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32-keyless Trumpet Organ

Lockdown modifications

The idea was to eliminate, or seriously reduce, high-pich screeching when the forte register is on. Interaction between the quint rank at 22/3 pitch and the out-of-tune bourdon celeste was to blame. The solution was drawn-out on paper and executed during the 2020 Covid lockdown.

I arranged the register action to automatically operate a new slider shutting off the celeste rank when forte was activated. The two sliders are linked to achieve that, but in addition I enabled the celeste slider to be manually operated for use when tuning the organ. I can now tune the bourdon straight rank on its own, and it is an added advantage of being able to play suitable books without using the celeste at all. It greatly enhances the sound of my collection of 18th century music by Hayden and Handel.

The modification required a new bourdon veneer to be constructed with a slider under the celest rank, leaving the straight-tuned rank supplied directly from the distribution board as before. The new slider was made fron 1/16" Foamex, actuated by Foamex bell-cranks linked by phosphor-bronze wire. The larger crank, actuated by the forte register linkage at the front, is pivoted on a moveable block, itself pulled sideways by a rod linkage running across in front of the bourdon to a new operating knob on the right-hand side of the organ. That knob is of the old square-style (in miniature) with a latch to prevent it moving when not required: the knob needs to be lifted before pulling out. The little red cloth washers are to prevent unwanted vibration.

The two bourdon ranks have been moved forward a little, allowing the large opening in the back panel to be filled-in, to encourage the sound from those pipes to be projected through the front instead of being lost among the action tubing.

Above: Left: New bourdon block showing groove for celeste slider. Right: Foamex cranks fitted on the left.
Above Showing the movement of the forte and celeste sliders. The left picture is normal play with celeste on and forte off: if the pivot of the large crank is moved slightly to the right by pulling out the square knob the celeste goes "off" without affecting the forte slider. On the right the forte is on and the celeste is off.
Above left: Bourdon veneer and forte top block fitted above sliders. right: The new cranks after the bottom of the "E" accompaniment pipe had been shaped to fit. The little pieces of masking tape are to prevent dust and small screws dropping into the trumpet wind holes while the pipe are out.
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