Technical Library


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Shading bass pipe mouths to lower pitch 51K jpeg
Shading of the bass pipe mouths to lower pitch

Tuning at non-standard pitches…

Depending on model, the keyboard of the Klop continuo organ transposes between A392/A415/A440/A466. There is sufficient pipe length to allow tuning at various nearby pitches over a wide temperature range. I’ve had to tune my 2004 organ in wintry churches at 13°C (55°F) through to outdoor rural India at 34°C (94°F).

For an intermediate pitch like A430, you may find that it is impossible to flatten a few of the bass pipes without the stoppers wanting to fall out. To avoid this problem, the mouth of any affected pipe can be shaded with a small piece of card taped on its face. Without interfering too much with the speech of the pipe, the card will alter the wind flow, lowering the pitch sufficiently for the pipe to be properly tuned. The card can be easily removed before the organ has to be retuned closer to a standard pitch for its next job.

Harmonic bridge for organ pipe 51K jpeg
Harmonic bridge fitted to offending pipe mouth to solve pitch instability

Unstable pitch from pipe played alone…

In some instruments—particularly the larger models—it can be found that one or more pipes sound with an extraordinary wave when played solely. The problem may not be evident when there are other notes sounding, when a particular case panel might be removed, or when the offending pipe is pulled from the instrument and blown by mouth.

Usually affecting the larger open bass pipes, the sound disturbance is caused by wind flow within the case.

The solution is to glue a harmonic bridge over the mouth of the pipe, using a ø2mm dowel or cocktail stick. This will stabilize the wind flow and solve the problem. The pitch may drop a little with this arrangement, and if this is more than can be corrected with the lead tuning roll, the pipe may have to be slightly shortened.

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