brass vs. iron

[Allen Wright]

Conrad, Ron, Roger, Don et. al.

The piano in question in my original posting is a Graf copy (1830's) by Rod Regier. It has a humidity-crowned soundboard and one iron gap spacer.

Ron, thanks for the figures on expansion of brass and steel. Of course this piano has iron wire rather than steel in the top, but obviously there must be a big difference between the two and it must be a factor. 

I talked to Rod Regier on the phone this morning to get his feedback on this. He feels that if an instrument goes out of tune really suddenly like this that it's a clear instance of the effects of temperature more than humidity change, and that in this case it was also probably more the length of the strings (amount of material to be affected?) than the differing materials that caused the pitch drop. 

When we moved the piano into the room at noon, I had wanted to take off the rather thick cover and expose the piano to whatever changes it might go through in the course of the day, and let it get acclimated. The pianist thought we should try the other approach, that is, to attempt to leave the instrument as isolated from the environment as possible - wrapped in its cocoon, so to speak. I think that theory makes sense only in the (much less favorable) situation where the instrument can only be moved into the room just before the recital, when there's not much opportunity for it to have the time to adjust and also be able to tune it well again. In my situation the cover was removed at 6:30 for the 8:00 recital. In a similar future scenario I'd be tempted to leave it uncovered and with the lid open all day - any other opinions on that?

I didn't stick around for the second half of the recital ( I figured things could only get uglier!) but I've since found out from the pianist that after my intermission touch up of the bass, things were pretty stable in the second half. Perhaps the effect of the temp. rise had leveled off by then.

I'm going to try and address the underlying issue of the folks in charge of HVAC here keeping things more stable in the room itself. One of the big problems is that voice faculty insist on having these hot spots on even for classes and not just recitals - in order to duplicate recital conditions - but they're ridiculously hot, in a small hall. Don't know if I'll have any success in that sphere, though. At least we could not schedule fpo recitals right after one of these classes.

Thanks for all the very interesting feedback on my original posting.

Allen