June 2002
Slider Soundboards	Show Menu

Stephen Adams 

The question why does an organ cipher is often asked. It’s not easily answered, although there is always a reason. The easiest way of explaining what can go wrong is to first go over how things work.

In the last article I mentioned that the action can be broadly separated into two principal areas: (a) the communication between the organist and the organ per se, we call this the primary action, and (b) what happens thereafter. In this article we’ll deal partly with (b).

In the majority of organs in Ireland (b) automatically entails slider soundboards. The benefit of this system is that the number of moving parts is kept to a minimum. This will perhaps not be completely clear here, until I get the opportunity to explain other systems.

Take a look at the sketch — it’s a very clear illustration of a slider soundboard. There are two controlling elements to it, receiving two kinds of input from the organist, key action and stop action. Inside the palletbox is pressurised. When a note is played the pulldown wire is pulled, and this opens a pallet. This allows air into the groove (you will see that the grid is assembled like a comb, with grooves travelling the depth of the soundboard). Ther- eafter, if the holes in the table, slide and upperboard above are in alignment (i.e., one or more stops are on) the air will travel up to a pipe or pipes. It’s very simple and robust. and I hear you ask. what is there to go wrong?

With modern, well-designed soundboards. not much can go wrong. But this is not typical of many organs here, in which most of the soundboards are over a century old. I’ll list the principal problems with these below, but first of all we must appreciate that one small detail is missing from the sketch. Obviously, the slides need to slide, i.e., move so that holes will line up. This means that there must be a slight gap between them and the table / upperboards.

This gap is crucial. Too loose and we have “runnings”. This is when small amounts of air will travel sideways and sound other notes (usually only discreetly) when we don’t wish it. More often than not, some escape of air is acceptable, but it can become disruptive, especially with quieter stops like strings. If we have severe runnings, well, it is a definite hint as to the overall condition of the soundboard itself. If it is severe we will not only have runnings, but the pipes we intend to sound won’t get their full quotient of air owing to air being lost in this same manner.

If the slides are too tight (common in Ireland due to dampness — the timber will swell in conditions of higher humidity) then we have stiff, or jammed stop action. (I’m sure you’ve all witnessed stiff drawstops).

The missing detail from the sketch is the means to alleviate these runnings. It is normal to have deep scoring between the holes, which connnunicateS with similar scoring travelling the length of the soundboard, and this will take excess air to atmosphere and therefore cause no disruption. These scorings would normally be about 4 mm deep and allow the inevitable slight leakage an escape. The organbuilder then sets the clearance between table, slide and upperboards to something mechanically satisfactory. This is accomplished by packing up the bearers (usually made from. the same material as the slides to ensure similar movement during climatic changes) with paper. So, by design, these soundboards accept a level of imperfection.

Furthermore, this scoring not only relieves excess air around the upperboard area, but also bleed off any slight leaks that may escape through at the pallet (which would otherwise cause whimpers, really small ciphers).

Modern soundboards use a different approach whereby each hole has individual seals fitted on the table and lower side of the upperboard. This prevents air tracking from note to note and has the added attraction of accommodating movement of. the timber (a common problem is that components will not stay flat or straight and seals will follow a curved shape more readily). Because seals are so effective, it is necessary to add small bleed holes in the grid (to atmosphere, not to the pressurised palletbox) to allow for slight leaks at the pallets.

The above alludes mostly to possible problems with the stop action end of things. In all older organs all components were made of solid timber that is liable to shrink, swell, warp and (worse) crack.

It would however be remiss of me not point out that runnings and ciphers can also be caused by internal problems with sound- boards. When timber moves in a significant manner it will not only move as mentioned above, but will break internal glue joints. This in animal bone glue, and is brittle. Not only will it fail to glue, but its side effect of sealing outside an actual joint (where it’s forced out during assembly) will also be lost.

The main causes of a cipher (if it’s found to be at the soundboard) are:

• Dirt on the pallet preventing it from closing (plaster, a chip of wood, a dead insect).
• A warped pallet, or a warped grid.
• Friction between the pulldown and the hole it travels through.
• The pulldown travelling unusually far (under excited playing) and the pulldown travelling through the hole at a point not usually used, and therefore not accustomed to the polishing effect of being moved up and down.
• The pulldown becoming rusty, causing friction.
• Not shown in the drawing are pins that locate the pallets side/side. If these rust or corrode it will result in friction.
• Bad alignment with the pulldown and/or what pulls them, or the pins.

Soundboards are a mixed bunch. If they’re designed and made properly, and not subjected to unreasonable conditions all will be well. Quite often we experience problems where an old soundboard suddenly gives a lot of trouble, and this can often be traced to the church heating being upgraded, causing the soundboard to almost self-destruct.

More often than not soundboards are arranged so that pipes are laid out in whole tones. This results in an accessible layout, giving the tuner good access to all pipes. It also separates semi-tones from each other, as this frequently causes instability, both in speech and tuning.

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