Principal Pipe Organs

May 20, 2009

A  Friday afternoon in May 2009 took the Forest of Galtres Society to another world. In that world we heard from an expert about sound textures, harmonics, materials, ageing, repair, mathematics and techniques.

Pipe Organs. Those large musical instruments we see and hear, in church or in concert halls. How do they work? Where exactly is the sound formed? What governs the brightness of the sound? How do you mend an organ when it is a hundred years old? How do you repair all the places where the air escapes when it shouldn’t, thus impairing the quality and the strength of the sound, so that it is only a fraction of its former self?

Principal Pipe Organs is a great place for a thorough overhaul, for new gaskets, refurbishment, remade pipes where metal oxidation has caused material collapse, retuning, and rebuilding. Spotted metal – yes, it is spotty when you look at it closely, makes a good tone and continues to be used. Different woods used to make pipes give a different brightness, each carefully chosen to complement the building where the organ resides. The various shapes comprising the pipe mouth all matter considerably to produce a sound with good harmonics and good tone. Here, we were definitely lacking in understanding of the names for the parts of the pipe mouth, so I will desist from putting my foot into it.

We looked at cedar strips one millimetre thick and several metres in length. So whippy, and yet strong and suitable for taking the action from the manuals. For the pedals Mr Coffin showed us two millimetre thick cedar which he uses – better able to withstand the strength of a human foot. We handled the fabric, natural skins or felts, which are used for the windproofing of the pipes and the air containment. Some materials with which we were not familiar, are very soft and supple. Cowhide is thick and strong. Sheep is good, but it and lamb; more delicate, last only half as long as cowhide. Half as long? Fifty years instead of a hundred years. That makes quite a difference, so governing when work next has to be carried out to keep an organ working properly.

Pipe organs still exist dating from the 1400s, but very rarely in Britain due to Oliver Cromwell’s zealous actions. These organs can still be played and they are quite small in comparison with later organs. The casework makes a beautiful visual appearance and setting for the organ pipes, and enables the sound to be presented into the space for which the organ is designed and tuned. The working parts, the bellows and linkages, all fit into the space behind.

Historically, organ action has been through linkages and pneumatic and physical action. More modern action has magnetically controlled stops (really satisfying to use) and predetermined groups of stops can be controlled by pushing just one stop –with much time and effort saved for the organist in a complicated piece!

Geoffrey Coffin showed us such a lot, and told us about what his company does. We handled the materials and blew on pipes and saw how much skill, learned over decades, goes into bringing an old organ back to pristine musical condition – just as full of wind and full of tone as it had been all those decades ago.

All we did not do was hear organ music, but how interesting it was to find out how such complicated instruments work.