I have no problem with Dampp Chaser products in more typical climates but there are special needs problems here in Las Vegas. The average humidity is around 12-14% with the exception of the so-called "monsoon season" from mid August through September, and a few spikes of humidity in the spring. Las Vegas has the lowest rainfall in the United States, about 4.5" annually. In fact it rains in Death Valley more then it does here. In these brief humid moments RH can go up to as much as 80-90% for just a few days at a time yet without a drop of rain. When it does rain it is typically isolated thunder storms in a particular area. One side of town might get 3" in 45 minutes and the another side gets nothing. The media goes nuts showing all the images of flooding in Las Vegas when it actually only consists of 12 square blocks. Nevertheless the entire city gets the humidity. I had been fighting tuning problems at the university for over 10 years when I finally decided to try to do something about it. The monsoon hits in mid August exactly when the fall semester starts and it's impossible to keep anything tuned. By the end of September when it's all over everything needs to be tuned again for about the 3rd time. I am not convinced that 42% is some sort of "magic number" that pianos must maintain. I'm not entirely certain how that number was derived but if I were to speculate I'd guess that over the last 100 years or so various labs or perhaps a few university research departments were given 50 different species and asked to determine "what's the best humidity for wood". Somehow "42%" was derived, (kind of reminds me of "Deep Thought's" famous answer for those Douglas Adams fans out there). It's a middle of the road number that balances with a lot of climates so it sounds like a good calculation. As piano technicians we all know that wood expands when it becomes humid and it shrinks when it becomes dry. After so many cycles of this the wood fibers fatigue and a cracks form, glue joints separate, or something becomes permanently warped to relieve the never ending tension. The real culprit is not maintaining the "magic number", it's the constant swing from one side to the other that eventually "wears out" the wood and causes the tuning to go haywire. Since the "normal" humidity in Las Vegas is in the teens and more or less remains there with the exception of a few annual atmospheric tantrums, I chose to NOT install humidification systems. It makes more since not to force the pianos into some magical number, but rather to maintain the piano to where it "wants to be" in the given environment. I therefore decided to install dryers ONLY. This may sound crazy but in fact most of the year they remain off. When we have one of those brief humidity tantrums the driers kick on and keep the pianos in what would otherwise be their natural state. Installing humidification units would involve pouring gallons of water into the pianos most of the year for nothing more then to maintain a magic number. Dampp Chaser does not provide humidistats that will go low enough to meet this criteria. I decided to go with Moisture King because they provide an optional adjustable humidistat that allows you to dial in the desired RH level. The humidistats are built by a third party and don't seem to be quite as accurate but they are sufficient enough that they can be adjusted to where I want them. I don't set them all the way to the average low, rather I keep them at about 28%. This provides a tolerance of about +/- 14-16% which is not enough to make much of a difference in tuning. I started with about a dozen units as an experiment and the results were almost instant. When the monsoon season came around the tuning on the controlled pianos was rock solid while everything else was wild as usual. I have since installed these in nearly all of the pianos and tuning stability has become dramatically improved. I'm not necessarily recommending this for all climates. Las Vegas is an extreme exception. In humid areas it would be completely inappropriate and in areas that have radical swings in both directions such as the Midwest a full system would clearly be the way to go. As for my specialized dilemma the problem appears to have been resolved and the university faculty is grateful. I've since installed the same system in my own piano and have had equally successful results at home. Rob Goodale, RPT Las Vegas, NV ------------------------------------------------------------------------------------------------------------------------------------------------- > Our current supply of humidistats average 51% for wet, 45% for normal and 39% for dry. We feel 55% is a bit too wet for a piano. > Moving the humidistat one way or another is for fine tuning. It is best to apply a wet to a gray market piano rather than try and "stretch" a > normal humidistat. > > There is a bit of confusion in our literature about wet and dry settings. The actual averages are dependent on the characteristics of the > switches we receive from our supplier. There is batch variability that cannot be completely managed through our calibration process. Thus > older literature may have wet at 50% and dry at 40%, if I remember correctly. These modest changes really don't compromise our technical > approach, but can lead to some confusion among technicians when comparing values we have listed in the literature. > > I hope this helps. > All the best, > Roger -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/pianotech.php/attachments/20100727/9be5f007/attachment.htm>
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