Accordions from A to Z (Part 3, R to Tr)

By David Tong
Accordions come in many shapes, sizes, and varieties but reliable information is hard to find.  Now halfway through the alphabet, this series of articles continues to help fill the gap.


Accordion Reeds

Accordion Reeds

A reed is a strip of special steel accurately mounted onto one face of a metal reed plate and able to vibrate freely in and out of a precisely matching slot in the plate.  One end is securely fixed to the plate and the other end is free to vibrate.  When air is forced through the slot past the reed it vibrates and modulates the airflow thereby producing the required note.

The pitch of the note depends mostly on the properties of the steel and the dimensions of the reed, and only slightly on the air pressure.  Once tuned, reeds remain adequately in-tune for years.

Reeds are trimmed to a higher pitch by filing metal away from the moving tip to make it lighter. Scratching metal away halfway along the reed lowers the pitch by reducing the stiffness of the reed.  The marks made by the tuning process are visible in the photograph.

The sound from a reed is rich in overtones and almost everything to do with a reed affects the character of the sound.  This includes the shape of the reed, its immediate environment, and the solidity of the reed plate and reed block.

Reed Block

Bass reed blocks

Bass reed blocks

A reed block is the subassembly onto which all or most of the reed plates for one particular voice are mounted.  Thus there are usually the same number of reed blocks in the accordion as there are voices.  Most reedblocks are made of wood and often pine is used, but when metal pins instead of wax are used to secure the reed plates, a harder wood such as alder is used.  This grips the nails better and is not liable to split.  The choice of material used for the block is also reputed to affect the quality of the sound.

Reed Plate

A reed plate is a rectangular metal plate to which a reed is riveted, or in the case of very large Helikon reeds, screwed.  The plate anchors the non-vibrating end of the reed and its properties affect the timbre of the sound.

The preferred material is duraluminium (‘dural’), a hard alloy of aluminium used in aircraft.  Aluminium is used in cheaper models.  Brass or zinc have been used, especially in concertinas, but while sounding good, these materials are too heavy for use in an accordion.

The two reeds required for a single note (one for each direction of the bellows) are normally riveted to one reed plate to form a small subassembly.  Sometimes a group of reeds share a single plate.  This tends to be more expensive but is claimed to improve the sound.  Some Russian accordions are built like this.

Helikon bass reeds in Beltuna instruments are also available with a whole octave grouped onto one plate.   These are called ‘piastra’ reeds (piastra being Italian for plate).


A semitone is the pitch difference between two adjacent notes in the chromatic scale, and hence between any two adjacent notes on a piano keyboard.  In the equal tempered scale, to which modern keyboard instruments are tuned, the octave is divided into twelve equal parts so all the semitones represent the same frequency ratio.

An octave represents a frequency ratio of 2, so a semitone represents a frequency ratio equal to the 12th root of 2, or 1.0594.  Knowing this, and knowing that A above middle C on the piano is tuned to 440 cycles per second, (‘440Hz’) you can calculate the frequency of any note.

For example A# is one semitone above ‘middle’ A so it has a frequency of 440×1.0594, or 466.2Hz.  On the other hand the F# below middle A is three semitones lower, so to calculate its frequency you divide 440 by 1.0594 three times.  The result is 367Hz.

Frequencies of notes in middle octave to nearest Hz

Frequencies of notes in middle octave to nearest Hz

The table gives the frequencies of the twelve notes in the middle octave of the equal tempered scale to the nearest Hz.

Sounding Board

The sounding board is the main structural bulkhead in the bass section of an accordion.  It is a rectangular plate of plywood equal in size to the cross-section of the instrument and it carries the bass reed blocks on one side and the bass coupler mechanism on the other. The varnished plywood sounding board in a Beltuna Studio model can be seen in the picture captioned Bass Reed Blocks.

Stradella Bass

This ingenious bass keyboard layout is based on the ‘circle of fifths’ and makes it easy to play a rhythmic chorded bass accompaniment to any tune.  The name comes from the Italian town of Stradella where reputedly it originated.

A ‘full-sized’ accordion has 120 buttons arranged in six long rows and twenty slanting columns.  It permits convenient accompaniment for tunes in any key. Smaller instruments usually retain the six rows but have fewer columns.

Only a small group of adjacent buttons is normally required to accompany a tune in a particular key, so the large array of buttons is ‘friendlier’ than it looks.  The rows are a musical fifth apart, so to change keys you can simply move up or down the rows keeping the same fingering.

Bass buttons on 72-bass Cooperfisa

Bass buttons on 72-bass Cooperfisa

The buttons in the long row nearest to the bellows are called the ‘counterbass’ and those in the next row, the ‘fundamental bass’.  Each bass or counterbass button produces a note from the chromatic scale but in several octaves at the same time, depending on the bass coupler settings.  Mechanically the counterbass row is simply a duplicate of the bass row, but shifted four columns to the right  (as viewed in the picture).

Buttons on the other four rows, moving away from the bellows, play respectively, the major, minor, seventh, and diminished chords.  Within a slanting column all the chords have the same note name as the fundamental bass button, and the counterbass button is a major third higher.

Only the bass and counterbass buttons but not the chord buttons can activate the lowest reeds in the bass section. This means you can define the inversion of a chord by pressing a bass or counterbass button at the same time to add the desired lowest note to the chord.

Since each ‘note’ plays simultaneously in all available octaves, and there are only twelve ‘notes’, twelve columns suffice to make them all accessible.  The sequence of note names along the fundamental bass row in a 72-bass goes in fifths as follows, starting at the end furthest from the chin (from the left in the picture): D-flat, A-flat, E-flat, B-flat, F, C, G, D, A, E, B, F#.

To help one to navigate the bass buttons by touch, the C button near the centre of the bass row has a dimple, and every fourth button up or down from there has a diamante inset, or some other mark. In the photo you can see these on the A-flat and E buttons.

To get the full 120-bass layout, the four columns at each end of the 72-bass layout are duplicated at the opposite end.  Although the sounds are duplicated, it makes musical sense to call them by their enharmonic names.  So the equivalent sequence of note names in a 120-bass instrument is: B-double flat, F-flat, C-flat, G-flat, D-flat, A-flat, E-flat, B-flat, F, C, G, D, A, E, B, F#, C#, G#, D#, A#.

Swing Tuning

Musette or Tremolo Tuning with detuning by about 10–15 cents is sometimes called ‘swing’ tuning and is often used in accordions intended for the English or German markets.  It sounds pleasantly ‘folky’, yet still sounds reasonable in more classical pieces.

Transit Damage

Locking the bass mechanism

Locking the bass mechanism

Accordions are quite delicate, especially ones with traditional Italian bass sections like the one in the photograph. There have been many horror stories on the Internet from people who entrusted their accordion to the airline baggage handling system without taking precautions first. The problem is that heavy shocks can make the buttons drop inside the case. Sometimes it’s just the diminished and seventh rows that disappear. In severe cases they all disappear.

It happened to me when I took a small Pigini 72-bass abroad on holiday. When I got home all 72 bass buttons were inside the case. To reinstate them I had to dismantle and rebuild the entire bass mechanism. Sometimes just a few buttons fall in and you can hook or nudge them back into position using a piece of hooked wire after first removing the base plate.

Reinforced accordion case

Reinforced accordion case

The way to avoid this kind of problem is to ‘lock’ the bass section. I discovered later that Italian manufacturers do this when they ship accordions from the factory. All you do is remove the base plate and insert along the back of the mechanism a long rolled-up piece of corrugated cardboard, as in the photograph. The idea is to stop the push-rods (the aluminium rods that carry the buttons) from being thrown inwards by a severe jolt.

Weltmeister and Hohner accordions tend to use a modular bass mechanism which seems far less prone to this kind of damage and nowadays I travel with a Weltmeister Rubin. It goes inside a vintage wooden accordion case that I reinforced with wooden struts that lock together when it closes. It looks crude but has survived many trips as checked-in baggage.

Treble Voices

Ordinary accordions are fitted with one or more of three basic treble voices.  They are one octave apart and from low to high they are called the bassoon, the clarinet, and the piccolo reeds.   Alternative names for the same voices are the 16ft reeds, the 8ft reeds and the 4ft reeds.  These latter names derive from organ terminology.

The clarinet reeds cover the mid-range and are almost always present, usually as a pair.  The deep bassoon reeds come next in popularity, followed by the high-pitched piccolo reeds.

Typically one of the pair of clarinet voices is tuned slightly high in pitch (see Tremolo).  Sometimes there is also a third set tuned slightly flat (see Musette).

Treble Coupler Labels

Treble coupler symbols

Treble coupler symbols

The symbols described here are unambiguous and used on most modern accordions.  You can tell at a glance exactly which reed sets (‘voices’) are selected at any time because each dot represents a distinct voice.  Also, you can count the dots on the master coupler (the one with most dots) to find out how many treble voices are fitted.

The system works as follows. A central dot between the two lines (left) stands for the ‘clarinet reeds’ or ‘8ft-reeds’.  A dot above both lines indicates ‘piccolo reeds’ or ‘4ft-reeds’.  A dot below both lines indicates ‘bassoon reeds’ or ‘16ft-reeds’.

Dots to the left and right of the central dot indicate the extra sets of clarinet reeds used for tremolo or musette tuning.  The symbol with all five dots indicates the master coupler on a five-voice accordion.

Treble couplers on older accordions are often engraved with names alluding to other musical instruments.  However this is often ambiguous when used for combinations of voices because the terms are not very well standardised.

Tremolo Tuning

Often labelled as ‘violin’, this is the sound made by two closely tuned reeds played together.  One set is at pitch and the other is detuned slightly sharp to give a beating or ‘tremolo’ effect when they are played together.

The effect is similar to three-reed Musette tuning, but the tremolo effect is slightly less pronounced.  The beat rate for two-reed tremolo is the same as for three-reed Musette for the same degree of detuning.

In both cases the perceived pitch of the combined note lies midway between the pitch of the reeds that are playing.  Thus, two-reed tremolo tuning sounds slightly sharp – by an amount equal to half the detuning.  For example, with French tuning (20 cents) the combination will sound sharp by 10 cents, or a tenth of a semitone.

Used in pairs, the three reeds used for French musette tuning can also provide three tremolo-tuned options.  The centre-tuned reed played with either of the outer ones gives tremolo tuning with the same beat rate as the musette coupler.  But one combination sounds slightly sharp and the other slightly flat.

Silencing just the centre reed in three-reed Musette makes the tremolo twice as ‘wet’ (twice the beat rate).  A coupler offering this last option is often labelled ‘Brill’ or ‘Brilliant’ as in the example below from an Allessandrini instrument.

Coupler selections on a 72-bass accordion with four treble voices and full three-voice musette tuning
Coupler selections on a 72-bass accordion with four treble voices and full three-voice musette tuning