Brass Instruments

The trumpet

Let us look first at how you make a trumpet, then we can look at its history in music in general from baroque and classical music through to the jazz of the early 1900s up to today.

Making a trumpet

The earliest metal trumpets were just a straight horns like a post horn or a fanfare trumpet. Probably the very earliest instruments were actual animal horns, hollowed out and with a mouthpiece carved at the end. Such a trumpet can only play a limited range of notes, as typified by the range of notes used in a military fanfare or royal salute fanfare.

By the 15th century bent horns were being produced that could play a greater range of notes. It was the invention of the slide valve in the mid 1800s that allowed a single trumpet to be played in any key. Prior to that a trumpeter would have a range of trumpets in different keys.

A basic trumpet includes about five feet of tubing, with additional tubing that can be added to the total length by the use of the valves.

A trumpet is constructed, normally from sheet brass, different thicknesses of brass sheeting being laminated together to achieve particular tonalities. Although a trumpet looks like a lot of tubing, it doesn't begin life as a drawn tube as one might think. It begins life being marked out on a brass sheet using a template.

The shape is cut out along the marked line using a manual nibbling cutter.The sheet is folded down the centre line in a press, the curve of the fold forming what will become one half the tube. Because the folded sheet has to be formed into a complete tube and joined together, notches are cut in the free edge so that it can be folded around roughly and clipped together. (This is rather like the techniques of making a plywood sailing dinghy such as the famous mirror dinghy which was designed for home construction. In the case of a sailing dinghy shapes are marked with a template then cut out of thin plywood. Plywood is bent and stitched together along the edges with twisted wire to hold it together while it is being glued.

In the case of the trumpet the brass sheeting is formed into shape with a soft mallet and the notches are used to roughly clip it together prior to brazing rather than glueing.

Brazing is a process rather like soldering, but at a higher temperature using a brass alloy. The trumpet is heated with a gas blow torch, a lower temperature version of an oxy acetylene welding torch. Brass alloy rod is used much like solder  to join the sheet metal into a tube. Great care has to be taken with the use of the blowtorch, as the brass sheeting has a melting point that is not too far away from the melting point of the brazing rod.

By this stage the Belle of the trumpet, a very important part for the projection of the sound is something of a crumpled mess. It is forced over a cone shaped mandrel and beaten into a better shape with a hand Mallet. At this point the trumpet is very crudely shaped, so it is forced onto another mandrel that is put onto a lathe. A steel bar is used to manually form the brass horn to the accurate mandrel in a process called spinning.

(This process is also used in the production of aluminum saucepans, parts for aircraft and many other engineering items that are symmetrical about an axis that are made of  a malleable metal. However, in most engineering processes, the spinning is automated using a CNC controlled tool to spin the material against its mandrel.)

Finally, the tube is filed smooth as it spins to remove any excess material from the brazing process. Next, whilst still spinning on the lathe, the ferril is formed on the end of the trumpet bell. Again this is done manually using a slotted brass rod followed by a forming wheel.  Before the ferril is completely closed a brass wire is inserted into the centre semi circle, and finally the ferril is completed giving an edge reinforced by is rolled over shape and the inserted brass wire. Once again the brazing torch is used, but this time to braze the ferrule on the end of the trumpet Bell.

Next the trumpet, which is at the moment a straight trumpet like a post horn, is prepared for bending. There are a number of ways of bending a tube without the tube collapsing. There is the method similar to that used by plumbers, where I spring insert is pushed up the tube. It can bend but doesn't allow the tubing to collapse. This is fine for a copper tube for a central heating system which has a constant diameter hole down the centre, but for a trumpet this isn't much good as the cross-section of the hole changes from end to end. One intriguing method that is used is to block off the small end of the tube, place it vertically and fill the tube with soapy water solution. This is frozen and once frozen the Tube is bent in a bending jig, much like the one used by plumber for bending pipe, but the tube is prevented from collapsing by the Frozen water in its Center. Because of the strong soap solution, the frozen material is not brittle like pure ice but can slide and deform. Having completed the band, the trumpet is thawed out.

As a separate unit, the valve block is assembled into the tubing arrangement that increases the length of the air column that can vibrate in the trumpet for different valve combinations. The pitch of a note produced by a brass pipe is depending on its length, so as valves are depressed the length of oval pipe is changed and the pitch of a note changes. For any given length of pipe there are a number of notes that can be played which are harmonics of the lowest note and by using various valve combinations complete scales can be played.

Certain of the pipe assemblies in the valve block can be slid in and out, rather like the slider on a trombone but stiffer. This is used to tune the instrument. This is necessary because pipe length changes with the temperature of the instrument (because of thermal expansion) and the note that is being pitched is dependent on the total length of tubing as well as air temperature and air pressure, which affects air density. A trumpeter has to tune their instrument each time they play as temperature and air pressure conditions are always different. Furthermore, as hot breath is blown into the trumpet, condensation forms within the tubing of the trumpet which cools it down. As condensation is drained from the instrument through the valves or by removing the sliders, the temperature of the instrument will continually change and so small tuning adjustments often have to be made during a long piece of music such as a Symphony, or during a Jazz session, where a jazz band may play continuously for an hour or so.

Finally the valve and tubing assembly have to be mounted and brazed onto the bell and tubing that was constructed from sheet metal.

So that's how you make a trumpet, Weather Hitchin trumpet being played in a jazz band or jazz Trio all being played in the brass section of a Symphony Orchestra, it's all the same instrument. So now let's look at the history of this amazing instrument.