There’s no doubt, that the accordion is a very complicated structure and it’s feel and tonal quality is the culmination of the many different components that all combine together to make up it’s construction. However, at the very heart of all these components is the most important component of all, and that is the REED.
The Accordion works on the principle of free vibration to produce its sound, and the easiest way to demonstrate this principle is to take you back to your school days! If you didn’t do this at school, then try it now. All you need to do is hold a ruler against a flat surface such as a desk, then ping the end of the ruler. if you slide the ruler so that the overhang is shorter, the note will become high, if you lengthen the overhang, the note will become lower and that in very simple terms – is how the reed works.
The reed assembly is made up of an aluminium reed plate which has two accurately cut slots in it. Above each slot, a flat piece of steel is riveted at one end and it is this steel plate or reed that as air passes over, vibrates to sound each note. On the opposite side of each reed, is a leather – or more increasingly in more modern instruments – a plastic strip that covers the slot and acts as a one-way-valve allowing air to pass over the reed in one direction only. therefore the reed on one side plays when the bellows are opened and the reed on the other side of the plate plays when the bellows are closed. This type of reed is known as the free reed and It is called ‘free’ because it has an elastic tongue which vibrates freely within a frame. These reed assemblies are then mounted on to wooden reed blocks, most commonly secured in place using a specially formulated beeswax and resin mix.
There are three main types of reed available and they come in varying degrees of quality. The commercial reed is produced by machine, they are by far the cheapest reed but also the lowest quality. Next you have the ‘Hand Finished’ reed (Tipo A Mano) these are a medium quality reed and as per the description, they are made by machine but finished off by hand. However the best reeds by far are those that are completely hand made (A Mano) and being hand made, they are made to far closer tolerances resulting in a brighter more powerful sound with very quick response but of course this craftsmanship comes a much higher manufacturing cost.
If you consider that a larger 120 bass instrument with 41 piano keys could have anything up to 500 individual reeds, and each one of these reeds has to be profiled and tuned by the craftsman. It is also the case that hand made reeds will usually be made from far superior materials such as harder grade Duralumin reed plates and cobalt steel reeds, so you can quickly appreciate how hand made reeds have such a high cost.
Animation by kind permission of Johann Pascher, Airflow illustration by Neczor both items via wikimedia commons