How does an orchestra tune for a piano concerto?

[Lionel Mandrake]

A piano sounds best when the octaves are stretched, so that high notes are perhaps 20 cents sharp, and low notes 20 cents flat, compared to tuning such that an octave is a doubling of frequency. So I'm wondering whether either the orchestra or the piano tuner makes some sort of compromise in its tuning during a performance of a piano concerto. If not, then the bassoon and piccolo, for example, would be noticeably out of tune with the piano.

[stopbush]

1. The concertmaster steps forward, plays a DMinor chord on the piano

and the orchestra tunes to the A in that chord.

That’s it. Any minor pitch adjustments are made on the fly. Most orchestras contract with a piano tuner who tunes the instrument to their specifications.

[no_hypocrisy]

3. I went out with a piano tuner and learned

that his MO was to tune to pitch one key on the instrument. The rest was painstaking to tune the other keys in relation to that key and to each other. It takes hours and a fine ear to hear even a key a fraction of a pitch "off".

[Lionel Mandrake]

4. In greater detail:

The A above middle C is tuned to exactly 440 Hertz. Each octave is tuned to avoid beats between the first overtone of the lower note and the fundamental of the higher note. Because piano wire is stiff, the first overtone is more than twice the frequency of the fundamental. Thus the octaves are "stretched".

[sdfernando]

6. Standard A440

But many Orchestras have upped to A=442. Many instruments are now built to A=442 rather than A=440.

[Lionel Mandrake]

7. That's unfortunate but interesting!

I hadn't heard about A=442. I'd hate to see a return to the bad old days (early 20th century), when the pitches of orchestras varied all over the place, and manufacturers had to make high- and low-pitch versions of instruments.

[sdfernando]

8. You can look at the webpages for insturment manufacturers to see this in action

I play the flute and have a hand-made solid silver from the 80s. Pitched at A=440. No you can look at Haynes, Powell, Muramatsu, Pearl, just to name a few as see they are starting to make A=442. For strings, it isn't that big a deal, but for woodwinds, building at A=442 necessitates a change in the geometry of the tone-holes (I imaging for brass that would the length of the tubing) to keep the instrument "in tune". So if you play a A=440 instrument tuned to A=442 you need to make a lot more adjustment as you play a piece, same if you play A=442 pitched instrument at A=440.

Story I heard is that A=442 is "brighter" then A=440....yeah?...so A=445 is "brighter" than A=442....How "bright" does it need to get?

[Lionel Mandrake]

9. I did the math and found

that 442 Hz. is only 7.85 cents above 440 Hz. That's a pretty subtle change of frequency, but it's enough to make things difficult for a woodwind player.

[Lionel Mandrake]

5. Thank you.

I wonder what those specifications are.

[empedocles]

2. Thank you