit Bb to get ordinary major and minor chords. Thus you know how to play the four most common chords, and that alone will take you a long way. Then you can experiment and see what happens to the sound if you try other buttons.


Even without any register switches, one will effectively have a bass system that corresponds to a Stradella with two register switches, since the proposed bass layout already allows you to play single notes in two separate registers – and you can do that without having to flick any switch.

The new bass layout would also be very useful on a digital accordion since it would be possible to assign one instrument voice to the bass buttons, and a different instrument voice to the harmony buttons.

Proposal for an accordion bass layout

For an acoustic accordion that would be made specifically for the proposed layout, one could imagine just about any register combinations. However, a bass like the one shown in nydanabass.pdf below, would have seven really useful combinations. Some of those combinations feature a continuous range within two octaves. Such register options can be used for playing melody lines without experiencing octave breaks. You can also play arpeggiated bass lines. One of the registers has only single reeds sounding. This can be accomplished without needing a so-called bass decoupler switch (usually situated near the air release button) that would mechanically disconnect the bass pallets from the chord/harmony pallets.

The accordion that would be made specifically for the proposed layout could have a bass layout with a rectangular outline. A total of 105 buttons seems reasonable for a smaller accordion.

The same PDF, but with Italian note names:

SaLaTa is an alternative note naming and interval naming system. A chromatic scale from C to C thus becomes:

Do Pa Ro Na Mo Fa Vo Sa Go La Bo Ta Do

Intervals correspond to the number of semitone steps (X = 10, Y = 11).

The SaLaTa version:

A PDF is provided below that shows the chord shapes for a C7 and a Cm7 chord. A simple major or minor chord can be obtained from those shapes by omitting the m7 interval (in this case Bb). There is also a suggested fingering for a diatonic pattern (in this case a C major scale). The pinky (little finger) is not used in that suggested pattern. It is possible to start on any tone within the sequence, and continue with the same fingering. Note that each tone has a designated finger, and that the third tone is the only one that engages the middle finger. The pattern can be played ascending or descending.

The same PDF, but with Italian note names:

The SaLaTa version:

Mechanical implementation

Safely skip the section below if you are not interested in the technical details!

The following PDF document demonstrates how the proposed bass could be constructed.

The whole arrangement of pistons (to which the buttons are attached), as well as pipes (fulcrum rods) and linkage, are supposed to be integrated into a cassette (the cassette would actually consist of two separable parts: one for the bass buttons, and one for the harmony buttons). A cassette solution will make access to the pallets a lot more convenient.

In addition to twelve bass pallets and twelve harmony pallets, there are also twelve passive pallets. A harmony pallet raises its corresponding passive pallet in a similar way to how bass and chord pallets traditionally are mechanically coupled. A bass pallet arm has a peg to raise its corresponding passive pallet. A passive pallet will be raised by the same amount, regardless if it is being actuated by a bass pallet or a harmony pallet, provided that the peg on the bass pallet arm is placed at the correct position along the bass pallet arm.

An efficient method for fastening the reed blocks has been developed specifically for this type of bass. It allows the removal of reed blocks without using any tools. Ordinary screws are attached to each end on the reed blocks. A wooden bar has two pieces of cork that exert a pressure on the screw heads. The screws can be adjusted for proper pressure. The wooden bar can be opened with a simple push of the finger on a flexible sheet metal post.

Proposal for an accordion

The PDF documents below show the layout of a C-system chromatic button accordion, equipped with the proposed bass system.

The same PDF, but with Italian note names:

The SaLaTa version:

The present button layout, as well as the mechanical solution that uses passive pallets, was introduced in 2011.

SaLaTa and Modulo Notation are provided by Nydana