We had a long cold snap that ran several weeks. The RH in the piano room was sitting around 25% to 30% for most of that time. I have a dampp chaser of course and I turned on the humidifier.

The tuning itself wasn’t all that impacted, it still has sounded mostly in tune the whole time. (You might have seen in another post where I mentioned that my tuner came just before New Year’s and said it didn’t need to be tuned because it had hardly drifted and that I should wait till the either changed).

Anyway, so the tuning was ok, but the piano itself had developed a “hard” sound. I don’t know how else to describe it, but I don’t really like it when it sounds like that. I mostly just ignore it, and it’s certainly not something anyone else would notice.

Well anyway, the cold snap ended and the it’s been a bit warmer and the RH in the piano room has been drifting up. Yesterday it got up to 40% and I think it was at that probably all day. When I played last night, that hardness was gone. The piano had its lovely round sound back!

I’m certainly this is from the hammers. I think they get just a little harder when the RH drops past a certain point, and they soften up a little when it goes back up.

My tuner is coming tomorrow (yay!) and I’ll be curious to hear what he thinks. It’s still not all that out of tune, but I do think now the piano has drifted enough to warrant a tuning.

I wonder if he’ll notice that it sounds different from when he was here and didn’t tune four weeks ago. (He may not remember!)

ETA: my piano is a 25 y/o Yamaha C2. (I really should set up a sig line)

    I also wonder about this but in my case I know the hammers were shot. I'll have to make notes about humidity levels and tone when I get my piano back. How old are your hammers? Have you had much voicing done to them in the past?

      Shiro, I have the exact same situation, I notice the tone of the piano changing as the RH in my room changes.
      I have a VENTA Humidifier in my music room and I was constantly filling it with water during the cold snap we just had.
      My RH was down to 30% - 34% and the tone was very hard sounding.
      It recently has moved back up to 40% - 42% (the ideal RH) and the piano has that old LUSH sound I am used to.
      In the summer my RH goes up to 50% - 55% and I have a dehumidifier in the room running 24/7 and I noticed the piano's tone becomes very crystal-like. Almost too shiny sounding.
      Just my take and wanted to let you know I hear the change as well.

      Joey

        danno858 How old are your hammers? Have you had much voicing done to them in the past?

        My piano was built in 2000. I bought it from the original owner in 2019 and had it regulated and voiced, and my tuner at the time said he could tell that the previous owner hadn't done anything like that. So just the one day's work of extensive voicing about 5.5 years ago. And I'm pretty sure I play it a lot more than the previous owner ever did!

        I don't think they need voicing again, given that it sounds great now. 25% RH is just too low, but it doesn't stay that low for very long....

          brdwyguy I think pianos are just very responsive to their environments!

          If it was always like that, I would have the hammers voiced again, but I don't think it needs it. Not yet anyway.

            Same here, my tech did say that I may need to replace the Hammers within in the next 5 yrs.
            the felts are becoming thin, esp in the top octave, from all the voicing i had him do after I received the piano
            Luckily, I don't need any voicing at this time as the changes are rather slight and are not extreme, plus it never feels perm. as the humidity is always changing from season to season.
            B

            ShiroKuro
            "...I have a dampp chaser of course and I turned on the humidifier...."
            I take it you're referring to an additional humidifier, as I believe the dampp chaser is just left on at all times, and either functions as a humidifier or dehumidifier depending on the need (I hope that its built-in hygrometer is accurate).

                pseudonym58 Yes, that was careless writing on my part. My dampp chaser is on all the time, and it functions as either a dehumidifier or a humidifier as needed. I also have a free-standing humidifier, which was put away but I got it out and set it up about a month ago, when it started to get so dry.

                  We have very hard water here, so unless we buy extensive quantities of distilled water (very expensive) humidifiers are not really practical. We used to use the cool mist types, but they were the source of a white dust over all surfaces which became a real nuisance! Now I just use a few slow cookers left open to slowly evaporate water. We also have a wood stove, and whenever that's running I have a large aluminum baking pan full of water, which evaporates fairly quickly.
                  I don't bother to test the relative humidity, as there's not much more I can do about it, unless I were to buy a home water distillation device and hook it up to a whole house humidifier...
                  That's not happening!

                  I guess one last option would be a water vaporizer, perhaps, the type that's used in infants' bedrooms. I don't know how those would function using water with a high dissolved mineral content.

                  I feel your pain, @pseudonym58 ! We used to live somewhere with very hard water and it was awful.

                  If you ever decide you want to get a humidifier, I recommend the Venta evaporative kind. No white dust, and Venta has an additive you add to the water to deal with hard water issues.

                  BTW what kind of piano do you have? (if you've mentioned it already, my apologies!)

                    ShiroKuro We have a Yamaha C2 from 2007. Very nice piano with a tone on the mellow side. The only problem we have with it is that it was one of those where the adhesive between the key tops and the keys was defective. Every once in awhile my finger catches on a key top outer edge and pulls it up. Last weekend we were rehearsing with a composer/pianist from whom we had commissioned a piece (link below). All of a sudden he stopped playing and said "Kurt, I broke your piano!"
                    I kept imagining a broken string or something, but it was just a key top that had popped off completely! Fortunately, the fix is simple: an exceedingly small amount of Elmer's glue spread as thinly as possible. (The piano is so well made that there is virtually no gap between the wooden key and the plastic key top.)
                    Link to Serenade: Emily Ferguson, oboe; Kurt Kaufman, cello; Bruce Lazarus, composer and piano
                    (This rehearsal recording was made in 2020 on the previous Yamaha we had, a 1970 G2)

                      Cool, have the same piano!! My C2 is from 2000.

                      I don’t have the key top problem (that I know of!)

                        ShiroKuro You would know it by now if that were the case. It's not like it happens constantly, but it's happened with a number of keys, so I know that there is a problem. Our tuner/technician was familiar with the problem and suggested that Yamaha might even repair it under warranty. But it's been 18 years since the date of manufacture and we are not the original owners, so I have my doubts.

                          Fortunately it sounds like it’s more of a hassle than a serious issue?

                          a month later

                          ShiroKuro

                          I’m certainly this is from the hammers. I think they get just a little harder when the RH drops past a certain point, and they soften up a little when it goes back up.

                          That is quite plausible. Humidity changes also can throw the unisons off just enough to make tone less sonorous, more percussive, and harsher. Another effect is that humidity level affects the speed of sound, so changes in humidity change the acoustic effects of the room, which can change the voicing requirements of the piano. Different frequencies may be accentuated, requiring a different voucing of hammers to compensate.