QMT Features: April 2009
Pitch Perfect
Simple temperature and humidity data loggers get piano tuning pitch perfect for music society

Helensburgh Music Society attracts world-renowned musicians to the public hall where it keeps its prize possession – a Grotrian Steinweg grand piano, favoured by the classical and jazz pianists who have used it. In its off-stage store room it is subject to large variations in temperature and humidity. Then on the occasions when it is brought on to the stage it can take 24 hours to acclimatise.

“Often time is short and our tuner has to work on the piano two or three times as the pitch changes,” says John Fleming, past treasurer of the Society. “It was clear that we needed to protect our magnificent instrument from extremes so we have added small heaters inside the piano housing,” continues John, “but also that we needed to learn more about the effects of temperature and humidity in order to get the tuning right for a concert.” John, a retired electronics engineer, working in the field of medical ultrasound, had a good idea what was needed and set about finding a system that could record environmental characteristics and log the data.

What he found, while searching the internet, surprised him. “We had expected to spend hundreds, if not thousands of pounds on sensors and data recorders and then a complex task of installing instruments and getting them to talk to each other. Instead, a simple device containing the sensors that both records and logs temperature and humidity was ordered and arrived within days”

A £50,000 concert grand piano is to be kept in the best possible environment thanks to the purchase of a small, easy-to-use USB-502 data recorder from Adept Scientific. “ The whole process is so easy, the data is downloaded faster than the laptop takes to boot up” Costing around £40, the USB-502 simply sits logging temperature and humidity in a pocket fitted in the end wall of the robust protective housing that completely encloses the prized piano. To collect the data the device is simply plugged into John’s laptop. “The whole process is so easy, the data are downloaded faster than the laptop takes to boot up,” enthuses John. The USB-502 comes with its own, comprehensive software and data is easily exported into a spreadsheet where John is able to run charts to show trends.

Accurate to +/- 1°C in the range -35 to +80°C, the USB-502 is IP67 rated for protection against moisture and battery operated, so requires no mains connection. It stores more than 16,000 temperature readings and the same number of RH measurements.

By building up a picture of the change – and rate of change – in environmental conditions, linked to the actual results of the tuning operations, the society and its tuner will be able to predict much more accurately how the piano will perform at the time of a concert. “This will enable the tuner to adjust the pitch by 1 or 2 Hertz to allow for the changes during the time between tuning and the musical performance and will reduce the time the tuner has to spend with us.” John concludes. “These data may also be very useful for owners of other pianos and even the manufacturers – for the relatively tiny investment in the USB-502, we can learn so much about the way concert pianos are affected by the conditions over time.”

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