32-keyless Trumpet Organ

3 Pipes

All the 69 pipes in this organ were made by myself. Shown here is the smallest of the main melody bourdon pipes - top "C" (transposed up 3 notes = D# - MIDI 75). A 50-pence coin is shown for size comparison (approx. 27mm across). The pipe body is 109mm long and the cross-section is approx. 17mm square. Its internal cross-section (the important bit) is a mere 8mm square. The stopper is shown before fitting. Allowance had been made for its leather plug, shown by the coin. At the other end of the pipe (out of view) is the foot, made as a separate piece on an engineer's lathe - a wood-turning lathe would not be accurate enough.

Pipe scaling was accomplished using my scale chart on an Excel spreadsheet. I programmed the original many years ago on a Casio pocket computer, now donated to the National Computer Museum in Bletchley. The scale progression from the largest to the smallest pipe is approximately half-size every 16 notes for the width and half-size every 12 notes for length. Every pipe has unique dimensions (paired for the two ranks of bourdons).

Here, I will show how a rank of pipes is made, using pictures of the smallest rank in the organ - the mixture quint (actual pitch A# to A# - MIDI 82-94). Above left: Small planks of suitable timber are quarter-sawn. Pine is used for backs and sides, maple for fronts. The blocks are laminated from pine with a thin layer of maple at the front - wood forming the wind-way must be something hard to minimize erosion from dusty air being blown through. Above right: The planks are cut down to relevant dimensions for the pipes, with final planing allowance. The narrow ones on the left are the sides, the long wide ones on the right are the backs, and the short wide ones are the fronts. The small pieces at top left are the blocks - the tiny pieces with them are for spacing the open end of the pipes, to be sawn off later.

Above left: The sides are glued either side of the blocks, planed at front and back and flue slots chiselled into the blocks. Above right: The backs are glued into position, and upper lips are chiselled onto the fronts.

Above left: Now the fronts are glued into position leaving pre-arranged spaces that will become the mouth "cut-ups". You can see the extra length of the blocks below the mouths. This area will be turned to a conical shape to produce integral feet. Some historical organ restorations have revealed this kind of construction, so I decided to try it on these tiny pipes. Above right: This is the make-shift tool for turning the feet. It is a small block of maple with a foot-taper bored into it. One corner of the block was cut away to allow a chisel to be clamped into position. This contraption was mounted into the lathe tailstock, and the pipes were fitted into a four-jaw chuck, and rotated by hand (power and drive disconnected). It was time-consuming but successful.

Above left: This shows the pipe feet turned parallel. Just visible are the centre points used for stabilizing the pipes at the tailstock end of the lathe. Above right: One of the pipes after use of the taper tool. At the bottom of the picture is the pipe's cap, showing the flue cut into it in the English style. All the flue pipes in the organ have these "English" caps. Mechanical organs usually have their flues cut into the blocks, but if cut too deep they are impossible to reduce. With this style, reduction is as simple as planing off a little from the surface of the cap, or even making another cap - much better than making another pipe.

The bass pipes, shown here, were mitred to fit under the organ's floor. They are always best in that position so the case plays its part in enhancing their resonance. These are the largest pipes in the organ, the longest being 23 inches (583mm), there was not room enough for them to be left straight, but in any case, their wind supply coming through a vertical transfer board running across the front of the case dictated where the pipes' mouths needed to be.

The mitring process, done after voicing, is simple using a mitre saw fitted with a thin blade, so not much length is lost. The only tricky part is where a mitre could interfere with the stopper; the "C" pipe was close!

Reed pipes

The "business" end of a reed pipe. Fitted into the block with a semi-circuler wedge is the shallot - a brass tube open for its length about one-fifth of its circumference, and fitted with an angled tip. Shallot-making is a skilled job, and I leave it to the firm of W P Williams & Co, who have made all my shallots (to my own specification) over the years. Across the gap is fitted a brass tongue which is very slightly curved at the open end. The curve is hand-formed, itself an extremely skilled job, especially considering all the pipes in a rank must have the same tone quality and power. The slightest mis-curve or kink would completely spoil the result. I have always produced my own tongues, for mechanical and church organs.

A bronze spring is pressed against the tongue limiting its free length. When wind is applied to the space around this assembly (encased by a "boot") the tongue vibrates in sympathy with its free length and the air column contained inside the resonator (not shown). Tuning is achieved by moving the spring to shorten or lengthen the tongue's vibrating length.

Above left: The trumpet rank in bare wood. The largest four are made from noticeably inferior timber, but that matters much less with reeds as the resonators only serve to amplify the sound and stabilize the pitch. If knots in the wood are beginning to separate they could be in danger of falling out in time. In that case a patch of thin leather can be glued over them on the inside. Above right: The trumpets, now finished. The boots (plastic tube covered with brown paper) are fitted to the resonators with tapered wood "feet" similar to the feet made for flue pipes. The boots, in turn, are fitted with shaped wood tubes for wind entry. Six of the pipes get their wind from the top of the distribution board, and the other three get it from the front. The tops of the boots are sealed with leather patches to contain the wind and dampen any internal resonance which could spoil the speech. At the bottom can be seen captive nuts used with bolts for supporting the resonators at the open ends. The pipes speak through the opening at the bottom the façade, with their tone quality strongly influenced by the space below the organ's floor. This tone is augmented by a rank of "helpers" mounted between the bass pipes under the floor, speaking an octave higher than the reeds.

Modification

In the summer of 2018, after spending much time arranging music for this organ, I realised that an improvement could be made if the trumpet ran from "C" to "C" instead of "C" to "B". I figured that an additional pipe could be accommodated on the existing music scale by running it into the melody section, with the extra "C" playing with the lowest melody note. The pipe could be winded from the forte pipe block, so it would only operate when the register is "on". A "helper" wouldn't be needed as the melody "C" would be playing with it.

I made some measurements and worked out that if two of the existing reeds were moved out of the way, the extra pipe would fit snugly. So, work began. Making another pipe would not be a problem, but the original shallots had been made by a specialist company, and an order of only one would be prohibitively expensive. So I made made it myself. I had plenty of brass sheet, and found some 16swg (1.5mm), and cut two pieces - one for the tube and one for the tip. With a suitable dowel I hammered the tube into shape, with an approximate opening down the length. Then, after grinding one end to a 45 degree angle, I silver-soldered the tip into position. After cleaning up the shallot and grinding the flat so the opening was the right size it was ready, see the picture.

Making the other pieces presented no problems, and so the pipe was made, and voiced to match the others. I then took out the forte pipes and their mounting block from the organ, together with two of the existing trumpets and the two register pneumatic motors. Measuring the space and doing a spot of carving I was almost ready to fit everything back in, see the picture which shows the pipe in position before the boot was covered to match the others.

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