[CAUT] harpsichord (was Re: temperature and pitch)

[Fred Sturm]

On Dec 16, 2009, at 6:33 PM, Fred Sturm wrote:

> Some of this is temperature, some is RH.


	I thought I'd give an update on the last two days with the  
harpsichord, as there were a couple interesting features. Wed at 5, as  
stated earlier, I tuned when the hall was 76F/10%. 24 hours later, I  
arrived to find the hall at 70F/9%. The hall manager told me she had  
kept the hall dark all day to get the temp down, as it had got above  
80F during rehearsal and there were complaints. (And keeping the  
lights off is really the only direct temp control she has, as  
otherwise it is just dependent on what the HVAC system does, and it  
doesn't keep up with the heat the lights put out - without lights, it  
will hold the 70-71 target quite well). So it was cooler (meaning  
sharp), but also the instrument had baked at high temp and dry  
conditions the night before, so the board and bridges would have  
shrunk a good bit.
	I checked tuning and found the bass (brass) strings sharp by about  
4-8 cents. So the cooling had more of an effect on them than the  
drying. The steel strings, though, were 6-12 cents flat. I figured at  
this point the instrument was approaching coming into stability with  
the dry environment. This being dress rehearsal, I took a little more  
thought and care. I tuned to 441, and tuned the bass strings up 1-2  
cents above that, as a way of hitting an average mid way through the  
rehearsal that would be reasonably close. The bass octaves can't be  
much narrower, or they will sound too bad as a first impression, and  
the conductor will freak (he conducts from the harpsichord).
	24 hours later, tonight, first performance. 70F/11%. Bass is where I  
left it (though I am sure they went flat during rehearsal last night).  
Steel strings are 2-6 cents flat. I tuned as I did last night. Things  
will be fine (they'd be better if I came at intermission and pulled up  
the bass, but money is tight).
	Anyhow, I hope this description is helpful to some of you who fool  
with a harpsichord once in a while. The real lesson is what happens to  
the brass strings. Temperature rules with them, and it takes very  
little change to produce a big result. Mostly you have to grin and  
bear it. The other thing is that the soundboard and other wooden parts  
adapt a lot faster than on a piano. A lot thinner and less bulky.
Regards,
Fred Sturm
University of New Mexico
fssturm at unm.edu