Hi, Maggie,
This is a good discussion on the relatively longer-term changes to tunings with humidity change. We deal with this in California a lot, because on this very day, we have a Santa Ana offshore wind blowing which is taking our sort of average fall humidity (and we have MANY sub-climates within a hundred mile radius) go from about 50-60% down to single digits for a few days. Today was predicted to fall to 1 percent. That’s the type of weather when you see our 60-70 mph winds and uncontrollable fires in the news. After a few days or a week, the winds return to on-shore flow and we’re back. (I don’t know what makes our dry air so hard on pianos, but after a nasty Santa Ana most of our pianos are flat, even when it only lasts a few days.) Local newscasters warn us of "Red Flag Warnings" (for fire danger) but to us they’re saying, “Every piano in the city is going out of tune right now”.
But Don mentions a very quick effect that I deal with often, that of temperature changes to the metal of the wires themselves. This can happen in minutes. Eric Schandall had an excellent demo of this effect. Find a good unison, and gently rub a felt mute up and down one string - not enough pushing to dislodge the string from contact/friction points but it warms it up. You can hear the unison noticeably “out” and as the string cools back off you can hear the unison go clean again. Warming wires are going flat; cooler goes sharp.
I have run into so many instances where this matters. A good tuning changes when stage lights hit the wires. A good tuning changes when the piano goes outdoors (on one remarkable day in Anaheim last July 2018 it was 114 degrees outside for a jazz concert). Any tuning on a piano with warm or hot strings or plate is absolutely wasted; it will change when the sun goes down. A piano in a hall which was cooled way down for a recording session, which would have air handlers turned off for three days, hit a low of 64 degrees. As the hall gradually warmed up, the pitch kept dropping, and changes were visible with every few degrees of temp.
I think these sorts of effects aren’t really noticeable on home tunings, when you may not see the piano again for weeks or months. If they turn on the furnace and the air gets warmer and dryer, they may not notice the changes until it gets drastic. It’s visible to you on pianos that you see often, usually for performance situations, recording sessions, and so on.
Very interesting discussion line. When that cold hall was warming up during the recording session I was trying to track pitch change but it got away from me. I think I was seeing about a cent change for eery degree of temp increase, maybe more. If anyone has occasion to track that, I’d be very interested.
Kathy
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Ed - That just explained a lot to me, thanks.
Don - I know humidity & temperature are intertwined, but my personal experience is that if humidity is stable, temperature can fluctuate & the tuning will be minimally effected. Can you expound on your experience with this? I think where I live has a lot to do with my perceptions on this topic.
All - I live in a temperate rain forest, so high humidity is a problem here (not to mention mold). Having said that, I have pianos in unheated churches & even outside that hold tune relatively well, but pianos that go between indoor heating during winter & humid summers suffer greatly. Can anyone comment on this? If I'm off topic, please PM me or I can start another thread.
Thanks!
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Maggie Jusiel
Athens, WV
(304)952-8615
mags@timandmaggie.net
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