Choosing an Accordion (Part 2)

By David Tong

Part 1 dealt with the basics of what to look for when choosing an instrument. This section considers some of the more technical aspects. (Click any picture to see a higher resolution version).

Good Reeds Pay Dividends

Since the reeds generate the sound, their quality determines that of the whole instrument. Critical factors are the quality of the steel and the method of fabrication. There are three main categories of reed, in increasing order of quality:

  • Machine-made (Voci a Macchina)
  • Hand-finished (Voci a Tipo a Mano)
  • Hand-made (Voci a Mano)

They differ in the type of steel used, the method of rivetting, and the quality of the finishing process. The steel is a special grade called ‘harmonic steel’ which is tempered in sheet form and the reeds are punched out from that. However the best quality reeds are made from steel strips that are tempered after being formed into strips of the correct width.

Various accordion reeds

A selection of different accordion reeds with a 10p piece as size comparison

Each reed is rivetted to a plate made of aluminium alloy and the tightness of the rivet is critical for best performance. For hand-made and hand-finished reeds the rivetting is done by hand. The rivet is carefully domed over and the reed maker takes extra care that the reed fits perfectly in its slot in the reed plate. The benefits are that the reeds ‘sing out’ better, begin to sound at the first breath of air, and sing louder for a given airflow.

Poor reeds sometimes need a kick start, and can be so sluggish that they are simply not heard when suddenly called upon. This tends to be most apparent with the lower bassoon reeds. Although hand-made reeds may add several hundred pounds to the price of an accordion, professionals and those ‘in the know’ consider them worth the money.

Bass Buttons

Accordions are usually characterised by the number of bass buttons they have. People refer to 120-bass, 96-bass, 72-bass, and 48-bass instruments. In each case there are normally six buttons in each diagonal row.

Sometimes the diminished chord buttons are omitted and this leads to 60, 80, and 100-bass instruments with only five buttons per row. The objective is to reduce the overall size and weight at the expense of buttons which are used less often.

Actually most of the weight reduction comes from the reduction in case size since the push rods themselves are quite light, and removing the diminished row has no effect on the number of reeds in the bass enclosure.

48, 60, 72, 96 or 120-Bass?

Weltmeister's robust modular bass mechanism
Weltmeister’s robust modular bass mechanism

The answer to this depends a lot on which musical keys you want to be able to play in conveniently. At the small and light end, a ‘48-bass’ is good for folk dancing or singing and for beginners. However most people find it too limited in range for use as a main instrument.

The problem is that a 48-bass does not have buttons for all twelve notes in the octave so it restricts which musical keys you can play in. Expert players can get round this to some extent by using inventive combinations of the chord buttons that do exist, but most people tend to restrict themselves to playing in key signatures that fit, such as the major keys from F to D.

A better solution now is probably a compact 60-bass instrument such as those made by Weltmeister in Germany. They are hardly any heavier than a typical 48-bass yet have a full range of bass buttons apart from the diminished chords. These instruments are ideal for taking on holiday or for parties, not least because their modular bass mechanism (see picture) is very resistant to shock, unlike the traditional Italian-style of bass construction.

Moving up in size, the 72-bass is generally considered to be the smallest ‘serious’ instrument, the 120-bass is the most complete, and the 96-bass is a popular compromise.

A 60 or 72-bass instrument has twelve diagonal rows of five or six buttons respectively, one row for each of the twelve notes in the octave. This means it provides ready-made chords for all twelve of the notes. However the fingering needed to access them is unrealistic when playing in, for example, major keys with more than four sharps or flats because it would need end-to-end jumps. To avoid this, 96-bass and 120-bass instruments have respectively 4 and 8 rows of buttons duplicated at opposite ends of the instrument.

The Bass/Treble Mix

Treble reeds in 3-voice 72-bass accordion
Treble reeds in a 3-voice 72-bass accordion

In general the more bass-buttons, the greater the range of notes provided on the right-hand side, and the larger and heavier the instrument.

Common configurations of piano keys/bass buttons are 26/48, 30/60, 34/72, 37/96, and 41/120. The 41/120 represents the standard full-range piano accordion. The 41 treble keys start in the bass end at f3 and end at g6 in the treble. (Here the octaves are numbered so that ‘middle c’ on the piano is c4).

On the smaller sizes keys are omitted from either or both ends of this range. Typical arrangements are: 96-bass, g3-g6 or f3-f6; 72-bass, g3-e6; 60-bass, g3- c6; 48-bass, b4-c6.

Because treble buttons are smaller than piano keys, button accordions generally have more treble notes fitted than piano accordions and there is more variation from maker to maker. For example, in the Beltuna range a full-sized 120-bass button accordion with 5-row keyboard has 46 different notes instead of 41, and 77 treble buttons. Similarly the button equivalent to a 37/96 piano accordion usually has 40 treble notes and 69 treble buttons.

Treble Voices

Between two and five voices are usually fitted in the treble. This means that each key can activate up to five individual reeds at the same time, the actual combination depending on which coupler is selected. The different effects are used to add interest and drama to the music, and to match the sound to the type of music being played.

Treble reeds in 5-voice cassotto accordion
Treble reeds in a 5-voice cassotto accordion

Extra reed sets add quite a bit to the cost, weight, and size of an instrument. Each note involves two reeds per voice (one for each bellows direction) so a typical 120-bass instrument with 41 piano keys requires 41 reed pairs per voice.

Reeds for each voice are mounted on a solid wooden ‘reed block’ and then individually tuned to pitch – in a 5-voice 41-key instrument, all 410 of them. The size, weight and cost of a five-voice accordion are all quite considerable so many accordions have only three or four.


Cassotto is another term for ‘tone chamber’. Cassotto accordions produce a mellower and less reedy tone than normal accordions. For certain kinds of music this sounds very attractive. However it is not necessarily an advantage for folk music where the more traditional accordion sound is important.

Pallets in tone chamber
Showing normal pallets plus pallets in the tone chamber

The cassotto effect is achieved by mounting one or two of the treble reed blocks, typically bassoon and clarinet, onto the wall of a special air cavity. The photograph shows the open mouth of the tone chamber in a Beltuna Prestige accordions. The cavity is about 12 cm deep, about 3 cm wide, and runs the full width of the keyboard. Each piano key has two actuating levers and controls two pallets, one in the conventional position and the other inside the chamber.

Both pallets in each pair must operate simultaneously because if one closed before the other, the latter would stay slightly open and leak air. This means that the construction and the adjustment must be done very carefully which adds to the cost. Also the couplers have to control the reed blocks in the cassotto section as well as those in the normal positions. So this requires a second set of linkages so that sliding valves can be operated below both sets of pallets. Parts of both mechanism are visible at the right of the photograph.

You can experiment with cassotto even on a standard accordion. Try partially covering the holes in the treble grille with masking tape and effect on the sound quality. The biggest effect is when the grille is nearly closed off. If you try this, make sure you don’t damage any fancy decoration on the grille. Good masking tape should peel off easily without sticking too hard or leaving any adhesive behind.

Bass Voices

5 bass voices in 120-bass accordion
Five sets of bass reeds in a 120-bass accordion

Each bass voice in the Stradella system uses 12 reed pairs (one octave’s worth) no matter how many bass buttons are used, so adding voices in the bass is not as complicated as with the treble side.

Some accordions have only three bass voices, but most have four or five. Three can sound a bit ‘thin’ for most purposes. The difference between four and five is less marked. Five voices tend to be fitted when the needs of the treble section make a larger case size necessary anyway.

As on the treble side, couplers are used to select different combinations of bass reeds. They allow the bass sound to be reasonably matched to the treble sound so that neither overwhelms the other. As a result the number of bass couplers tends to reflect the number of treble couplers, and hence the number of treble voices. Popular treble/bass coupler combinations include 3/0, 5/2, 9/3, 11/4, 11/7, 13/7 but other combinations are also found.

Tremolo Tuning

4 bass voices in 72-bass accordion
Four sets of bass reeds in a 72-bass accordion

When you play a single note on a normal three or four-voice accordion with the ‘violin’ coupler selected, you hear a tone that’s almost the same pitch as when you use the ‘clarinet’ coupler, but which trembles, or varies in volume several times a second.

This ‘tremolo’ effect makes the sound richer and more exciting and is characteristic to the accordion. The sound comes from two closely spaced notes playing at the same time. One is the clarinet reed, the other is an extra reed that’s tuned slightly sharper. If the difference between the two notes is say 3Hz then you hear the volume vary, or ‘beat’, three times a second, and so on.

Type of tuning Detuning Beats per second for A
American 5 1.3
Normal 15 3.8
Italian 18 4.6
French 20 5.1

A slow beat (say once per second) is called ‘dry’ or ‘American tuning’ and is good for the more classical styles of music. A fast beat (five or six per second) is called ‘wet’ tuning and is characteristic of French or Scottish accordion music.

The degree of tremolo is usually quoted in terms of the amount of detuning of the extra reed, and because the detuning is small the number is given in ‘cents’, or hundredths of a semitone.

Standard options from one manufacturer, Beltuna, are shown in the table. They normally tune cassotto instruments to 5 cents, and non-cassotto models to 15 cents.

Musette Tuning

‘French musette’ is similar to ‘violin’ tremolo but the tremolo effect is richer and more pronounced. It uses three closely tuned reeds instead of two. As well as having a set of reeds tuned about 20 cents sharper than the clarinet reeds, there’s a third set tuned the same amount flat. The beat rate that you hear remains the same (in this example, five beats per second for middle A).

There’s also another difference. The perceived pitch of closely spaced notes tends to be the average pitch. This means that two-reed tremolo appears slightly sharp (by a tenth of a semitone in this example) whereas three-reed tremolo sounds in-tune.

French musette fans are happy to dedicate three voices to the middle register, but in a three-voice instrument this leaves no spare voice for bassoon or piccolo reeds. With four voices you can have French musette plus either bassoon or piccolo, but not both. The only way to get the lot is to have a full five-voice instrument.

The Mechanics

Example of a forearm-friendly bass section
An example of a forearm-friendly bass section

The mechanism in a quality instrument should be unobtrusive and quiet. The buttons are usually isolated from the holes in the fascia plate by a layer of velvety material to avoid rattles. In top quality instruments the valves (‘pallets’) operated by the piano keys sometimes drop onto a leather surface instead of bare metal to minimise noise.

The keys should be flat and remain neatly in-line. In quality instruments the piano keys are usually made of wood not plastic. Lack of precision in making the keyboard parts can result in keys that become sluggish and occasionally stay down when they shouldn’t.

It’s not comfortable to have a sharp edge digging into the left forearm so some larger instruments feature a nice curved shape at that point.